New Canoe Hull Problem

Hi all.

My wife and I are new to this sport.

We spent the last couple of weekends demoing canoes until we found what we were looking for.

After purchase and the return home we placed the boat gunwhales down on a pair of plastic sawhorses.

One of the horses needed a 5/8 inch shim board on one side to keep the boat from rocking side to side (port bow to starboard stern).

Furthur investigation revealed an apparent twist in the hull as the concrete floor is pretty level and the horses were level without the shim.

The craft is a 16 foot royalex with a shallow arch.

I’m thinking this is not normal.

Please advise.



First, so some careful checking

– Last Updated: Jul-02-07 10:35 PM EST –

You said "Furthur investigation revealed an apparent twist in the hull as the concrete floor is pretty level and the horses were level without the shim." I can't tell from this statement if you are just using the sawhorses as a guide or if you looked more carefully at the boat. In my business, we occassionally check concrete floors of commercial buildings for flatness and levelness, and floors that look pretty flat often are not. Residential construction is typically pretty shoddy when it comes to concrete work, and 5/8 of an inch across the space occupied by a canoe would not be out of the question. The floor of my own garage is about that bad.

A second thing to consider is the "rise" of the gunwales toward each end of the boat. If the gunwales gradually get higher toward the ends, one or both sawhorses being just a little "off" from perpendicular to the centerline of your boat could be the cause or a partial cause for what you see. If I put one of my canoes on sawhorses, I can get (or get rid of) more than 5/8-inch of play by kicking one side of one sawhorse a little forward or backward, due to the combination of bad floor and "tapering rise" of the gunwales.

An alternative way to check your boat would be to set it upright on some cushioning and place two pipes or other very straight bars across the gunwales. Measure the distance between the spots where the pipes contact the gunwales and the ends of the boat to be sure both pipes are at a right angle to the centerline of the boat. Then sight down the length of the boat and see if the two pipes are parallel enough to "merge". If not, the gunwales aren't parallel in terms of height (the longer the pipes you use, the more sensitive this test will be, so don't get too carried away with long pipes. I bet that NO boat is perfect). It gets more complicated, though, because it could be that the main body of the hull is fine, but the top edges weren't trimmed straight or the gunwales weren't installed perfectly. In that case, it's a rather minor problem. It's also possible that only the sides of the hull are misshapen, and not any other part. If it turns out to be hard to pinpoint the problem, it may not be worth worrying about. What's the overall quality level of the boat? High-end? El Cheapo? Somewhere in-between? With a high-end boat, you've got more reason to gripe.

Some of the people here who do lots of work on canoes might have other ideas (you may hear more "don't worry about it" s too!). Odds are good that you'll never know the difference when the boat is on the water.

This is what I did
Hello GuideBoatGuy,

Thanks for the reply.

I did use a 24 inch carpenters level to check the floor and the sawhorses.

The floor had no more than 1/8 inch deviation from flat across the 2 ft. level (at the shimmed sawhorse location, less at the other horse) which would bring the actual shim to between 1/2 and 9/16(?).

With the sawhorses flat on the floor (unshimmed)

the level’s bubble was basically centered on each horse.

Just eyeballing the horses relation to each other they appear parallel. As far as their perpendicularity to the centerline of the boat, I can’t really tell without devising some way of measuring.

Would just a small deviation from the parallel/perpendicular produce that much gap?

By the way it’s a new 2007 Wenonah Aurora.


Not necessarily worrisome. What you
want is for the hull shape to be as the designer intended in the water. That the top edge of the hull was not trimmed right, and/or the gunwale material was not shoved down all the way, may not affect performance.

I have a Mad River Guide, bought used. It was a stupendous value for the price I paid. It does not sit down symmetrically on the car racks, and I know the racks are square. In fact it takes a ridiculous amount of cross-rope tightening to get four point contact of the gunwales to the rack crossbars. But after paddling the boat quite a bit on the water, I could find no indication whatsoever that the hull was running “off” in one direction or the other.

You can work this out with your dealer as you see fit, but it is quite possible that you are pursuing a non-functional issue.

May not be a problem,

– Last Updated: Jul-02-07 11:46 PM EST –

How much effect having one or both sawhorses non-perpendicular with the centerline would cause what you see would also depend on where they were placed along the boat, since I'm sure that the rise of the gunwales is more pronounced toward the ends. If you want to check this more carefully, try the two-pipe method I describe above, and place the pipes at several locations along the gunwales to see just where the irregularity occurs. This should help you to see if perhaps a portion of one gunwale wasn't seated all the way when it was riveted to the hull.

See g2d's post below, and I'm betting that he turns out to be right. You know, it really seems like a miracle that canoe hulls are as symetrical as they are when you consider how the curvature in two directions is dependent on how the gunwales and thwarts are attached. A friend of mine had extremely warped wooden gunwales on one of his canoes for a few years, but it didn't seem to have any effect on the shape of the working part of the boat, or how it moved through the water.

One other word of caution. When trying out the boat and checking to see if it "pulls" to one side, rememember that even a very slight wind will cause the boat to turn once you start coasting, as will the effect of your last paddle stroke and even a small amount of lean toward one side. That means two things. 1) It may take quite a bit of experimenting and practice to even recognize a problem unless it is severe, and 2) it doesn't take much to counteract a minor tendency of the boat to turn since you'll find so many instances where such a tendency is normal anyway.

Cut it out
You are worring about nothing. Just paddle it about a thousand miles, scrape it up on a thousand rocks, and bend it around a few whitewater boulders, set it in the sun to straighten and you’ll fall in love with it.

Really I don’t think you’ll notice this while paddling.

Don’t worry
All my 4 of my canoes do this. Royalex, plastic and kevlar on sawhorses, storage racks or the racks on my truck it doesn’t make a difference. It always seems one gunwale or the other is not touching on one of the four points of contact. But, they all seem to paddle as they were designed. Unless you see an obvious twist to the hull i wouldn’t worry.

Why not call Wenonah and ask to speak to a technical rep.

I have three different Wenonah Canoes, and have called them on numerous occassions.

They are a first class, and I don’t think they would BS you like a dealer might try to.

I would be interested in hearing their response, so if you check with them please report back and let us know what they say.



Spoke to Wenonah
…they said it was common due to handtrimming of hulls and/or gunwhales not being all the way down on the hull.

Thanks for all your help.


hull twist

I’d wouldn’t necessarily be put off by a factory’s brush-off. Usually, trimming is far bettter than that, and Wenonah knows how to make hulls.

Managing twist is pretty familiar to anyone who’s first paddled a boat with rotten gunnels in rough water, then re-railed it. If you took the gunnels off, you’d find that the shell is pretty floppy in torsion, and it’s the gunnels that establish alignment and provide stiffness (but not too much) in torsion.

You didn’t say what kind of gunnels your boat has, but if you have standard wood inner and outers attached with screws, I would recommend fixing the twist:

1.) prop the boat upright on some stable platform (specialty boat cradles are fine; I’ve used sawhorses, sandbags, or trenches dug in the yard lined with logs I can move.)

2.) leave all the inner structure (decks, seats, and thwarts) intact.

3.) Loosen all the screws holding the outer gunnels to the inners.

4.) Check for twist. Your framing level is fine for the purpose, maybe on fore and aft thwarts if you have them, maybe with a straight board to span between gunnels. Try to get it perpendicular to the hull long centerline.

5.) At this point, it should be very easy to deform the boat in torsion and get level readings fore and aft. You’ll notice that you can torque the boat by pulling across a diagonal, because this mode couples with torsion. When I install new gunnels, I run diagonal ratchet straps from, say, forward port thwart attachment to aft starboard thwart attachment. This makes for a very rigid, stable structure.

6.) When everything is set up straight and level, tighten all the outer gunnel screws. Use a sensible pattern. Start at one end, alternating sides. I use a cordless screwdriver and run up against its torque setting so all the screws have the same tension. I check straight and level a few times during the process, but when I spend enough time on the setup, it never moves.

7.) You’re done.

If you have riveted vinyl or aluminum gunnels, you’re basically, parn the expression, screwed.

If it were my boat and it had riveted gunnels, first, I’d be pissed that I had to deal with it on a new boat, but that’s the modern way. Now even (formerly) prestigious canoe houses only produce kits from which the new owner has to make a decent boat. Don’t get me started.

After I got over that (never mind complaining to the manufacturer), I’d go through the above procedure (without loosening or drilling out rivets) and see whether I could straighten it with the diagonal ratchet straps. I’d try to load it up and get a feel for the beast. Overtwist it and leave it in the sun? Maybe. Walk along and rap the gunnels with a soft mallet while it’s overtwisted? Maybe.

If any of that didn’t work, I’d probably quit and just get used to it. After the first time I pinned it around a rock, it wouldn’t matter.