Canadian Canoe Routes
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pulling in gunwales w/ new solo seat??
http://www.myccr.com/phpBB3_PROD/viewtopic.php?f=49&t=29274
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Author:  pghportager [ April 1st, 2008, 8:06 pm ]
Post subject:  pulling in gunwales w/ new solo seat??

I posted this on another board, and it was suggested I check here due to the number of boatbuilders and customizers here.

I plan to add a new seat to my MR Explorer TT (RMPoly construction) for solo use. It's a 16' tandem that I often use solo - usually by turning it around and sitting in the bow seat.

I bought a 44" cane seat that I planned to cut to size and mount roughly 2 feet behind the yoke, removing the original stern seat, rear thwart and yoke and using the thwart holes for the seat's front bolts. I will be using wing nuts on the hardware so that it is easily interchangeable based on solo/tandem use.

I have read a few times on various boards about others doing this as well as taking this opportunity to create some tumblehome for solo use by cutting the new seat and new yoke a little short - thereby pulling in the gunwales a bit - maybe an inch or two.

Advice/info I'm seeking includes:

I'm wondering about the degree of impact this would have on the cross section of the hull, considering that the MR Explorer is a shallow v hull, and thus:

1. potential impact on the boats initial and secondary stability (guessing would reduce initial, have little/some impact on secondary)

2. potential change in the way the boat handles sideslipping in swift water.

3. impact to rocker? Others have posted that bringing the gunwales in will push the ends down, thus decreasing the rocker – not something I want to do.

4. do I risk damage/decreased structural strength/possible oil-canning when I revert back to tandem use because of the added stress I'm putting on the hull when in solo use?

thanks in advance.

Author:  pghportager [ April 2nd, 2008, 8:58 am ]
Post subject:  more info

I should have added some info about my use of this boat.

I rent a Kevlar when I head north (BWCA, Quetico, WCPP).

I use my MR 95% on moving water. 60% of that use is on wide, easy-going rivers with some riffles. the other 40% is on swifter, more narrow streams with Class I and Class II and a few patches of Class II-III water. I am hoping to be able to add tumblehome around this seat without having a significant impact on the boat's handling in this water.

thanks

Author:  pghportager [ May 1st, 2008, 5:03 pm ]
Post subject:  results

Well, in case anyone else ever has the same questions and does a search, here's some info on the results.

I removed the rear thwart and used the thwart holes for the leading edge of the seat, drilling new holes behind. I ended up cutting a new thwart to place in the front holes from the original rear seat placement, as the rear half of the boat needed stability that the new seat hung from hangers could not provide. In doing this, I brought the gunwales in about 1-1.25 inches at the original rear seat/new rear thwart.

On the water, I noticed no difference in initial or secondary stability, nor did I notice a difference in turning or tracking (granted, this was the first trip of the season, so any minor difference would have gone unnoticed from performance last fall).

I did notice increased responsiveness in draw and pry strokes, as I seemed to be able to slide the boat side-to-side better than I had ever before - very happy about this. I do think that this had more to do with seat placement than with any change to hull shape, as I was paddling from nearly dead-center with the new seat placement, whereas before I would have been 18 inches further from the yoke if paddling backwards from the bow seat.

Experiment a success. Glad I did it. Hope this info helps someone in the future.

Author:  Canoeheadted [ May 1st, 2008, 8:40 pm ]
Post subject: 

Hey Pghportager, thanks for the results.

I would have thought that your max. secondary stability would decrease a lot. I guess you'll find out when you push that envelope.

Author:  pghportager [ May 2nd, 2008, 12:42 pm ]
Post subject:  secondary fine - pushed already

No problems with the max secondary stability. I am used to heeling it over on flat water and paddling on one side for extended periods of time with the gunwale very close to the water - within 3 inches or so. It's still very wide where the new seat is located, as the boat is still 36" wide at waterline, and so I did have her heeled over for many miles on saturday, and felt very comfortable. I didn't push it as far as I've done in the past (pre-modification, screwing around without any load to see how far over I could go -- a few times too far) but I was heeled pretty far over without any stability issues this weekend.

Of course, I only pulled in the gunwale about 1 1/4, 1 1/2 inches tops at the rear seat, with no change to the original yoke.

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