Turnstone Marine Surveys
Marine Electrical, Corrosion, Prepurchase, and Casualty

Turnstone Marine Survey LLC offers complete marine surveying of sail and power vessels, including damage claims, appraisal, and consultation. Also available for marine electrical design, diagnostics, corrosion, and consultation. This company is dedicated to the highest standards in the boating industry as addressed by SAMS, ABYC, NFPA, CFR, COLREGS, etc. Recognized and complimented for thorough inspections and timely reports, rivers, lakes, and harbors of Southeastern New England to Mid-coast Maine east of the Connecticut River is home territory, but travel can be arranged almost anywhere! A variety of report formats is available. Unsolicited references available on The Hull Truth.com 

Turnstone Marine Survey
Marine Electrical, Corrosion, and Casualty


Before you launch your boat this year, be sure it’s shipshape and won’t let you down somewhere
offshore, or worse. A Pre-Commissioning Survey can be done in about an hour, and a check list of items needing attention will be
presented and  discussed.  You can be sure the inspection will be thoroughly and independently done by an accredited professional yacht surveyor from Turnstone Marine Survey.

When your insurance company or financial institution requests a survey on a vessel you already own, they are asking for an update on
the condition and value of your boat. It is how they ascertain the risk involved in issuing a policy and updating the value of the boat
based on it’s condition. The engines might not be started and there is no sea trial involved. The Condition and Value report will be
smaller and more focused on problems, (deficiencies), found during the survey process. Also, photos will be used only to enhance the
verbal descriptions. Keep in mind these reports are being looked at by agents familiar with boats.

No matter what type of survey or service I perform:

  • I take my time.
  • I use all my skills, tools and experience to the best of my abilities.
  • I report all that I see relative to the type of report.
  • I am foremost concerned for your safety.
  • I make sure your boat and it’s systems are within the standards, guidelines, and regulations of all related overseers.

I am never a cut-rate surveyor. I know what my work is worth and how long it takes me to perform a survey. However, there are
surveyors, credentialed and not, that offer surveys at reduced rates, (they know what their work is worth)- and I don’t try to compete. I
don’t agree with compromise when it comes to anyone’s safety. You will always get the best of what I have to offer and I guarantee that!

“Reliability is designed in… Quality is built in”, and a good professional Marine Surveyor makes sure it is!

NOTE: If you’re shopping for the least expensive surveyor- I’m probably not it.
Not all Marine Surveys are alike. Nor are all Marine Surveyors. You pay for quality and quality pays you back. If you are shopping for the
lowest cost surveyor to inspect this complex machine that you are placing you, your friend’s, your families lives in the hands of, then you
are making a costly and possible dangerous mistake. My experience, my training, my dedication, my education, and professionalism add
up to what my product is worth. Now after all that, read on, and you’ll find I charge less than the yard that paints the bottom of your boat!

                                     2021 Season  Available Services and Costs

Pre-purchase Survey  (Includes Sea Trial)

  • All sizes brokered power vessels: Costs will be quoted based on the age/size/complexity/condition of the boat and hourly rate– minimum $750
  • All sizes private (non-brokered) power and sail boats hourly rate. (Estimate may be given, but work will be billed by the clock).
  • Sailboats (brokered): Costs will be quoted based on the age/size/complexity/condition of the boat and hourly rate. (Usually more than power boats).
  • Multi-hulls are usually more time consuming.
  • Large, complex yachts (>60′) are surveyed at the hourly rate for the time necessary to complete on the on-board survey and write the report.
  • Small (<30′) boats: There is a 6 hour minimum charge for pre-purchase surveys.
  • Pre-purchase surveys typically include a sea trial which is included in the price quote.
  • Use the Cost Estimator button for a direct personal quote.

2021 hourly rate= $125.00

Condition and Valuation (Insurance Survey) 
Hourly rate. No two used boats are alike even if they are the same size. Time spent on a survey is affected by the condition
of the vessel, its location, the extent of equipment aboard, time necessary to accumulate information and to provide a report document. If your 26′ boat is well maintained
and simply equipped, you should not expect to pay the same as a 26′ boat loaded with extras and/or not well maintained. A quote will estimate time spent on the vessel plus
time to write the report. (Minimum C&V Survey cost is $625 and vehicle/travel expenses apply).

Valuation (only) Same as Insurance Condition and Valuation Survey. Valuations of homemade, rare or vintage boats will be billed by the hour- applies to all survey types.
Be prepared that the valuation takes much more time for one of these vessel.

Good News Deductions! Valuation survey for charitable donation to non-profits will receive a 10% deduction.

Consultation, Electrical, Damage and Claims surveys, pre-commissioning surveys, return surveys, penetrant dye testing, sea trials, galvanic/stray current testing,
electrical systems (testing, design, consultation), and/or bonding system analysis billed per hour, ($250 minimum). (Travel expenses apply for the round trip from my office).

“Drive-by” inspections are for far away customers interested in a local listing. I will do a cursory inspection of the vessel, take photographs, then produce a bulleted list
summarizing my findings. The photos will be posted via cloud and the link will be given. This usually takes me 3 hours and mileage round-trip is charged. NOTE: 2 hours of
this charge is credited towards a pre-purchase survey if subsequently ordered.  

Open inspection of sails is additional and I will need assistance.  (Cursory from deck level Inspection of rigging and a sail inventory/in-bag inspection is included at no
additional cost).

Outboard engine survey (beyond normal observations) includes engine startup, warm-up, then cylinder compression test, lower unit operation and oil check: $100 per
engine. (I can do this for most outboards, but I always recommend this be done by a factory trained technician- especially late models). Electronic Control Module (ECM)
inboard and outboard downloads must be performed by outboard professional technicians or dealerships with the appropriate software.

Oil Sample Analysis including engine start and warm-up or following the sea trial costs $100 for each sample- engine/transmissions.  Boat owner or representative must be
present to prepare and start engine(s).  (Travel expenses apply if not part of vessel survey).

Travel expenses are not charged for Pre-purchase surveys if the job is within 50 miles of Interstate 95 between Mystic, CT and Portland, ME and the survey value >=
$875.00.  Island surveys will be charged air or ferry transportation costs, parking costs, and island taxi if necessary, but not travel time. Travel expenses will be negotiated
before survey. For all other work, round trip mileage from my office to the job will be billed.

Electronically printed reports are emailed then posted on the TMS website upon completion for future reference.  Optional printed Pre-purchase Survey reports are in a
handsome bound report cover using high definition color printing and utilizing both sides of high quality HP® Presentation Paper.  $35 to cover printing and shipping costs.   

Classic boats, boats older than 20 years, commercial or charter boats: 
See Condition and Valuation Survey. Costs to be agreed upon prior to survey or when on site.

Pre-commissioning survey. Get your boat ready for the season. Make sure your boat is shipshape before you launch. (See pricing for “Consultation” above). Also useful
to long distance shoppers- Don’t waste your time or travel expenses! I will prepare a list of deficiencies and take current photos, then email and report findings by phone.   

  • Turnstone Marine Survey reserves the right to assess additional hourly rate surcharges if the survey process is slowed by circumstances beyond the control of the surveyor.  Such as a vessel
    not properly prepared for survey as per instructions, third party contractors not hired by TMS, vessel equipment located elsewhere, a vessel in poor condition, etc.
  • Customers will receive an invoice for services rendered at or before the survey.  Payment in full must be received before the report is released.  You may pay by check, cash, or Master Card,
    AMEX, Discover, and Visa via the PayPal system linked to via my webpage.

In a Pre-purchase survey, all accessible parts and systems in the boat are carefully examined.  Whether or not the vessel is out of the
water determines how much of the hull can be examined.  It is strongly recommended that an in-water boat be hauled so the underwater
components can be accessed and the wetted surface checked for blistering, etc.  The hull and deck are checked for moisture incursion
and tapped with a phenolic hammer in a grid like pattern, which to the surveyor’s ear will locate problems if any in the fiberglass
laminate. Voids in the laminates might or might not have water in them, but if they do, they should be properly repaired.  The fuel system
is checked.  The propulsion system is checked.   If requested, the engine(s) is started, warmed up and then oil samples are drawn from
each motor if applicable, and sent for analysis. A sea trial is included in the price of a Pre-purchase Survey. Full outboard surveys are
available and arrangements for larger inboard diesel and gasoline engines can be arranged.  The electrical system is checked.  
Generators, shore power/AC system, air conditioners, marine electronics, stoves, heaters, fresh water, toilets (MSDs), superstructures,
towers, steering, hydraulics, sailboat rigging, winches, stanchions, hatches, lifelines, ground tackle and rode, davits…the list goes on
and on.  All these things are checked for condition, catalogued, and compared to federal (CFR, MARPOL), international (ISO,
COLREG), and state regulations and standards set forth by the ABYC, (American Boating and Yacht Council), and NFPA, (National Fire
Protection Agency), for compliance.  Deficiencies are listed according to severity at the end of the report.  Many photographs are taken
and included in the report for clarity.  The hull ID number is documented and pertinent papers such as registration or federal
documentation are examined and reported.  Finally a value is placed on the boat.  It is not unusual for the survey to take 3 to 6 hours
and at least as much time spent on the research and report writing.  The report will be posted on TMS website for viewing and printing
as soon as it’s completed.  Report is instantly accessible only by you and people you give the password to.  If requested, you will receive
an attractive bound report in a ring binder with a large color picture of your vessel on the cover plus many pertinent photos within.  
Printing is done on both sides of the paper, and only HP® Premium Presentation paper is used.It is a thorough, professional report that
will put you in an educated position to bargain for price or itemize work to be done before taking ownership.

I will not offer statements about any part of the boat that is not readily accessible or beyond the scope of my expertise.  Removal of screws, panels, personal belongings, or junk will only be done with owner’s permission and extra cost.  I will not offer a statement of condition for motors, transmissions,(see engine survey FAQ), sailboat rigging higher than 6 feet above deck, or sails.  If there is any doubt as to age or condition of these components, I will recommend someone more qualified than I look them.  Removal of bottom paint for moisture metering may be done with owner’s permission at additional cost.  Core samples can be taken and analyzed by an independent lab.

A phone call to me is the first step.  I’ll ask a few questions over the phone.  I like to know for whom I am working and obtain basic info about the vessel.  I’ll fax or mail a Turnstone Marine Survey work order package to you that must be signed and returned to me before the survey can start.  Upon receipt of the work order, you and I will agree on costs and then I will start to gather information about the vessel from all my sources.  Weather permitting, the survey will be done upon the agreed upon date.  The survey purchaser or vessel owner must arrange, (and probably be asked to pay for), haul-outs, launches, sea trials, engine starts, etc..  The
best time for short hauls for most boatyards is midday.  The owner or licensed captain must pilot the vessel for any sea trials.  After the survey, unless otherwise agreed, I will have a report ready within 2 business days of the survey – guaranteed, or no charge.  I will present you with the survey, which must be to your satisfaction – guaranteed, or no charge.  Payment is expected at the time of survey or at least before the report is released.

Upon receipt of the Request to Survey and Terms and Conditions for Survey, please take care to respond to all applicable questions on the Request to Survey.  I use this information to prepare and aid in my pre-survey research.  You need not sign the Request to Survey until the survey pricing has been added, but pricing must be agreed upon and signed before the survey.  The Terms and Conditions for Survey must be signed before the survey.  Please get this paperwork back to me as soon as possible.  Next, inform the seller that I will be surveying on agreed date.  If survey is to include starting the engines, hauling or launching the boat, performing a sea trial,
etc., it will be your responsibilities to arrange for, and pay expenses incurred.

First of all…
1.        Proof of ownership is necessary: vessel’s state registration, title if applicable or USCG documentation will do.  Please have these documents available at the time of the survey.

2.        I must see the HIN, (Hull Identification Number), which is stamped into the hull usually in the upper starboard corner of the transom.  If there is a different location, please inform me.

3.        If USCG documented, the documentation number must be fixed to the hull somewhere… please inform me as to its location.

I only report what I see…
4.        For instance: “I’m installing a new VHF radio but it’s not wired in yet”.  Survey says: “VHF does not power up –not serviceable”.  This will be a reported deficiency to be explained to the insurance agent or lender.  At least have electronics available, if not on board, for inventory.  If the vessel is being worked on, it’s not ready for a survey.  Please schedule when work is completed.

5.        Please leave in plain view all safety equipment to avoid time wasted looking for: Personal Flotation Devices, non-expired signaling /flare kits, horns, first aid kits, searchlights, EPIRB and EPIRB registration, etc.   Make known the location of all fire extinguishers.

6.        I do not open locked or screwed down panels or hatches so if there is a secured electrical panel or a fuel tank under a secured deck hatch, please remove locks or screws to provide accessibility.  Please have batteries on board, charged and connected.  If a shore power system, also plug in if possible.  If the engine is to be started on the hard, have a cooling water source connected and ready to go.  (Owner or representative must be present to start engine(s)).   

7.        Hint: A clean, organized, (shipshape) vessel always helps the overall rating.  So please, either stow personal items or better yet, remove them so they do not impede the inspection of something important.

8.        If the survey is a Repurchase, ask what is to be included in sale.  There is no sense in my surveying a  life pod or EPIRB if the owner will not be including these items in the sale.

9.        For safety reasons, the survey will stop if:
      a.    Odor of propane is detected.
      b.    Odor of gasoline is detected.
      c.    Any condition surveyor deems too dangerous to be on board, or vessel is unfit.

10.    Survey stopped for any reason will be billed at ½ the agreed full survey cost.

The difference between a Pre-purchase Survey and a Condition and Value Survey, (or Insurance Survey), is only in the focus and types of information given in the report. A Condition and Value report will focus more only on the vessel’s system deficiencies whereas the Pre-purchase report will identify most or all the vessel’s systems including entertainment and furnishings with more photography… a larger report. The physical process of the vessel’s inspection is just as thorough for all types of surveys. Depending on the vessel, but not limited to, the hull and deck structure(s) and systems, propulsion machinery and fuel systems, electrical systems (AC and/or DC), electrical supply systems, batteries, bonding systems, genset, heads and waste systems, domestic water system, hot
water heater, pumps and filters, galley and related equipment, LPG or CNG systems, air conditioning and/or heating systems, steering, navigational equipment, anchoring and docking systems, sailboat rigging, spars, chain plates, sails, and especially- safety systems
are included in the inspection process.

Pre-purchase Survey is most beneficial when purchasing a used or even a new vessel. It will better describe all the complicated systems typically found aboard the contemporary boat. It will also be universally accepted by insurance and financing companies. There are times when your insurance company or financial institution might request a survey of your vessel initially and/or henceforth every 4-6 years. They want to know the present condition, location, and value for establishing risk etc. The costs for all surveys are given in the rates section of this site. Sometimes conditions do not permit a full Pre-purchase Survey in which case a Condition and Value Survey and report will do. There are times when only Vessel Valuation is desired for estate purposes, etc. This is the same as a Condition and Valuation Survey.  An accurate vessel valuation cannot be determined and usually not
accepted without a complete inspection of its’ condition. If I am requested to return for a resurvey to check for corrective actions on deficiencies, my hourly rate applies plus travel charges.  

Turnstone offers remote surveys, where I will act as eyes and ears for a buyer. This saves time and travel expenses for a buyer from a distant locale.  I am Passport ready to travel literally anywhere.  Time rate and travel charges apply.  This is usually requested before a Pre-purchase survey, the report is more a written list of deficiencies plus verbal and may include photographs or HD video.

In this part of the Northeast, Pre-purchase surveys in the winter present a different set of problems for vessels stored outdoors or in non-heated barns. They include access to the boat, snow and ice, winterized engines and water systems, frozen hulls, shrink-wrap and items removed from the boat for storage. Complete Pre-purchase surveys including sea trials are seldom possible. My personal concern is injury from slips or falls. Some of my electronic equipment especially the digital camera fails to operate when cold. IMPORTANT: Hull moisture and/or delamination cannot be determined when the hull and deck laminates are
Controlled tests have been conducted in the laboratory and the field on the reliability of moisture meters which have shown them to be ineffective and not reliable for detecting or reading moisture content of wet frozen materials including wood, fiberglass, and foam. Furthermore, percussion soundings of frozen materials will give misleading results.  For these reasons, I seldom survey during the months of January and February. I will always recommend that the survey be postponed until more favorable conditions permit me to be more thorough. When winterized the engine(s) will not be started and electric pumps etc will only briefly be powered on unless arrangements have been made with the seller. As in all surveys, (if I do survey), I need access to all parts of the outside of the hull and machinery and the ability to SAFELY get inside the boat. There must be at least one battery connected for the DC systems and electronics check, (electronic navigational instruments should be in place and connected if possible), and if the vessel has a shore power system it should also be powered up. If batteries and AC power is/ are not available, I carry my own power supply but charge $25 to connect. When ambient temperatures have been above freezing for at least 48-72 hours, a survey is possible if the bilge temperature is above freezing. (No ice sighted). If you are buying a boat in the winter, along with the information gleaned from a C&V survey, I
recommend an agreed amount be held in escrow until commissioning and/or a sea trial can be performed to assure the boat will operate as represented. Please pass this information along to the broker or seller if buying a boat. If there are any 3rd party charges for preparing the boat, they might be the obligation of the buyer and should be discussed with the seller and agreed upon before the survey. I take pride in my work and for the reasons stated above, I might refuse to take assignment when conditions could possibly compromise the accuracy of my results. I usually take time off from January to mid March, (or as long as extreme winter conditions exist). My time to catch up with the “Honey-do list”, my educational requirements, and prepare for the coming season.

HIGHLY RECOMMENDED  The chemical analysis of the crankcase oil of a gasoline or diesel motor speaks volumes about problems in that motor.  The presence of metals indicates wear, antifreeze or water can indicate blown head gaskets or cracked blocks or heads.  Fuel in the oil can indicate misfiring cylinders.  It is the best place to start as to whether an engine survey is justified.  Oil samples are meticulously drawn only after the engine has run long enough to reach operating temperature.  Note: Fuels and lubricants can also be analyzed.  (2cycle outboards cannot have oil analysis as they do not have oil sumps).

The rule of thumb here is that every 50 hours of marine use is approximately equal to 3000 miles of automobile travel.  Today’s cars get 120-150,00 miles out of their no-lead gasoline motors, so 2000-2500 hours is about max for gasoline marine motors and outboards.  Diesels are more rugged, run at lower RPM and 6000-8000 hours is the high end before rebuild. Age is also a factor especially if salt water cooled. Older, low hour engines are not necessarily a bargain as lack of use can present another set of problems. Here in the northeast, 50 hours of use per year is considered the norm. Always ask for maintenance records.

Will you be doing a compression test on the motor when you survey the boat?

All surveys include an external inspection of the engine and drive train, fluid levels, belts, hoses, wiring, etc., at no additional cost.
The newer outboards and inboard engines have computer download capabilities that will generate a report of diagnostic problems
and usage. It will show any alarm events of overheating etc., and hours of use broken down to time spent at different rpms. This is
useful to show how hard the boat was driven. (Over-revving events indicate the boat was driven airborne off waves which will seriously
damage engines and drive trains).  Note that the software required to get a download is proprietary to the engine manufacturer and
must be done by a dealer/service centers.  Minimally, for any 4 stroke engines, (gasoline inboards, diesel and 4 stroke outboards) I
strongly recommend sampling then analyzing the lubrication oil after running the engine for a period of time until it has warmed up
or after the sea trial, (see the Oil Sample FAQ). Only a sea trial* will determine the ability of the engine to perform under load to
manufacturers specifications. A complete engine survey by an independent certified technician will only be recommended if either or
both the oil sample analysis or observations during the sea trial point to internal problems with the engine. The cost of an oil sample is
minimal compared to a full engine survey. The sea trial is included in a Pre-purchase Survey, (See pricing section for details). A
cylinder compression test will only be recommended for a 2-stroke outboard that either fails to run properly on the sea trial or a sea
trial isn’t possible. I can perform this test myself on most outboards after the engine has been warmed up.

To summarize, a visual inspection of the engine and drive train, sea trial and engine oil analysis is basic. Only if indicated will a complete
engine survey be recommended and then should only be performed by a qualified factory trained technician with the proper equipment.
A compression test will usually be performed during a complete engine survey. Keep in mind, a compression test alone is not a fail safe
indicator for the condition of the engine and should not be overrated or routinely expected in a Marine Survey. It will show problems with
heads, gaskets, valves, pistons, rings or cylinders but tells nothing for bearings, pumps, electronics, carburetors, fuel injection and all
the rest of the components that make up an engine. Ask for credentials for anyone offering to perform engine surveys.

*Considering the high cost of diesel engine repairs or replacement it is strongly advised to include a certified diesel technician to be on
the sea trial for larger yachts with diesel power plants.  Turnstone Marine Survey will make the arrangements to do so with a reputable
local professional.

The Use & Misuse of Moisture Meters

By James G. (Jim) Merritt, SAMS® AMS®



I’ve noticed that whenever a group of marine surveyors spend time comparing notes and discussing their profession, the conversation often turns to moisture meters. Reactions and comments range from “they would make a good doorstop if they were heavier” to “it’s absolutely essential on a Fiberglass boat in order to do a good survey.” That’s quite a range of opinion considering the tool has been used for years in other industries but has only recently become prominent in the checking of fiberglass boat hulls.

Fiberglass has many good attributes but it isn’t a perfect. As with all other types of materials, there are drawbacks, some of which are less obvious than others. I will present these drawbacks in a practical (and somewhat over-simplified) manner, based in part on science as well as 40+ years of experience. The latter, I’ll admit, involves my personal feelings and a little speculation.

First, a few statements about basic material properties:

  • a. Strands of fiberglass, either “E” or “S” type, do not themselves absorb any water. None. Put a glass bottle in water as long as you like and it will not dissolve, gain weight, or lose strength as a result of its exposure to water. It is one of the very few materials in the world, either manmade or natural, that is unaffected by water immersion. (It can, however, be eroded by water flow of sufficient pressure and speed.)

  • b. A properly catalyzed and fully cured resin, be it “ortho” or “iso” polyester, vinylester, or epoxy, will not absorb enough water to make any significant gains in weight or loss in strength. (Note the qualifier, “properly catalyzed and fully cured.”)

  • c. Nearly all core or strengthening materials have some affinity for water and will be affected by exposure or immersion, often with disastrous results.

  • d. Chemical bonding-achieving a homogenous mix-can be accomplished with careful control of the lay-up process between various layers of like resin. All other bonds are secondary and are in effect glue bonds. This includes resin whenever prior layers are allowed to cure sufficiently before more resin is applied.

  • e. Due to their very low molecular weight and size, water molecules will penetrate almost anything. Nearly all substances, including gel-coats and paints, have some porosity that allows water molecules to enter.

Meters What happens after water has entered? In the case of fiberglass construction, not too much, provided there are no exposed core materials and the resin was fully catalyzed and cured. If any resin components did not get linked to other components by the catalyst to make a long chain closed molecule, then the open ends of the molecule mix with water, making a “salt” (not table grade) that is larger and heavier than it was before. This is now trapped in the laminate, is usually acidic, and will continue growing so long as more water can be drawn in the entry and additional unlinked resin components can be found. It will also start attacking the glue or encapsulation bonds of all the other materials in the laminate, including the laminate layers that were not chemically bonded during the initial construction.

Many undesirable things happen afterward. Minor blistering is the first; delamination between layers may show up, usually found by visual observation or hammer (percussion) sounding; delamination of FRP layers to various strengthening cores may occur with failure of the structure to carry the loads if the FRP overlay was not strong enough by itself; increased moisture levels of the core materials with wood of any type being particularly vulnerable but plastic cores are also susceptible to major damage.

How does a surveyor or boatyard employee determine how much moisture is present and, more important, assess its potential for damage and possible failure of the structure? Visual inspection and sounding, the first steps in the process, have already been mentioned. Next, the moisture meter is useful in verifying that water has been trapped within the laminate. Without regard to the make or type of meter, I will state that none give a reading that can be related to anything other than an arbitrary scale, which meter manufacturers adopt as their standard for moisture level. Cured resins do not actually absorb enough water to be measured as a percentage of either weight or volume of the resin; the glass strands absorb zero, only the space around the fibers can hold water if the bond has been broken. What the meter is showing is a relative reading based on a resistance or capacitance in relation to a laminate that has had no water exposure. Good information, as it verifies what is already suspected, can often locate the boundaries of the trapped moisture.

Meters After the meter has verified the presence of moisture, more invasive or active procedures are necessary to determine the gravity of the problem – does it threaten the structure or is it normal aging?

I work primarily in an area where boats often go three to four years between haulouts. The water is warm, clear, and clean-a veritable laboratory for studying the effects of water and continued exposure on FRP structures. After using a moisture meter on over 1,000 surveys, I have yet to see a recently-hauled boat that indicated anything less than “high” (7+ on a scale of 1 – 10) on surfaces below the waterline. These readings have been taken with a variety of meters, including Sovereign, Novanex, GRP-33, and Protimeter. The ban of tin compounds for anti-fouling paint and the advent of high copper loads along with special interior barriers have now given consistent “pegged” readings on nearly all hull bottoms. The end result is that I ignore meter readings below the waterline while still paying close attention to exterior surfaces above the waterline, particularly around through-hull fittings and any deck hardware. Meter readings inside the hull are often helpful, but care must be used in assessing potential problems where the bilge has been allowed to hold water. (A brief aside: NOTHING good ever comes of water in the bilge.)

Inside the boat, even small amounts of water can, over time, create major problems as it will penetrate the layup and, through capillary action and wicking, spread to areas far beyond the immersed depth or section. This is where judgment has to be used; the yard or surveyor can’t always know if the builder used a wood (or foam) form and whether this form was meant only to shape the laminate or to help in bearing heavier loads. In the case of engine bearers and hull stringers, any collapsing or deformation of the laminate is cause for concern; if everything looks OK with no alignment problems and fasteners are tight, no further action beyond a note in the survey or work order is justified. This is true no matter what the moisture meter said. Wood can be “wet” and still have excellent strength; just take a look at any living tree. Large, deep stringers will often have delamination of the covering FRP layers due to expansion and contraction of the wood across its width breaking the glue bond of the resin. This can lead to rot that requires major replacement; but in many cases there is no lasting effect, as the wood is still sound and the laminate is strong enough to support the imposed loads. Verification of condition can be accomplished by drilling small (1/4″) holes and observing the chip fallout as well as resistance to the bit and further probing in the hole with an awl. Again, a note in the survey to monitor the condition on a regular (at least annually) basis and to keep the bilge totally dry is all that is needed. No trauma or extensive invasive testing even though the magic meter said it was wet.

Meters A major benefit of the moisture meter is in its use for locating moisture penetration areas around through-hull fittings and deck hardware. A quick check with the meter can find evidence of moisture around fittings with good assurance that there is a potential problem unless the item in question is pulled and at least rebedded with a marine grade sealant. Every item on the deck or hull sides is suspect, even the innocent looking self tapping screws used to hold a horn or light bracket in place. With deck structures, I have seen a loose screw lead to massive areas of rot. In the case of an air conditioning water discharge through hull in a cored hull, a tiny leak led to a $10,000.00 repair bill. Use of a moisture meter in these examples would have indicated the problem long before it could have been found by sounding.

A high reading does not necessarily mean the boat’s laminate is in peril. It could be, but in most cases the boat is quite usable. I have yet to see water in the laminate sink a boat or render it unusable.

What about cored hulls and decks? Because cores increase strength and reduce weight, they are now widely used. Checking for moisture is more complex than it is with solid laminate. Some meters give better depth penetration readings than others but the readings are always suspect if taken from surfaces outside the core. Foam cores themselves typically do not absorb water. But water, sometimes many gallons of water, may become trapped between the core and the outer laminate. With balsa cores, water may normally be at a level of 10%-12% by weight and wind up at 500% (that’s not a misprint) without any appreciable expansion in volume.

When a hull and deck appear to have all of the overt signs of water intrusion, it is best to use a moisture meter from inside the boat. A large section (2″- 2 1/2″ can be removed and sent to a laboratory analysis for moisture content. A pin-type meter can be used by drilling two small holes for pin insertion into the core and checking at various depths to ascertain if the moisture is primarily on outer or inner surfaces of foam cores. Balsa cores will normally show nearly equal readings on either surface. Note that balsa can be saturated and still not have an appreciable loss of strength, its longitudinal cell structure allows water to fill the insides without much weakening of the compressive strength. The major concern with cores of all types is delamination or separation from the covering skins. If the bond is intact, removal or replacement of the core is not warranted, drying (another subject) is in order along with finding and correcting the source of the water intrusion. Sealing the skins with some moisture inside is not a bad thing.

In conclusion, my own belief and current use of the moisture meter is that it is indeed useful. Care, experience, and judgment are all necessary in its application and to that extent it should almost be the last tool that comes into play when assessing a boat. An experienced surveyor can deliver a very creditable report with just visual observations, but today’s boats require specialized instruments to more fully determine problems and recommend proper maintenance or repairs. I personally would like to see a better and more precise method of testing than we currently have (IFR and X-Ray techniques are not the answer at present) and would also like to see more definitive data on aged FRP laminates. Perhaps one of the boatbuilding schools could undertake testing of 10-to 40-year-old laminates from boats that are already consigned to the landfill. Some very useful data charts could be derived as guidelines to acceptable performance of older laminates from sections cut out above and below the waterline of a given hull.

James G. Merritt SAMS® Accredited Marine Surveyor 1992
Tangent Development Co., Marine Division
1715 Harlequin Run
Austin, Texas 78758
512-837-9170-O, 512-835-9629-Fax

Two dissimilar metals immersed in an electrolyte will start to flow electrons from one to the other via the electrolyte.  The metal giving up electrons is known as the anode and the metal receiving the electrons is the cathode.  The two metals are a galvanic couple.  In the case of a vessel in the water, the electrolyte is the salt water.  The common metals found under water on a vessel are bronze, stainless steel, aluminum, lead keels and sometimes iron or steel.  The more noble (cathodic) metals, like stainless steel and iron will draw electrons from less noble (anodic) metals like aluminum or zinc.  The result is the destruction of the anode or galvanic corrosion.  If the bronze through hulls and seacocks become the anode to the stainless steel
propeller shaft, the through hulls will deteriorate.  This can sink the boat.  If the aluminum outdrive becomes the anode to the bronze through hulls, goodbye outdrive.  It’s survival of the fittest.  Zinc and magnesium are the least noble of most marine metals and are commonly mounted on the bottom of the vessel to become the sacrificial anodes.  Keeping large metal surfaces under water coated with paints or epoxies also helps.  Typically, a vessel with zinc anodes will have an underwater current between the zincs and more noble metals of less than 0.3 or .4 volts and measured in milliamps.  It’s not much, but remember, it’s working 24/7. Imagine that your bilge pump float switch starts to leak and 12 volt DC current is introduced to the salt water standing in your bilge.  It wants to go to ground, so it flows through the salt water in the bilge to a thru-hull fitting then outside the hull via salt water to the propeller shaft and finally to the motor and back to the negative terminal of the battery.  This is much more serious because now instead of a couple hundred millivolts, we’re talking 12.5 to 14 volts.  This is stray current corrosion, and has been known to destroy a through hull in a matter of hours, causing boats to sink.  An aluminum outdrive can be eaten to just the internals in a matter of a few weeks.  Photo below of stray current destruction of lower IO drive from a defective bilge pump.

Electrolysis is used to remove unwanted hair.  Scientifically, in a galvanic cell, it describes the chemical alteration of the electrolyte, which, in reference to boats, is the ocean.  It is incorrect to use this word to describe electrolytic or galvanic action as it pertains to the
metals in a boat.  

ABYC recommends bonding all metal parts, which come in contact with seawater.  Using  #8 gauge green, or green with yellow stripe stranded wire, each part is connected to a common metal so if any electrical charge is built up, it will be harmlessly grounded back to the negative terminal of the battery.  This includes any type of electrical charge at the fuel fill.  But just as important, think of a bad bilge pump float switch that is leaking 12 volts of DC current into the seawater in the bilge.  All that electricity is searching for a pathway back to the battery negative, so it finds a brass through-hull sea cock and flows out into the salt water to the propeller shaft back up into the boat to the negative battery terminal.  That through-hull will become an anode and eaten alive in just a few hours.  Or a less noble aluminum outdrive will be swiss cheese in a few weeks. The boat sinks!  The bonding system would have been an easier pathway back to the battery and avoided damage to the through-hull.  Note:  Bonding is not meant to protect from lightning. Picture below illustrates stray current corrosion in a sail drive. Notice the holes in the aluminum casting. This was caused by a broken grounding

Simply put; stainless steel is an alloy of iron, carbon and chromium, and in most cases stainless steel is maintenance free and will last for years.  But it has some drawbacks, of course.  It has a low modulus of elasticity, which means it doesn’t bend and flex well.  It
develops microscopic stress cracks, which are very hard to spot, and have a tendency to cause sudden, unexpected total failure of the part.  The other problem is that stainless steel protects itself by oxidizing its surface, (chromium oxide).  When deprived of oxygen, the
oxidation cannot occur and the ferrous component of this steel alloy begins to rust.  This is so called crevice corrosion.  Typically found where a nut has covered the thread of a bolt, or a bolt passing through a wooden bulkhead.  The SS wire inside a swaged fitting.  Behind a chain plate, or inside a stress crack.  The result looks like some kind super-rat has been gnawing the metal. (A word of caution, avoid painting stainless steel!)  You have to know where to look and have a magnifying glass or microscope handy.  The magna-fluxing of
suspect pieces can show cracks imperceptible to even a strong lens. How long will the rigging last on my sailboat?  Amount and type of use, length of season, and climate will dictate. (See FAQ: Inspection of sailboats; Sails and Rigging). I will perform a cursory exam of rigging at the deck level, but age and signs of stress or crevice corrosion will lead me to recommend a thorough examination of all the standing rigging.  I offer magna-fluxing of any component suspect of stress cracks.  This would include swage fittings, chain plates, turnbuckles, tangs, prop shafts, propellers or any metal, (especially stainless), that takes a lot of stress. Perhaps the best stainless steel for underwater machinery is called Aqua met, an alloy of iron, carbon, manganese, silicon, chromium, nickel, phosphorous, sulfur, molybdenum, vanadium and a few others.

Types of Stainless Corrosion

According to the DOD Technical Bulletin Corrosion Detection and Prevention there are 8 separate types of corrosion, with only a few having a major impact on stainless steel. Please be advised the descriptions below are extremely brief and written in laymen terms. Before acting on any particular application, qualified advice particular to such application should be obtained.

1. Uniform Attack – also known as general corrosion, this type of corrosion occurs when there is an overall breakdown of the passive film. The entire surface of the metal will show a uniform sponge like appearance. Halogens penetrate the passive film of stainless and allow corrosion to occur. These halogens are easily recognizable, because they end with “-ine”. Fluorine,
chlorine, bromine, iodine and astatine are some of the most active.

2. Crevice Corrosion – this is a problem with stainless fasteners used in seawater applications, because of the low PH of salt water. Chlorides pit the passivated surface, where the low PH saltwater attacks the exposed metal. Lacking the oxygen to re-passivate, corrosion continues. As is signified by its name, this corrosion is most common in oxygen restricted crevices, such as under a bolt head. Swaged rigging fittings and chain plates are always suspect.

3. Pitting – See Galvanic Corrosion. Stainless that had had its passivation penetrated in a small spot becomes an anodic, with the passivated part remaining a cathodic, causing a pit type corrosion.

4. Galvanic Corrosion – Placing 2 dissimilar metals in a electrolyte produces an electrical current. A battery incorporates this simple philosophy in a controlled environment. The current flows from the anodic metal and towards the cathodic metal, and in the process slowly removes material from the anodic metal. Seawater makes a good electrolyte, and thus, galvanic corrosion is a common problem in this environment. 18-8 series stainless fasteners that work fine on fresh water boats, may experience accelerated galvanic corrosion in seawater boats, and thus it is suggested you examine 316 stainless.

5.  More rare- dendritic or sensitized stainless steel corrosion from overheating the alloy during a welding process. The chromium in the alloy is lost and self protecting ability of the SS is lost. See photos below of a welded shaft strut made of a lower grade, (less chromium), SS- note the pitting and stress cracks near the weld. Welded SS tanks such as for waste water
must be watched carefully. Same for underwater welded SS hardware.

Dye penetrant process is used to find microscopic cracks in metal.  It is a three part process.  First, the metal part is degreased with a cleaner/solvent.  A penetrating oily dye is then sprayed or applied to the area to be tested and allowed to set.  The dye penetrates into the microscopic crack(s).  The surface is then wiped to remove the extra dye.  A developing white powder is then sprayed on and allowed to sit.  The penetrating dye leaches back out of the crack(s) and stains the white powder red.  Voila, there it is, a microscopic crack in what looked like a healthy Monel propeller shaft, which will inevitably fail.  Dye penetrant testing is ma service provided by Turnstone Marine. 

When installed and used properly, it’s a great fuel for heat and cooking.  There are many CFRs and recommendations written by the ABYC and NFPA pertinent to installation and use of propane and CNG, and it is something I am very aware of while surveying a vessel.  If it isn’t right, these problems are written as “Type A” infractions that have to be corrected before the vessel can next leave the dock.  LP is heavier than air, settles in bilges and should never be used on a vessel without “sniffer” alarms! The owner of the 40′ Irwin shown below ignored the smell of gas in the cabin and turned on his laptop computer. He later succumbed to his injuries.

If in the hull molding process, a void or particle of dirt or whatever was formed under the gel coat, eventually, water will osmose through the gel coat at that spot.  The water reacts with the resin and forms glycol and acids, which slowly dissolve the plastics.  The formed molecule is larger than the water molecule and is now trapped behind the gel coat.  This causes a swelling (1/2 to several inches) outward of the gel coat like a pimple.  That’s a blister.  As the blister grows it eventually leaches into the glass cloth and causes delamination below the water line.  A few blisters is usually not a problem, but large blisters and/or blistering of most of the wetted surface requires a grinding back of the gelcoat then a long drying process (months) then an application of a moisture barrier system and reapplication of the anti-fouling paint.  Definitely desirable in southern climates where boats spend more time in the water and
the 75 to 85 degree water is perfect for blistering. Photo shows open blisters from a 50′
trawler yacht in Florida.

There are several ways for water incursion to happen.  Below the waterline over time the pressure exerted by the water will push the water through gel coat into voids in the laminate formed during the construction/layup process.  Gel coat is not totally waterproof and some types of resins are more permeable than others.  Vinyl ester and epoxy resins are most resistant.  Be careful to use the right products for hull repair.  Above the water line, damage to the gel coat will admit water.  Poorly sealed or loosely mounted hardware will allow water to penetrate the protective gel coat skin into the core material.  In northern regions you can imagine what freezing and thawing of this moisture will due to the laminate structure.  Water incursion can be prevented by careful manufacture of the fiberglass laminate.  Modern methods such as SCRIMP molding all but eliminate voids in the laminate.  Correctly mounting seacocks is vital to prevent seawater seeping around them into the hull structure.  All deck-mounted hardware should be painstakingly sealed, and resealed every 7-10 years.

Hello, I have been looking through your web sight vary informative. I have a 1989 52’ Jefferson Marquessa that has will over a thousand little gel coat blisters on the bottom. The marina sand blasted the bottom and now is suggesting I have them gel coat strip the bottom. They then want to put five coats of a barrier coat on the bottom, then the primer and then finish. My question is should I have them fill the blisters or strip the gel coat. If we take the gel coat off will this hurt the boat?

Thank for your time, J

First, let me state that surveyors should not dictate how repairs are made.  In addition to the obvious blisters, has the wetted surface been checked by a surveyor for moisture incursion and/or delamination?   I can tell you that in the case of severe blistering, (boat pox- see photo below), which you appear to have, that the common approach is to strip the gelcoat back to healthy laminate, routinely wash with soap and water to remove the glycol (chemically produced when water and resin mix) while the laminate is drying over a period of several months, then fair the surface and use a barrier coat such as Interlux Interprotect 2000.  Finish with your favorite anti-fouling
paint.  This unfortunately can be a long and expensive job, but your motor yacht is well worth the job.  Note; the drying process can be accelerated by a mild, dry climate or inside storage with heat lamps, etc.   Marine surveyors commonly supervise the drying process by routinely testing the laminate as it’s drying for moisture content.  It will be a waste of money if the laminate is not dried properly before restoring the surface.
Thanks for the question and good luck,
Peter Spang, AMS

Photo of “boat pox”

Inspection of sailboats: Sails and rigging.

Whether it is a Pre-purchase or Condition and Value survey, all care is taken to inspect the sailboat rigging, standing and running as
available to the surveyor. With the mast standing, deck level rigging is examined for signs of failure or imminent failure. Cracks in or rust
stains from swaged terminal, chain plates, turnbuckles, stainless wire, mast connections, toggles, etc., indicate problems. Broken strands
or “fish hooks” are an indication the rigging wire should be replaced. Recommendations may be made for a complete rigging inspection by
a qualified rigging expert in such cases. Running rigging is checked for aged lines, block or sheave failure, operation of track(s) and
travelers, condition of furling equipment, vangs, cunninghams, etc.  There might be a recommendation for an expert rigging inspection
only due to the age or mileage of the system. (Follow this link to the Navtec Guidelines for Rigging Service). If the mast is down, this allows
more careful inspection of rigging at the masthead including halyard blocks and sheaves, lighting and other electrical components. Dye
penetrant studies are available if cracks in any of the rigging are suspected but not entirely visible. Any stains from rust or water leaks
seen internally near or on the chain plates will generate a recommendation for removal and close inspection of the chain plate and

Inspection of the sails is optional. If off the boat and a clean space is available, the sails can be opened and laid out, inspected for
abrasion damage, stitching failures, tears, cringles’ condition, tell tales missing, battens and pockets’ condition etc. I require a helper to
open sails then flaking when done. Sails that have lost their shape can only be identified on a sea trial.

Operational condition of the sails and rigging systems can be best ascertained on a sea trial.

Sea trials

A sea trial is usually conducted as part of every Pre-purchase survey and included in the quoted price- not an extra cost.
The best way to describe it is to compare to buying an automobile. You would expect to take a test drive with a trusted mechanic to
identify problems, if any, and get a feel for the way the vehicle handles. During a sea trial, the captain at the helm of the vessel is
responsible for safe navigation and the general safety of everyone on board. The captain should be familiar with the vessel and an
experienced seaman. This task is usually assigned to the boat’s owner or the broker involved who usually has their Master’s license.
The surveyor never takes the helm. The surveyor will give directions to the captain who will then carry them out when safe and legal to
do so. The typical sea trial will involve cruising the powered boat at different rpms and take readings at each level. Readings will include
speed of the vessel, engine temperature, oil pressure, battery voltage, and any other displayed information. The surveyor will expect the
captain to operate the vessel at wide open throttle if conditions permit for several minutes. The surveyor will also be moving about the
vessel while underway to observe the engines, outboards, outdrives, prop shafts, transmissions, bilges, and the cabin spaces looking
for problems. Additionally, a “dead engine” test will be performed on multi-engine installations. This entails powering up each engine
individually to wide open throttle with the other in neutral or if outboards, shut down and raised. This only lasts long enough to establish
top speed and maneuverability. It is to discover the vessel characteristics and simulate the ability to make port if this should actually
happen at sea. Additionally, it demonstrates the engines are balanced power-wise. The engines should match each others’ rpm and
speed attained. The sea trial is a busy time for the surveyor and a lot to accomplish in the alloted time which is one hour.
Sailboats follow the same protocol. Time will not be given to navigate under sail. However, if rigged, the sails should be opened to
observe the operability of the sail handling equipment and to check the condition and shape of each rigged sail.
The sea trial is not the time to introduce others to your new boat. Attendees should be limited to the buyer(s), the surveyor, and
whomever is piloting the boat. Many times the buyer will ask to bring a personal advisor along and that is OK if the boat is rated for at
least 4 people. There should be all the required safety equipment aboard in operable condition including a PFD for each attendee.
Water tanks and fuel tanks should be reasonably full. Decks cleared. Loose items in the cabin safely stowed or secured. The vessel will
be pronounced ready for sea trials by the surveyor. Knowing that deck hatches and engine hatches will be open, high speed maneuvers
will be performed in all sea conditions, and the surveyor and captain should not be distracted from the business at hand, the buyer is
asked to refrain from bringing children, pets, alcohol or drugs, (or be under the influence of either).  After the technical aspect of the
trial is compete, the buyer should take the helm with the captain at his/her side to get a feel for the boat.
The seller or broker, if asked, will usually take a second cruise with the buyer’s family aboard as well as explain, answer questions, and
give directions for using the systems on the vessel.