Composite boat-building materials & techniques

[44'cruisingcat]

You're wasting your time Dave. The guy was proven totally wrong in another thread, and knew it, but absolutely refused to admit it. He wouldn't even own up to a simple spelling error FFS! (Once might have been a typo, as claimed, but twice?)

He's spent the last few months arguing the supeiority of a material he has absolutely NO experience of using.

[cat man do]

LOL, Thought as much

Dave

[Little Otter]

when doing epoxy try to vaccum seal the matierial and distibute epoxy through tubes i believe that Kellsal catamarans has pictures of it but im not entirely sure it is that website

[Robertcateran]

Originally Posted by Little Otter

when doing epoxy try to vaccum seal the matierial and distibute epoxy through tubes i believe that Kellsal catamarans has pictures of it but im not entirely sure it is that website

Derek would have kittens if he thought that someone thought he used epoxy. He hates the stuff and reckons his boats have stood for years using polyester, and if you have to go fancier, maybe vinylester. He has some good points, and for a foam sandwich hull, it is probably good enough. I am still tossing between vinylester and epoxy for my next boat. If you do the bulk of the hulls in one go, the vinylester should attach pretty well. I have used aluminium ply and strip plank but plan to use polyprop honeycomb,
Robert

[BigCat]

"Curious that amongst all the posts regarding the esoterica of the various resin properties, no mention of the expected life span of the total structure is mentioned."

The oldest fiberglass boats are still going strong, so no one knows how long they will last. I have had to have the gel coat completely removed from two yachts, and have them given the cure for blisters. This is why I am going with vinylester, which was formulated to resist all kinds of corrosive environments. It is used in highly corrosive chemical factories worldwide.

I read a post recently on another thread where the poster is yet another rabid epoxyphile. He owned a boat in which there were balsa core deck delamination problems, which he blamed on the use of polyester resins. Properly done, balsa / polyester decks are quite bullet proof. Contrary to his wild generalizations based on one boat, dropping heavy items on such a deck does not cause delaminations. Batwing is just one example of a boat with a poly / balsa deck that has been campaigned very hard for 35 years with no problems with its balsa/ poly deck.

By properly done, I mean that the resin must be forced all the way into the spaces between the balsa core squares, and attach to the opposite laminate face. I have my doubts about the use of core on any hull made in a female mold, if the design has a lot of compound curvature. My concern is the inability to check adhesion of the core to the laminate on the outside of the hull, and the gaps which the compound curvature create between the stiff, flat core and the curved outer laminate. You are supposed to use a lot of 'bog' in that circumstance, but that is hardly a light weight construction method, and you can't see if there are, in fact, voids.

I, too, am shocked at the construction I have seen on some recent boats I have seen at boat shows. I walked up to one large, beautiful power yacht about 6 months ago and deflected the hull inward with my thumb visibly enough for my wife to see the movement. That was just plain scary.

[neelie]

By "structure", I meant the core plus laminate. I did not intend to refer to solid FRP, sorry I should have been more explicit.

[BigCat]

Originally Posted by neelie

By "structure", I meant the core plus laminate. I did not intend to refer to solid FRP, sorry I should have been more explicit.

Hi, neelie - same answer, though. We don't know of any age limit to the cored laminate, except for damage through blisters, or wacking with a rock, except for extreme racing boats, which sometimes fatigue due to flexing, because they were built too lightly. When large areas get water damage in the cores, it seems likely that they were already delaminated, either because they weren't bonded to begin with (aka neverbond), or because the scantlings were too light.

If the cored laminate was built with small squares with webs of resin between them, water can't spread from poorly treated penetrations, no matter what the core is made of. This is why I use small squares in the core even for flat panels-it weighs more, but water can't spread, and the resin 'web' strengthens the panel. This is how those long-lasting cored decks were built. This is all straight out of advice from the Balsa suppliers, by the way.

If you use epoxy resin, btw, make sure you keep the sun off of it. UV destroys epoxy very quickly. Another plus for vinylester, IMHO.

[knottybuoyz]

Originally Posted by BigCat

The oldest fiberglass boats are still going strong, so no one knows how long they will last.

"The only things to survive a nuclear holocost will be cockroaches and fiberglass boats" (author unknown)

[cat man do]

Originally Posted by BigCat

If you use epoxy resin, btw, make sure you keep the sun off of it. UV destroys epoxy very quickly. Another plus for vinylester, IMHO.

Strawman argument.

How many clear finished Vinylester boats are out there?

Some epoxies have uv inhibitors allowing clear finishing, others uses quality two pac clear over the top to protect the epoxy

At the end of the day, the vast majority of vessels are painted or gelcoated, making sun degredation irrelivant.

Dave