Not even one?

Here is what you need to read:  Short answer, it is not the boat!  Good luck to you...

http://www.sit-on-topkayaking.com/Articles/Instruction/PaddleStraight.htm

One of the first problems most new kayakers encounter is going in a straight line. Their kayak will tend to wander like a stubborn mule with a mind of it's own. This is due to lack of experience, and to some degree the type of kayak they have choose. It is almost never because of a defective boat, even though this is the first thing to come to mind.

Kayak lessons will help. The instructor will teach a variety of paddle strokes and strategy to accomplish your goals on the water with those strokes. A good instructor and lesson program will teach you quite a lot more than stokes. I highly recommend taking a lesson.

Some kayaks will never go straight, they are not meant to. Surf kayaks and white water boats are just not "true trackers". Long touring kayaks will paddle straight, with some skill. Short recreational kayaks are easy to turn, but can also be paddled in a straight line with some practice.

Paddling in a straight line is the most efficient way to get from point A to point B. It is also nice to be able to "aim at a target" and "hit your mark." Wind, currents and distractions can knock you off your path and point you in the wrong direction quite easily. After all the surface of the water is a dynamic fluid environment. While a "snake trail" may burn more calories, a straight path will be more efficient and sometimes that is needed more.

Proper strokes and even application of power are the keys to paddling a straight line. Even pressure on each side is the first step. Understanding turning strokes, how they work and when to use them is the way to combat the dynamic fluid environment. Boat leaning can also be helpful on some kayak models.

   That is really good advise from Oceanluvr.  The only other suggestion is to verify that your cockpit/seat location is per the plans.  Moving the seat back a little will help the boat track, and moving it forward will make the boat more maneuverable.  I mount my seats with velcro so that I can move them as dictated by the conditions.  On my race boat, even 1/2" makes a difference.  Same can be said for anything that you have loaded inside the hatches.  If you are carrying a couple of extra water bottles, putting them in the back will improve tracking.   

   Also read up on leaned turns. You may be steering without realizing. 

  "leaned turns" can be found under "cutting an edge" turns........

Were you with the wind or against it? With the current or against it.? Paddling or coasting?   Did you have this problem in other boats? 

   Just about all those conditions occured. Seems I'll do alright for awhile and then when it starts to drift off to one side or the other, I have a hard time bringing it back. The only other boat I've paddled is a ten foot plastic boat and I did just fine with it. Hopefully I just need more time behind the wheel.

The main thing determines whether your boat tracks well or not is the relationship between the center of gravity, center of lateral resistance and center of effort. 

Center of gravity (CG) is the point where the gravitational forces balance, like the fulcrum on a see-saw. Center of lateral resistance (CLR) is where all the moving underwater forces balance. Center of effort (CE) is where all the wind forces balance. A good approximation of CE is to think of a piece of cardboard shaped like the silhouette of you sitting in your boat. The point where that cardboard balances is the center of effort.

If the CG is behind the other two centers, the boat has positive stability and will resist turning. If the CG is in front of the other two centers, the boat has negative stability and will be constantly trying to turn. If the centers are all at the same point, the boat has neutral stability and will keep its current orientation until something acts on it.

This is why Mark's advice above works - he's shifting the CG by moving where he sits and where he carries things.

Your paddle strokes affect steering depending on the location of the blade. The article referenced above talks of a power zone and a steering zone. This is because the blade is applying a force at the end of a lever (the shaft). The result is a torque, as well as forward thrust. If the paddle is well ahead of the CG, the torque is small and the boat moves straight forward (power zone). If it's close to or behind the CG (rudder zone) the torque is larger and the boat responds with a turn.

Of course, this is all somewhat simplified. All the centers are inter-related and affect each other (as you move the CG the CLR changes, if you move forward to move the CG the CE moves, too, etc.) and there's other centers that have an effect, too, like the center of buoyancy. But, this is a good enough approximation for explaining how paddle strokes and boat loading affect tracking.

Some rules of thumb for tracking:

1. Paddling into the wind put the weight up front, lean back a bit and put the paddle into the water ahead of you

2. Paddling downwind put the weight in back, lean forward and put the paddle into the water behind you

3. Paddling with the wind on your side, keep the weight and yourself close and put the paddle in the water next to you.

The reason why you had more success with the plastic boat is because plastic boats tend to have a lot of underwater lateral area. This is because ABS plastic is not as stiff as plywood, so they have to include a large stiffening ridge that also acts a keel/skeg combination, which resists turning. Also, the heavier plastic boats tend to have more inertia than the lighter plywood boats, so they resist outside forces (wind, waves, paddles) more. They track better, but are slower to turn and accelerate. Taurus instead of sports car.

Good luck,

Laszlo

   The C-17 has a lot of freeboard for a kayak. It is a touring boat and can hold a lot of stuff. It gets real stable with a load.  Of course that works against you with some wind and wave situations.  As Laslo said the boat tends to go straight until something acts on it. Depending upon balance, windage, etc wind may cause the boat to fall off the wind or round up.  On my boat wind or current will cause the stern to come around and the boat lies beam to the waves. But not "under power" when I'm paddling. If the conditions want to turn you left paddle more on the left for a right turn to counteract the force. Using my greenland paddle I'm often with more length out one side or the other to counter the turning. The thing is be ahead of the turn not behind it.  

Seems I have some reading and studying to do. The more I think about it, I've convinced myself it's mostly the seat position (which means that's probably not it). Won't be able to test any of these options until Sun at the earliest. Thanks to everyone for the help.