Electric trolling motors work well for trolling on flat water, but when it comes to going in choppy water and in the ocean, another type of propulsion comes to mind, and that is small, lightweight, portable outboard gas engines.
This is because electric trolling motors have a low effective power output relatively to the combined weight of their engine and battery, or batteries. They offer a reduced effective activity time, and that could be a problem in long trips, or in adverse weather.
Another advantage that gas (fuel) motors have is the fact that refueling them is easy, so their range is not as unlimited as the range of electric motors is.
An overpowered boat, or kayak, is unsafe, and keeping safety in mind, most small outboard boat engines are too big and powerful for kayaks – even for the stablest kayak, which is the W500. However, smaller outboard gas motors are hard to find.
We do not recommend using big and powerful engines, simply because going too fast in such a small boat (or any boat, or vehicle) can be dangerous, as both directional stability (tracking) and lateral stability are reduced at high speed that can be reached with such motors. Also, the more powerful the engine, the heavier it is, which could lead to steering problems.
More on motors for kayaks: http://wavewalk.com/blog/2008/07/14/thrust-in-electric-trolling-motors-for-fishing-kayaks/ »
Read more about motorizing fishing kayaks »