The Offshore Voyaging Reference Site

Six Warnings About Buying Fibreglass Boats

Here are six important things that Phyllis and I are taking into account as we think about buying a fibreglass boat.

And at least two of these warnings apply to the purchase of boats built from other materials, too.

Let’s dig in:

Login to continue reading (scroll down)

More Articles From Online Book: How To Buy a Cruising Boat:

  1. The Right Way to Buy a Boat…And The Wrong Way
  2. Is It a Need or a Want?
  3. Buying a Boat—A Different Way To Think About Price
  4. Buying a Cruising Boat—Five Tips for The Half-Assed Option
  5. Are Refits Worth It?
  6. Buying a Boat—Never Say Never
  7. Selecting The Right Hull Form
  8. Five Ways That Bad Boats Happen
  9. How Weight Affects Boat Performance and Motion Comfort
  10. Easily Driven Boats Are Better
  11. 12 Tips To Avoid Ruining Our Easily Driven Sailboat
  12. Learn From The Designers
  13. You May Need a Bigger Boat Than You Think
  14. Sail Area: Overlap, Multihulls, And Racing Rules
  15. 8 Tips For a Great Cruising Boat Interior Arrangement
  16. Of Cockpits, Wheelhouses And Engine Rooms
  17. Offshore Sailboat Keel Types
  18. Cockpits—Part 1, Safe and Seamanlike
  19. Cockpits—Part 2, Visibility and Ergonomics
  20. Offshore Sailboat Winches, Selection and Positioning
  21. Choosing a Cruising Boat—Shelter
  22. Choosing A Cruising Boat—Shade and Ventilation
  23. Pitfalls to Avoid When Buying a New Voyaging Boat
  24. Cyclical Loading: Why Offshore Sailing Is So Hard On A Boat
  25. Cycle Loading—8 Tips for Boat and Gear Purchases
  26. Characteristics of Boat Building Materials
  27. Impact Resistance—How Hull Materials Respond to Impacts
  28. Impact Resistance—Two Collision Scenarios
  29. Hull Materials, Which Is Best?
  30. The Five Things We Need to Check When Buying a Boat
  31. Six Warnings About Buying Fibreglass Boats
  32. Buying a Fibreglass Boat—Hiring a Surveyor and Managing the Survey
  33. What We Need to Know About Moisture Meters and Wet Fibreglass Laminate
  34. US$30,000 Starter Cruiser—Part 2, The Boat We Bought
  35. Q&A, What’s the Maximum Sailboat Size For a Couple?
  36. At What Age should You Stop Sailing And Buy a Motorboat?
  37. A Motorsailer For Offshore Voyaging?
  38. The Two Biggest Lies Yacht Brokers Tell
Inline Feedbacks
View all comments
Richard Elder

Hi John
I’d put an exclamation point behind every sound comment you’ve made! And add a #7: Never buy a fiberglass boat with a full liner, regardless of whether it is bonded in with bearshit or a flexible adhesive like Plexius.

Perhaps we should add a #8: never buy a fiberglass boat that has the chainplates bolted in and covered with fiberglass to cause crevice corrosion .

And for me at least: never buy a boat with a cored hull unless it is built with epoxy resin.

Richard Elder

Hi John
See my note to Drew below:

Resin infusion with polyester? Why? Only because the bean counters told you to!
Now if the outer skin is as thick as a typical single skin boat and multi-layer epoxy barrier coat is applied underwater and is sufficient to prevent moisture penetration, the hull might remain sound over its lifetime. Is it a “good” resin infusion job? Not in my book.

Airex foam has a very low heat distortion temperature rating that can be reached in direct sunlight. As such it is not really suitable for decks, and hulls should not be painted blue or black if they are bound for the tropics.

Vinylester resin is “more” resistant to water penetration than polyester, and somewhat tougher. And a lot cheaper than epoxy. Exactly what that means requires more information than can be gleaned from a ASTM data sheet. “Trust but verify!” Is it suitable for balsa core infusion in hull bottoms? The more important question is: are the bean counters managing the company? Is this the last hull out of the door before bankruptcy? Or the first before the process has been refined? Do the court records show someone trying to hold the manufacturer liable for a failure?

Dick Stevenson

Hi John,
As one who had a LeComte Northeast 38 for 15+ years, I was intimately introduced to many of its shortcomings as it was bought as a complete insurance write-off. We made it into a wonderful coastal cruiser for my family with 3 children: but it took awhile.
That said, I will add one more general caveat: not every wonderful coastal cruiser, especially fg boats, will enjoy the transition into offshore passage making. Some of the problems you mentioned on our LeComte only appeared on a boisterous offshore passage to Bermuda. Others appeared as well and convinced us that, much as we loved her, she was not going to be the boat we would sail off into the sunset. Offshore is much rougher on a boat and reports of a boat’s performance and toughness coastal cruising may, in no way, reveal limitations that arise on a challenging ocean passage.
My best, Dick Stevenson, s/v Alchemy

Neil McCubbin

Your distrust of venture capitalists is a good warning. The world is full of companies who make a fast buck by buying a top quality manufacturer then selling cheaply made product at high price. The frequent bankruptcies of boatbuilders make this field ripe for such scams. Even when the venture capitalist is in good faith, one has to wonder how he can do better than the original guy who built the reputation

Henry Rech


If there was a chance, however small, of bashing, at hull speed, into a container floating around in a transatlantic shipping lane with your name on it, would you believe that a soundly built fibreglass boat would be strong enough to survive the collision?

Andrew Craig-Bennett

I’m not John. I run container ships, and in 40 odd years in the business no ship in a fleet managed by me has lost one over the side, so far.

To try to answer your question, containers are water perméable and will flood quickly. There’s a video of empties being blown into Hong Kong Harbour in the recent typhoon and sinking in a couple of minutes. The container will often stay barely awash if it contains goods packed in lots of Styrofoam. Since it is barely afloat it is hard to see but a sailing yacht’s forefoot will ride over it so some deceleration will occur before the keel contacts the container.

The forefoot is one of the stronger parts of the boat; whether the keel remains attached depends on all the factors that would apply to a grounding at similar speed but in this case some of the speed will have been lost as the forefoot rides up and over the container.

So yes, a typical GRP yacht stands a pretty good chance of coming out of an impact with a floating container still watertight and seaworthy enough to continue her passage.

Henry Rech


Reading your comments above and others in your other articles in this vein it seems to me that whatever construction material you use, whether it is FG, steel, aluminium even ferrocement, the general admonition is to know your boats construction history and have it thoroughly surveyed. It seems to me all construction modes have their advantages and disadvantages and your preference is generally formulated around avoiding what you fear most.

Anyway, personally, I would not touch a FG boat to be used offshore unless it had 1″ at least thick solid lay up in the garboard and the bow area.

Philip Wilkie

“the general admonition is to know your boats construction history and have it thoroughly surveyed.”

Which can be a lot easier said than done. The survey we had done was for insurance purposes only; I damn well knew it wasn’t the whole story, and in the end I decided to rely on my own judgement. And once a boat has passed through several owners it’s impossible to tell truth from fiction.

Fortunately we found the original owners who had spent 13 years sailing our boat around the world and were able to visit them (after we had bought it). That gave us a lot more confidence that we hadn’t bought a total lemon.

Brent Cameron

Having sailed on lots of older boats but also having owned (and recently sold) an old Paceship, I get your point about old not necessarily being better – although my Paceship was built like he proverbial brick shit house. I had the occasion to use a hole saw to drill a 2” diameter hole through the hull for a speed/depth/temperature transducer and another 3/4” one near the rub rail for a bulge pump so I got to see exactly what it was made of. Not a whiff of chopped strand matting in either sample and the 2” one was almost 1-1/2” thick while the one near the rub rail was 3/4” thick. The resin was perfectly wetted and absolutely packed with cross directional matting. Having the unpleasant experience of running her aground not once but twice into a rock ledge in Georgian Bay (the second time at hull speed) and doing nothing more to it than denting the lead keel (and destroying my pride), I’d say to anyone that an old boat built right can be VERY strong but I’ve also seen many of that vintage or newer with mostly chopped strand matting that I wouldn’t touch with a 100’ pole. Walk around a marina and see where they haven’t put a stand against a bulkhead and you won’t sleep nights!

I’m in the market now for a good Amel Super Maramu or 54 and having crawled through dozens of them I can say that they are almost all very well built but it doesn’t take much for a bad owner to completely destroy the value in one as well. You know it is a strong boat when the manufacturer recommends lifting the boat in and out using the chain plates! Having sailed over 5000 miles in them up and down the Gulf Stream, I can say they take a real beating and don’t squeak and rattle even when REALLY pounding upwind.

That said there are a few really bad ones that should be sold for scrap because they were badly damaged and then shoddily fixed by yards with no ethics. One in particular (that is on the market now and pops up every few years) was blown off its cradle in a hurricane caving in one side and they simply glassed in a huge patch and didn’t properly tie it off to the bulkheads. The manufacturer said the only way to do it right was to put it back in the mold but they did it on the cradle and over course it isn’t true anymore. If that wasn’t bad enough they replaced all the rigging with something off another brand so destroyed the advantages. Some poor sod bought it and shortly after that ran it into a rock ledge that sliced the keel clean off it. Amazingly, it didn’t turn turtle or sink and they managed to get it to shore (thanks to the 5 watertight compartments I’m guessing). It was a write off again but somehow someone managed to buy a new keel for it but as they couldn’t lift it high enough in their boat house, they cut 6” off the bottom of the keel to make it fit! It’s out there for sale as not even the cheapest model hoping some other poor soul will think “it’s an Amel so it has to be good” just as you say.

John is exactly right on surveyors as well. I’d add that you should get a good surveyor who also knows the brand of the boat intimately (not the same thing has having surveyed them before). There are lots of surveyors that will say they know the boats but most will have no idea about the particular intricacies of the model and will call out things that are as designed and ignore flaming red flags. Also, I would add don’t get an “insurance survey”… they just care about valuing the boat and looking for obvious things to write in the report like expired fire extinguishers. It is your last chance to get stuff fixed at the prior owners expense (or deducted from the cost). Get a very thorough prepurchase survey that YOU pay for. On Amel’s the best surveyor used to be the QA guy at the Amel factory who did the final inspections and customer turnovers. He does a two day survey on a boat he know inside and out (and most likely recorded every single change to the boat). It costs money to fly him from France but he’s worth every penny as he will find things that could cost you several magnitudes of his cost that even very experienced boat owners might miss.

Great article.

Neil McCubbin

Paceships were built somewhat as a hobby by a company who was strong in industrial fibreglass. I bought some of their work. Quality and strength was way above the typical recreational boat.

Drew Frye

Two rather specific tips:

1. If there are fender washers backing ANYTHING up, check to see if they are bent into shallow cones. If they are, there is core damamge. 90% of the core damamge problems I have had to deal with was caused by thin fender washers being used as backing plates. The other 10 % was due to…

2. Poor wet-out on the inside of cored sections. I’ve owned boats that were vacuum bagged to economize on resin, with the end result that there were tiny, tiny pinholes in the laminate. Water gets in the core and it rots. There needs to be a resin-rich top coat, even on the inside.

I actually like cored boats (multihull guy), but attention to detail in the build and maintenance must be impeccable. I also think many should go solid in more keys areas than they do.

Richard Elder

Hi Drew
To elaborate on your #2;
The use of foam cores in fiberglass boat construction doesn’t mean everything is all peachy! I learned the hard way on my first large hull layup. We were using CoreCell (reputably the best available core material.) Vinylester resin, gell coat surface backed up by resin rich skin coat, Triax fiberglass, and core bedded into the recommended polyester based Core Bond putty under vacuum. Procedures were followed exactly as per written instructions and verbal instructions from the tech rep. The bond and core failure was so extreme that we caught it as soon as it came out of the mold. After a year in the courts we were eventually compensated.

Lesson: Core materials are inherently difficult to bond to. Secondary bonds are inherently weaker than primary bonds. Infuse it and use the best bonding resin possible: epoxy. And tent it so you can introduce enough heat to get the benefits of post cure strengthening and print-through resistance.

Andrew Craig-Bennett

I converted from wood after 40 years. I bought one dud and then one which is 44 years old, Halmatic / Camper &Nicholson, built for the British Ministry of Defence who sold her to me. Phenomenal mileage but maintenance not really an issue. So far, so good (grabs one of the few wooden bits!)?

Richard Elder

Hi Methersgate
Personally I’d take a cold molded hull built from Alaskan yellow cedar, with a 24oz glass outer skin bedded in epoxy over any cored fiberglass hull. (provided the hull interior was completely epoxy coated as well.) Of course I’d have to keep it forever. It could never be sold in North America because of the overwhelming prevalence of Woodphobia.

Peter Nell

Great and very interesting article – agree with all the points. The older the boat, the more careful one needs to be – and that’s before getting into rig, engine and all the rest.

“No fibreglass construction lasts longer than single skin”—Chuck Paine
Interesting, since Chuck designed the Oyster Lightwave 39, which has a balsa cored hull. I owned one, which had been raced in the UK, sailed to South Africa via Brazil, and then bought by me as a sailing school boat. She is is still going strong.

Charles Starke MD

Hi John
A friend drilled a core to install a thru-hull in a fibreglass hull. The inside layup was Chinese newsprint.
Best wishes
Charles L Starke MD
s/ v Dawnpiper

James Evans

My little Nellie Lamb was built with Coremat: a textile material that has holes in so the skins are also bonded together. It was very light, (2800 lb, 24 ft loa) very stiff – and I hear she’s still going after 34 years.
I haven’t heard about this stuff for years but it might be worth looking into.

Jeff Sowell

Hi John – I’d be really interested in seeing a discussion with examples of proper construction techniques (e.g., tabbing/bonding, structural reinforcement, etc.). The reality is that many of us are not boatbuilders and may have trouble knowing what to look for. Sure, I can look at a bulkhead and see that it’s been tabbed, but what makes the job properly done?

John Tynan

Hi John,
Following up on aluminium, my ideal would be “Strongall” patented by the famous French architect Michel Joubert and manufactured by the “Meta”.
Strongall is thick aluminium, about 2 – 3 times heavier than the normal. given this thickness it does not deform when subject to high intensity welding and the resulting structure is so rigid that it does not need reinforcing with bulkheads. It is also treated with a silicate galvanising process which enables them to guarantee against the possibility of electrolysis.

Michel Joubert and Jean-Pierre Brouns, another well known architect, used Strongall for their personal boats (both twin keelers incidentally). Obviously the boats are chined hulls given the rigidity of Strongall.

Andre Langevin

Remember osmosis never sleep !

Jeffrey Harris

Many comments address the requirement for using epoxy & vacuum bagging with balsa coring. What manufacturers do this? The only one I know of is Tartan. Are there others? This would certainly help narrow the list. Any comments on Tartan?

Matt Marsh

I’m not aware of any nice consolidated list of which builders use which techniques. It’s hard enough trying to get this information out of a sales rep at the boat show, when you’re standing there looking like a buyer and asking technical questions. Half of them don’t even know which parts of their hulls are cored, let alone what the materials are.

I don’t think I’ve ever seen a curved cored-sandwich construction work, repeatedly and reliably, without vacuum bagging. Hand layup simply can’t guarantee 100% core to skin contact, and “core bond” putties seem to be almost universally crap. There’s a huge amount of bad information floating around the boatbuilding sector, much of it coming from vendors of low-quality materials. A lot of shop foremen are convinced that they have a good system, because they’re using the “right” products and following the instructions for those products, not realizing that both the products and the instructions are bad.

Requiring epoxy will rule out basically all production fibreglass boats. You’ll be choosing between polyester and vinylester resins. If it’s vacuum infused, vinylester is the more likely choice, as it’s more osmosis-resistant and and it’s easy to make a strong ultra-low-viscosity vinylester that flows nicely for infusion. (On that note, any modern hull should be vacuum infused, rather than hand-laid or chopper-gunned; it costs a little more in vacuum bagging materials, but you save almost that much in wasted resin, and end up better than break-even once you factor in not having to deal with warranty claims from de-bonded hull skins, or OSHA hell from the styrene offgassing stinking up the whole shop.)

David Pascoe may seem like an angry old curmudgeon when he sits down to write, but not without good reason; he’s still pretty much bang on about how badly some of this stuff can fall apart:

Richard Elder

Hi Matt

If people think that the magic words “resin infused” or “vacuum infused” guarantee nirvana they should explore a bit further. Especially if it is done in conjunction with a foam core. The hidden pitfall in the process is the fact that the critical bond between the core and the outer skin is done blind, with no possibility of QC until the entire hull and bulkheads is pulled from the mold. All those $$$$ invested by that point certainly motivate the bean counters to insist that you charge on ahead instead of starting over like you should when the lamination bond sounds suspicious!

We were feeling pretty proud of ourselves after cranking out six infused hulls and decks of a high speed megayacht tender without a hickup using balsa and vinylester. The designer had worked hard to created the most difficult shapes for infusion possible, with lapstrake hulls and tall, narrow coamings around the cockpit. Fitting balsa to those shapes was beyond silly, but once we pulled a vacuum over the complete layup stack the actual lamination was a mornings work for two people.

The major project in the shop at the time was a 155′ motor yacht, so we set to work building interior bulkheads on the layup table. What could be simpler, spray gell coat, lay on matt for print control, triaxial glass for structure, Core-Cell with factory perforations, more structural fiberglass, and pull the resin into it. The bonds between the core and outer skin that came off the table were so dry that you could pull it off the core by hand! We ended up having to hand drill 3x as many 1/8″ holes in the core as the factory had supplied in order to make the process work. And that is why I prefer balsa over closed cell foams for resin infusion even if it is heavier.

PS: I doesn’t tell you in the instruction manual, but if you pull a vacuum over a styrene -rich resin system or bonding putty it can turn SAN foams to mush.

Just hope that the laminating foreman that built YOUR cored hull boat went through the school of Hard Knox first!

ps: If you ever intend to fly again DON’T read Pascoe’s article about the rudder failures on Airbus 300 airliners. The rudders are built from thin autoclaved carbon over Nomex cores with a huge unsupported cavity in the middle. That cavity has to be open to the atmosphere to compensate for altitude pressure changes, and therefore develops condensation during every freeze/thaw cycle on every flight. And you thought that owning an unpainted steel boat was a nightmare!

Terence Thatcher

I think presumably identical production boats vary immensely. For instance, secondary bonds vary by when they were made. Did the crew break for the weekend? Or were the secondary bonds finished the day after the initial layup. My Morgan’s secondary bonds have held up for 40 years, including many rough passages and both an Atlantic and Pacific crossing, but a sistership had broken bonds after one Atlantic crossing. Our boats also have corecell cored topsides, but solid glass below the waterline. That seems a good compromise and I would not own a boat with a cored hull below the waterline. My surveyor found no problems in the hull when the boat was 38 years old, but a leak in a deck fitting had rotted 2 square feet of plywood coring. That was due to my own negligent failure to find the real source of a leak for two years and a production error that placed a deck fitting in a cored portion of the deck. (All other deck fixtures bolt through solid laminate.) The real concern, if you are looking to buy, I guess, is what can escape a survey and whether there latent defects that may appear a year or three after a clean survey. I don’t think there is a perfect sailboat, but Morgan’s Cloud always seemed pretty close and now you guys are walking away from her. Surely there are aluminum vessels of slightly smaller dimensions you could choose. I will watch your search with much interest.

Matt Marsh

The question of why the boatbuilding industry is so bad at quality control, and what can be done about it, is an interesting one.

Let’s say you make car parts. Not as an OEM, but as a tier-1 or tier-2 supplier. You sell some simple component, let’s say it’s a welded steel blank, to a carmaker for $25. You let ten bad parts through, out of 100,000. The flaw is discovered in pre-ship inspection at the OEM, so you’re lucky – you’re only on the hook for 10 brand-new junked cars at $45,000 each. You just lost $450,000 on a $2.5M job that only had 9% profit margin to start with. If only you knew about QC earlier.

Or let’s say you make something for aviation. Make it a minor, trivial component, like a hydraulic hose crimp fitting. A chunk of bar stock of the wrong alloy makes it into your production line, then a batch of the things develop microcracks during swage pressing, then one spews hydraulic fluid all over the runway, and now we’d like to introduce Mr. Smith and Mrs. Jones from the FAA who are going to spend the next twelve weeks auditing your supply chain and all your internal records.

Boatbuilding has no comparable standard of accountability. Even if a vessel is built “in survey” with the ABS or Lloyd’s guy dropping by the shop daily to check up on things, the builder’s always under much more pressure to keep costs down than he is to verify the correctness of the work. QA procedures, workflows, and best practices are poorly understood and often ignored in the name of expediency.

Richard Elder

Funny that you should chose the FAA as an example of QC that we should emulate. Boeing thought they had the problem under control by simply (bribing?) assuming the FAA’s oversight capability and doing it themselves. Looking over their shoulder at the Airbus competition, Boeing Sales demanded that Engineering save money by hacking the 50 year old 737 fuselage to accommodate larger and more fuel efficient engines. The result is an albatross called the 737 MAX that is so unbalanced aerodynamically that it needed electronic systems to override pilot control to avoid it self-stalling. Rather than providing redundant electronic pilot assistant systems, they again saved money by only providing a single airspeed and stall data input. And then compounded the problem by not telling the pilots how to override the system– again to increase marketing penetration by eliminating the cost of re-training pilots.

And you thought that sailboats designed by bean counters were a problem!!!!

Matt Marsh

I did not say we should emulate the FAA. I said that if you are selling things into a sector regulated by the FAA, and you screw something up, you’ll be extensively investigated and it’ll cost you a lot of money. Very few boatbuilders, in any size or price class, face nearly the same level of independent external scrutiny. As several navies have found in recent years, even paying a nine-figure price per ship is no guarantee that it won’t develop major structural flaws on its shakedown cruise.

Regulatory capture, as happened in the 737 MAX story, is a different, related but distinct, problem from having poor quality control and minimal consequences for failing at QC.

Eric Klem

Hi All,

Quality is definitely tricky and I think it is worth looking at where in the product cycle we are talking about.

Quality starts in the design phase. In many cases, there are standards that must be adhered to although these standards are usually related to safety not performance. In most industries, it is common to have an outside company test for your compliance to the standards. In design, you create your own requirements that cover things not covered by standards and then it is how good these are and your adherence to these that determine how everything ends up. Design is also where you do things like set up what requires inspection, etc so something like an out of tolerance part slipping through in manufacturing could actually be a design issue because no inspection was ever specified or the tolerance was set too wide.

On the manufacturing side, the concept is a bit more straightforward although it isn’t necessarily straightforward to implement. The most common quality standard is ISO 9001 and its variants such as 13485. Companies typically get certified by specialized companies to these standards and then you know that they have systems in place that should at least flag and deal with most quality issues. Quality systems should also cover how to deal with supplier quality as well so that you can control quality of purchased components and assemblies as well as ones you make yourself.

Then there is service. To do service right on more complicated systems, you need to document how to do it and do a good job of training people to do it. The products that I design are only serviced by our own employees and even then there are often issues, they are complicated enough that most people would not be able to root cause most problems. As a result, you typically end up with highly specialized service people when you get to complicated systems.

I have not worked in the boatbuilding world but have been involved with boats enough to know that the boatbuilding world does not approach quality in the same way as most industries which while not perfect is significantly better. The safety standards that would be typical in many other industries are lacking, there are some standards like ABYC or CE but these are very systems focused and don’t look at the design as a whole. Then, the builders are self-certifying to these and they are not doing a good job of it as evidenced by things like the seacock installations that don’t meet ABYC. One of the more surprising things to me is how underdefined the designs of most boats are, it means that the same design could be built in multiple different ways which is kind of crazy if you want to ensure quality (a wild guess: the higher volume builders are likely much better at this as part of scaling is getting everything documented to be easily repeatable). Going to the building side, it is pretty clear that rigorous quality systems are not in place at many builders. Many people would contend that one sure way to have no quality control is to allow un-approved changes to occur on the floor. On boats not designed to really low safety factors, there are many skilled workers who would hate this type of rule as they possess the judgement to do this kind of thing but then again, you also wouldn’t end up with people drilling random holes through cored hulls and then not sealing them properly so pick your poison. While it undoubtedly varies from manufacturer to manufacturer, it is pretty clear that quality systems could be improved. Service is a complete disaster in the boating world, people are expected to be able to do everything and a suprising number can’t do anything at all well, both owners and “professionals”.


Eric Klem

Hi John,

Ouch, sorry to hear of the troubles.

It will be interesting to hear your thoughts on how to be your own QC department. Our way of dealing with it is to simply do everything ourselves but that is a far from perfect solution and there are times when we feel like we are falling behind although those times are always short lived. On boats that I have owned, the only 2 services I have ever paid for are having the boat lifted and having the mast lifted. At some point, I am sure that this will not be sustainable and I will need to learn how to have others do the work.

One unfortunate part of the increasing complexity of everything is that the skills to repair it keep becoming more specialized. It isn’t as bad as it sometimes seems as more and more parts are meant to be replaced instead of repaired (different environmental issue here) but it is still not easy.


Richard Elder

Hi Matt
Right you are. I should have used a better choice of word than emulate. And failure of QC and regulatory capture are two different issues. My comments should have more properly been directed at design failures introduced by sales and financial directives rather than engineering imperatives.

Steve D

I’m going to jump in here in defense of cored composite construction. While most builders avoid it below the WL, it’s not for technical reasons, at least not anymore, it’s for sales reasons, and that’s because many early FRP vessels that had cored bottoms ended up with wet cored bottoms, because the builder made mistakes in the construction process, or aftermarket installers were the culprit. They in turn generated a very poor reputation for cored bottoms that endures tot his day.

I’m actually sitting in an airport, on my way home form a week long inspection tour at an Asian yard, where every hull, topsides and bottom, is fully cored, albeit using synthetic core and vinyl ester resin infusion. That builder is absolutely religious about proper core closeout where ever they haven’t already installed solid laminate for hardware installations like struts and shaft logs. With that level of attention to detail, I have no concerns what so ever about a cored bottom, when designed properly it’s light, strong and stiff.

In the absence of that level of engineering and production control, well, I have much greater concern, however, the flaws are often all too easy to identify. If a builder says they rely on sealant to close out core, anywhere, above or below the WL, that’s a massive red flag, and yet it is all too common.

Several years ago, while I was managing a boat yard, we had a case of a late model 26 foot power boat, all cored hull, that was essentially a write off. The owner purchased it new, and had the dealer install a transom mounted transducer, the person who installed it drilled a few holes, slathered some sealant over them (over the bottom paint no less) and tapping screwed the mount in place. Water got in and migrated through much of the hull. The owner simply could not give the boat away, a real heart ache, not the builder’s fault and totally avoidable. If a bottom is cored it should be synthetic core and while resin infusion isn’t mandatory, I feel better about an infused cored bottom as opposed to a hand-laid cored bottom.

I routinely tell owners of FRP vessel, virtually all of which are cored at deck and cabin and often hull sides above the WL, you must be well-educated on this subject, don’t let anyone near the boat with a drill or saw until you know that they understand cored composite construction and proper closeout technique, and of course to make that determination you must be educated on the subject. More about which here

Steve D

To be clear, I’m not suggesting anyone seek out a cored below the WL hull, I’m simply saying they should not be dismissed out of hand if the builder has a good reputation. You’d evaluate a potential vessel for wet core above the WL, as well as moisture in the laminate below the WL in any event, so this is little different.

I’ve had above the WL core saturation issues, with balsa and plywood, run into the tens of thousands of dollars for repairs, a wet bottom is an equally undesirable heart ache. I’m simply saying you have core everywhere else, and rain water is actually more likely to promote rot than seawater in timber core.

Closed cell SAN foam core is highly resistant to water absorption. If it’s been infused then it’s virtually water proof, as the unfilled kerfs, as you note, can allow water to enter in a process known as channeling.

There are a number of high quality synthetic core materials that will not absorb water, Gurit PVC and Corecel M are two popular examples. The latter carries GL, DNV, RINA, BV, Lloyds and ABS certification.

Gerben Van Duyl

PVC/foam core comes in many different qualities, and a properly engineered core schedule (different weights/qualities of core appropriately used in different locations in the hulls and decks) should be perfectly fine, especially when combined with a properly engineered lamination schedule and infused with vinylester, in a single mold infusion for the entire hull (avoiding secondary bonding as much as possible). At least that is what I have learned as I am preparing the build of CAT43, an affordable 43′ adventure catamaran (think A40, but a cat). Yes, balsa is to be avoided, of course.

Richard Elder

Hi Gerben
As you proceed with your project it is important to realize that it is possible to produce a construction disaster using the “best” materials and following the manufacturer’s recommendations to the letter.

“balsa is to be avoided,or course” I’m afraid that that statement is based upon an incomplete understanding of the infusion process.

All materials have their strengths and weaknesses. In the case of infused balsa there are several key differences compared to foam: 1. greater stiffness along the end grain. Indeed, balsa can be too stiff for fiberglass skins, and is suitable for higher modulus materials like carbon fiber. 2- superior bond strength between the core and skins due to the presence of open kerfs filled with resin. 3- more error free infusion due to greater paths for resin flow, and therefore more suitable for first-time users.

A balsa core infused lamination will be nearly as impervious to water intrusion as a foam core lamination. Indeed it may be superior due to greater resistance to core sheer failure.

Infused foam core.
As you suggest there are many different types of foam with different properties. I’ll limit my comments to SAN foam of the CoreCell brand.

1- All varieties of vinly ester resin are not the same. The builder must be absolutely certain that the combination of the resin, core material, and high vacuum pressures are compatible.
2- Vinyl ester resin is inherently more demanding for amateurs than epoxy resin. It demands proper mixing of promotion agents and catalysts in small quantities to perform properly at different temperatures. And open times are short, making knowledge of how to fix infusion problems on the fly critical to make the process a success.
3- In the absence of the large open kerfs of end grain balsa, ensuring full resin flow to the outer skin is critical to a successful infusion. This is a blind process that cannot be QC’d until the hull is completed and cured. I highly recommend clear/no gell coat be used to enable visual examination of the outer skin before proceeding. The cost of failure of an entire hull is high. And add hull painting to the already high cost of the SAN foam.
4- CoreCell foam has two substantial advantages: 1- It’s stiffness is more closely matched to that of fiberglass skins, producing a structure that has considerable impact resiliency. Under impact a stiff balsa core will transfer the stress directly through to the inner skin blowing the laminate apart, while a similar layup of somewhat resilient SAN foam may remain intact.
5- Due to it’s reduced resin absolution and initially lighter weight, foam cored hulls will be substantially lighter—- an important consideration when building a multihull.

Gerbin, I see that you are planning to infuse your hulls in a female mold. Unless you are using an existing mold, building an infusion-capable mold in order to produce two hulls is very uneconomic. The break-even point for mold tooling usually falls closer to four units.

Bottom line: Foam core vs balsa core for underwater hull structures:

—–Moisture intrusion risk is very low for both systems
—–Failure modes are different, with the advantage going to SAN foam.
—–Cost is substantially lower for balsa.
—–Foam holds the edge for weight-critical applications.
—–Epoxy resin is superior on all dimensions except cost.
—–Excellent hulls can be produced with properly executed resin infused vinylester.

While I’m on a roll, let me destroy the myth that infusion is always better than hand layup.
Anybody who disagrees should watch how it’s done in Jim Betts shop in Anacortes WA.
His boats are all built with an epoxy wet layup carbon skin over foam cores, and squeegeed to the point where the resin to fiber content is at least as low as an infused lamination. The large sheets of rigid CoreCell are “tortured” over an open birdcage male mold, making use of the self-fairing nature of the material when used in this way. QC is continual on every layer of structural material that goes onto the hull.


So what would the consequences be for a wet cored hull out of the water for the winter and then freezing? Would it expand and wreck the hull?

Richard Elder

Hi John,
Traditional cold molding at yacht scale is almost never done anymore due to woodphobia, but also because it is so labor intensive. I know of a 50 footer built for the Admiral’s cup in the late 70’s that has hulls built of 17 laminations of 1.5mm veneers! If I were building a wood ocean cruiser the size of MC I’d edge glue a strip plank cedar core and then do two veneers on the diagonal. Or more likely just overlay the strip plank with glass and epoxy like the Kiwis used to do.

The Kurt Hughes cylinder mold process is so different that it really shouldn’t be called cold molding. It is actually a method for building curved plywood and then torturing it the rest of the way into a fully developed, fair hull form without the use of a mold.* With the high cost of foam cores and resin it is enjoying a moderate revival. The hull form needs to be 10/1 or better just like a proper catamaran hull. Almost exactly diametrically opposite of traditional cold molding, it is the cheapest and by far the fastest way to build a long, skinny, fully rounded hull. Somewhere in Kurt’s files he has a time lapse video of a 70 ‘ half hull being built in a single day.

* Kinda like the magic Garcia Sr. used to perform in aluminum with his giant roller,

Devon Rutz-Coveney

Hello John!
Great subject to debate on….
As the owner of a 70’s era Uniflite Valiant 40 I know what you are talking about. As a young lad (28 years old) I bought the boat with the idea of sailing into the sunset and enjoying life…. I had recovered from cancer and wanted to live a bit. The ‘marine surveyor’ I hired from the San Francisco bay area was supposedly a reputable guy. In retrospect he was an idiot…
The mid 70’s Valiants had big issues…. as we all now know.
It was 30 years ago that I bought the boat and moved aboard. I knew how to sail my first boat, a Lido 14 well and had experience as crew on other people’s boats racing……. and that was it.
As you can well imagine, it was a very steep learning curve, on a 40 foot cruising boat, sailing out the Golden Gate, singlehanded and ‘turning left’.
I have fixed (almost) every single thing the people at Uniflite (with the best of intentions) did building the boat.
This is the point of my contribution: if I could do it, so can others…
Sure, it takes time and money…. so what….. that is life. In retrospect, the boat ‘saved’ my life. At the time I could afford my boat and it was my way of having a life I could have only dreamed of! I have managed to keep it going for over 30 years, having a great time! I have lived within my means and fixed all the issues myself: replacing the aluminium tanks with integral (epoxy/glass) tanks, re-skinning the entire hull with new glass and epoxy (encapsulating the funky keel Bob designed on the earlier boats… even though he said it would not work, it is….. 20 years on now and counting!), re-wiring every single system, re-plumbing everything.
The boat had very little offshore kit so I paid people early on to select and install items only to discover hundreds of miles from shore that the money I spent was for very poor quality workmanship….each and every job failed due to some shortcut taken by the ‘professional’ installer! Essentially I had to learn refrigeration, marine electronics, plumbing, diesel and outboard service, fiberglass work, rigging, sail repair …. etc…. ALL the things that every good sailor does to keep his/her (fibreglass) boat going….
The point: why on earth contribute to consumerism and waste by discarding that which seems too old or unfit to fix? Many, many people, over the years, told me to ‘give the boat away’ and get something without all the issues.
More recently when repairing the boat’s oven/stove (the company who made it was out of business), a local classic aircraft restorer told me, “if someone built it, you can figure out how to fix it”…. he is right.
IMHO leave the new ‘flash’ boats to people with big wallets and no imagination…. they mostly just sit in the marina anyway!
People who aspire to cruising (in a ‘sustainable’ way) should consider an older boat needing work. They will learn the boat for sure and learn the skills they need to keep it going…. IMHO
One day, when I’m too old to keep the boat going, “they’ will drag me off of it…. Until then, I’m going to keep sailing!

Richard Elder

Hi John,
I’m not sure I agree with your suggestion that it may be better to live life as a wage slave until you accumulate the funds to buy that illusory perfect cruising boat. A recent survey shows that 70% of Americans hate their jobs, so Devon’s 30 year adventure with his Valiant seems pretty appealing in contrast. One thing for sure— it has made him a different person than if he had spent the same years in an office cubicle bowing to the whims of a boss. LOL

Richard Elder

Hi John
Looks like you haven’t been any more of a fan of being a wage slave than I!
Your career choice of being an AppleMan was certainly more profitable than my choice to design and build boats!

I used to lease the plant where your boat was built and employed a couple of guys who claimed to be yacht carpenters from the Valiant era. Finally got tired of fixing their botched work and sent them over to my laminating division run by a good ole boy Harley Davidson rider. End of problem!

Devon Rutz-Coveney

One last item… yes! I also re-tabbed all the lightly tabbed bulkheads… to the hull and deck, epoxy and glass and then screws (per Alan Viatses & Dave Gerr’s books on the subject)

Devon Rutz-Coveney

Thanks for your comment John… I appreciate I can be very opinionated about issues, after all …. I’m a sailor!
It is all about enjoyment isn’t it…..
For my part, and I suspect there are heaps of sailors who feel the same, the journey (fixing stuff, installing stuff, using the stuff, investigating the stuff…ect) is a lot of fun all by itself.
I wouldn’t change my experiences even if I had the opportunity…. It has been a wonderful journey. This is why I commented on the forum: an older boat, with issues does not mean that a lot of enjoyment cannot be had…. and help save the planet from un-necessary waste caused by consumerism… All the best….

Jeffrey Harris

I am well down the road of a new boat purchase. For the benefit of members contemplating the move I will forward along my experiences and advice while in the AAC tradition, trying to avoid brand bashing (although you can probably figure it out). I have owned other boats, but this was my first experience with a new build. Most of my comments simply reinforce what John has already said in his article.

Utilizing AAC recommendations, I aimed toward an epoxy glass one shot structure, no secondary bonds, vacuum bagged, with foam hull and balsa deck coring. This manufacturer also fabricates their own in house carbon fiber masts. The structural build and longevity of the company passed all muster, having been in business since 1960 with a well known and regarded designer at the helm.

My overriding advice is not to confuse the emotion and excitement of a new yacht with a business transaction. Do not expect any of the “comraderie” we share in other aspects of boating. To enter in to a big ticket item such as this should be handled as any other business purchase, with appropriate contractual oversight etc. Avoid the naivete into which I entered this project. From the first deposit, this is really a blind leap of faith and trust that your builder will perform as agreed. Mine did not. At almost every step of the way the contract was casually violated, and all “handshake” agreements were worthless. Understand going in that once the money starts changing hands the builder is at will to ignore the contract with little recourse.

Some examples I reference as follows: At the agreed to completion date the boat hadn’t even been started. The initial deposit was placed in October for a spring completion. The entire season has now been lost. An electric propulsion system had been diligently designed by the Oceanvolt representative at a mutually agreed to price by all parties only to be unceremoniously defaulted upon by the builder. Other customizations such as adding a cabin heater were at a cost 10% above what any boat yard would charge, despite the 20% discount oem builders receive from suppliers. Communications were nearly non existant. About the only time I would hear from the builder was in soliciting more money, which more often than not was an incorrect figure. Most egregios of all was the written agreement of a specified credit for use of my new boat for display purposes in two boat shows. Without so much as any notification or explanation this figure was arbitrarily reduced 15% . When queried the explanation was that because most of the original options (including the electric propulsion system) were deleted, the net price of the boat had changed. Of note is that the most expensive options were deleted by the builder, and that no where was this credited amount based upon a sliding scale of the price of the boat. The point is that even with a reputable builder, a buyer is unusually at risk. Once the money starts changing hands you’re not likely to get it back.

Purchasing a new boat should be a more pleasant exercise than contract law. I was sadly naïve in that I expected something of the blue water ethics we all share, but this is not the way it works, at least with an American builder.

So my friends, regardless the longevity or reputation of the company you choose to do business with, don’t forget it is absolutely a buyer beware situation. Sadly, don’t be surprised to consider the need of having a few lawyers on standby as you go down this fairway!

In the end, I believe I will be reasonably happy with the quality of the product. The overall “building a new boat” process however was very much a disappointment. Given the known quantity of the many well kept brokerage offerings, I would be more inclined to go that route next time.

Richard Elder

Hi Jeffrey,
I’ve been an expert technical witness in several such situations which reinforces my conclusion that when it comes to money, boats and sex, liars lie all the time.

I observed one such situation where the yachtbuilder and the client had developed a thorough hatred for each other. When the builder tried to rip the customer off to the tune of a half million dollars the customer took me aside and said “you don’t know who I really am, but I have people who will take care of that F*********.” ” When he’s gone I want you to take over the company, finish my boat and run the business for me.” I ran like hell like anybody who valued their thumbs would. A few months later the yachbuilder was driving his new Mercedes convertible on a lonely rural road when he ran off the road and broke his neck.

Would you like a referral to an attorney who represented a wronged customer in another boatbuilding liability lawsuit that was settled in court rather than on the road? His trade name in Seattle is “Mac the Knife.”

Jeffrey Harris

Thanks Richard! The whole idea of buying a boat – especially a new boat – is supposed to be fun, a reward for other things done well. Having it go to litigation or worse is certainly not in the plan. That is what my “warning” post was meant to convey. Other AAC articles and John’s posts are similar. Your referral reinforces the point!