Question about Royalex construction

Okay, considering my intended use of my solo canoe, this is too trivial for me to lose any sleep over, but I’m still curious. Today I happened to look up at my Wenonah Vagabond hanging in my garage, and I noticed that the “peak” or “point” of the rear stem is obviously off-center. The two sides of the stem seem symetrical enough, but the peak of the straight portion of the stem is locatted at about one-quarter the stem thickness from one side, rather than being halfway between the two sides. At the waterline, the asymetry is not as bad, with the point being more like the one-third point from one side. I looked at the other end and it’s off-center too, but not by as much.

Based on this, I’m assuming that the mold for Royalex is on the inside of the hull, and when the stuff is heated, the foam core might expand unevenly at the stems due to minor stress differences within outer layer of vinyl. Is that correct? Anyway, it seems to me that they could “coax” the outer layer of material to stay centered during heating with a supplemental exterior mold.

Anyone know more about this?

they use a vacume mold
its not a Male / female press. I used to have some neat video of the process but I removed them from my website. One thing is for sure, it is not an exacting process by any means.

Royalex vacuum-forming
I don’t know about the foam core expanding… but I imagine that We-No-Nah molds there Royalex hulls like most builders do. Pre-heated Royalex flat stock carried out from an oven and laid on a platform (“outside” up). A female mold (aluminum I believe) is then lowered onto the sheet and it is drawn up into the mold with a vacuum and held in place until it cools. After cooling the mold is lifted and the shaped canoe hull is then popped out. A video of this process and another of the edge trimming process were posted by Memphis a few months ago here at PN. As I recall these were only up for a short time due to bandwidth limitations. I copied them to my hard-drive… but I don’t know how to post them or forward them to you. Perhaps someone else will pipe in on how you could get a copy of these vids.

I’m just speculating… but it seems to me that the mold would pretty much have to be “whacked” to produce an off-center hull as you described. These molds cost an “arm and a leg”. With such a large investment it just doesn’t seem likely that QC at We-No-Nah would let an off-center mold slip through… Though most We-No-Nah canoes don’t appeal to me personally I’ve never heard many stories about lax quality control at their factory… they have a first class reputation for quality. … I just don’t know…

I’m curious… Does this canoe pull to one side when you paddle it?

It’s not unusual for Royalex hulls to
have minor asymmetries. My Mad River Guide does not sit square on the car racks, and perhaps there is a slight twist in the hull. I have not been able to detect any effect on its paddling behavior.

You could invert the boat on some horses, the crossbars of which you have checked for squareness. Then you can sight on the underside of the hull to see if it appears symmetrical. If you want to go farther, use some white tape to create white cross stripes at fixed distances from the ends. If it’s out of whack, you can take photos and send them to the factory.

Besides uneven contraction of the sides of the ABS during cooling, another influence is how careful the builders are when cutting the rim of the hull and installing the gunwales. Small differences in the stress created by the gunwales could cause what you’re seeing.

Even my pricey Bluewater Chippewa (over $2k list for vacuum-bagged epoxy/Nylon/Kevlar/foam core) has a small asymmetry in the front end of the foam core. Seems to have no effect. Probably only the Grumman/Marathon aluminum boats are going to be perfectly symmetrical.

Haven’t noticed any problems
I think it would take a bigger imperfection than this to affect the tracking enough for me to notice it. The stems are quite blunt and thick, so even if they are a little deformed, it doesn’t seem possible that such an imperfection would act to steer the boat in any way. Certainly it’d be no worse than a loop of rope hanging off a painter and dragging in the water, as far as tracking goes. Anyway, like I said before, it doesn’t seem serious enough for me to worry about.

If I understand the process you describe, the mold is in contact with the outside of the hull, not the inside like I had thought. Maybe the hull does not get fully sucked into the pointy end of the mold sometimes. It really looks like that might be what went wrong; it would only take a tiny gap in contact in this part of the hull to cause the type of deformaty that I see. I’d have to agree with you that it seems unlikely they would have any imperfections in their molds.

How are you liking the Vagabond?
I just got mine a few weeks ago, & have only had it out a couple of times, but am really pleased. Significantly faster & stabler than my old Sandpiper, I believe. Haven’t noticed any symmetry problems such as you describe, but I’ll look closer.

More on Royalex
Glad to hear this minor defect in your hull doesn’t cause tracking problems. I thought g2d’s comments offered some interesting possibilities as to the cause of this problem. While watching that Mohawk edge trimming video I noticed the workers simply cut the edges off by “eye” with a simple hand-held router. I imagine other builders do much the same, I know Old Town does. This coupled with uneven application of the rails could cause some distortion in the hull, but probably nothing serious…

You might find this interesting. A step-by-step photo lay-out showing the forming and trimming of a Royalex hull is shown in Susan T. Audette’s book: “The Old Town Canoe Company - Our First One Hundred Years”. This book discusses the development by Uniroyal of the first Royalex hulls. BTW, Thompson Boat Company was actually the first company to offer Royalex hulls, not Old Town. But it was Lew Gilman of Rivers and Gilman (canoe company) who worked with Uniroyal to develop the first practical Royalex canoe hulls. One of the many innovations Gilman came up with for working this new material was having the female mold lowered onto the heated Royalex - rather than the other way around. This came about when Gilman saw a Uniroyal worker accidentally drop his cigarette lighter into a (right side up) mold… After the molding process was completed there was that lighter… stuck to the bottom of the boat! Obviously with the mold held “down-side up” nothing could inadvertently drop in the mold. Rivers and Gilman’s canoe factory was destroyed by fire in 1968. By 1969 Gilman accepted a job at Old Town and the rest, as they say, is history…

BTW, it was Lew Gilman who single-handedly invented roto-molded polyethylene canoe/kayak hulls while working for Old Town. Canoe liveries and chiropractors everywhere are I’m sure forever grateful! ;^) Randall

I believe your assumption is correct …
“I’m assuming that the mold for Royalex is on the inside of the hull”.

I have been on the wenonah factory tour and watched the royalex molding process. I remember that it is indeed a metal hull that the royalex is formed around (male mold?). I remember them saying that manufacturers do it either way - male or female molds. Wenonah, for reasons I don’t remember, decided on the male mold.

Interestingly, for the composite boats, Wenonah uses female molds.

A lot of labor goes into the composite boats. Conversely, the royalex boats have little labor, but the royalex sheets are very expensive.

I wish I could give you a full report
I’m pretty much in the same boat as you (Ha! Crackin’ myself up here), in that I haven’t had it long and haven’t been out in it that much so far. I got it last fall, and only took it out a few times. So far, I like it pretty well, but my solo paddling skills need work. I was looking for something pretty basic and durable that would be suitable for small rivers and creeks, and as far as I can tell so far, it was a good choice for that. When test paddling, I compared it to the Sandpiper. Compared to that boat, I liked the better speed and more load capacity, and with a bit of muscle it manuevers nearly as well. Both models feel as stable as an aircraft carrier in comparison to either of my main rowboats, which was surprising to me.

I own a Sandpiper. I like it fine. I bought it the year before the Vagabond came out. I have gotten to test it. I wish I would have waited a year to purchase. I like the Vagabond much better.

I had the Vagabond out on the Mississippi River on a widy day with some pretty good waves and it was stable as could be.

Thanks, Arkay.
Interesting stuff.