: Then when I need it I could simply lower the skeg when I need more
: tracking.

While a skeg can be used to add "more tracking" (like the fixed fin on my old Sterns IK116) - that is not really what a retractable skeg on a sea kayak is for. A skeg shifts center of lateral resistance. It balance the hull in certain wind conditions.

Simplified example (Weathercocking 101): Paddling in a beam wind (paddling, NOT sitting). Bow is cutting into the water and this creates a higher pressure area, AKA "pinning" the bow. The stern is in a lower pressure area and thus relatively more "loose". With a beam wind pushing the kayak sideways the stern will blow downwind more easily than the bow. This causes the kayak to turn into the wind - AKA "Weathercocking". Most kayaks do this to some degree - almost NONE are really neutral (though some are quite well behaved like Jay's OI), and some leecock which can be pretty dangerous in offshore wind scenarios (a reasons many designs settle on a balance that leaves in some degree of weathercocking). The skeg, if the hull is designed for it and it is used correctly allows one to change between all three conditions (and in betweens)in the same hull. The skeg simply adds more resistance aft (a bad way to say it might be "pinning the stern"), and balances the slip (incrementally, as warranted/beneficial).

Other ways to increase resistance aft: Shift some weight aft and sink the stern a little more (eg - many traditional designs with cockpits more aft of center - and Mariner sliding seat to make it a bit adjustable) - design in some amount of fixed skeg/keel strip - and/or have less freeboard aft so there's less for the wind to catch in the first place (notably Greenland and Greenland inspired designs). A perfect hull for all conditions does not exist (or need to).

Another related point: Once the weathercocking is balanced by a skeg - the kayak still crabs to the side in beam winds - so the skeg blade is not truly running straight through the water (couldn't really provide much resistance to stern slip if it did). Given this, Henk's comment about rudders being "worse due to their angle" doesn't quite turn out to be that simple. Both are running with an attack angle - amount of which is determined by varying wind and hull forces.

With either skeg or rudder, when used properly, the added drag from the blade will be less the the efficiency gained in being able to keep the effort in forward vs corrective strokes. GPS (and HRM) readings will EASILY demonstrate this. If not, pull them up (except on designs meant to use rudder full time of course). I have used this to fine tune the mount of skeg deployment on the rare times I want to hold same heading in same wind over any distance (and also to remind me when the skeg is still down and no longer needed).