how much knee bend in sit-on-top?

I normally paddle a sit-in kayak and can paddle for 6 hours without any discomfort. So today I was at a beach in France where they had only sit-on-tops. I never paddled one before, and it was a lot of fun. I started off paddling with my legs in pretty much the same position as in a sit-in kayak, but of course with my heels rather than balls of my feet making contact. But after 45 minutes, my thighs were killing me. I experimented with straight legs, and with knees together rather than splayed. Nothing really got rid of the pain. Seemed like the least pain was with knees bent more than in a normal sit-in posture but together. But that was in pain-mitigation stage and nothing was pain free at that point.

What’s the best posture in a bare-bones sit-on-top that has no outfitting? How much are the knees bent? Are the knees together or apart? I would like to go out for 3-4 hours, but at least today, I don’t I could have.

Footwells, foot rests, pegs
Most SOTs have foot rests or pegs … so you can adjust how much knee bend you have. Usually most comfortable to have about 1.5 to 2 hand widths of space under your knee, also more comfortable for controlling if you use thigh straps.

whatever works for you
Comfort is an individual thing.

I can see where thigh braces would be nice, but the kayaks available do not have any outfitting at all. I will try the 1.5- 2 hand width advice.

High enough for comfort, low enough
not to interfere with your paddle.

SOT in France
I wonder if it was a RTM kayak? This past spring I bought a Disco SOT(made in France). I actually tend to sit w/my knees bent-not splayed to the sides like I would in sit in kayak. About a 45 degree angle. The balls of my feet are planted on the feet rests/cut-outs. But I agree, you certainly would have to make that determination of comfort. Perhaps a different model kayak would work better for you…if they had any.

I think it was an "Explorer"
Didn’t really pay attention to model, since there was only one available. Very basic - maybe 12 feet long, no outfitting, scupper holes, heel rests but no pegs. I’m going out tomorrow for as long as I can. Will try with knees bent and together. Any way of being on the ocean is great.

One thing I love about renting kayaks in France - no delay to sign waivers acknowledging danger etc - just 10 euros and you’re free to grab a paddle and pfd and head out.

If the seat is not
well sculpted but is flat instead or too wide, and you are not flexible enough to sit upright comfortably, then there is a chance you won’t be comfortable in these things. Also, if you have large feet and no support for your toes, that’s additional strain …

I would think that without side support for your legs you should be better off with knees closer together rather than splayed.

Your thighs and your control will
benefit if you get a SOT with thigh straps, or install them.