Heat-moldable plastics

Seeing c2g’s nicely-decked canoe at Raystown got me to thinking. He used a heat-moldable plastic (Kynar? Kydex?) to form boat-wide panels that clipped to the thwarts and tensioned the fabric decks. Very original.

Which made me think that another way to attach decks to flatwater canoes would be to fabricate and heat-mold clips to the profile of the outwale/inwale of my Bell Magic and sew them into the fabric at, say, one foot intervals. The clops would have more than enough to grab onto in the Bell profile, to my thinking.

My old standby, McMaster-Carr Supply, does not have these plastics in the catalog. Any plastics experts out there care to suggest another resin or another source?


Here’s a Kydex source:


I’d think that any plastic that can be vacuum-formed would work.

Yeah, it was once common practice
to make Kydex skid plates by heating, molding to the boat ends, cooling, and then attaching with epoxy.

I have noticed a tendency of some cheap vinyls to get brittle with age. I will have to check my Kydex sheet in the basement and see if it is at all brittle.

I was impressed as well

– Last Updated: Oct-16-08 5:25 PM EST –

with c2g's set up. Very ingenious. He also molded a section of it to act as a secure holder for his GPS. Dave is clever guy!

Other than these comments, I have nothing to add Jim. Sorry!


A simple Google search
yielded several on-line sellers of small quantities of Kydex. My plan is to carve a section of red oak into the Bell outwale/inwale profile +1/16" or so in all directions, 24" in length. Clamp the Kydex against the male mold, heat with a heat gun and drape the heated sheet around the curves. Probably need to have some wood forming tools available too, as c2g said holding the hot plastic in position was at times difficult. After cooling, I will use a table saw to cut the long profile into 1" sections.


Sewing plastic clips to spray decks

– Last Updated: Oct-17-08 9:58 AM EST –

seems like it would present a real challenge. Is this approach inspired by a reluctance to install traditional hardware, like snaps, to your hull? Maybe you could install snaps to your clips instead. What's going to keep your clips from sliding along the rails?

I'm curious because the pics of c2g's(?) decks on ness's boat made them look very neat and clever and I'd like to know more details of their construction and installation.

Edit: Boozer's right about the oven approach. Evenly heating anything bigger than your hand with a normal heat gun is frustrating. If you are using a household oven, preheat and turn off when your piece goes in, as ovens cycle on/off and can get too hot too fast. Diligence is key.

Oh, yeah. I've had good luck thermo-forming garden variety PVC pipe as well as plexi, ABS, and polystyrene. I think Lexan will work, though I've not tried it, I have seen pieces that were vacu-formed.

I thought I was at Raystown
But I sure missed alot, including the boat and canoe cover under discussion. Did it make it into any of the photos?

How does one work with that plastic sheeting? The working temps seem to be 350 to 385 degrees F. Hot! And as I learned when I attempted to melt the oil-canning out of my boat, applying the heat uniformly is important, and difficult. Seems like slowly heating in an oven is the best approach. How big is your oven?

I’ve seen canoes with partial covers cut from plastic trash cans. Molding sheet plastics seems much cooler.


Plastic clips
interest me because it seems as though nobody else has used them. Snaps on Cooke covers, bungies & buttons on Northwaters etc. I think I can do a credible job and have done a number of sketches to work out the kinks. Clip pockets, bungies running from clip to clip to reef extra material (to accomodate a bulging load) and a stiffener for the amidships edges have all been on my mind for the past week.

I plan on heating a strip of material, maybe only 12" x 3.5" at one time. Only one bend at a time. I also have access to IR thermometers to monitor the material’s heat.

Or I may punt and order a Cooke’s. Hard to say.


I wouldn’t second-guess
your ideas, Jim. I’m sorry if I’ve given that impression. You obviously put a lot of thought into your projects and, like me, seem convinced that there must always be a better way. There’s no question regarding your craftsmanship either, as illustrated by your many generous and informative reports and pics.

As for the spray decks, I’m genuinely curious. Please keep us updated on your results. If there are mistakes to be made, I’d rather learn from yours! I will try and return the favor with what little I have to offer.

As far as heating large pieces of materi
When I was in college, I worked at a pool center, repairing patio furniture. When making repairs to plastic strap type pool furniture, I had to heat the strapping to get a good tight fit on the aluminum frame furniture. Anyway, to accomplish this, We had built a plywood box of considerable size which acted like a crude oven. The “oven” was heated by an industrial heat gun inserted into the box via a sheet metal heat shield. With a little insulation on the outside, you should be able to maintain considerable, somewhat even temperatures.

I’d like to see a homemade Kydex decked Robroy.

Heat molded clips/ decking
I have seen molded pieces to wrap the gunnel. Kevin Carr of Chosen Valley Canoe accesories has done a fair amount of moldable plastics.

Are you looking to do the whole deck or jusr provide the mounting of a snap or a sleeve/pocket reciever?

I have not spent a great deal of time with this, but as with any design there are possibilties of sucess and additional problems.

Dan Cooke

Similar to teh one described
in Clif Jacobsons book Dan. I am toying with the idea of cross-boat tunnels for shock cords (with extra fabric for larger loads) reefed via cordlocks. The clips would reside in the ends of the tunnels. Of course, there would be a need for an access slot which would complicate the sewing job.

Of course, if all of this planning causes my head to explode I will simply order a set oc bow & stern covers (ala Mike McCrea) from you come the new year.

And best wishes for a speedy recovery!



– Last Updated: Oct-18-08 8:43 PM EST –

Kydex is the only heat-moldable plastic I've ever worked with. I got the idea from having used it to make a few knife sheaths. I have a few thoughts about using it with covers, and I'll throw them out in no particular order:

Sources: Depends on how thick you want it and how big a piece you want to work with. I got my last batch from Interstate Plastics
http://interstateplastics.com The reason I went with them was because they sold pieces large enough to span a boat side-to-side, and they sell it it different thicknesses and colors. Most of the knife stuff is the .060" thick stuff, which IMHO was probably a bit on the thin side for what I wanted. I used the .125" material, but will probably drop down to .093 for my next attempt. .125 was more difficult to work with than I would have preferred, and I think the thinner material would still have been plenty strong.

Option 1- If you are just going to be doing gunwale clips, you could use a toaster oven (popular with the knife sheath crowd) set up near your boat. That way you could hold a few pieces at the right temperature instead of having to heat them one piece at a time with a heat gun.
Option 2 - Use a heat gun ($25 or thereabouts from Walmart, Home Depot, or wherever). I use the high setting because I am impatient, but if you do that, keep the gun moving or you will bubble the kydex.

Gloves - Use leather gloves or something else that will keep some of the heat from your fingertips.

Where to shape - I'd do it right on the boat.

Size of clips: The bigger they are, the harder they will be to get off. I'd say no bigger than 2" long to start with

Cover design thoughts:
-Reason for covers: I use them to reduce the effect of wind on the boat. Most seaworthy boats won't take on much, if any, water. However, I'm also a sit-and-switch paddler for the most part, and the cover keeps the paddle drips out of the boat and off of my gear.
-Side-to-Side Tension. I like a bit on my covers to pull them tight so that water doesn't pool on top. Dan Cooke, who obviously knows 100 times more about covers than I ever will, doesn't tension his. Even with an un-tensioned cover you won't get that much water on top, and I don't think the reduction in wind effect on the boat will be much different whichever way you go.
-Front to back tension: Dan's covers don't need it because the snaps hold everything in place. The way I do my covers (with side-to-side tension) you also need some from front to back. If you go this route, I'd suggest molding some kydex around the thwart and using bungee, er, I mean shock cord, on the nose. Make it plenty short so it will pull nice and tight. Hook the nose on first, pull back, pop the kydex clips over the rear of the thwart, and you have the front-to-back tension taken care of.
- To coam or not to coam - I have used a bit of a coaming on each of the three covers that I have done. I did it on the first one, the one that Ness currently has, because I paddle on the Chesapeake Bay and I wanted something that would kick the water aside if I misjudged conditions and accidentally took a bit over the bow. The cover I got from Dan for my Voyager, which was one of his standard covers, did not have one. Again, Dan has done a lot of covers over the years, and I've only done three, so you might want to think about whose lead you are going to follow.
-I think you mentioned shock cord running side-to-side. You won't need it to hold the clips on, and if you are looking for side-to-side support for the cover, IMHO it would be easier to use a single piece of kydex.

Kydex Clip design thoughts:
I had actually started doing a cover for my wife's Merlin II and would not require any fittings permanently attached to the boat, so I have given this a little bit of thought, with the key word being little. I had considered a couple of possibilities.
1. Attach the clips to the cover, but don't bother with side-to-side tensioning.
2. Fabricate clips that would incorporate something that could also serve as a shock cord hold down. To do this, you would want to leave the kydex on the outside of the hull a bit long. The first think I would try would be molding a downward-facing half circle into the lower part of the clip.

I'll try to get some picture taken tomorrow - assuming I can corner my wife or son long enough to borrow a camera. I may even try to mold a couple of sample clips so that you can see what I'm trying to explain. Heck, I might even order in some more kydex and do a cover for my wife's Merlin II or a replacement for the ugly-a** thing I have on my current Osprey.

And please remember, you didn't pay a cent for the forgoing advice, and it may be worth exactly what you paid for it. LOL

edit: For attaching the kydex clips to the cover, I'm going to try using webbing instead of sewing the clips directly to the cover fabric. It sounds like a good idea, so there is probably something wrong with it, but I'm going to give it a shot anyway.

A quick note about safety and Kydex
When Kydex gets too hot (IIRC ~400 degrees) it creates a very potent toxic gas (HCl). So be careful and make sure you’re in a well ventilated area, because accidental overheating is easy.

Don’t they call canoes with decks


But then again a canoe hull would put it in the tank class.

Paddlin’ on


got me one er dem, too, but it’s easier to get to der beanie weenies widdout der hard dex. Wise guy LOL



concept cover made - see separate post
I did up a quick cover to check out the concept. It’s posted under “Merlin II/Magic spray cover concept”. It looks to me like the idea will work, although getting the rig just right will probably take a little bit of experimenting - or maybe just someone a bit smarter than me, and that shouldn’t be hard to find!

Problem may be solved

– Last Updated: Oct-20-08 11:14 AM EST –

without any heat-molding. Look at Paddlingpika's covers in this thread.



c2g: Thanks a million for your thoughts. Luckily I have no materials on hand, so I cannot rush off and start sewing. I plan on giving this much more thought over the next several months. ANd while I wouldn't need a pinat of plasma as Mike may have needed after a sewing project, it still is a daunting undeavour.