How do I cut Kevlar?

I plan to replace the aluminum rails on my Wenonah Prism with wood gunwales. I’d like to trim the top edge of the boat all the way around so the rivet holes won’t show beneath the new wood gunwales. What would be the best way to get a clean cut all the way around my canoe?

Thanks for any advice on this.

Glass comes in tape widths;I suspect

– Last Updated: Apr-27-10 12:42 PM EST –

Kevlar does also.Yep.

A rotary cut-off saw would be best…
…but most people don’t have one. A jigsaw with a fine-cut (metal cutting) blade should work well. Cover the area of the cut with masking tape and mark it. If you feel comfortable doing so, scoring the surface with a utility knife would help to create a cleaner cut, but only if you can get through the gelcoat to the fabric (I’m somewhat hesitant to recommend this).

Cut carefully, letting the blade dictate the speed of the cut. Once you’ve made the cut, DO NOT attempt to sand the edge, as the Kevlar will will become fuzzy. If you need to clean it up, use a sharp scraper instead. If the edge is going to be hidden, I would just seal it with a coat of epoxy and not try to clean it up.

Thanks for the suggestions
I think I’ll try it with my jig saw and a metal blade. It’s a ultralight prism so no gel coat. I’m tempted to score a line using the bottom edge of the aluminum rails while they’re still mounted to try and get the cleanest cut. I don’t know if that’s the best place to cut, but it’s the only way I’d be able to keep my utility knife from going off line.

Thanks again!

If you have a choice cut the kevlar side

– Last Updated: Apr-27-10 4:19 PM EST –

of the laminate on the bottom (furthest from saw foot ) of the pull/cut stroke.

Use brand new blades too + Don't feel funny about switching them if you have to do some long cuts.

If you really have to sand top edge due to a wobbly cut, just go for it with a block and fresh 60 - 80 grit. If using the yellow 3M type sticky back discs, even better. If you generate large stuff ( fuzzys ), o.k. to cut with scissors. Finish sand with fresh 120 or 150 or 180 - 220 wet works pretty good too if you have time to wait for dry.

If kevlar is sandwiched between plys of glass, above will be limited to a small fuzzy top edge.
If kevlar not sandwiched, try to cut it straight : ) .. Or a little more light weight sanding to try up edge.

good lord man , don’t use a jig saw …
… if you can help it !!

In the first place , it’s way too much tool for the job … then you have to protect the hull from were the saw base needs ride along , then you’d need to use a super fine blade which will heat things up and be slow cutting anyway … and you still will end up with a rough cut and frayed edges .

It will be difficult to hold the jig saw in position , and the hull will be flexing with out it’s gunnels .

A dremel cut off disc would be my first choice … followed by a roto zip tool as a second choice .

I’ve got a dremel tool and that might
allow me to get a cleaner cut. Thanks. I’ll look into getting a cutting wheel and try that method first. If I can stay close to my line I figure the wood gunwales will hide any rough edges.

Laminate trimmer!
I’d try a laminate trimmer (or small router, like 1 hp or less) before a jigsaw. I really don’t like jigsaws though. They’re hardly precision tools.

If you could clamp a strip of wood along your cut line (like 1/4" thick, so it bends along the curve of the boat) you could use a pattern cutting bit in the laminate cutter and the bearing would just ride on your strip of wood. Use clamps every couple feet, and first do the spaces between the clamps, then one by one move the clamps to the spaces, and go back to trim the spots where the clamps used to be. Should produce a nice clean edge that you don’t have to sand at all.

Same problem
I have the same situation, though my solution is to ignore the little holes and work up a few stories as to why they are there intentionally. On mine, at least, they are just below the new wood.

  1. There for tying in certain accessories.

  2. Drain holes, like scuppers

  3. Make the canoe lighter

just get a pack of them …

– Last Updated: Apr-27-10 11:56 PM EST –

...... you might find them in a clear palstic cylinder pack (like quarters in roll) , or else lesser quanity packs .

It may take you a couple/few disc snaps to get the hang of not binding the thin little cutting disc (and the thin ones are better) , it's just a fine ballance and not too much pressure .

One thing can help when cutting long lines though sheet material ... use a little light wedge (wood or other) now and then trailing behind and in your cut to help prevent any possible bind if it seems needed ... and also maybe put a piece of tape now and then over the cut to help keep the cut away strip from flopping in and out as it gets longer .

I'm also just wondering , since you want to cut your hulls top edge so prior holes don't show beneth the new gunnels ... is it possible or fessable to just make the gunnels "taller" so they cover those holes ??

You must own a cheap jig saw
A quality saw with quality blades and a zero clearance insert will make a clean cut. I agree that cut-off wheels are the best option and said as much above, but a Dremel is a bit light for this application.

If you’re going to use a Dremel…

– Last Updated: Apr-28-10 7:15 AM EST –

...makes sure to get their fiberglass-reinforced cut-off wheels, unless you like having bits of cut-off wheel flying all over the place. The reinforced wheels won't break and they come in a larger diameter that cuts faster. They're easy to spot, as you can see the weave of the fabric in them.

Dremel also sells a carbide cut-off wheel, it you're willing to spring for a few extra bucks.

We did this at Pb
We cut down carbon/Kevlar composite laminates quite often, RapifFire as a test to a better profile, StarFire until we found the courage to cut the mold down before flanging it.

’ Used a straight piece of rail stock to Sharpie a fair line, then cut the stern down with a Bosch Jig saw. You’ll want sharp blades, and may need to change blades, but no problem.

The larger issue is why are you cutting the hull down?

I was under the impression that the old
rivet holes from the original aluminum rails would show beneath the wood gunwales. The prism is a pretty tall boat so I didn’t think making its profile 1/2-1" shorter would hurt and might actually help with the wind. I guess I could patch the holes, but I figured trimming the top edge would be a better option.

yes you will need to trim it
But 1/2 is plenty. Depends a little on whether you’re using kerfed gunwales or just sandwiching the hull. If you use the aluminum rails as your guide, I’d be afraid that you’re cutting too much off. The thing you need to be careful about is how high do your ribs come up the hull on the inside. If you trim too much off the top, your inwale will interfere with the rib and you’ll have more work to do trimming the rib down.

Good points. I’m installing kerfed
gunwales from Ed’s Canoe. I’ll make sure I trim enough to cover the holes but not too much where I interfere with the ribs.


You could just put rivets back in the holes. I’m considering this rivet gun which would enhance the beauty and visibility/safety:

Thanks but I don’t think I need
a blinged out canoe :^)

Good call, that’s hilarious!