Help with lloyd's standard

[jfblouin]

My friend had a 34 feet wood boat that's need renovation. It is a square plank hull in mahogany with ribs in mahogany too. The planks are 3 inches wide. The wood condition is good for a large part of the boat, he need to replace some plank and rib.

My friend want to fiberglass the hull. He want to finish to dry the boat (it's out of water since 2 years), replace rotten wood, seal all crack with epoxy and add exterior and interior fiberglass in epoxy.

The local boat inspector dont accept that. He said that the wood will rot fast between 2 coats of fiberglass. He said that he will only accept exterior fiberglass only like a exterior paint to allow wood to wet and dry from inside. For him fiberglass add no strengh. And final argument "it is a Lloyd standards" and it is the same for others standards.

We speak to him about Dave Gerr and West System. He answer with Chapelle...

What is true ?
Where I can find thoses standards (in easy understanding terms)

Thanks a lot

[FAST FRED]

Your inspector is correct , sloping a coat of glass over a conventional hull does NOTHING structural.

Boats designed to be constructed of covered wood are either very thin pieces or plywood covered with glass.

Wood is what is needed for the repair,

FAST FRED

[Raggi_Thor]

It is true that Lloyds regards wood covered with glass and polyester as "non existing", that is with no strength. The reason (I guess) is all the wooden stringers in grp boats that simply dissolved into a "goo" (I think you call it :-).
It's very risky to cover an old structure with glass, even when you use epoxy. Are you sure you can make a complete covering everywhere?

[rxcomposite]

Jf,

Lloyd's Special Service Craft can be ordered from Lloyds Register for about USD 400+. This applies to small watercraft. The other Volume is for building ships.

But i will advice you that you will be wasting your money just to prove a fact. The small watercraft volume no longer covers wooden boats. It is for professionals who deals with Lloyd's Standard. The volume covers everything from building in steel, aluminum, or fiberglass plus all the rules and regulations regarding building a watercraft. The volume is about 12" thick.

I do happen to have a copy of their very old publication regarding wooden boats but no rules exist on cladding wood with fiberglass. I beleive it does not exist.

Cladding wood with fiberglass (stitch and glue) method is accepted method of boatbuilding but not to hide rotten wood. Will write about this later.

Rx

[jfblouin]

Thanks to all

I understand about Lloyds...

If we put fiberglass and epoxy outside, do you suggest us to put nothing or just epoxy resin or fiberglass+epoxy resin inside ?

[D'ARTOIS]

Jean-Francois,

If the boat is throughly dried out - thoroughly, with a % of humidity no more than 0,8 - you may be able to coat inside and outside without the chance of rotting of the wood inside.

Even epoxy allows for a small - very small percentage of evaporation. If the action is wise, is another story.

You may cover your boat from the outside, in order to avoid excessive leaking, but in any case I would renew the foul planks and ribs.

Ater this has been done, cover the epoxy with an UV filter by way of protective paint.

The disadvantage is that you might disturb the integrity of the construction.
I have seen it done without problems as a result, but it might be better to replace the affected parts and to leave the boat as it is.

[jfblouin]

With or without fiberglass and epoxy, they will replace rotten wood.

About humidity 0,8 mean 8% ? 0,8% is very very and I think that we can't go to this point.

[D'ARTOIS]

If you want to enclose the wooden hull and sort of "packing" it inside and outside in a fibreglass cloth, with epoxy, the the humidity in the wood is still too high to do so. Even in the best outside temperatures, the rate of humidity is still too high to do the cascovering exercise with success.

And, in this case inside rotting is well visible because of the slow evaporation process that an epoxy sheeting does allow: 0,8 % - therefore that your exercise is only justified to avoid leakage - structurally it does not have any reinforcement caracteristics. Apply only the outside surface.

[rxcomposite]

Jf,

Fast Fred, Raggi, and D' Artois have given you very sound advice.

Wood by itself is structural. You have to repair it like it was built otherwise you would be guessing if the fiberglass you added would add more strength than the wood you removed or replaced.

Adding fiberglass or cladding will increase the "waterproofness" of the boat. It is the resin that makes it waterproof so you have to use fiberglass that absorbs much resin such as mat, or tissue mat on the outside layer.

Generally when it is wood, i will use epoxy because epoxy penetrates the wood deeper and makes a better grip. Iso or Vynil ester works also but a very dry surface is needed.

For the inside, why not paint it? Fiberglass will not help except add weight. Paint will seep into crevices and small cracks thereby gluing it together. I normally use epoxy paint on the inside.