Seat height vs balance point question

-- Last Updated: Jul-25-12 3:28 PM EST --

Howdy, all;

I recently picked up a Mohawk Odyssey 14 that I'm pretty stoked about, to serve as my river fishing and solo playboat in up to class II rapids. I love the lines on this boat.
I have NOT had it on the water yet. I bought it as a "demo" boat....right of the trailer...she's never even been wet. However, the factory had the seat rigged relatively low, I assume since it was a demo boat, so that I can't even come close to getting my feet under the seat. I've raised the seat slightly : about 1/2 ' in front and a full inch in the rear with HD rubber spacers, to both raise it slightly and give it a slight cant. I can now fit my feet underneath....just well enough for me to worry about entrapment.
However, if I raise the seat more, I'll be sitting (when using my sissy cushion with backrest) almost even with the gunnels, and if I DON'T raise it anymore, when kneeling, my weight will be just forward of the balance line of the boat. I'll be "centered" when sitting back on my knees, but if I rise up on my knees I'll my weight will be 3-4" forward of that point.

I often find it comfortable, whether needed or not, to paddle on my knees and resting my "bum" on the seat edge for awhile before retaking my seat.

EDIT: the current seat height is 3" below the top of the gunnel, but raising it any would require either trimming some wood from the seat or spreading the boat another 1/2" or so, due to the tumblehome ( did I say that right?) :)

Advice and input, please?

I’d lose the cushion
Finding the right compromise between getting your feet when kneeling and having stability when seated is tricky enough. Having a cushion under your butt just makes it harder. If you’ve got the ability to kneel, you’ll be able to get on your knees to deal with a sore butt.

Seat Adjustment and Weight Trim

– Last Updated: Jul-25-12 3:58 PM EST –

I have the same boat, and the seat rests on a sheetmetal 'L' on each side of the boat. Mine is rigged with factory-supplied plastic spacers to raise the back edge of the seat about one inch, which for me, works well for kneeling. With the addition of a footbrace, it would be great for sitting as well (a footbrace is great for sitting on a slanted seat - very comfy - and because you'll feel "locked in" between the slope of the seat and your feet on the brace, you probably won't even want the backrest). I usually sit only when in "relax mode", and in that case I simply put my feet up on the front thwart, so I've never bothered to install a real footbrace, but doing so is often a good idea.

Anyway, when it comes to kneeling, I wonder about the lack of room beneath the seat that you describe. Regular shoes can make it impossible to extend your ankles enough that the tops of your feet can rest on the floor, and people with poor flexibility sometimes can't do that anyway. Still, my first thought is that some true paddling shoes or flexible sneakers might fix this problem. Is the front frame of your seat resting on that sheetmetal 'L'? How many inches of clearance is there between the bottom of the seat (front edge) and the floor? Knowing that dimension will help me figure out whether the problem is you (big feet and inflexible ankles) or your boat (a seat that really is lower than normal).

By the way, SITTING puts your weight farther forward than kneeling, because your legs are out in front of you. Yes, sitting up higher on your knees shifts your weight forward too, but that's not always a bad thing because sometimes you might want that to happen for a moment.

In any case, don't worry too much about fore-aft weight distribution until after you get some experience in the boat. It changes a bit depending on whether you are kneeling or sitting, but probably not so much that you can't easily compensate, if it's even necessary, just by shifting the location of a small item of gear. Just remember the "teeter-toter" rule. You can move a large weight (you) a small distance away from center on a teeter-totter, but can counteract that and keep everything in balance by putting a small child at the opposite end. Thus, if you feel your own center of gravity is a little too far forward when sitting, putting a small daypack several feet off-center in the opposite direction should be more than enough to compensate. Actually, you'll find that the boat is not extremely trim-sensitive, so if you get it "pretty close", it'll do.

I suspect that I’m the issue …
With my size 12’s and my highly inflexible hips and ankles.

There’s almost 8" of space between the bottom of the bracket and the boat hull @ Center line , but with my hips wide to brace my knees against the boat, that space changes to only about 5 inches and change.

Still, though, I’d rather make a small change to the boat now , so that it fits my needs, than wait until I make improvements to my physique.

From a shoes perspective…thanks a great point…I’ve tried it with my docksiders on, but not my water shoes…

My experience, and a quibble

– Last Updated: Jul-25-12 5:38 PM EST –

My experience in kneel-sit combo boat is to put the seat as low as tolerably possible. For me, that is an under-seat clearance of about 7.8 inches at the front of the seat and an inch higher in the back. I'm 5-9 and wear a size 11 shoe.

It's a squeeze, but doable even in my old age as long as I wear low volume shoes with very flexible tops (insteps). No stiff insteps, thick soles, or big honking boots. Low cut neoprene shoes like the Sperry Ebb Tide or NRS Kicker work well.

In a boat that spends most of it's time in WW, I would install a foam pedestal to solve the foot clearance problem completely. If you shape the pedestal cleverly, you can also sit on it.

The quibble is with one of GBG's statements. In the usual situation the paddler's center of gravity is further forward when kneeling (vs. sitting), not further aft, because the torso moves forward and it weighs more than extended legs. Authorities greater than I hold this opinion.

Here’s how I see it

– Last Updated: Jul-25-12 6:30 PM EST –

When I kneel, my butt is only a few inches farther forward than when I sit, so shifting my legs to the outstretched position when sitting more than makes up for being centered a few inches farther back in that case.

I don't know what "authorities" say about this, but in past years, at various times, a number of posters here have made the same observation as I. Speaking for myself, I haven't noticed more than a smidgeon of trim difference between when I sit or kneel, but the smidgeon I see is a weight shift forward when I sit. Mostly, I was just remembering what a number of other people have said about this, and remembered that it "made sense" to me at the time (and like the teeter-toter method illustrates, the legs may weigh less than the upper body, but their position moves a whole lot farther). I suspect it all has to do with how far forward you move when you shift from sitting to kneeling, and how much you weigh. I expect that the bigger the paddler, the more a small amount of fore-aft shifting would affect trim. I've got loads of flexibility and don't weigh much (about 165#), which I think helps let me keep my butt mostly on the seat when kneeling, as long as the seat has the proper slope (I always thought the purpose of the slope was to allow more comfort and contact area). It sounds like you move forward on the seat a lot more than I do when shifting to the kneeling position, and though I don't know your weight, I've noticed that the AVERAGE canoe paddler weighs about 75 pounds more than I do, which, to put it in perspective, is easily equivalent to the gear load needed for a fairly long trip. Maybe I shouldn't use my own experience to project how kneeling versus sitting might affect trim for the average person.

Bracket Height

– Last Updated: Jul-25-12 6:49 PM EST –

Yes, that sounds exactly the same as my boat. At the edges, I'd say it's more like 7 inches (a measurement of 5+ inches would be somewhere partway up the near-vertical sidewalls of the hull). Also, I checked the height of the rear shim, and it's 1.25 inches, not one inch as I said in my first post. I think raising the rear of the seat another quarter-inch would be reasonable, but have never tried it. My feet are size 11.5, and I can actually kneel for hours in that boat when wearing clunky hip boots, but I don't think the average person could.

If you've already got the seat shimmed a little higher than the bracket at the front edge, I'd expect it to be workable. You mentioned in your earlier post that you were reasonably experienced at solo paddling, and the "standard" clearance beneath the seat of this boat is about as much as one normally sees in the average solo canoe, which makes me think that perhaps you've made this work before. If not, raise it as much as you want, and see how you like it. If you do, trim the seat narrower as needed (or buy a new seat and trim that one, keeping the original at its original width to simplify switching back again).

Maybe experiment with it in high wind
See if dropping to your knees doesn’t result in a bow down reaction. It works for me, when I want that.

My experience is clear re my COG
I have no doubt about my COG in terms of how I sit and kneel in my solo canoes, and I consistently have stated my experience on all forums.

Citing names doesn’t prove anything, but I know Harold Deal agrees about the COG issue and Charlie Wilson has consistently said the same thing.

I suppose a given paddler could sit and kneel in a particular canoe such that the sitting COG was further forward than the kneeling COG. Anything is possible.

I’m sort of talking about my case, which I think most akin to the general case. When sitting in performance paddling you are usually as far back on the seat as possible, against the rear lip on a tractor seat, with your feet on foot pegs tending to push you aft on each stroke. In addition, when seated, the paddler may sometimes be paddling with only one leg outstretched or both legs folded up Indian style.

Paddlers will usually shift their entire torsos forward when kneeling and sit closer to, or on, the front lip of the seat. On the catch, the kneeling paddler leans much further forward than a seated paddler, and he exits his stroke and body movement earlier (further foreward) than the seated paddler. All these combined static and dynamic torso and arm movements usually result in an average COG for the kneeling paddler that is further forward than the average seated COG for that same paddler.

The only thing anyone can do for their own situation is to experiment with their own boats and styles. I agree the opposite phenomenon could prevail in individual cases or that the COG could remain in the same place. The difference isn’t great in any case.

If I were outfitting a new boat in which I intended to both kneel and sit, I’d outfit it so it trims best for me when in the kneeling posture.

I could be wrong

– Last Updated: Jul-25-12 7:35 PM EST –

I wasn't thinking about the fact that a kneeling paddler also leans farther forward. I do know that I don't shift forward much at all when switching from sitting to kneeling, and I know that I can't place a gear pack RIGHT behind the seat because my toes will hit it if I do. The thing is, for me, I NEVER use a sitting position unless paddling power and technique don't matter at all. The rest of the time I kneel, which means I really can't compare what happens between sitting and kneeling during "real" paddling. I am very sure that the difference in trim is extremely small when I shift positions, probably a smaller difference than the natural variation that occurs just from placement of gear packs. For choosing pack locations, it's a compromise between "those two spots look like about right places to place these two packs and keep the boat level" and where they will actually fit without being in my way. That's FAR from precise, but I question how many people take a carpenter's level with them on trips ;)

You’re probably right for you

– Last Updated: Jul-25-12 8:46 PM EST –

In my SRT with a Deal bucket seat the change in COG is noticeable by the feel of the boat performance. In waves, wind or whitewater, I can feel the bow go down when I move to my knees.

I haven't been on any flat cane seat where my butt is in the same place, re fore and aft, while sitting and kneeling. In fact, I think that's physically impossible. You can't sit and kneel at the same time. If fully sitting on the full seat depth, you have to move forward at least a little bit to kneel.

Not sure if I’m right or wrong, …

– Last Updated: Jul-25-12 9:40 PM EST –

... about center of gravity, although now I'm sure it's a pretty minor point. I do know that the statement "you can't sit and kneel at the same time" is irrelevant and reflects no understanding of what I said. All you have to do to get your whole butt onto the seat when kneeling is bring your knee position rearward a few inches and allow your butt to be about an inch higher, which should be no problem if the seat is canted forward. How would that very tiny adjustment in body position comprise the "impossible" act of sitting and kneeling at the same time? Anyway, I don't position myself THAT far back on the seat. I only pointed out that this COULD be done, and only to illustrate that skootching forward just a few inches to kneel, instead of across most of the seat space, is anything but unreasonable.

Then again, the weight issue could be at the bottom of this. I'm 6'1" (used to be 6'2", but I'm shrinking as I get older), but people who are half a foot shorter than me are sometimes quite a bit "taller" than me when sitting down because their butt and thighs are so huge in comparison to mine. Big thighs would make it a lot tougher to do what I describe. Maybe try to imagine what you could have done while still young and skinny.

Oh, and I just thought of something else. This becomes a geometric problem too. I have very long legs, and therefore the standard slope of a seat is a closer match to the angle of my thighs when kneeling than would be the case for a person with shorter legs. A person with short legs would need to greatly increase the slope of the seat to have the same situation that I have, OR they'd have to make it a lot lower, but lowering it wouldn't be an option on account of needing foot room.

You know, this has really gotten silly.

seems pretty good, you didn’t mention
your weight…but the lower you go the more stable of course.

Pedestals and glueing em’ onto a flat dense foam platform can often be the answer to many issues… $.01

People kneel differently
I think different folks utilize kneeling thwarts and canted seats differently. Some just contact the front of the seat with their butt and others have more of their backsides up on the seat. How much and whether the COG shifts going from kneeling to sitting probably depends on other factors as well, such as seat height and paddler femur length.

I spent many miles paddling a Mad River Traveler solo canoe with a sliding center seat. I paddled it both sitting and kneeling. I found that when I went from sitting to kneeling in that boat, I needed to slide the seat back 2 inches to maintain trim. So for me in that boat, if the seat had been fixed in position, my COG would have shifted forward going from sitting to kneeling. But I tended to use the seat frame as not much more than a butt prop when kneeling.