dacron on Old Town

[Ed Moses]

Ceconite

Peter,

Is your "barrier to adhesion" trick some other material like wide saran wrap laid over the surface of the hull before the ceconite is applied and shrink fitted? Without an underlying barrier, does the ceconite adhere as a result of the heat shrinking process or from bleed thru of whatever you are using for weave filler?

Ed

 

[peter osberg]

ceconite that I know had a coating already, it was the covering for my trembly canoe from St Felicien Quebec (1970), but maybe I have my names wrong. I have used raw aircraft dacron, that is heat shrinking. When I first started the fellow at the aircraft shop told me to use saran wrap to prevent adhesion; after initially not following his advice.... I discovered it worked, and it is invisible except in the mind of the builder. It prevents the puckering as the wood moves and swells. Use scotch tape to keep it in place until the dacron is loosely laid on. Then use the iron. It does not allow any penetration or bleed through of the plastisizing paint. I use additional layers in abraded areas, but have those layers bonded to the first. I have tried the aircraft paints but they are not hard enough for my purposes, hence using epoxy/graphite as the filler layer, then base/colour coat. Using epoxy as a filler also prevents paint incompatibility issues. I have not had any issues with the colour coat not adhering.
In my big canoes, I am surf launching and landing, so the niceties of not allowing sand and gavel into the canoe are not on. So I used an addition bonded to the wood layer, beneath the 'normal' fabric coating layers to prevent gravel from getting under the fabric cover.

 

[CParker]

Stetching Canvas

I just had to add my $.02 worth to the discussion on dacron vs canvas. I've just finished putting canvas on my 1940 OT; it's the only time I've ever done it, and I've never used dacron.

I shared the concerns over using come-alongs with clamps, then adding weight in the boat to get the canvas to stretch.

Instead I used the upside-down method on a pair of saw horses.

In order to get the length-wise stretching provided by the come-alongs, I simply tightened the canvas by rolling it up like a towell vertically on both ends, and then held that in place with one of those large ratcheting-style clamps. Worked like a charm.

It took me several tries to get everything as tight and wrinkle-free as I could get it. Then before I stetched and stapled the canvas on the stems, I wetted it all down with a wet rag (except the ends), which got rid of all of the small puckers that otherwise didn't seem to want to go away.

Then I tackled the ends, got them as tight as I could then wetted them down with a wet rag.

I thought it went quite well, and I didn't need anyone else to help.

That'll be $.02!

 

[trouts2]

I’m not familiar with Trembly canoes but I’m assuming they are wood strake and ribbed canoes originally covered with ceconite. Since he covered the ribs with saran wrap he must have taken the ceconite off and applying a new Dacron cover.

Can someone explain two sentences from his description? (by peter osberg post number 22)?

>>>I use additional layers in abraded areas, but have those layers bonded to the first.
How can he have abraded areas on a new cover? Is he applying patches over the top of his first full Dacron cover?

>>>So I used an addition bonded to the wood layer, beneath the 'normal' fabric coating layers to prevent gravel from getting under the fabric cover.
That seems to me to say he had a skin glued to the wood layer probably on the wood before the saran wrap was applied. Is he putting on strips or a large sheet of something on the bottom may be up the sides an inch or two?

 

[peter osberg]

Trembley canoes are the standard wood ribs and planking, with a fabric cover. The Saran wrap layer is applied before the first layer of fabric to prevent adhesion to the wood once the Old cover is taken off. I used extra layers in areas that were going to be abraded (the bottom). Trembley canoes used ceconite (also called verolite ) which was thick enough to cover some imperfections in construction (like canvas).
On my ocean freighters, I added an extra layer to deal with the gravel that accumulates in the bottom from beach (surf) launching and landings, this layer was intentionally bonded to the planking (very little additional weight), then I applied the covering, ....... Saran wrap(to allow the cover to move independently), then multiple layers of dacron.
Peter

 

[Dan Miller]

Trembley canoes used ceconite (also called verolite )

Tremblay did use Verolite, which was a vinyl impregnated canvas. Ceconite is a trade name for aircraft-grade heat-shrink dacron. Two entirely different products...

Dan

 

[peter osberg]

Dan may be correct although I was told when I bought a Trembley new, that the covering was a vinylized Dacron initially marketed to the home built aircraft market. The same story was repeated a decade later when I talked with a former worker at the plant. I have worked with the cover and managed to successfully reapply some sections of covering and do not believe what I have is canvas. I have tried to do the same things with canvas and it has behaved differently. It is how I started to explore the succesor fabrics used in the home built aircraft market. I know ceconite is a name used for aircraft Dacron usually as raw fabric.
Peter

 

[woodfyr]

Ceconite is an aircraft dacron available in various weights. We use a 3.7 oz. material caleed warbird or agricultural grade. This material has a shrink factor of 20% when the "proper" heat is applied. We have used this material exclusively since 1993 on various makes ans models of canoes including square sterns. Our process uses no tacks. a bonding thermal tape is applied to the areas where tacks would normally be used.
The question of application in high abrasive areas: In hard chine applications, strips of dacron material (yes, the material is available in strip/tape form) is applied using thermal bonding tape(in the case of aircraft, fabric cement) The use of an inner skin of fabric applied from water or bilge line to (ditto) to help reduce effects of sand/debris abrasion from the inside has been done with some success. It is applied in the same manner, with bonding tape, heat shrunk and sealed.
As the dacron material is of a fine weave, traditional filler is not required. Waterborn/latex paint works well as a sealer and newer paints can achieve a high gloss. Traditional oil based or epoxy paints can also be used.
We have a kit available for DIY applications.

 

[trouts2]

Peter,
Sorry to be overly dense about this point. I’m still not quite up with you and would like to know what can be done with sand as it’s often mentioned in as a drawback to Dacron.

I get the Saran wrap and think it’s a great idea. It would be the last thing between the rib and Dacron. It’s the added layers that are confusing, their size and placement.

It seems like additional layers are going in two places.

>>I used extra layers in areas that were going to be abraded (the bottom).
Are these layers added to the initial cover outside or inside between the initial layer and rib with Saran? Was it a full hull overlay, full lower portion only or strips?

>>>I added an extra layer to deal with the gravel that accumulates in the bottom from beach (surf) launching and landings, this layer was intentionally bonded to the planking (very little additional weight), then I applied the covering, ....... Saran wrap
This seems to be a separate layer from an added external layer. This seems like strips running between ribs and attached directly to the planking/strakes. If not strips it might be a large bottom layer attached to the planking on the inside. That would make rib, Saran, bottom large layer covering bottom only then the final cover.
Actually I don’t think I have any of this right.

 

[peter osberg]

Sand and gravel are not really appreciated in canvas or Dacron covered canoes, hence the tradition of cleaning off the sand before, you bring your feet in when tripping. This is not an option when launching in surf. I tried to address this by a bonded (to the planking) layer of light weight Dacron, which prevents sand and gravel getting under the planking ( the sand and gravel then accumulates between the planks and in the 'bilge' when underway). After that is finished, I start the actual cover that is the skin of the canoe and instead of canvas I use Dacron which I can build up multiple layers where it is needed. On the forefoot along the keel for example. This enables me to minimize the weight of the canoe (by having a lighter covering on the sides as compared to the bottom).
Peter