C-Forum

Anyone have any experience with adjusting the width of their boats? (In this case a 15.5' tandem open canoe.)

Part of me thinks bring the gunwales in from 37.5" to 35" or so would make it a higher performance boat.

But part of me thinks having lots of width makes it drier ("flare") and adds to the stability when leaning it way over.

What are the advantages or disadvantages of making a tandem boat more narrow by a few inches??

Thanks, Pat.

I'm curious...why do you think decreasing the beam will make this a "higher performance boat"? I'm fairly sure that at least in some designs, pulling the gunwales together can actually decrease the rocker...

-K

I agree. I don't know why the idea of pulling in the gunwales occured to me for improving ww performance. I understand that if I pulled in the gunwales that they, staying the same length, would push down the ends and reduce the rocker.

However, I was surprised that my Prospector 16 which is specified to be 16' and 36" beam actually measures 15' 6.5" and 37.5" inches across. It looks a little short and chubby. At some point, a wide hull design must have its disadvantages too, like perhaps wetness at midships?

I guess I see boats like the Starburst or the Synergy and Caption that are narrower, but of course, with much more rocker.

I'm re-thinking toying with the gunwales.

Pat.

This ought to be fairly easy to figure out by experimentation. Set the boat on a level surface and measure the height of the ends. Adjust the gunwales and repeat. You could also set up a camera on a tripod to record any other changes in shape. I've thought about doing that with one of my boats but haven't got to it yet.

I'll be setting up an ME this summer and will probably be doing that same experimentation.

I did pull in the gunwales on my Viper 12, about 2" at the seat thwart and similar at the forward thwart (also moved it forward about 8"). I can't prove what it did to the rocker, but I suspect it reduced it. However, it did make cross strokes easier and I *thought* the boat was faster.

Pat,

remember that the other boats you mentioned (Caption...) are designed to
be paddled in the middle. That means they have to me narrow. Otherwise paddling them would be to awkward. (vertical paddle shaft)

A wide boat is not wet. The opposite is true. More width means more volume and more flotation. i.e. it does not break through in bigger waves (as long as the hull is deep enough).

If you bring the gunnels closer together, you will loose dryness since, as you said, you create tumblehome.
I would not recommend it. You paddling it alone would be the only reason why I would consider it.

Tim and I were on the Chilliwack 2 weeks ago. We ran the canyon twice and also the easier bottom section of Slesse Creek. Everything was supa dupa waterlevel and it was a roller coaster ride. Especially the little Canyon section on Slesse was to fun to be true

On the river, Jan

Thanks Jan,

Most advice I've had on this has been hesitant on moving the gunwales. I may experiment with it a little bit anyway - 37.5" just seems wide for a Prospector, and I do plan on moving the seats towards the centre a little from the factory placement, so that's (the vertical strokes) one of the reason that narrower would be nicer.

Glad you had fun on the canyon. I only know a very few Vancouver canoers who paddle there. I've never been up, the "easier" section below Sleese is all I can handle, and Tamihi and below only at low water for me. The canyon sounds like a hectic, rocky place to swim, so I better work on my rolls before I go there.

Cheers, Pat.