Should I sheath my 1933 planked 38ft yacht?

[Keith Stewart]

I am 63 and experienced with various boats and fixing since age 9.

I have just spent 3 weeks helping the owner of a 1933-built hardwood-planked classic ocean cruising yacht take it down to bare planks, repair dry rot and recaulk etc.

It is still out of the water cos he had to go back to work to earn more $$ to feed his boat habit. <Heh Heh Heh!!>

He is worried about the caulked planking having opened up etc.

I am suggesting that we should sheath it in Mylar or similar fiberglass, as are two of my own larger yachts.

Has anyone any comments on this?

We have put lots of salt inside and are keeping it wet inside.
Thanks in advance.
Keith Stewart - Brooklynboats - Hawkesbury River Marina. N. of Sydney NSW Australia
Where you'll think you've died and gone to heaven, the fishing is great and the large Pacific osters are FREE !!

ENDS

[PAR]

Cool, I get to be first to yell. DON'T SHEATH A TRADITIONALLY CONSTRUCTED HULL WITH ANYTHING OTHER THAN PAINT OR VARNISH.

Lets not talk about polyester as it has no place on wood if you want to keep it or want to have the sheathing survive, this leaves epoxy and reinforcement (cloth, dynel or other) plus a few other odd coatings that are very debatable, I'll stick with epoxy, though I like lagging compounds.

Traditional construction requires the pieces to work together as a family of parts. Quite literally the pieces MUST move or work against each other for the structure to sustain loading, impact and the like. When you bond this structure to a skin of anything it can't move as was designed and local loading occurs. For a short time this is cool and dry and all's well, but then the loads once shared by many pieces, that have now been isolated, start braking things, like frames, planks, stringers and you know the little things that just ticks off the boat so it starts pissing in the bilge just to spite your new sheathing job. Then comes depression, not you, the boat. It feels bad, as the moisture content in the lumber doesn't stabilize, rot starts to creep in, as is apt to happen when they start feeling down (carrying that much extra water weight makes your wife understandable similar)

All kidding aside, if you want to kill a traditionally constructed craft, sheath it with 'glass. Not one restoration or repair outfit I've ever known would recommend this act, unless it's to get a few more seasons from a very tired, can't be fixed boat. Cold molding, strip planking or other option may be available for this yacht, but for the vessel's sake, don't ask it to die early, just so you don't have to chew on the maintenance issues any more.

[Ilan Voyager]

I agree totally with PAR, who gives an excellent technical explanation.
Do not believe any advertisement, claim or pseudo technical article; there are not plastic miracle solution for old wooden hulls.

There is not miracle epoxy remplacing the rotten wood, there is not any sheathing able to transform a classic wooden hull in maintenance free plastic hull.

A part fixing by classic means, there are only 2 options:

-to use the old hull as mold for a new polyester one (E. Tabarly did that for rescating the 1898 Pen Duick).
-to use the old hull as base for a cold molded wood epox sheathing with enough scantlings to take all the loads. The inside hull has to be epoxied. It's a long job.

Planking re-tightens when the boat is in the water: a wooden classic hull must not dry too much or it will open at the seams.

[Andrew Mason]

Do not sheath under any circumstances, the materials that allowed this boat to survive for 70 years are the ones it needs to survive another 70. Caulk it gently if it has opened up a bit, use some white lead putty if you can get it, and let the planks take up naturally.

If the boat is leaky with traditional caulking it probably has some ribbing or fatsening problems, as long as the ribs and planks are sound a traditional carvel boat should be tight and leak free.

And by the way, make sure its painted white, there's nothing worse for a carvel hull in Australian sunshine than a dark paint job.

[PAR]

A few additional notes about your interest in saving an old hull. Typical maintenance would require the planking to be replaced after a period of time, as it is considered a consumable element, just like an air filter or engine oil. If the maintenance is performed in reasonable cycles, the framing system and other structural members will remain in good shape.

This is rarely done however and issues start cropping up, like excessive leaking, panting, hogging and many other things. The owner is then faced with a large repair bill which most just don't complete. The work that gets done is enough to just keep up with the individual issues as they present themselves to the owner, in short a Band-Aid repair rather then a cure to the real problems harassing the vessel's structure. Before long the issues amount to a near or total rebuild, just to bring her back into a reasonable sailing form.

A hull can be saved several ways. The best way is to address the problems and effect a cure for each, but if the structure or economics prevent this, other methods can sometimes be used other than the traditional ones.

You can skin a hull with a sheath of 'glass, but it must be done with a very thick coating, basically one that encases the hull in a new hull structure of GRP of enough strength to disregard the wooden structure somewhat. You end up with a boat in a boat kind of affair, that is much heavier and will promote rot to consume the remaining structure pretty quickly, when compared to traditional techniques. You'll see this done on work boats a lot. They're not concerned about, the drop in performance if they can postpone buying a different work boat for a number of additional seasons. This is the least likely method of providing a long lease on the next part of this craft's life, but can be the least expensive.

You can skin a hull with cold molding techniques. In short a new skin of several thin layers of lumber are glued to the planking. The hull planking must be really dry and the support structure sound for this to work. You get a real smooth hull that will be quite leak free, but it's very labor intensive and will require many gallons of epoxy and reinforcement.

You can skin the hull with strip planking. This technique builds another hull over the current one from square or near so sections of lumber, increasing displacement a bit, but sometimes the additional girth adjusts for this. This method uses less epoxy and less labor, though it still is labor intensive. It too produces a fair, smooth hull.

Personally, I'd look at the traditional repairs, before I went to the glue and screw route on a different method. Traditional construction is intended to be repaired and generally the easiest to perform. Those type of repairs also will permit the craft to see another 70 years of service, which I don't think you'd get from any other type of repair. Carvel hulls are the easiest of all the methods and why you see so many of this construction method.

Good Luck,