Anybody ever use non-standard canvas thicknesses?
- Thread starter Howie
- Start date
MGC
Scrapmaker
Can anyone comment on the advantages of using the double-sided tape as the adhesive other than the obvious? Does the thickness of the tape matter? Granted, the tape should be covered by the outside rails. What about on the stems where there is nothing to cover the tape other than the cloth. Does it stand proud?
OP
OP
Howie
Wooden Canoe Maniac
Glenn... What's the advantage to using '7.25 ounce polyester/cotton canvas interweave' over Dacron? Is it because you can stretch the stuff and staple/tack like we do with cotton Duck and not use clothes iron? Is it stronger than Cotton Duck? In other words, what does the polyester give you?
And what does he use to fill the material?
And what does he use to fill the material?
Sorry, Howie, I'm not a builder or restorer, so I can only repeat what people tell me or I read. I've discussed Dacron with Alex over the phone several times and read his article. In the following 2021 post, in a thread about Tom Mackenzie's Loon Works canoes, I repeat what Alex told me about the reasons he was beginning to experiment with the poly/cotton hybrid fabric:
The Loon Works canoe
Hello, I recently discovered one of Tom's boats up in ME. I could not resist and it is now in my possession. I can not find a lot of information on his boats. I would love to know the specifications for this canoe. Specifically the capacities and materials used. I believe Tom used Dacron for his...
www.canoetripping.net
Here is what I wrote in that post:
"In recent discussions with Alex I sense he now has reservations about Dacron and is moving toward a hybrid polyester/cotton fabric instead, which is heavier than Dacron but lighter than canvas. One of the reasons, aside from the tear-strength and abrasion fragility of Dacron, is that Dacron sometimes pulls or bubbles away from the wooden hull planks after a time under certain conditions. He suspects that Tom MacKenzie may have sometimes glued the Dacron as well as shrink ironing it to the hull to deter these issues, but no one can really be sure until they try to remove the Dacron from a MacKenzie canoe. This suspicion may also be wrong."
It's a good question as to what fill Alex Comb uses with poly/cotton. I assumed he was using the same thing he uses with Dacron, but in all honesty I should probably say I don't know. Alex is very approachable and, especially since he sells fill and other canoe building materials, I expect he would be willing to answer that straightforward question via a phone call or email.
I looked back in my emails with Alex Comb and in one he confirms that the poly/cotton hybrid fabric is stretched on like regular canvas, not ironed on like Dacron. No mention of the type of fill.
Todd Bradshaw
Sailmaker
Just for clarity, be aware that "Dacron" is just Dupont's trade name for polyester. There are many different forms of polyester, as well as polyester blends. Anybody who owns a dress shirt these days probably owns something made from a poly/cotton hybrid. Get a poly/cotton fabric heavy enough and you can stretch it over a canoe, though "stretchability" will probably depend mostly on the weave as polyester fibers have noticeably less stretch than cotton, nylon etc. Heat-shrink Dacron is a very different form of polyester and for canoes the most critical factor may be its thin-ness. It's going to telegraph any irregularities in the wooden surface and make them stand out like a sore thumb.
To piggyback on Todd's comment, polyester is a generic word for a family of petroleum-based artificial fibers. Dacron is Dupont's trade name for a proprietary polyester formulation that became very popular because it resists mold, mildew and water. Ceconite is a brand name that uses the Dupont Dacron chemical formulation, but implements it for the lightweight aircraft industry in different weaves, weights and thread counts than Dupont Dacron.
Greg Nolan
enthusiast
You should check out the videos made by Larry LaLonde, the owner of Geodesic Airolite Boats. The videos cover virtually all aspects of covering and coating and fastening Dacron to a canoe (or other boat).
There is also a good deal of information about Dacron on the Geodesic Airolite website. And Geodisic Airolite is a very good source for Dacron – they now sell it at $17/yard in 8.4 oz weight. See LaLonde’s discussion of this fabric in one of the videos in the link above, where he focuses, in part, on its durability and puncture resistance. It is likely that LaLonde has built more SOF boats than almost anyone else, and is certainly familiar with the strengths and weaknesses of various coverings and finishing. Even though the canoe I am building is not from one of his plans (I did buy my material from him) he did give me some good advice when I called him with a small problem.
There is also an older (2010) discussion of some coatings at https://forum.woodenboat.com/forum/...lternatives-for-sof-kayak-coating#post2731932 that may be of value.
The fabric of SOF canoe hulls is often, indeed usually, not filled. The texture of the fabric, apparent through most coverings, does not affect performance, and it is not clear to me that most fillers add much of anything in the way of strength to Dacron, at the expense of needless additional weight.
There is also a good deal of information about Dacron on the Geodesic Airolite website. And Geodisic Airolite is a very good source for Dacron – they now sell it at $17/yard in 8.4 oz weight. See LaLonde’s discussion of this fabric in one of the videos in the link above, where he focuses, in part, on its durability and puncture resistance. It is likely that LaLonde has built more SOF boats than almost anyone else, and is certainly familiar with the strengths and weaknesses of various coverings and finishing. Even though the canoe I am building is not from one of his plans (I did buy my material from him) he did give me some good advice when I called him with a small problem.
There is also an older (2010) discussion of some coatings at https://forum.woodenboat.com/forum/...lternatives-for-sof-kayak-coating#post2731932 that may be of value.
The fabric of SOF canoe hulls is often, indeed usually, not filled. The texture of the fabric, apparent through most coverings, does not affect performance, and it is not clear to me that most fillers add much of anything in the way of strength to Dacron, at the expense of needless additional weight.
Greg Nolan
enthusiast
Consider using iron-on (Heat’n’Bond) adhesive tape. Larry LaLonde has an instruction video on how to attach Dacron to a canoe hull with it. In the videos at this link: https://www.youtube.com/channel/UC_RdzjWwXg06-1Q3eXETj4g/videos?view_as=subscriber
I’ve had pretty good luck with it on a SAOF canoe I am currently building. The iron-on tape contributes essentially no thickness because it mostly melts into the fabric when the bond is made.
Greg
MGC
Scrapmaker
Anyone seriously considering using Ceconite/Dacron/Polyester whatever should be making a few phone calls to lock in on the details. There is a great deal of anecdotal information stirred into this thread. The devil is in the details and it looks like there are too many details that go down rabbit holes.
I'd love to hear what Dan Miller has to say about this and I would definitely plan to give Alex a call. It would also be interesting to learn what Gil had to say about using this fabric with the different fillers.
I'd love to hear what Dan Miller has to say about this and I would definitely plan to give Alex a call. It would also be interesting to learn what Gil had to say about using this fabric with the different fillers.
OP
OP
Howie
Wooden Canoe Maniac
I think the last step when applying Polyester is to turn the iron to the hotter temperature and get the Polyester tight. But does that make the Polyester brittle to some extent? So after I canvas I often find that I've left a tack or two a little too high. With canvas it's no problem to tap the tack down through the canvas. How about with Polyester? Is pounding down pesky tack heads a problem?
MGC
Scrapmaker
The 250 degree temperature that you use to set the material does not damage it or make it brittle. Properly shrunk, it retains flexibility.
If you use a heat gun (in lieu of your wife's best iron) and do not control the temperature exactly, you might damage the material.
All of the process documents attached to this thread are very specific about the need to accurately control the temperature.
If you use a heat gun (in lieu of your wife's best iron) and do not control the temperature exactly, you might damage the material.
All of the process documents attached to this thread are very specific about the need to accurately control the temperature.
Frankly, if it was me, I'd just cover with no. 12 (or the next lightest if such a thing exists), rather than try a new method with all the possibilities of going awry. Use one of the lightweight fillers, and you are probably good. Keep in mind that if you save an extra 5 pounds, the paddler has to gain 5 pounds to have the canoe float on its designed waterline 
.
If you truly want lightweight, buy a Hornbeck.
.If you truly want lightweight, buy a Hornbeck.
MGC
Scrapmaker
Another case of 15 pound bicycle, 200 pound cyclist. 
I'm perfectly content with my collection of 20 pound bicycles and 75 pound canoes but if this really is so easy to do, as rugged and much lighter, it would be fun to try.
The recent note about gluing it to more places on the hull is a bit worrisome.
In all things, if it sounds too good to be true, it probably is.
I'm perfectly content with my collection of 20 pound bicycles and 75 pound canoes but if this really is so easy to do, as rugged and much lighter, it would be fun to try.
The recent note about gluing it to more places on the hull is a bit worrisome.
In all things, if it sounds too good to be true, it probably is.
Todd Bradshaw
Sailmaker
"As rugged" is kind of a questionable call. Polyester/Dacron fabric's lack of stretch can be both a strength (sailcloth, for example, where we need the sail to maintain its designed shape in use) and its weakness, due to its tearing properties. It is prone to what is called "explosive tearing". The nutshell explanation for this concept is that the yarns making up the weave don't work very well together - helping each other to take strains on the cloth and distributing that strain over an area. Instead, it's more like the first yarn trying to take all the strain until it is overpowered and breaks, followed by the second yarn, the third, fourth, etc. This happens quickly. I have seen cases where huge spinnaker sails or large sections of Dacron hot air balloon envelopes suddenly tore all the way from bottom to top or between web reinforcements in a second or two. I can also take a hunk of heavy duty12oz. Dacron sailcloth, cut a small slit, half an inch long in on edge, grab it on either side of the slit and in one quick motion, tear the whole piece in two. I basically just need to apply enough force to pop the first yarn to start the tear.
On a planked canoe hull, where the cloth is not suspended freely, that isn't likely to be a big problem. If, however you run over something sharp enough to snag and puncture the Dacron, its lack of tear strength might allow the tear to quickly get a lot bigger. So, its "ruggedness" may depend most on the type of water you paddle.
On the other hand, Dacron is pretty much moisture proof, so you aren't likely to ever need to worry about it rotting from being in a wet environment. I personally take solace in this as ten years ago they replaced my upper aorta with a piece of Dacron tubing, and at least that part of me still isn't moldy.
On a planked canoe hull, where the cloth is not suspended freely, that isn't likely to be a big problem. If, however you run over something sharp enough to snag and puncture the Dacron, its lack of tear strength might allow the tear to quickly get a lot bigger. So, its "ruggedness" may depend most on the type of water you paddle.
On the other hand, Dacron is pretty much moisture proof, so you aren't likely to ever need to worry about it rotting from being in a wet environment. I personally take solace in this as ten years ago they replaced my upper aorta with a piece of Dacron tubing, and at least that part of me still isn't moldy.
Greg Nolan
enthusiast
I have not used this Dacron fabric, but for what it's worth:
MGC
Scrapmaker
The following is a snip from an email Howie and I exchanged earlier today.
It's interesting. This has been a good discussion. I think it comes down to a simple detail. How will the canoe be used? If you want to loan it to a boy scout troop, don't put Dacron on it.
If the owner is more likely to be a dipsy doodler and into Omering while wearing a tux and blaring Vivaldi from a boombox, it should be fine.
Somewhere in between is "should be fine territory" knowing that rough use is better suited for traditional canvas and filler.
If you blow a hole in it, the material is repairable as is canvas. The risk that the whole thing blows up, so be it.
I think it's relatively low risk but I would not do as Larry suggests. I would properly fill it with EkoFil and then follow the finishing steps that were described in the Stewart boats instructions.
It's interesting. This has been a good discussion. I think it comes down to a simple detail. How will the canoe be used? If you want to loan it to a boy scout troop, don't put Dacron on it.
If the owner is more likely to be a dipsy doodler and into Omering while wearing a tux and blaring Vivaldi from a boombox, it should be fine.
Somewhere in between is "should be fine territory" knowing that rough use is better suited for traditional canvas and filler.
If you blow a hole in it, the material is repairable as is canvas. The risk that the whole thing blows up, so be it.
I think it's relatively low risk but I would not do as Larry suggests. I would properly fill it with EkoFil and then follow the finishing steps that were described in the Stewart boats instructions.
