View Full Version : glass on wood
12-21-2004, 09:55 AM
i have a 40' cutter, double cedar plank over ipol( oak) frames. resorcinol glued on edges and faces. the boat has been completely stripped of paint for a year, inside and out, to dry out it's 35 yrs old. the cedar is in excellent shape. my question is this, can i cover the exterior with 6 oz. cloth and epoxy for abrasion and general strength? does anyone have any experience in doing this. i know the subject ignites a world of arguements, pro and con.
12-21-2004, 11:21 AM
I friend of mine just bought a 5.5 Meter boat that he will restore (I need him to get on the forum...)
Someone glassed the bottom of the boat back in the mid 80's. It has been sitting in a yard for 5-6 years before he bough it.
It needs the entire bottom half of the boat replaced among other things.
Attributed to glassing, the non-glassed areas are not rotted away.
12-21-2004, 12:26 PM
If you are fortunate enough to have a 35 year old cedar hull in excelent shape, I believe that would fall under the "if it works don't fix it " catagory. I would take advantage of the best paint system appropriate for your type of hull construction and go for another 35 years.
12-21-2004, 12:28 PM
Originally posted by joe moore:
it's 35 yrs old. the cedar is in excellent shape. Why mess with success?
12-21-2004, 12:52 PM
One layer of 6oz cloth on an otherwise sound, double-planked 40 foot cutter is not going to add any meaningful strength.
As far as abrasion resistance?! I'm not sure what you're thinking. The only meaningful form of abrasion resistance for a 40 footer is to avoid colisions and running aground. You really shouldn't be planning on hitting or "abrading" anything, if you catch my drift.
On the other hand, the construction you describe almost sounds like a primative form of cold-molding. It sure isn't traditional plank on frame if you've got the planks edge-glued and glue between the layers. It's not unusual for a properly built cold-molded hull to have a layer or layers of glass in the construction.
I am inclined to think that the only advantage to a single layer of 6 oz might be worm protection until it's cracked by banging against something.
I'm in the "don't fix what's not broken" camp. Why do you think you need to increase the strength of the hull or increase the abrasion resistance?
Thad Van Gilder
12-21-2004, 01:14 PM
I think it's a better idea to eat your own feces than to glass a planked boat.
Different types of construction methods are always, of interest to me. Especially how they hold up over time, the ultimate test. You have a double planked hull that is 35 years old, and is solid and sound other then needing repainted. I say lucky you. Appearantly the construction method has proven itself.
Probably half of the people on this board, think that without cpes, fiberglass cloth and epoxy, your wooden boat will surely rot away or have a hole abraded through the bottom of it.I think your boat has proven that theory to have a few holes in it.
Have you thought about selling that old wooden boat and buying a nice,slick and shined fiberglass model? But be carefull,a 35 year old glass model probably won't be in anywhere near the condition of your 35 year old wooden boat.
The fiberglass and aluminum boat manufactures have done a fantastic job of selling the public on the idea that wood is a bad material for boats.
12-21-2004, 01:53 PM
My uncle glassed a wood boat years ago and totally ruined it, not from rot, but because whatever he used swelled up between the planks. I always thought glass would guarantee rot by trapping water under it, but there are those who swear by it. How can it not trap moisture? Isn't it a dream to think it will keep moisture out completely? Yet it is still done quite widely. There must be something more to it.
There was an article in WB a while ago about a ginormous gazillion-dollar wooden yacht being built, and she got glassed.
[ 12-21-2004, 01:56 PM: Message edited by: Victor ]
Here is a picture of double planking as well as batten on seam, carvel and traditional strip planking.You hardly ever hear of double planking, or batten and seam, they defintely are a lot of work and quality first class construction. You can read more about them on hankinson's site as well as in chapelle's boatbuilding book.
12-21-2004, 05:44 PM
You can also read about double planking in Gardner, Steward, I think Rabl and certainly Paul Gartside has used it to advantage:
Jessie is double planked. After the frames have been installed and faired, a layer of 1/8-inch cedar is fitted and glued at a 45° diagonal. This is followed by the outer planking of 1/4-inch red cedar laid fore and aft, laid in epoxy glue. http://www.gartsideboats.com/pgimages/surpriseplank.JPG
"Surprise" was built upside down using our standard set up procedure. The molds are set up first, then the backbone is lowered into place and temporary ribbands bent around. Frames are steam bent oak boxed into the backbone and notched through the deckshelf. Here the planking is well along, and the spiling batten is being used to take off the plank shapes. The inner planking is ¼ inch thick; the outer layer ½ inch with the joints staggered. Planking is laid in epoxy glue and fastened with bronze screws.If the planking has been totally stripped of paint, Smith's C.P.E.S. on the bare wood followed by the quality paint of your choice should be just fine.
Put me firmly in the "If it ain't broke, don't fix it" school of thought.
In the Swamp.
12-22-2004, 10:18 AM
The method you describe is really a hybrid of cold-molding and double planking. It's closer to cold molding because the glue binds everything together to make a giant two-layer monocoque piece of plywood in the shape of the hull. Traditional double planking involves building one hull over another, with some sort of flexible goo (traditionally white lead) between the hulls. Traditional double planked hulls were not edge glued. They were closer to batten seam than to cold molding. People were building double planked hulls long before epoxy and other modern glues.
Joe Moore's boat sounds like a transitional type of construction. If it were built today, epoxy would be used liberally, and the hull would be truly molded. It would be common to cover it with a layer of glass in epoxy.
I don't really know how a layer of glass would effect Joe's boat, but I don't think it would add much benefit in terms of strength or abrasion resistance. If the hull is sound, I would just paint it, maybe with LPU, using and epoxy undercoat, like CPES.
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