I don't know how extensive your drywood termite problem is, but if it's small... here's a technique I was able to use to get rid of them in my head
1) Locate all the galleries(rooms termites make for themselves) - I found, at least in my case, that where there were galleries, there were some kind of "water stains" on the outer layer of the plyood laminate. This helped me to figure out where the galleries were.
2) Go to Home Depot and get "Spectracide Termite Killing Foam"
3) Take a small drill bit (just big enough to stick the little, red WD-40-like straw from the termite poison can into), and drill many *many* holes into the wood
where there are galleries set up. Try and get at least one hole for each gallery you can imagine being there. It isn't necessary to drill all the way though the wood, because you are just trying to make a hole to fill the galleries with poison.
4) After drilling about 60 holes in a 1sq ft area, fill each hole with as much poison as it will take until it either starts spraying out another hole, or backs up out of the hole you are spraying into.
That's all it took to get rid of a fairly large conoly of drwyood termites in my case.
Probably not applicable to a mast, but there may be some knowledge that can be taken from this and applied, or at the very least someone searching for drywood termites in boats can see this method.
So far, so good. No more termite droppings (which was how I found them during my self-survey)