adding another cold molding layer?

[totrecal]

I'm rebuilding a Glen-L design "Jolly Roger". A 30 ft. wood trawler. The hull is "cold molded" marine plywood. Two 3/8 inch layers at 90 degrees to each other. The boat was glassed, but 90 percent of the glass has been removed. Glen-L says the boat has to be glassed, but I've already repaired the problems glassing has caused. What I'd like to do is put another 1/4 inch layer of plywood glued with 5200. Looking for opinions on how well this might work to make the boat more seaworthy.

[On Vacation]

Was the boat glassed with polyester resin? It sounds like to me that it was if it has been removed. Most of the time, with an epoxy glassed boat, the wood will come with it, if stripped off. Instead of another layer try using 1808 or 1208 and finshing clotth on top for a fill and fairing instead of another layer of plywood. Also a product called c-flex, which is overkill can be used and has in many commercial work boats to extend the life. Yes I will duck now . :D

[totrecal]

I'm not sure what the synthetic was on the boat. All I know is that it peeled like a 30 foot banana. There were gallons of water between the plastic goo and the wood. I guess I support the theroy that wood moves differently than plastic. Seems like if I was going to add a covering to help seal the boat, wood makes more sence than glass. I have a friend who's a glass expert. He says he's never heard of a reglass job that's ever held up. I guess the c-flex would stay on the boat since you can fasten and glue. The thing is if I wanted a fiberglass boat I wouldn't have bought a wood one.

[wolfietuk]

Boats are designed specific ways for specific reasons. If the designer says it has to be glassed then you should glass it. Some people have glassed wooden boats that should not be with disasterous results. It would be just as bad to not glass a boat that was designed to be glass. True there some times it is optional. The designer is probably the best judge of this.

I would agree that this was probably a case of poor construction. Either a polyester or vinyl resin (cheap stuff) or possibly improper mix ratios. It would definately cause me to examine the rest of the boat closely. Are the cold molded layers holding together?

Rick

[On Vacation]

Since it is a Glen-L design, I suspect it is built with fir plywood as home projects are done. Going back with wood as an alternative layer doesn't make the boat better in this case. Most boats built with multilayer cold moulded construction, are glassed.

Painted plywood hulls are not too pleasing to the eyes for finishing unless the plywood is mahogany or a good hardwood product. Fir has a big time problem with holding paint overall. What year was this boat built? DO you know who built it? If so, ask them and also see if they would have pictures of construction as iot would help you and us in the quest to answer the reason for the glass coming off.

If it wasn't done with polyester, the wetting out stage was improper. You will have to search long and hard to find "Good" epoxy and glass that peeled off of plywood in sheets if the boat hull was done when new. Perhaps you may have some shots of the boat that you can post? I will also look up the site and take a look at the design closer.

Neat looking boat. Is this it?

http://www.glen-l.com/designs/cruiser/dsn-jrg^.jpg

JOLLY ROGER... a 28' cruising yacht
Build in PLYWOOD or FIBERGLASS

CHARACTERISTICS
Length overall: 27'-9", Length waterline: 25'-0"
Beam: 10'-10"
Draft: 2'-9"
Displacement: 10,433 lbs.
Freeboard forward: 5'-6", Freeboard aft: 2'-10"
Hull depth: 8'-3"
Height overall: 12'-2"
Headroom: 6'-1" to 6'-5"
Cockpit size (approx.) : 5'-0"x 9'-6"
Cockpit depth (nominal): 31"
Fuel capacity: 190 gals., Water capacity: 120 gals.
Cruising range (approx.): 1000 miles
Sleeping accommodations: 4
Hull type: Semi-displacement hard chine hull with practical cruising speed of 7 1/2 knots. Build in plywood or "one-off" fiberglass. Bottom features deep bulbous forefoot with reverse curve at the chine. Plywood version: double diagonal plywood planking on the bottom to a total thickness of 3/4", sheet plywood sides to 1/2". Topsides feature broad flare with raised deck forward. Fiberglass version utilizes fiberglass planking or PVC foam or balsa core sandwich construction.
Power: Single diesel engine recommended of approximately 25 continuous shaft horsepower for 7 1/2 knot cruising speed. This power figure includes a 50% reserve to offset adverse wind and sea conditions. Engine weight should range between 500 and 700 lbs. Gasoline power is optional.

Hull construction is either plywood, using double diagonal planking on the bottom and sheet plywood planking on the topsides, or "one-off" fiberglass using fiberglass planking or foam core sandwich materials and methods. A full length skeg assures directional stability in all sea conditions, and the hull features a bulbous forefoot at the keel for a soft entrance with reverse curve at the chine for dry running.

[ 08-25-2002, 07:42 AM: Message edited by: oyster ]

[NormMessinger]

Sand a bit on the glass that remains. The stink, if any will tell you the resin was not epoxy.

--Norm

[totrecal]

wolfietuk
The boat was completed in 1990 and the builder has died. I have repaired some delaminated areas in the hull, and in those areas the cold moulded layers were not well glued together. There are other areas in the boat that indicate either poor repair or construction. I really should probably give this boat up, but my wife loves it. It's seems a toss up on repairing this one or building one from scratch.

[totrecal]

oyster
You've found the right boat. Mine has been streched out a couple of feet beyond the design length. I've got a ton of pictures. I'll see about scanning one in.

[ihrig]

Cold molded boats are supposed to have dry wood in them. Dry wood sealed in epoxy is much stronger than wet wood. If the wood is wet, the hull is weaker. So I recommend glass.

Epoxy will work better than polyester, which while cheap is semipermiable to water. Polyester doesn't stick as well either.

I recommend making sure the wood is dry, (not cooked). If the wood is wet, vacuum bagging it might help. (Lower pressure speeds evaporation.) You want the wood dry enough to absorb the epoxy for a good stick, but not so dry the wood is weakened.

What I really recommend is to get yourself the Goudgeon Brothers book on boat building! Read the first few chapters and it will explain the whys of cold molded boat building.

I have built the John Marples cold molded Puffin. Mine isn't glassed but is epoxied. I wish I glassed it. Next time.

[On Vacation]

That appears to be fir plywood or at the worse, pine. With the surface appearing to be in original shape, polyester comes to mind. Sand the wood down and check for burring up. This is when the wood is wet or has been damp for a while. From what I can see, I wouldn't forgo the project unless the layers are coming apart. Tap on the sides and see if it sounds deep or a higher pitch thump throughout sections. This will tell you if you have a more serious problem.

[thechemist]

Originally posted by totrecal:
[QB]
Finally got my brain wrapped around how pics get posted here.

QB]Ummmm.......close, but not quite. You made the picture too big and now none of the posts are easily readable without moving the bottom scroll-bar back and forth and back and forth.

Those wiser than I can tell you how to size the pictures correctly.

[totrecal]

Sorry Chemist. I'll reduce the pics next time. Just in too much of a hurry to get them posted. I've been thumping and tapping all over the boat for months. There was one section on the side away from the picture that was in pretty bad shape. It's been replaced using fir plywood and 5200 as sealer/adhesive. The rest of the boat sounds like it's solid

[totrecal]

ftp://csisuper:01spt01@ftp.pressenter.com/BOAT%20AFTER.jif

This should make reading this post better. Guess what the boat used to look like isn't too relevant right now.

[On Vacation]

Planking can be corrected. Its not like a bunch of ribs and frames need to be removed and replaced. Scarf in pieces , which is easy to do and sand it down. Then if you wish to skin, use only 1/4 inch plywood of good quality and then glass it. My .002 cents worth.

[David Tabor (sailordave)]

Are you really sure you want to use 5200 to glue/seal the new pieces? Epoxy to wet everything out and then recoating with thicken epoxy is a "much more better" thing as my 7 y.o. says! And to hear the description of 'glass coming off in sheets, that alone convinces me it was put on w/ polyester resin...
You definitely want to dry the boat out and letting it sit sheltered for several months or a year should do that w/o harm unless you are in an extreme environment (think Phoenix, et al or Olympia rain forest!) then coat w/ epoxy and fair. Replace wood as necessary. I'm not convinced you need to put on another layer of ply, but if you do, you may be able to get by with a 3mm (1/8") layer of good ply and vacuum bag it down with epoxy. And definitely go with at least a light layer of glass on top.