How to deal with wet balsa core below the waterline part 1. Above the waterline, the hull is cored with endgrain balsa. Notice on this hull how the blisters run along a band about one foot below the waterline. I have read 2 articles that say the opposite one says solid fiberglass the other core at bottom of hull. Books by parker and mcknew list the hull of subject boats as fully cored. The part that surprised me was that coring was below the waterline, not above it. Cored fiberglass deck and house top with integral canvas textured nonskid surface. Boats searay sea ray fiberglass lamination problems. We are looking at a 1987 p392 but it appears that there is a discrepency regarding the construction of the hull below the waterline.
By laminating a lightweight core between two fiberresin skins a lot of stiffness can. I had a survey, engine check, two test runs and bought the boat. Hatteras hull bottoms are handlaid in solid fiberglass with no coring below the waterline. Jan 16, 2020 a poorly effected repair below the waterline allowed water to wick throughout this cored hull, which then froze. Im finishing up the last areas on my hull that needed balsa drying or replacement. Cored hull bottom failures are starting to show up in increasing numbers, just as i had predicted. They have cored bottoms but light years away from your average yacht scantlings. Although it may be tempting to simply drill a hole through the boat and fit the lights, water can find its way into the coring, eventually damaging the boats structure. Cored fiberglass hull with solid fiberglass below the waterline. I understand why some opt for a cored hull, but for my commercial fishing use, a solid glass hull is the only way to go. I was glad i got the book as there was considerably more in depth information in the book than the web site. Worse there are boats like the sabre 34 mk1 where they changed from no core to a core during the production run. Repairing wet balsa below the waterline followed by.
Many production sailboats also incorporate a core in the hull. Balsa cored hulls below waterline i guess my question is if i were to purchase a new production built cat with balsa core below the waterline, considering they used vinylester resin how long would it take for the water to migrate through the fiberglass and start affecting the core. I dont know if your boat has a cored hull but you might be able to see it. The uks largest kitchen furniture, appliance, sinks, taps and ancillary kitchen products supplier, to the independent kitchen specialist sector. Extra frames and stringers can be added for stiffness. Catalina 470, the hull is solid below the waterline, and is cored from. Local impact loads are borne by a single skin only. At this point, the transom is ready for drilling and installing the new transducer.
The weight savings could justify the additional cost with fuel savings over the long run. Further, if you do have a cored hull even above the waterline only. The hull is solid fiberglass below the waterline and cored above. The problems, i believe, involved actually coring the bottom of the hull, which was stopped. Also note how they appear in clusters lower down on the bottom, and that some areas between clusters are not affected. All hatteras hull bottoms are handlaid in solid fiberglass. I was there for the survey and watched as the surveyor banged all over the hull with his hammer just as it was lifted out of the water. Jan 26, 2016 its well known that the lf38 hull is cored above and below waterline. Mobo hull construction balsa core sandwich ybw forum.
Atop the deck may be a deckhouse and other superstructures, such as a funnel, derrick, or mast. Cored hull bottom failures are starting to show up in increasing numbers, just as i. And so we had our first foam and honeycomb cored boat hulls that ultimately fell. Some boaters i know have had to have their entire transoms rebuilt because of water seepage. Any underwater core will eventually be invaded by some small. Coated with a thin resin film to enhance bond with epoxy, ve and polyester resin systems.
Divinycell used as a core material and strong backing plates that are. Is there a p392 owner out there that knows whats what and can tell me how to identify the core in the hull. Worse yet this did not always happen during a model year change. Bill i would save the money and go with a solid glass hull. Did these boats have wooden core s, or were they solid glass. I am amazed at some of the misconceptions being put forward here. Those warnings havent been heeded as numerous builders jump on the cored hull bandwagon.
Its well known that the lf38 hull is cored above and below waterline. I think balsa cored above the waterline is a great way to go. The fun part of this entire project is getting to do all of this. After all, the industry went though this ridiculous situation in the 1960s, again in the early 1980s and now in the decade of single digits. Generally, powerboats have cored hulls below the waterline. Theres nothing wrong with a cored hull, even below the water line, and in fact a properly done cored hull will have more strength and far better proprties in terms of strength, and damage tolerance than an equivalent weight solid hull. Fiberglass is known to be water absorbent enough as it is without adding more risk to the mix.
Pascoes thoughts on cored hulls related to the above yachtsurvey link were dated in 2001 or before. I read an article that maxum is all fiberglass with no coring on the hull, which surprised me, while larson is balsa cored in the hull. Further, they are likely to know of reference books available to surveyors. Oct 20, 2019 but the other problem with cored boats, particularly those with core beneath the waterline, is that if the outer skin is breached, say by bumping on a rock or installing a seacock without properly removing the core, even a cored boat that was in fine shape when we bought her could be compromised, or even rendered worthless particularly if the. In addition, if the hull has been damaged at some point, you dont know how much moisture has been taken up by the balsa core before a repair was made. The mould is made in two parts, which allows us to build the hulls with an integrated. What is most important when core is used below the waterline, is for the builder to remove the core and replace it with solid glass where a thru hull fitting is to be installed.
Cored below the waterline where i agree with pascoe on this is that i cant find any valid reason to do it in the first place. Hallbergrassy from 2008 with delaminated hull ybw forum. Moving to the back of the boat the big deck hatches i have never drilled but the small one in the center is cored with the same crunchie foam as the sides. Kevlar is added to the laminate in forward areas of the hull from the keel up. Three piece hull mold, split longitudinally with separate transom piece all tooling highly polished between parts. We all know that its hard enough to keep the superstructure of the boat from leaking, but to keep water out of a core below the water line may nigh well be impossible. Solid glass below the waterline and lighter, stronger above. Hand laid lamination using knitted mat and woven roving. After drying out andor replacing wet balsa core the next part of the project is to fair the balsa out and then reglass the hull. Mar 19, 2014 in a perfect world there is an easily accessible location for the thru hull valve combo and then a nearby bulkhead to mount the pumps and strainers that keeps them well below the waterline. If hull thruhulls are installed in non cored sections, then theres no real difference in terms of leaks between this hull and a boat with a fully fiberglass hull. For this job, the final steps were to sand the repaired surface smooth, and then apply an overcoat of waterproof fiberglass resin that is suitable for use below the water line. Above the waterline, i dont think balsa coring is such an issue so the question you should be asking, imho, is whether the hull is balsa cored below the waterline.
The deckto hull marriage is shoeboxed, bedded with 3m 5200 and stainless screwed every 6. A reading below the waterline of 5 or less on a sovereign meter is considered sufficient. And in the case of our sea ray boat here, extremely little of the internal hull is visually accessible, so not much of the internal hull can even be inspected. The location you finally select must be low enough in the hull so it remains below the waterline when the boat is heeled but not so close to the keel that the signal could return through it and show shallower water than the true depth. We never have built a model that was just cored from the waterline up. I bought a 30 yr old beauty that i had seen in the water. Dmldragon are generally whole hull, except where they leased a mold from someone else. Id dismiss as insane any hull cored below the waterline there had better be layers of roving on the outside of the core material. Areas above the waterline where thruhulls will be used are also solid fiberglass, and heavy stress areas in the. Balsa cored hull below waterline sailboat owners forums. I was reading another thread about cored hulls and water intrusion that got me thinking about which manufacturers are using wood coring below the waterline.
This is a step youll see in more expensive boats and often in offshore performance machines. I have a lot of information from albin but it does not address the question of construction. Could i expect offtheshelf prelaminated panels to be stronger than handlayed solid frp. I use brassbronze fittings below the waterline and always connect the pump and strainer to the boats bonding system if it has one. As far as balsa cored hull buttoms if the boat is ok when you buy it and you hit something submerged and it breaks open the outer laminate water is going to enter the core and turn it to mush no matter how well it was done. Quite a few people have written or called to tell us that they know of some proven methods of repairing bottom blisters that constitute a full and final solution. Anyone know of any good booksarticles on solid fiberglass hull. May 12, 20 i dont like the idea of drilling holes below the waterline on fiberglass boats to mount transducers, trim tabs, swim platforms, etc.
They claim that moisture spreads very slowly if at all horizontally due to the end grain cut of the balsa core. Holed below the waterline meaning in the cambridge. It adds a lot of structural reinforcement in the hull wo having to add a lot of glass increasing the total boat weight. Vacuum bagging the core has become very popular and ensures full penetration of the core material and a good bond to the fiberglass. It does not save that much weight, and weight down low is good for stability anyway. That area will flex under pressure, tearing at the edges of the bond and over. Below the waterline the hunter 40s handlaid hull is solid polyester laminate with vinylester in the outer layers and npg gelcoat to resist osmotic blistering. Illustration of water absorption from a hull interior many water saturated hulls dont blister by david pascoe, marine surveyor.
While increasing her draft through the increasing weight of the cargo, the submerged piling finally pierced its way through the hull of the vessel, allowing the ingress of seawater into the portside water ballast wing tank. I need to mount an in hull transducer in my pearson 27. Nov 29, 2008 i was glad i got the book as there was considerably more in depth information in the book than the web site. Sometimes they would do a hull bottom to go with the leased kit, sometimes not. Installing a transom mounted transducer on a piece of starboard that is thrubolted above the waterline prevents transom rot from occurring. But above the waterline i think i would really want cored. My 1994 lagoon 42 tpi is balsa cored throughout hull and deck, since our purchase in may 2011 i have needed to fit three additional sea cocks and two skin fitting about the water line in every case when i cut thought the balsa core it was completely bone dry and very well bonded to the skins, so i have found no evidence of any issues with water. This allows the thruhull fitting to be sealed and tightened without compressing the core. If hull thruhulls are installed in noncored sections, then theres no real difference in terms of leaks between this hull and a boat with a fully fiberglass hull. How do the mid to late 70s hulls compare with later, lighter ones. In many of my previous articles i raised some warning flags about this latest trend toward coring boat bottoms, pointing out the potential for some very serious problems. Aug 25, 2009 in addition, if the hull has been damaged at some point, you dont know how much moisture has been taken up by the balsa core before a repair was made.
The grid system is an advanced design that reinforces the hull under the waterline. What is most important when core is used below the waterline, is for the builder to remove the core and replace it with solid glass where a thruhull fitting is to be installed. Fitting underwater lights in a cored hull presents some unique challenges and requires a little additional work. And even if just the topsides are cored, any boat of the vintage we are looking at will likely by now have had some hefty knocks when coming alongside. Many cruisers believe no serious cruising boat should ever have cored laminate below its waterline. The line where the hull meets the water surface is called the waterline. It provides additional stiffness and sounddeadening properties. Contoured probalsa plus is a coated, contourable, endgrain balsa wood for use in marine and boatbuilding applications. But, like all cruisers yachts, the hull including the running surfaces is balsa cored. I want it to be an easy build i have no boatbuilding experience and dont want cored hull below the waterline. Cored decks have been standard since the earliest days of fiberglass boat production. While this is more labor intensive, the end product is a lighter and stiffer hull.
Sailnet community sealing through hulls in balsa cored boat. The stringers are all yellow cedar and the bulkheads are fir ply. If it is solid, where is best location for the transducer. Actually, balsa is used not only for weight, but because it actually limits horizontal water migration if it does get wet. An iconic krogen design with a ballasted displacement hull and tremendous storage a proven cruising or liveaboard yacht. Cored composites respond to impacts in nearly the same way as solid composites, with one very important difference. Oct 11, 2007 trumpeters kits are generally whole hull.
Oct 11, 2006 cored hull bottoms sorry about your luck cored hull bottoms are a big problem. How to use epoxy to fill in holes below the water line, sealing holes. Balsa is widely used to core decks and often the sides, usually above but sometimes below the waterline. But what is often unstated is that its not cored everywhere. I have followed your threads and there are also some boats that do not have core below the waterline but do use it above such as the cs 40. On boats with severe blistering above and below the waterline, especially those produced using fire resistant resins, effective treatment and repair may be impossible. Eight long range cruisers with full displacement hulls. Im just beginning my research into this subject i have been looking at a lot of boats and believe the albin 35 cb is what fits what im looking for but the cored hull question below the waterline kinda bugs me. This will work only with solid fiberglass hulls excluding balsa core or laminated hull construction that might contain air pockets. Nov 06, 2012 i own a 1985 sisu 26 with a partially cored hull. The entire balsa cored hull was stripped and replaced with divinycell foam coring end quote. Ive heard and seen horror stories about cored hulls so even though i got a healthy survey report, i redid the hull penetrations the first year i owned the boat. The previous responses are good, use a moisture meter to locate the troubled areas and tap with a plactic hammer to find softness. The manufacturers of balsa and balsa cored hulls tell us that wet balsa in a hull does not compromise its structural integrity.
In an effort to build a stronger, lighter hull, boat builders began constructing hulls with a cored material sandwiched between layers of fiberglass. Holed below the waterline meaning in the cambridge english. The hull may open at the top such as a dinghy, or it may be fully or partially covered with a deck. Balsa cored hulls below waterline originally posted by dmmbruce smj, there is or was a view expressed by some surveyors, that fibreglass hulls should be left to dry out, on the hard for some months, before putting on a new seasons antifouling. Thus, when buying a used boat with a cored hull, even a survey is not going to prove a reasonable probability of a defectfree hull. Its formulae and extrapolation and maybe a couple of. Well i guess theres some comfort here for us albin fans if they are indeed using vacuum bagging for their hulls below waterline. The carbon fibre hull shell is only 3mm thick below the waterline and just 1. The risk is too high that something will go wrong, mistakes either by the builder, the owners of the boat, or someone working on it.
Theres an anecdotal, possibly apocryphal, story about a salesman at a boat show bragging about his companys new cored fibreglass hull. This results in a higher glass to resin ratio which makes the hull even stronger. Cored hulls, meanwhile, are also quite common, particularly on performance cruising boats and. The transom is cored with 34 plywood for some of the upper portions but the below waterline is solid fiberglass over 12 thick. His veins run cold when he realizes whos been haunting the homestead all along duration. One cannot use balsa underwater and not expect it fill up with water, which is. If youre installing a through hull fitting below the waterline yourself, and your hull is cored, not solid fibreglass, make sure to epoxyseal the perimeter of the hole you drill to prevent water from entering the core. Early trumpeterminihobby models hull bottoms are misshapen to go with a powerpod attachment for bathtub use. I dont like the idea of drilling holes below the waterline on fiberglass boats to mount transducers, trim tabs, swim platforms, etc. Install a transducer without holes below the waterline.
I think a cored hull would be fine if money was not an issue and the builder was very competent at coring hulls. Buying a boatnever say never attainable adventure cruising. I dont like the foam or honeycomb coresthey tend to delaminate real easy. This is why some builders insist on building only solid hulls and others will core a hull above the waterline, but never below it. Two ways to install a transducer that wont compromise your hull. That said, there is no question that cored hulls have some big time benefits, including being stiffer and stronger, on a weightforweight basis, than any solid hull. Above waterline layup is fiberglass cored with klegecll for stiffness and weight reduction. I did quite a bit of research and epifanes was the only company that said it was ok to use their product below the water line. Install a transducer without drilling a hole in the hull. How to figure out what you need in your next boat, and where theres room for compromise firsthand lessons from our technical editor, one of americas most experienced boaters. I was actually gonna start a thread a few weeks back when i saw these comments on yachtworld, i was looking at bertrams and of course the biggest ones come up first. But, on the other hand, for longevity, the safest bet is a well built hull without core, particularly below the waterline.
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