: I have an old Fiberglass Frontiersman Sea Kayak. . . .
: Should I consider putting a rudder, skeg on it our should I just leave it
: as is? Can I build one? What is the big difference between a rudder and
: skeg? (performance wise?)

Sounds like you ARE considering putting a skeg or rudder on it, so answering your first question could be a challenge.

But I love challenges, so let me give this a shot.

Whether you need to add anything to your boat depends on how well that boat performs for you. Your weight (plus the weight of any gear) will determine how deep the boat sits in the water -- and that affects tracking. The placement of your seat (fore or aft) will determine the front-to-back balance of the boat, and influence the amount of control the hull shape has by itself. If adjusting these areas -- either by adding ballast, losing weight, or shifting the seat position -- does not give you the type of performance you want from this boat then you have really very few choices. One choice is to get a different boat that suits you better. The other choice is to modify the hull with some type of control surface, a keel, a skeg, a rudder, os some other part.

A skeg is a fixed, vertical, control surface that resides inline with the keel, or the centerline of the bottom of the hull if there is no keel. It usually is at the rear end of the boat. Water pressure, generated as the boat moves forward, presses on the skeg and helps the boat stay on a straight line as it goes forward.

A rudder is attached to the tail end of the boat, and with kayaks it usually is designed so it can flip up should it hit an underwater obstruction. Usually it can be stored on the rear deck when not needed. A rudder can be fixed in one place, and thus serve as a skeg, but the real value of a rudder comes when you want to make a turn. A boat that tracks straight beautifully will be a terror to turn is a short distance, usually. Moving the rudder (usually by using footpedals, or handlines) causes water pressure on the sides of the rudder to cause the stern to turn. And when the back end of the boat moves, the front end does too!

You can make either a skeg or a rudder if you have the time, rudimentary tools, and a few dollars. . They are not difficult to fabricate, and a look at the ones on the market will give you a clear understanding of what is needed to make them.

I'd go with a rudder on any boat before trying a skeg. if I found that I was leaving the thing set in a central position for 90% of the time, or more, then I'd pull it off and replace it with the simpler skeg. Some people would do this in the opposite manner, and construct the skeg first. If they got a good performance response from that then they would either leave things alone, or try to tweek things by adding a rudder. On the other hand, if performance declined, they would either remove the skeg, or add a rudder.

Not a large palette of choices to pick from here.

If you check the archives of this board you'll eventually find several plans for constructing skegs and ruddders.

Best of luck with this.

PGJ