What you wanted to know but were afraid to ask – Martin S

What is a skeg and what does it do?

There seems to be quite a lot of confusion in some people’s minds as to exactly what a skeg is for.  So I thought I would have a go at explaining.  If one is fitted, a skeg is a little 'fin' at the stern (rear) of your kayak that you can raise or lower using a control mechanism which resides, usually beside, your cockpit. 
(I will say a few words about what to do when it does not drop, later on).

Most sea kayaks have a better grip on the water at the front than at the back.  As a result, when the wind blows, the stern tends to blow down wind and the boat weathercocks (turns toward) into the wind.  This is fine when paddling into the wind but a pain anywhere else.  The amount that this happens depends on the shape of your boat and the way it is laden.
 
Those boats with a flat keel line and a fairly vertical stern tend to do it less than those with more rocker and a less vertical stern.  A boat with ‘rocker’ is one that when placed on a flat surface you can see a curve and you can literally rock the boat by pushing the bow or stern up and down. 

Rockered boats were relatively rare when I built my boats 18 years ago but are now common, with some designs having a very pronounced curve indeed.  As a general rule of thumb, rockered boats will be easier to turn and straight boats will be straighter tracking, but there will be other factors such as the shape of the bottom and whether it is chined (has an angular hull shape) or round and of course when dealing with wind, how much ‘volume the boat has (i.e. how much sticks out of the water - but also how much space there is to store your tent, sandwiches or Gucci rescue gear). 

As we do not always want to paddle upwind, the skeg has been developed to enable you to paddle more easily in other directions.  By putting down the skeg you increase the grip at the back of the boat so that it now tends to want to turn down wind.  If your skeg mechanism is any good you can use smaller amounts of skeg for a smaller effect when paddling across the wind. 

Obviously if you put the skeg down it will also make the boat more difficult to turn when you want to so don’t go rock hopping with the skeg down.  Every boat design is a compromise.  If you want to carry a tent and two week’s worth of food, then you’ll need a relatively large volume boat and you’ll want it to track straight so it will probably have a straight keel and a fairly vertical stern.  If you want to spend your life rock hopping then a more rockered boat may be more fun.  No boat will do everything fantastically so perhaps you should think hard about what you want to do with it before going out to buy one.  The more specialised a boat is, the more likely it is to get into trouble when out of its zone of specialisation, whether it is rock hopping in an expedition boat or taking out a sea kayak that is designed mainly for surfing in a high wind.

What to do without a skeg?

There are other ways to correct your boat’s tendency to turn into the wind and it is a good idea to practice these against the day that your skeg breaks (as it will!).  Firstly you can alter the grip of the boat on the water by shifting weight to front or back.  Going upwind it will be best to have most weight in the front;  down-wind, more in the back to try to increase the amount of the stern in the water and increase its grip. Edging (lifting one side by raising your knee) your boat will help too.  If you edge your boat to the right you are giving the boat a more curved shape on the right which will tend to make the boat want to turn to the left and obviously the opposite if you lean left.  By edging the boat you are not so much increasing the effects on the side towards which you edge as lifting the ‘uphill’ curve to a less effective position.  How well your boat edges will depend on the bottom shape.  I suspect that a relatively rounded shape will grip the water less and edge a bit less well than a more chined one.  Conversely the rounder bottom is probably easier to turn without edging and feels more stable when just sitting around.

Skegs seem to attract stones like hedgehogs attract fleas. jamming with monotonous regularity.  Applying brute force at best achieves nothing and at worst wrecks the skeg mechanism.  Try not to let the back of your boat drag off a stony beach, always test your skeg once afloat and if it won’t work ask some kind soul to reach under your boat and pull it down with that bit of string that you have thoughtfully put through the little hole provided in the skeg for this purpose.  If that fails, go back to the beach and get out your Swiss army knife. 

I have said nothing about rudders, but basically a rudder will have the same effect as a skeg but can also steer the boat so you don’t have to learn to edge.  Against it, the steering mechanism gives a less solid brace for your feet when the going gets rough.  The rudder being right at the stern can come right out of the water too in rough water. It is rather vulnerable and to my eye spoils the line of a boat.