Ebb,

I'm not sure if I'm reading you right or not. The strop is a means of attaching the clew to the boom so it can't fly upwards. The outhaul can then be used to move the clew in or out to help flatten or bag the main belly. Of course this means the aft foot or so of the boom can't have a bunch of accessories on it. I don't envision the clew having to travel forward more than that.

Maybe that's the question. How far do the active sailors out there move their clew, fore and aft, to tweak their mainsails? And then who's busted a boom.

Even though the line would be lead back to the cockpit via the mast, wouldn't the pressure difference be between the tack and clew, independant of the mast? We're really 'stretching' the foot of the main between those two points. That said, I've put a fairly generous mating surface on the 'mast end' of the new goose neck. More so to keep it from pulling out rather than being pushed in and crushing anything.