Remove hog from hull to improve turns?

Joined
Sep 16, 2013
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So here's my story of a hogbacked hull...

I have an old woodstrip pro boat. I've enjoyed paddling it from time to time but I do notice that it is a PAIN to get it around the tight twisty corners of our tiny local river. Awhile ago I took a look down the keel-line and noticed that it has at least 1" of hog in it -- the ends are well lower than the middle of the hull. Ouch! That makes me think it would run straighter than straight. So I unfastened all thwarts and seat-braces and have wedged the gunnels wider -- about 2.5" in the middle and 3" about 5' from the ends. Now the hull is pretty flat. The hull made some strained sounds as I wedged those gunnels wider but in general they seemed fairly flexy and nothing has cracked. I haven't permanently lengthened my alum-tube thwarts yet.

Now, given our twisty river I'm wondering if it might be nice to actually have a touch of rocker in this hull. It might be neat to be able to actually whip around my turns. Or maybe I should be happy with just getting it flat again.

Anyway, do you think I'll find that it turns a lot easier now that it's back to being flat rather than concave?

Not many people really lean a touring hull and they talk about "tracking" so maybe there's more going on with turns than just getting the ends out of the water in a lean. Well, either way, hogging can't be good.

Widening my tumblehome or whatever it's called might also increase my final stability, not that we need much of that. But we're not edgy racers anymore. I like a light fast boat still but the old pro boat might behave more kindly when it's loaded than it used to. Now I can be rewarded for tossing a cooler and duffles in it rather than getting scared!

I hope the hull won't mind the stresses of the wider thwarts. It's under new tension.

It was an old garage sale find so it won't be such a big deal of something odd happens. ...I wonder what I could do to relieve the tension or if it will eventually warp/adapt to it. It has a glassed exterior.
 
Joined
Sep 2, 2011
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Raymond, ME
My story probably will be different. I have a wooden boat(minus) canvas to restore. The prior owner left it right side up on sawhorses all spring. It rained quite a bit and the boat is not leaky enough. It hogged where it sat on the gunwales. Restoring it means being true to its history (minus the keel!) so we put its butts in a sling (three actually ) and used our unused ( for the time being, its not winter) tube sand in the bottom where the hogs are. Seems to be working.

In this case widening is not an option because I want to be true to the original boat.

I would probably end where you did. Heeling the boat might make it more maneuverable if the stems are sufficiently "loose". Some old Sawyer boats used in amateur races were straight keeled and needed to be heeled to turn.

I would give you as of now result a trial spin (so to speak) so you can see the effects of lengthening the thwarts. I would guess that the main complaint would be from the gunwales which now want to be longer and as they can't have increased your rocker.
 
Joined
Sep 16, 2013
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I'll figure a way to make nice thwart extensions then take before/after pics and I'll give it a test flight to see if the monkey business was worth it. : )

The physics of this stuff is funny, like all physics tends to be. Yellow Canoe seems to say that my spreading the thwarts is trying to make my gunnels longer. It's not trying to change gunnel length at all that I can tell. By spreading gunnels I'm exerting force that's trying to make the HULL *shorter*. Since it can't shorten it then curls upward. If I were to pinch the gunnels then I'd be exerting a force that's compressing the arc of the gunnels and lengthening a straight line drawn between their ends -- the keel-line of the hull. Since that can't happen, either, it would seem to push the ends downward. ...Maybe?

I made a paper boat and kinda tested all this and I seem to be right but really my paper boat wasn't THAT great or clear of a test.
 
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Joined
Feb 29, 2012
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Schenectady, NY
Jeff, Is that old boat an epoxy hull, or is it polyester or vinylester resin? If it's an epoxy hull, I wouldn't worry too much about over stressing it. If it is a polyester resin hull, I would work on my heeling technique...the bond (if it exists at all) between wood and glass is fragile at best. You could always take a belt sander to the stems and shape them the way you want, and fill in with some wood and glass. It's not black magic!!
 
Joined
Sep 16, 2013
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Well, I extended the thwarts and that seems to have gotten rid of the hog. Here's a report with pics: http://outyourbackdoor.com/newarticle.php?id=2082. Yeah, sanding off the bow and stern ends also sounds like a neat idea. That's next if it still doesn't turn enough. I bet it'll lean a long ways now with stability. It's 3" wider at the top! I dunno how it was built but a lot of it is corroding, degrading. For now I just wanted to see if I could get it to turn. I wouldn't mind a touch more stability for paddling with my semi-paddler teens on our twisty little river.
 
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