Surveying Fiberglass Sailboats

A Step-by-Step Guide for Buyers and Owners

By Henry C. Mustin

International Marine

139pp  B & W drawings and photos



 Publishing Main Page / A Note About Our Reviews

This book is a clear and concise explanation of fiberglass construction and how to judge the condition of fiberglass boats. It will be of great value to all fiberglass boat owners, and, especially, those who are shopping for a fiberglass boat. It will also serve well those who simply want to learn about surveying as a trade.

As you tour our website and our publications, readers will see repeated references to the importance of surveying. In our opinion it is one of the most important aspects of the marine industry, and perhaps the side of the industry with the widest range of practitioners in terms of competence, ethics, and quality of service to the public.

A survey is a detailed inspection of a boat for the purpose of discovering its defects, determining their cause, recommending appropriate solutions and, to some extent, predicting the cost of those solutions and the value of the boat in question. A survey is a vital part of purchasing a boat, and in many instances it is essential to good relations between owners and those who may be working on their boats—it’s a way for the owner to know the repairers are doing what needs to be done. A survey provides peace of mind to the many boat owners who are more knowledgeable about the use of their boat than they are about the way it is put together.

After approximately 35 years in the boat industry, I can testify that there are a whole lot of sad stories that begin with a bad survey or with the absence of a survey. Many, many times I have seen boats surveyed after they were purchased, resulting in a list of unanticipated problems disastrous to the plans and the finances of their new owners.

Frankly, in my opinion the surveying field is a bit of a mess. For years insurance companies have been settling for surveys which were nothing more than “walk-arounds” by the “surveyor”, who does little more than count the life jackets and turn on the running lights, resulting in poor assessments of risk and driving up insurance premiums for everyone, not just those with faulty boats. In some areas, wooden boats are virtually uninsurable because the often-victimized insurance companies lump the basket cases together with the gold-platers. This state of affairs has encouraged numerous lazy individuals to get into the field under the impression that one can get paid for doing very little, and in fact they have sometimes been right.

Organizations intended to “certify” surveyors generally have no serious requirements for certification other than paying one’s dues (financial dues, I mean), and actually prohibit the membership of anyone currently working in the marine field as a boatbuilder, repairer, etc. This prohibition is to prevent conflict of interest, but with boat repair in particular being the single best way to learn surveying (it’s all about how things come apart), it has been disastrous to the quality of the surveying trade.  I have done nearly all of my surveying under a technical conflict of interest that I have been careful to explain to my customers, and I feel that as long as the conflict of interest is stated and is not too immediate, it is not a problem.

There is a natural antagonism between boat brokers, who hunger for a sale, and surveyors, who are apt to report defects that often prevent such a sale. Naturally the brokers have a tendency to recommend surveyors who are not “too picky”.

The surveying trade is completely unregulated, such that anyone can call themselves a surveyor and go into business whenever they want. While I would hate to see a raft of regulations, the unregulated market does mean that those who wish to purchase a survey must really do their homework to ensure they are getting the right surveyor.

None of this does anything to detract from the importance of a survey, and it all serves to emphasize the necessity of finding a good surveyor. There are quite a few, and the best of them quietly make a tremendous contribution to the welfare of the boating public and to all those working in the trade. Ask around and you will hear the same names mentioned over and over. Those are the people you want.

Note that, typically, a pre-purchase survey actually costs less than nothing. It is a very rare survey that does not turn up some problem that will knock more off the purchase price than the survey cost. By far the most expensive survey is the one that is not done.

I have greatly enjoyed a modest surveying career as a side job, and have drawn heavily from my experience working in repair yards, my familiarity with design courtesy of my brother Tom’s career, my work as a broker, and from many years just owning boats and examining all the boats I can. I regard it as an absolutely fascinating field. Every boat is a story to be read, and if you like all the forensics programs on TV nowadays you will find that figuring out the mysteries of a boat’s condition based on physical evidence  is much the same thing!

Based on my own experience I found this book to be “right on” in almost all respects. It would serve very well as a textbook for those learning surveying. The primary reason we offer it through Fore and Aft, however, is that it will be of great benefit to those shopping for boats. I do NOT suggest that anyone forgo a survey because they have read this book—there is no substitute for experience. But it will help anyone to quickly weed out a whole lot of boats as they look around, and will help to clarify the virtues of a boat that may be very sound beneath poor cosmetics.

I have now owned ten sailboats, all of them of wood construction as it happens, and when I go boat shopping I essentially survey any boat that interests me, right on the spot. It can be an efficient process, because one can look first for the kinds of problems one does not want to deal with. A familiarity with surveying helps to predict what and where these are likely to be. If they’re there, you go home. If they’re not, you keep looking at the boat until you either decide the smaller details still add up to too much, or you want to make an offer. Normally a professional survey involves inspection of the entire boat no matter what is found, but there is no reason why a prospective buyer can’t tell the surveyor, “If you find such and such, just stop.” This makes sense when the surveyor is working by the hour.

Once the details of their construction are understood, surveying wooden boats is fairly straightforward.  The original strength of the vessel can be easily understood because one can see the size of the timbers and the nature of the materials and workmanship. Because a glass boat takes its shape and finish from a presumably flawless mold, and because the interior of a glass hull is likely to have been largely covered up by a liner or other materials, it is difficult to assess the condition of a young fiberglass boat. A nice, new paint job can cover up a multitude of sins rather successfully in an older boat. So, from the surveyor’s point of view the easiest boat to survey is an older boat that has not been spruced up for sale. With many great glass boats approaching 40 years of age, most of them are telling a story (happy or sad) about their condition, which can be read quite clearly with the help of this book.  Fortunately the book also describes techniques for looking beyond the surface to defects that may lie underneath.

The author points out that the better built boats generally have decent access to most of the inside of the hull, whereas in the poorly built boats it’s almost as though the builders didn’t want us to see the structure, and have covered it up. I recall one instance where a boat in our yard needed a radio grounding plate. The owner was very concerned about us drilling the necessary holes in the hull because the dealer had told him there was a vacuum between the hull and the hull liner and drilling a hole would let air in. After we talked him out of that notion we soon felt we had figured out the real reason the builder didn’t want any holes drilled: we found the hull of this 33’ sailboat was less than 3/16” thick near the centerline of the boat.

A disease of marine publishing in general is an overriding desire not to offend anyone, especially advertisers, so advice in books and in magazines is often generic in nature. One of the things I like about this book is that the author mentions specific brands of boats and their problems, when it is relevant to the point he is trying to make.

Those who are familiar with our editorial and professional biases already know that we here at MacNaughton Group favor time-proven design characteristics, strong construction, and simplicity, when choosing a cruising boat. If there is any point made clear by this book it is that solid glass layups thick enough to provide good rigidity are the number one way to ensure a long-lived boat free of structural problems. Not coincidentally the boats with the best designs for cruising and offshore work are often built this way, while it is the round the buoys racers and lightweight inshore cruisers built down to a price that tend to have problems resulting from attempts to reduce the cost and the weight of their materials. The author also seconds our dislike of spade rudders, which besides having severe limitations to their performance in heavy weather are often poorly engineered as well. He also points out that strong, thick-walled spars need far less complicated standing rigging in order to be strong—we cast our vote for about anything that is strong, simple, and has the fewest possible individual parts.

From his work in the structural analysis of yacht structures, my brother Tom has produced considerable data suggesting that the light-weight cores typically used in glass construction are often not adequate for the job they are intended to do. The author of this book doesn’t get far into the engineering, except to point out that core failures are common when the skins on either side of the core are too thin. He does, however, get into age-related problems with cores. We have scooped enough partially-composted balsa core out of decks to take a dim view of it, but there is no question that quality of the original construction and subsequent decisions with regard to mounting new hardware or repairing damage, have a great deal to do with how a balsa-cored structure will perform over the years. We and the author agree that balsa core does not belong in hull construction using conventional resins, which are not entirely waterproof and will eventually cause the core to become wet and rot, unless positive remedial measures are taken early. Likewise, our structural analysis does not favor foam cores in hull construction, an exception being when the foam is laid on the inside of the hull and lightly glassed over, just as hull insulation rather than a structural element. Note that everyone, including the author, emphasizes the importance of solid glass structures rather than foam- or balsa-cored structures at areas of high stress. This recommendation has always seemed to me like a good reason for all-solid-glass construction. Note, however, that while there are many boats on the market with solid glass hulls, there are only a few with solid glass decks. Deck cores are pretty much a fact of life in used fiberglass boats, so the primary point is to make sure they are in good condition using the techniques explained in this book.

One issue the author does not mention is the typically disastrous combination of teak decks laid over balsa-cored glass decks. In almost every case we have seen, the teak deck was screwed down to the fiberglass deck, with the screws passing into the core. The structure relies on the rubber bedding of the teak for watertightness, but as the decks age, the screws typically let large amounts of water into the core, with wholesale destruction of the balsa the result. One of the worst experiences of my life was replacing the balsa core in such a deck—had I set my contract price where I should have, for that job, the owner would never have had it done, and I wouldn’t have had to do it! As the author points out, it is very easy for the cost of a big deck core job to exceed the market value of the boat, which for most people would mean that they should buy a different boat, or if they already own it they should sell it for whatever they can get rather than pay to repair it.

The book returns over and over to the subject of rigidity, which is of great importance to the lifespan of fiberglass boats. The author points out that if a deck flexes whenever you walk on it, it will tend to be short-lived, and since the weight of a person walking on a small boat deck is the same as a person walking on a large boat deck, there is a limit to how lightly one can build the small boat’s deck compared to the large boat’s. While hulls usually encounter distributed loads rather than “point loads”, they, too should be rigid under all the conditions in which they are to be used. Unfortunately many entry-level small boats were built well below this level of rigidity, and tend to simply wear out after a certain amount of use.

The first section of the book thoroughly defines the elements of typical fiberglass boat construction, and the boat owner will be much better off for knowing this information, just as the owner of a wooden boat benefits from understanding how it is put together. Understanding the structure makes it much easier to detect, understand, and deal with problems early, while they are small.

The author points out the heavy strains that can be put on boats with hydraulic backstay adjustors and vangs. In our opinion hydraulic backstay adjustors are strictly racing gear, and have no place on a cruising boat or in inexperienced hands. They can produce enough strain to seriously damage almost any boat, and because they can be slacked a lot, suddenly (without human intervention if a hose should fail), they can put the safety of the rig in question. We are slightly more enamored of hydraulic vangs, which are certainly elegant and easy to use, but again we have seen unsuspecting owners accidentally place horrific strains on their rigs through over-enthusiastic use of the vang.

While on this subject I’ll toss out a couple more, related, observations. Over-tightening of rigging in general is one of the most common ways to badly damage a boat. The amount of strain that can be introduced with turnbuckles, let alone hydraulics, is tremendous, and most boat structures, whether wood or fiberglass, are designed to resist a sensible amount of strain resulting from natural causes, not an enormous strain caused by human error. Once the slack is taken out of the wire, every amount one takes up on the turnbuckles has to come out of the boat someplace. A tight headstay is desirable for a couple of reasons, but there’s tight enough and then there’s way too tight. Working in the yards one of the most frustratingly illogical things I would see all the time was rod rigging tightened up far more than one would ever tighten wire. If questioned, the owner will always say, “It’s rod rigging, it’s supposed to be tight.” The fact is the advantage of rod rigging is its minimal stretch. Therefore, it can match or exceed the performance of the wire at much less tension than wire rigging. This should be one of the advantages of rod, but almost invariably rod rigging is set up so hard that it puts the structure at risk.

In another related matter that has little to do with this book, I would like to point out that if a boat has been re-rigged (much more common in older wooden boats than in glass boats), the mast step areas and chain plate areas should be looked at very carefully. The structure of most boats is designed for a specific rig whose elements are in specific places. Moving the mast step or the chain plates should involve re-designing the structure to resist new strains in new places, and this is not always done.

The book contains an excellent discussion of the fiberglass blistering phenomenon, and this should be read by anyone contemplating remedial action for such a problem. The author notes that blistering has never been much of a problem in early fiberglass boats, even though they can be fifteen years or so older than the blister-prone boats of the 1980’s. The reasons appear to be thicker gelcoats and thicker, less flexible structures in the older boats. More points for heavily built boats.

I feel there is an omission in the chapter about seacocks, in which the author states that there are two kinds of seacocks, namely gate valves and ball valves. Nearby he shows an illustration of a traditional, cone-type seacock and points out that it can be disassembled for lubrication. He correctly condemns gate valves, which have no place below the waterline though they are often seen. A cone type seacock is actually a third type entirely and I would not lump it in with ball valves. The cone type seacock works with a bronze-against-bronze seal that can last nearly forever if it is properly greased, whereas the ball valve depends on plastic contact surfaces that have a fixed lifespan. The bronze cone can even be lapped with valve grinding compound to renew the accuracy of the fit. We feel that in this vital safety-related component there is no substitute for bronze cone-type seacocks, and we particularly recommend the Spartan brand, despite the fact that in our opinion they over-machine the cones, which when new should sit a little bit “high” in their sockets to allow for future lapping of the cones. Instead, on all the ones we’ve seen, they fit a little low in the sockets. To the best of my knowledge, so far the manufacturer has not been interested in this objection, but they are still the best seacocks of which we are aware.

The author emphasizes the importance of stringers and bulkheads in producing a sufficiently rigid boat, and describes how bulkheads can be installed to allow a bit of hull flexing without creating a localized strain in the laminate. I would just like to add that the thicker the basic hull laminate is, the less it must rely on added structural members for rigidity, and the less its flexibility must be taken into account.

On page 70 there is an illustration whose caption says it shows an Edson rack-and-pinion steering gear, but I would call it a push/pull arrangement. This is probably a production error. To me rack and pinion is a toothed cog connected to the steering wheel, turning a toothed quadrant on the rudder shaft. In this section the author correctly points out that traditional Edson worm gear steerers eliminate “feel” of the rudder. This is true and might rule out the system for some owners, but having sailed for many years with such an arrangement on my father’s boat I wanted to point out that one advantage is that if you let go of the wheel it tends to stay where you left it without lashing it or clamping it, which is quite a nice labor-saving feature if you can live without the “feel”. He sensibly mentions modes of failure to look out for, on the worm gear units, but I would also like to point out that they are probably the longest-lived and most reliable type of wheel steering system.

In his discussion about bilge pumps, the author touches on a couple of my own pet peeves. Probably more boats have been sunk by their own bilge pumps, right at their own moorings, than from any other cause. Usually this is a result of the omission of a vented loop in the discharge line. A simple loop above the waterline is not sufficient, because the weight of the water running back down to the pump in the bilge is enough to cause back-siphoning. This is most likely to be a problem when the boat is underway, but with the discharge through-hull just above the waterline it could happen right at the mooring if the boat was already low for some reason such as a leak. Another common fault he points out is the use of the very cheap corrugated plastic hose sold by some pump manufacturers. In the real world, this hose is prone to puncture, crushing, crimping, and fatigue, and depending where it is installed, its failure can result in a big leak or a run-down battery because the water being pumped never leaves the boat. Only wire-reinforced smooth rubber hose is suitable for critical applications like bilge pumping.

There is no mention in the book of electrical bonding systems, in which all of the metal items underwater are bonded together in an effort to resist corrosion. This type of bonding system is commonly recommended in books about marine wiring. Whatever its theoretical advantages, in the real world these systems usually seem to encourage widespread corrosion rather than reducing it, and most surveyors we know routinely recommend that bonding systems be removed. In glass boats it is only the metal hardware that is at risk. In wooden boats both the hardware and the wood can be affected.

In one section the author says that carbon fiber masts are to be recommended for long distance voyaging yachts because of the increase in stability resulting from the reduced weight aloft. While this is technically correct, in my opinion few voyaging yachts would find the cost to benefit ratio to be favorable enough, and we note that recent studies have proven that while stability is increased by ultra-light rigs, resistance to capsize induced by waves is greater when there is a certain amount of weight in the rig.

When discussing rigs, the author points out how efforts to keep cockpits clear by sheeting the main boom from its mid-point, forward of the cockpit, are misguided because the booms tend to break. While these booms probably do fail rather frequently it is surely a matter of engineering the booms correctly—the configuration ought to work if this is done.

The section dealing with surveying the rig omits discussion of cracks in swages, though it points out the swages should be inspected. In my experience cracked swages are easily seen when any surface corrosion is removed with a Scotch-Brite pad. No crack in a swage can be tolerated. Cracks are more common at the lower ends of the stays than the upper ends, presumably because the upward-facing swages allow some water to drain in, through the channels provided by the lay of the wire. Cracks and crevice corrosion in swages occur more often in boats used in warm climates, where the combination of salt and heat greatly encourages corrosion. Many owners and riggers work a small amount of silicone sealant into the tops of the lower swages to help the water to run off.  In my surveys I give high marks to Norseman or Sta-Lok mechanical terminals, which seem to be excellent and have none of the disadvantages of swages. Note that they can also be re-used if the internal cones are replaced each time.

The author assumes nobody uses three-strand rope anymore, which is statistically about right, but I use it exclusively because it’s cheap, it looks right, it splices easily, and it often lasts longer because it is less prone to sudden failure from chafe or from hooking the braided shell on something like a cotter pin. Braided rope can stretch much less depending on the type, however.

There is a good section about writing up a survey, to which I would only add a couple of things. As the author points out, the surveyor’s job is partly to establish the suitability of the boat for its intended purpose. Since purposes can change, I approach this a little differently in my surveys. Early in the survey I write about “Limitations of the vessel in terms of its Design”, meaning “What can’t you do with it?” and then, “Limitations of the vessel in terms of its Construction” meaning as built originally or as modified, what can’t it take? Thus the questions are answered for a range of possible future uses. In my write-ups I always list areas that cannot be inspected, and because surveys are usually lists of faults unrelieved by positive information, I usually phrase the beginning of each section by saying, such and such an area was inspected using such and such a method and “Found to be in good condition with the following exceptions:”

In discussing valuations of boats, the author correctly points out that cosmetics greatly affect price, and he suggests that they can affect value by 10% to 25%. In my experience it is more than that, and I would go so far as to say that a really poor-looking boat is nearly impossible to sell compared to a great-looking boat. In my experience appearance even seems to trump fundamental condition for many buyers. This is illogical, but my observation is that if the customers can’t emotionally bond with the boat due to its poor appearance, they will not buy it, whereas if they fall in love with a pretty boat they will overlook many things they should not, in order to buy it. Few repairs justify themselves in terms of market value, but cleaning always does and cosmetic paint and varnish sometimes do. As the author points out, a new or recent engine can often recoup its own cost or something close to it, and at the very least makes the boat more likely to sell fast.

Lastly, the author discusses the need for professional surveyors to be able to make recommendations to bring the boat into line with various standards organizations such as ABYC. I would just note that very often yachts for serious use should be outfitted to higher standards than these, and a professional surveyor should also be able to point out when a higher standard is warranted.

While I have used the various points above to present some of my own views and to point out a couple of minor defects in the book, I am very pleased to recommend this book to anyone who owns, or is shopping for, a fiberglass sailboat. If everyone who needed to read this book did so, they would have a lot fewer bad experiences, boat sale values would become more rational, insurance rates would go down, and safety would be increased. The purchase price of the book is insignificant compared to the amounts the information in it can save.  $17.95


Dan MacNaughton

Searsmont, Maine

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