Solid Glass Multihull

[Factor]

My point, badly made, was that there are many many many variations on the theme of Solid Glass

[colemj]

OK, sorry I was harsh. I think you were trying to describe differences in layup, layup materials and layup schedules.

Mark

[Schmacko]

I did not mean to cause constenation between members and being mech eng qualified I can indeed understand the difference between single element, spaced element and laminate construction. However all I was trying to say was that pound for pound, dram for dram laminate or spaced element construction can always be stronger in flexure than its solid counterpart. But designers design for a specific strength in two axis normally with a third axis being reference only.
Having said that, none of this was criticism towards any design.

BUT....FP, SA Cats and to a certain extent Lagoon have had undeniable and well publicised problems with resins breaking down allowing water to permeate the foam core....osmosis not on every boat but with some manufacturers a high percentage.

My comment about not being able to trust an overseas surveyor to detect osmosis was simply meaning that I dont think "tapping" and using a "thermal signature receiver" is good enough for me to spend $450000.00 on a 2 year old boat with a company that has proven history of osmosis.

My desire for a solid vinyl esther hull BLW was simply a means to mitigate risk.

My money..my choice

[Factor]

Originally Posted by Schmacko

My desire for a solid vinyl esther hull BLW was simply a means to mitigate risk.

Thats the bit I dont get, a cored boat - all other things being equal - will be no more or less likely to have osmosis. Mitigate that risk by avoiding polyester resins with a vengeance. And by looking at the manufacturers history of osmosis issues.

Worst case of osmosis I ever saw was on a "solid glass" boat

[Teeto]

Originally Posted by toddedger

I think Shionning designed some cats that are cedar stripped with glass on each side that have relatively good performance. I think the only way to get a really good cored hull is to build it yourself. You could add some extra kevlar on the bottom if you plane on running aground.

Some Chamberlin cats are cedar strip with epoxy over. Light, more forgiving of a bumpy docking and no osmosis. Why aren't more boats built with this method?

[Sand crab]

Originally Posted by Teeto

Some Chamberlin cats are cedar strip with epoxy over. Light, more forgiving of a bumpy docking and no osmosis. Why aren't more boats built with this method?

It doesn't work well for production boats. The big players want to build the exact same boat out a mold. This way is probably cheaper.

[cwjohm]

I am not sure I understand the logic here.

The problems of osmosis in production boats were proven to be the fault of resin suppliers, and significant court action resulted. Since 2010 most production boats have a vinylester layer applied below water, and there has not been a single case since that major change occurred.

What I don't understand is assuming the resin is faulty how a solid glass core will mitigate this issue. Yes, you can crack a walnut with a sledgehammer by insisting on a fully vinylester core but even then if a supplier problem occurred, or it was incorrectly applied, no matter how unlikely, you could have issues.

So it seems to me that we confuse the manufacturing process with the technology. Polyester cored boats have been built for decades with no signs of osmosis. The problem was in the process, not the technology, and if the process is not first class then no matter what the technology a bad boat could result.

From my observations since most production boat manufacturers adopted ISO around 5 years ago the repeatability of quality has been reasonable, whereas before one boat of the same model could be very different to another.

[Factor]

Originally Posted by cwjohm

Since 2010 most production boats have a vinylester layer applied below water, .

And many custom builders and production builders never ever used polyester.

Polyester boats mainly solid, were busily building blisters for years in the mono hull world, it was well known by the mid 80's as to the cause and well known the cure. Not sure why some manufacturers waited till their pants got pulled down.

[boatsmith]

[QUOTE As for floatation, most J Boats wont sink past deck level, but their never the same when they get to that level.[/QUOTE]
I don't buy that
It takes more than hull core foam to float a lead keel

[toddedger]

Well I know a J-29 that got hit by lightning while on a mooring. When the owner arrived the next day it was floating at deck level. It didn't go down even though the lightning blew a few hole in the bottom. He sold the boat and purchased a new one. That was over twenty years ago and that original J-29 is still in use today. I might add that when repaired it got fully awlgriped, and it has some nasty balsa print through showing on the hull sides. I don't know how heavy it is, but it hasn't won any races in a long time.

[ozskipper]

Originally Posted by Factor

Thats the bit I dont get, a cored boat - all other things being equal - will be no more or less likely to have osmosis. Mitigate that risk by avoiding polyester resins with a vengeance. And by looking at the manufacturers history of osmosis issues.

Worst case of osmosis I ever saw was on a "solid glass" boat

Agreed. Though, in the case of blisters you can grind as deep as you like without exposing a moisture sensitive core. That aside there isnt much difference assuming identical layup and layers yada yada

[Pointless]

We are getting off course here, if you'll pardon the bad pun. I never said I was trying to avoid osmosis or blistering. I am trying to minimize water intrusion, the damage it wreaks, and avoid as much delamination as possible.

[robert sailor]

Actually most of the boat builders moved to vinylester for the first layer in the mid to later 80's. Beneteau had the biggest problems and had to pay for repairs on so many boats they lost money.

[boatsmith]

Originally Posted by toddedger

Well I know a J-29 that got hit by lightning while on a mooring. When the owner arrived the next day it was floating at deck level. It didn't go down even though the lightning blew a few hole in the bottom. He sold the boat and purchased a new one. That was over twenty years ago and that original J-29 is still in use today. I might add that when repaired it got fully awlgriped, and it has some nasty balsa print through showing on the hull sides. I don't know how heavy it is, but it hasn't won any races in a long time.

a J29 has a 2100 lb lead keel. NO WAY is there enough foam in the core to provide positive buoyancy.

[neilpride]

Poly is still a fine resin to make boats ,with a good barrier coat can last forever with no osmosis or delam isues, most of the production boats today still use poly for the hulls with the diference of a last good barrier coat of vinylester or epoxy for osmosis protection, but sometimes even with the vinylester blister show up, FP are a example...