: Okay, I admit I'm still at the pacing and handwringing stage of this project,
: but you guys did not answer one of my questions from an earlier post! How
: much does a 1-2 inch fore/aft difference make in seat placement, with
: regard to weathercocking and steering strokes? How do you determine the
: best location precisely? If this can only be done by trial and error on
: the water, what do I look for? Again, this is a Pygmy AT17, and I'm
: installing a foam seat per Vaclav's plan (link). I do plan to use velcro
: so I can remove the seat, but I'd prefer to cut the cheekplate notches for
: a snug fit.

I moved my seat back 2-1/2 inches in my 16’ Yare by cutting off the coaming and lengthening the cockpit opening. Prior to moving the seat it was all I could do to keep the kayak on course in a good crosswind. After moving the seat it was neutral in crosswinds.

I also experimented with adding a fixed skeg, which also reduces weather cocking, but it also dramatically increases tracking i.e. makes it harder to turn. Since my kayak tended to broach in following seas (and boat wakes) I needed increased tracking so I added a fixed skeg.

So here is the trick. Install the foam seat with Velcro. Then move the seat back an inch or two at a time and test it in a crosswind. When you run out of back space at the coaming (notice I did not say if), add a good-sized, fixed skeg that is bigger than is needed so the kayak will lee cock. Then by trial and error trim the skeg down until the kayak is neutral in a crosswind. After you get the skeg sized so the kayak handles in the wind to your liking you will have to decide if you like the way it tracks. If the kayak tracks too hard then you will have to lengthen the coaming and cockpit opening and continue to move the seat back and trim the skeg by trial and error to keep the kayak neutral or just slightly weather cocking. Keep moving and trimming until the tracking is acceptable.

Here is my take on the physics of a kayak in a crosswind that I posted quite some time ago:

If you picture you in your kayak crosswise to the wind, there is an area presented to the wind that creates drag, a force applied by the wind. That drag force pushes you and the kayak sideways. The sideways movement of the hull through the water creates a lateral resistance force on the side of the hull pushing opposite in direction to the wind. Both of these forces can be represented as point forces acting at their respective centroids. If the centroids line up vertically with each other your kayak will not tend to turn (yaw). Now then, if your kayak is "weather cocking" the wind force is behind the lateral hull resistance force and a moment (rotation force) is created that will rotate the bow of the kayak into the wind.

So how can you reduce this weather-cocking tendency? Two ways. 1- Put less front keel in the water and/or more aft keel which will move the lateral center of resistance of the water on the hull aft. 2- Put more wind area (deck) forward and/or less aft which will move the lateral wind force forward. Adding ballast aft or moving the paddler aft will raise the front keel, lower the aft keel, raise the front deck and lower the aft deck, all help move the two centroids toward each other.

You can also reasonably modify the kayak to add aft keel by adding a skeg or rudder. However adding a rudder will guaranty you will need to use it in a crosswind. In the up position, it will act as a sail on the rear deck making weather cocking much worse. Raising or lowering the decks is a much more aggressive modification and not likely to be considered. A retractable skeg is worth while and allows you to dial in the added tracking by partially lowering it.