How to identify Kevlar

I am considering purchasing an old canoe,…(1985 OT Columbia) that is either made of Kevlar or Fiberglass. I cannot tell visually but it does have the distinctive diamond pattern on the inside bottom. How can I definately tell if its kevlar or fiberglass?

Contact OT with the HIN?

– Last Updated: Aug-28-12 8:06 PM EST –

If the inside is painted, you could scrape off an area to see the color of the fabric or, maybe, just weigh it.

I'm pretty sure the inside of the only one I've seen was the natural tan color of the Aramid fibers.

shoot it with your handgun

– Last Updated: Aug-28-12 9:13 PM EST –

if the bullet goes through, it's fiberglass.

Is this another Columbia? Googled this boat and you had the same question in november, and the answer was fiberglass, which you knew.

Yes same boat but NO on material!
Yes this IS the same boat but NO I never did get the question of material answered because I just assumed it was fiberglass. Upon closer inspection it looks like possibly kevlar!

Kevlar vs Fiberglass
Its been so long since i sat in a composite Old Town that i could not remember if they painted the insides on the kevlar hulls.

But i did find an old buyers guide that lists the weights for glass and kevlar hulls with both aluminum trim and wood trim. The aluminum trimmed hulls weighed in at 59# in glass and 54# in kevlar. The wood trimmed hulls were 66# in glass and 61# in kevlar. The weight of a kevlar Columbia was was more than an 18’ Wenonah Sundowner in corestiffened glass. And the fiberglass Columbia cost as much as the kevlar Sundowner. A reason the Columbia did not sell well. I have a core-stiffened fiberglass Sundowner that is 52# on the scale with a sliding front seat, foot brace and padded yoke. Tough to ante up another $500 in 1991 for a kevlar Columbia that weighed more.

The Columbia was their nicest paddling hull and well built, but Old Town’s insistence on not vacuum bagging their hulls because it left wrinkles of resin in the interior cost them many sales.


Incompetents. My Bluewater

– Last Updated: Aug-29-12 5:11 PM EST –

was vacuum bagged epoxy/Kevlar and has no inside wrinkles. Seventeen feet, very strong, 48 pounds.

One of my vacuum bagged Millbrooks has no wrinkles, the other has a couple of minor wrinkles, having been the first made in a new mold. My vacuum bagged Dagger has no wrinkles, and it is the first-out-of=the=mold.

Those weight differences are small for Kevlar versus glass, and indicate that OT was using a relatively small proportion of Kevlar. Smart, if they didn't yet know what they were doing.

How are the seats mounted?
From the few that I have seen -

fiberglass canoes usually have seats that are drop-mounted to the gunnels.

kevlar canoes have seats that riveted to the sides.


kevlar canoes tend to have a “pinched” bow and stern that makes for sharper ends.

The above may not apply to all cases…

Our Kevlar/Nylon/glass Bluewater
has seats suspended from the gunwales. Our old Moore has seats supported by L brackets riveted to the sides. I don’t think there’s a general rule about seat mounting, except that canoes with thin, flexible sides are more likely to have seats hung from the gunwales. Otherwise it may be necessary to locally reinforce the sides of the hull to withstand the rivets.

Hanging brackets let the seats shift from side to side, but minicell pads wedged between the brackets and the hull will cure that.

Seat mounts may vary
and riveting is found on both fabrics.

And the shape of the boat is not dependent on whether its of kevlar or fiberglass.

Some times its hard to tell as BOTH materials are often found in the same hull.

Very close visual inspection tell?
Is there some tell-tale method by looking very closely at the unpainted material. I have heard that kevlar is always amber and FG is never amber? The inside is unpainted and amber! The cloth is very tight-knit also!

Aramid made in Europe rather than by
DuPont can be closer to cream in color. The inside of one of my Millbrooks is cream, the other is honey colored. Both are aramid, one is probably DuPont Kevlar. Aramid exposed to sun may go from cream to honey to almost brown. That used to make people concerned that the fibers were deteriorating, but apparently they don’t weaken near as much as the color change implies. However, sun is not good for vinylester resin, and more harmful to epoxy.

The resin affects color, too. Epoxy resin is likely to be darker than vinylester. I don’t mention polyester because it is no longer used in quality canoes.

In a used boat, if there are worn areas caused by foot movement in the boat, glass will wear smooth, but small, short glass fibers might be picked up with a bit of adhesive tape. Kevlar fibers don’t break off easily, so a wear area will be a bit fuzzy.

ID hull
Lots of folks, BlackHawk, Lotus, OT, etc would put one layer of 5oz Kev on the inside of an otherwise glass boat, replacing 8oz E glass, and call it a Kevlar hull. They tended to be a few lbs lighter, but weather and lamination crew fatigue had more variation on hull weights. I’d hate to weigh a hull to inform a guess.

Obviously, FG/ Kevlar/Carbon boats are built in the same molds. RX requires different molds because the material cannot be bent to fine stems and the mold needs vacuum “ducts”.

The scuff test as above is the surest way. If feet haven’t already scuffed the bottom they will, or sand a little patch up under the rail aft of the stern seat for immediate knowledge, then repaint to match.

In the end, it doesn’t make any difference, the used boat weighs what it weighs, and paddles as it paddles. Being an OT, probably not exceptionally well in the latter regard.

There was a time when wet or dry bagging often presented some wrinkles in the interiors. No serious builder has any issues at all with that currently. The reason may be proprietary, so we’ll just left that rest.