Sliding front seat.

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tom in caledonia
Posts: 45
Joined: Tue Jul 20, 2004 1:13 pm
Location: Caledonia ON

Post by tom in caledonia »

I don't know if I buy into that one either but thanks "J". I don't do enough solo paddling to worry about it. Plus, I'd solo in a smaller canoe than a Redbird.
Thanks guys.
jcolten
Posts: 30
Joined: Mon May 10, 2004 12:12 pm

Post by jcolten »

Sliding bow seats are of limited use in trimming a canoe with different sized paddlers. By "limited" I don't mean without value, just not huge value. They can compensate for weight differences and/or shift you from stern heavy to bow heavy and back only if the weight difference is relatively small.

Let's try to quantify it. Two commonly used rules of thumb are 1) a seated paddler's center of mass is located approximately over the front edge of the seat and 2) if you accept the first rule, for a canoe that is trimmed level, the stern paddler's mass times the distance from the front of the stern seat to the longitudinal center of buoyancy (LCB) will be equal to the bow paddler's mass times the distance from the LCB to the front edge of the bow seat. LCB is at the middle of the hull for a symmetrical hull. The Bear Mountain plan I have seen (Freedom 17-9) shows you the location of the LCB for some value of displacement.

Looking at this web site's page for the Redbird, the suggested seat positions have the leading edge of the bow seat approx 40 inches forward of center and the leading edge of the stern seat approx 50 inches aft of center. Applying the rules of thumb, when Tom is in the stern at 215lbs, you'll have level trim if the bow paddler weighs 215*50/40 = 268.75 …. a long way from his spouse's 115. To get a level trim with her in the bow, her seat's leading edge would have to be 215*50/115 = 93.5 inches forward of center ….. more or less under the trailing edge of the front deck …. not workable.

I think Tom might be able to get a reasonably level trim if he paddled from a sliding bow seat and his spouse paddled stern with a 5 gallon water jug behind her seat. Or, like I have, he could get used to paddling a stern heavy canoe and being land bound in winds that a well trimmed canoe would handle and also being able make a back ferry work. :cry:
tom in caledonia
Posts: 45
Joined: Tue Jul 20, 2004 1:13 pm
Location: Caledonia ON

Post by tom in caledonia »

I think that I've always paddled stern heavy. :x High winds definitely make it more exciting and more of a workout. I guess that I could also put my wife in the bow, the dog right behind her (he can take the place of a 5gal water jug plus he can carry himself) and the heavier pack behind him and get better trim as well. I prefer to have this problem (my wife being only 115lbs) than the alternative. I don't always go canoing with my wife but I'm usually the heaviest person in our group so when I go with "the guys" a slider may be of more use then. I like your humorous and mathematical approach to my question "J". Thanks.
Jeff in Pembroke
Posts: 83
Joined: Wed Jun 30, 2004 8:26 am

Post by Jeff in Pembroke »

For what it's worth, I put a sliding bow seat in my Redbird and it works really well. The logic behind the sliding seat is to be able to adjust the position of the bow paddler to help with trim. Despite what Martin says, I couldn't find any logical reason why you wouldn't want to be able to adjust the trim in a symmetric canoe so I went ahead with the sliding seat. It won't work well paddling solo while sitting backwards in the front seat but I almost always paddle tandem so it wasn't an issue. There was a discussion about this in the forum some time back and a number of people advocated a kneeling thwart behind the carrying thwart as the best way to paddle solo anyway - not sitting backwards in the front seat.

Jeff
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Glen Smith
Posts: 3719
Joined: Sat May 08, 2004 9:08 am
Location: Baie-St-Paul, Quebec, Canada

Post by Glen Smith »

Why did it not work well sitting backwards? Details please.
Jeff in Pembroke
Posts: 83
Joined: Wed Jun 30, 2004 8:26 am

Post by Jeff in Pembroke »

Hi Glen

I put the attachment brackets that hold the seat to the sliding rails on the front and rear stiles of the seat. When I slid the seat fully back to the stern, the brackets bumped up against the cross-rail that supports the stern end of the sliding rails. As a consequence, the rear end of the seat was slightly forward of the supporting cross-rail, creating a 'step' effect that was quite uncomfortable to kneel against. I suppose if I had foreseen that problem I could have modified my bracket position. However, the rear supporting cross rail is too low to get my feet under so I couldn't kneel paddling backwards anyway.
Paddling facing backwards while sitting wasn't a problem.

Hope that somewhat tortuous explanation is clear enough.

Cheers,

Jeff
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Glen Smith
Posts: 3719
Joined: Sat May 08, 2004 9:08 am
Location: Baie-St-Paul, Quebec, Canada

Post by Glen Smith »

Isn't there a way to install a sliding bow seat without having that rear crossmember? Maybe not. I can see how that would make it useless in a reverse situation.
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