Cored hull below the waterline book

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. How to use epoxy to fill in holes below the water line, sealing holes. 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. Nov 06, 2012 i own a 1985 sisu 26 with a partially cored hull. Balsa cored hull below waterline sailboat owners forums. Hand laid lamination using knitted mat and woven roving. 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. 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. Books by parker and mcknew list the hull of subject boats as fully cored. Repairing wet balsa below the waterline followed by. The problems, i believe, involved actually coring the bottom of the hull, which was stopped. 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. Did these boats have wooden core s, or were they solid glass.

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. The line where the hull meets the water surface is called the waterline. Buying a boatnever say never attainable adventure cruising. Solid glass below the waterline and lighter, stronger above. The hull may open at the top such as a dinghy, or it may be fully or partially covered with a deck.

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. 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. But, on the other hand, for longevity, the safest bet is a well built hull without core, particularly below 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 thru hull fitting is to be installed. If it is solid, where is best location for the transducer. Id dismiss as insane any hull cored below the waterline there had better be layers of roving on the outside of the core material. It does not save that much weight, and weight down low is good for stability anyway. I want it to be an easy build i have no boatbuilding experience and dont want cored hull below the waterline.

But, like all cruisers yachts, the hull including the running surfaces is balsa cored. Theres an anecdotal, possibly apocryphal, story about a salesman at a boat show bragging about his companys new cored fibreglass hull. I would agree that having a cored hull, especially below the waterline, is asking for trouble unless of course you build it in a similar fashion to the rnli trent class 14m. Dmldragon are generally whole hull, except where they leased a mold from someone else. Cored fiberglass deck and house top with integral canvas textured nonskid surface. Contoured probalsa plus is a coated, contourable, endgrain balsa wood for use in marine and boatbuilding applications.

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. But above the waterline i think i would really want cored. One cannot use balsa underwater and not expect it fill up with water, which is. Anyone know of any good booksarticles on solid fiberglass hull. 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. 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. 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. Fitting underwater lights in a cored hull presents some unique challenges and requires a little additional work. Extra frames and stringers can be added for stiffness. Atop the deck may be a deckhouse and other superstructures, such as a funnel, derrick, or mast. I use brassbronze fittings below the waterline and always connect the pump and strainer to the boats bonding system if it has one.

The manufacturers of balsa and balsa cored hulls tell us that wet balsa in a hull does not compromise its structural integrity. I need to mount an in hull transducer in my pearson 27. Kevlar is added to the laminate in forward areas of the hull from the keel up. His veins run cold when he realizes whos been haunting the homestead all along duration. 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. 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. Early trumpeterminihobby models hull bottoms are misshapen to go with a powerpod attachment for bathtub use. 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. Also note how they appear in clusters lower down on the bottom, and that some areas between clusters are not affected. The weight savings could justify the additional cost with fuel savings over the long run. 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. The uks largest kitchen furniture, appliance, sinks, taps and ancillary kitchen products supplier, to the independent kitchen specialist sector. We never have built a model that was just cored from the waterline up. The deckto hull marriage is shoeboxed, bedded with 3m 5200 and stainless screwed every 6.

This will work only with solid fiberglass hulls excluding balsa core or laminated hull construction that might contain air pockets. That area will flex under pressure, tearing at the edges of the bond and over. Some boaters i know have had to have their entire transoms rebuilt because of water seepage. 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. How do the mid to late 70s hulls compare with later, lighter ones. 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. The carbon fibre hull shell is only 3mm thick below the waterline and just 1.

Install a transducer without drilling a hole in the hull. 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. Jan 16, 2020 a poorly effected repair below the waterline allowed water to wick throughout this cored hull, which then froze. Fiberglass is known to be water absorbent enough as it is without adding more risk to the mix. 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. 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. They have cored bottoms but light years away from your average yacht scantlings. Oct 11, 2006 cored hull bottoms sorry about your luck cored hull bottoms are a big problem. Many production sailboats also incorporate a core in the hull.

Well i guess theres some comfort here for us albin fans if they are indeed using vacuum bagging for their hulls below waterline. 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. 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. Cored hulls, meanwhile, are also quite common, particularly on performance cruising boats and. An iconic krogen design with a ballasted displacement hull and tremendous storage a proven cruising or liveaboard yacht.

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. The mould is made in two parts, which allows us to build the hulls with an integrated. I have read 2 articles that say the opposite one says solid fiberglass the other core at bottom of hull. Those warnings havent been heeded as numerous builders jump on the cored hull bandwagon. Holed below the waterline meaning in the cambridge. The transom is cored with 34 plywood for some of the upper portions but the below waterline is solid fiberglass over 12 thick. Notice on this hull how the blisters run along a band about one foot below the waterline.

It provides additional stiffness and sounddeadening properties. 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. Bill i would save the money and go with a solid glass hull. We are looking at a 1987 p392 but it appears that there is a discrepency regarding the construction of the hull below the waterline. Many cruisers believe no serious cruising boat should ever have cored laminate below its waterline. It adds a lot of structural reinforcement in the hull wo having to add a lot of glass increasing the total boat weight. Hatteras hull bottoms are handlaid in solid fiberglass with no coring below the waterline. Installing a transom mounted transducer on a piece of starboard that is thrubolted above the waterline prevents transom rot from occurring. Generally, powerboats have cored hulls below the waterline. By laminating a lightweight core between two fiberresin skins a lot of stiffness can. 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. Vacuum bagging the core has become very popular and ensures full penetration of the core material and a good bond to the fiberglass. The grid system is an advanced design that reinforces the hull under the waterline.

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. All hatteras hull bottoms are handlaid in solid fiberglass. 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. Install a transducer without holes below the waterline. I have a lot of information from albin but it does not address the question of construction. While this is more labor intensive, the end product is a lighter and stiffer hull. And so we had our first foam and honeycomb cored boat hulls that ultimately fell. Local impact loads are borne by a single skin only.

Cored decks have been standard since the earliest days of fiberglass boat production. Cored hull bottom failures are starting to show up in increasing numbers, just as i had predicted. I was glad i got the book as there was considerably more in depth information in the book than the web site. Mobo hull construction balsa core sandwich ybw forum. A reading below the waterline of 5 or less on a sovereign meter is considered sufficient. Actually, balsa is used not only for weight, but because it actually limits horizontal water migration if it does get wet. The hull is solid fiberglass below the waterline and cored above. Hallbergrassy from 2008 with delaminated hull ybw forum. Three piece hull mold, split longitudinally with separate transom piece all tooling highly polished between parts. How to deal with wet balsa core below the waterline part 1. Holed below the waterline meaning in the cambridge english. This results in a higher glass to resin ratio which makes the hull even stronger. Worse yet this did not always happen during a model year change. 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.

Eight long range cruisers with full displacement hulls. Catalina 470, the hull is solid below the waterline, and is cored from. 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. Two ways to install a transducer that wont compromise your hull. 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. This allows the thruhull fitting to be sealed and tightened without compressing the core.

The entire balsa cored hull was stripped and replaced with divinycell foam coring end quote. I am amazed at some of the misconceptions being put forward here. Worse there are boats like the sabre 34 mk1 where they changed from no core to a core during the production run. Cored fiberglass hull with solid fiberglass below the waterline. But what is often unstated is that its not cored everywhere. Could i expect offtheshelf prelaminated panels to be stronger than handlayed solid frp.

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. I bought a 30 yr old beauty that i had seen in the water. Its formulae and extrapolation and maybe a couple of. I dont like the foam or honeycomb coresthey tend to delaminate real easy. I think balsa cored above the waterline is a great way to go. Jan 26, 2016 its well known that the lf38 hull is cored above and below waterline. The fun part of this entire project is getting to do all of this.

Above waterline layup is fiberglass cored with klegecll for stiffness and weight reduction. 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. I think a cored hull would be fine if money was not an issue and the builder was very competent at coring hulls. Areas above the waterline where thruhulls will be used are also solid fiberglass, and heavy stress areas in the. Is there a p392 owner out there that knows whats what and can tell me how to identify the core in the hull. 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. 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. 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. Sailnet community sealing through hulls in balsa cored boat.

They claim that moisture spreads very slowly if at all horizontally due to the end grain cut of the balsa core. In an effort to build a stronger, lighter hull, boat builders began constructing hulls with a cored material sandwiched between layers of fiberglass. On boats with severe blistering above and below the waterline, especially those produced using fire resistant resins, effective treatment and repair may be impossible. I dont like the idea of drilling holes below the waterline on fiberglass boats to mount transducers, trim tabs, swim platforms, etc. Sometimes they would do a hull bottom to go with the leased kit, sometimes not. Above the waterline, the hull is cored with endgrain balsa.

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. This is why some builders insist on building only solid hulls and others will core a hull above the waterline, but never below it. 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. Cored hull bottom failures are starting to show up in increasing numbers, just as i. 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. 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. Balsa is widely used to core decks and often the sides, usually above but sometimes below the waterline. I dont know if your boat has a cored hull but you might be able to see it.

Pascoes thoughts on cored hulls related to the above yachtsurvey link were dated in 2001 or before. The part that surprised me was that coring was below the waterline, not above it. The stringers are all yellow cedar and the bulkheads are fir ply. The previous responses are good, use a moisture meter to locate the troubled areas and tap with a plactic hammer to find softness. Further, if you do have a cored hull even above the waterline only. At this point, the transom is ready for drilling and installing the new transducer. Boats searay sea ray fiberglass lamination problems. This is a step youll see in more expensive boats and often in offshore performance machines. Further, they are likely to know of reference books available to surveyors. 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. Coated with a thin resin film to enhance bond with epoxy, ve and polyester resin systems. Any underwater core will eventually be invaded by some small.