If you get sued after a sailboat core fills with water or its keel falls off, take your lumps because you deserve to get sued for not finding the problem. There is only one safe way to handle a cored sailboat bottom, and that is to declaim all knowledge of what is going on inside that core. You can't see it, test it or know what is happening inside unless a failure is already well advanced.
Failures involving cored bottoms are legion. Even worse, it can happen that there are no visible, outward signs of trouble before failure occur. Failures can occur suddenly, and without warning. Disavow all responsibility, in writing, in detail, and all ability to determine the condition of the hull. To determine whether a hull is cored or not, look for those areas on the interior hull where the core terminates. In this photo, the core can clearly be seen standing out around the bow of this yacht.
Stress cracking on hull sides is something that generally did not happen until the mid 's when builders began skimping on hull side laminate. Hull sides have gotten so flimsy in the last decade that its almost laughable if the construction of some of these boats wasn't so pathetic. Hull side cracking is a problem that shows up almost exclusively in low to mid price range boats.
The cheaper the boat, the more likely you'll find it. This is rarely a problem to the hull side itself. The cracking usually occurs as a result of severe panting because the sides are thin and unsupported. The sides themselves don't fail because the panels are so large and the flexing occurs over such a large area that the radius of bend is too large to cause damage to the laminate strictly as a result of panting.
However, because the stress is transmitted vertically up the hull side, the forces of interlaminar shear are very high. Therefore, delamination becomes a distinct possibility. Nowhere is this more true that in vessels that have been repowered with more powerful engines. In this case, total hull side failures have been known to occur even with high quality boats. Hull side panting can be a problem because there are other things attached to the hull sides. A boat with floppy hull sides is not very likely to have the deck bonded to the hull, but rather just be screwed on.
This is why we find so many boats with the rub rails falling off. Hull sides should be generally sounded cored or solid and closely examined for stress cracking. Stress cracking is most easily telegraphed through painted on boot stripes because the paint is more brittle, so look for it there.
Because side failures are rare, the cracking needs to be evaluated in terms of the whole structure. The cracking is more likely to be a sign of other problems. Suspect bad deck joins and look for broken bulkhead tabbing. Also watch out for through hull fittings that may be loosened or damaged as a result of panting. Builders are always searching for ways to reduce labor costs, and one of these is the use of interior liners.
Experienced surveyors are all too familiar with the problems that liners present. First is that a liner tends to obscure all internal structural members so that the surveyor cannot make an evaluation of the hull structure.
Secondly, liners tend to preclude the use of proper bulkheads and frames because a liner can't be placed where a structural bulkhead exists. Thirdly, the design of the liner needs to substitute for the structural members is has displaced. Fourth, the liner usually affords no access to examine its structure and how it is attached. Liners are most commonly used in boats up to about 32' but have been found in boats up to 42'. The larger the boat, the greater the potential for trouble because of this tendency of liners to displace or eliminate traditional framing methods.
Boats with liners over 30' are known to have a disproportionately larger number of structural problems, a situation that is entirely predictable. When liners displace bulkheads and frames, several things happen. First, the hull becomes highly prone to twisting or wracking. When bulkheads are eliminated, unsupported panel size naturally increases. And when that happens, panel deflection and failures increase. Because the liner usually covers up so much of the interior, this makes the surveyors job doubly difficult and exposes him to more risk of failure to locate serious problems.
So far, the use of grid liners is limited to only a few builders of small boats, but the idea is likely to spread because it presents the possibility of eliminating all the difficult laminating detail work of bulkheads and stringers inside the mold. With a grid liner, the detail work can be transferred to a low profile mold on the shop floor that is more accessible and easier to work. While this may streamline production, this method has a number of problems. One is that the liner has to be bonded to the hull, and obviously the builder cannot laminate it to the hull once it is set into place.
The only solution, of course, is to glue the liner into the hull. The problem with adhesives is that they only work perfectly under perfect conditions, something we don't see much of in boat building. The only things that glue together well are parts with identically uniform surfaces. For example, gluing two pieces of wood together that are perfectly flat makes for a very strong joint. But allow the slightest surface irregularity and the joint becomes very weak.
That's not just true of wood but any material. Unfortunately, the interiors of laminated hulls can hardly be called uniform. Only time will tell. Our experience with bonding putty in cored hulls tells us that there's not likely to be any better level of success in this application than for foam cores.
See related article Hi Tech Materials. Essentially what they are doing is spreading the glue on the interior of the hull, and then dropping the liner in and hoping that a complete bond takes place.
The builder will never know because he can't see the results. The bonding surface is just as likely, indeed, probably more so, to be full of voids or gaps where the two parts are not bonded together. And a void in a glue joint or laminate is a stress initiator that propagates delamination.
Fortunately, a sailboat hull is considerable more amenable to this design, both by its shape and the fact that they are not subjected to the forces of high speed. Yet even their smaller models were widely known for liner failures. If this method gains wider acceptance, its going to pose a whole new range of problems for surveyors. When liners are used, they either have to sit on top of stringers, the bottom, or be suspended from the hull sides.
In either case, the liner is not completely isolated from the hull, and if the hull is experiencing problems with excessive panel deflection or panting, that deflection is most likely going to be transmitted to the liner in one way or another. In sailboats, liners are either tabbed, glued to the hull or both. In powerboats, liners usually rest on top of stringers and are usually joined to the hull at the deck, whether by bonding or mechanical fasteners. Flexing of the hull is usually transmitted to the liner.
Linered boats usually have a number of wood components inside such as cabinets, trim seating and the like. These components are usually fastened to the liner with screws. If both the hull and liner are flexing, then it is common to find evidence of this. Look for screws backing out, misaligned parts, cracked moldings and little piles of wood dust that indicates friction against the wood. Unusually large gaps between parts or things like built-in refrigerators backing out of their holes are often indicators of trouble.
This stress can come from improper design, or it can be the result of imposed stresses from within, without, or both. It can be the result of aging or faulty application such as excessive catalization or hardeners. By far, the most common reason for stress cracking is due to improper structure design. Even the finish on a flat panel will crack when bent too much.
When it comes to large, flat panels, cracking usually results from excessive panel flexing or panting, such as on an unsupported hull side. Cracking also occurs as a result of an engineering phenomenon called a stress riser. A stress riser occurs at point in a panel or hull skin where a normally somewhat flexible area is suddenly made rigid without a means of transferring the imposed stress gradually to the rest of the laminate.
A good example is a strut attachment to the bottom without any kind of doubler. Another example would be a bottom stringer butting hard against the laminate with no fillet to distribute the load. Yet another is a railing stanchion attached to a deck laminate with no fillet or doubler beneath. The end result is that the amount of stress suddenly rises at a certain point and so stress cracks are likely to appear. David Pascoe - Biography David Pascoe is a second generation marine surveyor in his family who began his surveying career at age 16 as an apprentice in as the era of wooden boats was drawing to a close.
Fix it when you have time. Romain 0 Posted February 28, Seems to be only fairing No worries. Slowboat 22 Posted February 28, Oh man - big bummer - though I can't imagine that the job would take that many hours.
Bcam 1 Posted February 28, Wess 2, Posted February 28, Squalamax 62 Posted February 28, Slowboat 22 Posted February 29, Posted February 29, The series SS seem to be working out pretty well after 12 years of hard sailing.
He's got bigger fish to fry. TheOwnersWife 0 Posted February 29, Me thinks the builder got it right. Jem 0 Posted February 29, SailRacer Posted February 29, Sail safe! Tommyboomer 0 Posted February 29, Squalamax 62 Posted February 29, HOW 4 Posted February 29, THe way we sail in Newfoundland, who know what will happen in the next few years Tommy.
NyJboat 0 Posted February 29, Kevin Schultz 1 Posted February 29, Nothing a little duck tape can't fix. Shorthanded Posted March 1, Posted March 1, Squalamax 62 Posted March 1, Danceswithoctopus Posted March 2, Posted March 2, Might be a good time to read the liability waiver thread Black Dog 8 Posted March 2, I looked at this I turned out to be in the fairing only, no structual proplem. Posted March 3, Eric 0 Posted March 4, Posted March 4, Sparky 0 Posted March 4, What caused the cracking of the fairing in the photo?
Seems to me that the fairing wouldn't crack unless the keel is flexing. I've had no cracks on my boat for 12 years and now its all over the joint. Why would it start flexing suddenly? It's time to grind the cracks out and find out how deep they are. Tommyboomer 0 Posted March 4, Eric 0 Posted March 14, Posted March 14, Should be good to go soon. Never was 13 Posted March 14, Is there a slot on the front of the keel for a kelp cutter?
HOW 4 Posted March 14, Posted March 16, Haddock 0 Posted March 16, Widowmaker 0 Posted March 16, So has this problem been corrected in newer builds? Squalamax 62 Posted March 16, Why will you not replace the gel-coat? Surely you want to keep the water outside the hull? Iron washers!? Thats just appalling. Posted March 17, Is this a stress crack? NyJboat 0 Posted March 17, HOW 4 Posted March 18, Posted March 18, Hasl Free?
Black Dog 8 Posted March 18, What In The Hell Happened? Eric 0 Posted March 18, Jem 0 Posted March 18, Did it just fall off a wave or did they run aground? It's a J that started to take on water after the first race on Saturday. I sure would like to know why the keel failed and the hull number. Can you PM with some contact information? Squalamax 62 Posted March 18, Craven Moorehead 0 Posted March 18, I just got an email explaining that Hasl Free did not hit anything prior to the water coming into the boat.
They experienced a complete failure of the grid system in the floor. This process might need to be repeated a few times until you have the gelcoat at the level you want. I went back at least twice on most of the cracks to touch things up.
Air bubbles are your enemy during this process. Do what you can to avoid them by not stirring the gelcoat vigorously and when applying be sure to push it around with the brush. I spent much more time going back to fix air bubbles than I did anything else. Once the gelcoat is dry and sanded, take a knife point and gently tap the surface of your repairs to make sure you don't have any air pockets hiding behind the surface. If you do, grind them out and re-coat. I had some extra gelcoat in the paint tray and remembered I had a strake underneath with a chunk missing, so I fixed it, too.
The process is the same. Clean the area I use acetone , sand to remove any loose material and to blend the broken area into the hull surface, mix and apply gelcoat, cover with wax paper and masking tape, keep it at 70 degrees for a while, remove, sand, check for air pockets, buff.
I also fixed some corner damage, probably a dock hit. The red was a much better color match! Note my heating mechanism. Very redneck, very effective. This picture was taken right after removing the wax paper. After sanding this one will probably need another pass with gelcoat as the damage was pretty extensive and I couldn't get the wax paper to mold the corner on the first go-around.
That's pretty much all that's required to fix stress cracks. They're not challenging by any means. The primary thing to work on is the color matching of the gelcoat.
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