Dan, I was hoping somebody would bring this up. Apparently, if mast compression is a problem, it does not bother Bill Roberts, designer of the Supercats, since their halyards attach at the bottom of the mast. Maybe compression is not as much of an issue if the halyard comes down the aft side of the mast through the sail track, rather than down the front of the mast? I have no idea.

And I have been told that the problem with external halyards that attach at the top of the mast on the forward side (Hobie 14, 16, Wave) is that with the larger, more powerful sails, it puts too much strain on the sheave(s) at the top of the mast and on the cable that has to bend over those sheaves. Seems as though those are problems that could be easily overcome, as Hobiegary described in the thread about "reefing points."

One problem we used to have back in the 1970's with using the Hobie 16 system (but on the Sizzler catamaran) was that the swaged balls on the cable portion would not always hold under a lot of pressure, and the ball would slip on the cable.

Seems like the ideal would be to be able to use a hook and ring at the front of the top of the mast, with the hook facing down. And you could even have two rings, at different levels on the cable, so you could easily reef. BIG PROBLEM: How do you get the ring(s) through the hole and over the sheave to get it to the front? Hmmm. Guess I have to dream on this a while. Maybe a bigger fork-type cleat on the mast and use thin, non-stretch line instead of cable, and use a knot to hold it in the "cleat." ??? You could have as many knots as you needed at different levels, too, for reefing purposes. (Line probably would have to be replaced fairly often, since knots weaken a line at the knot point.)

But even if the problems could be solved for cleating on the front top of the mast, you still have that halyard coming down on the outside of the mast and creating, heaven forbid, windage.