Dart 15 Forums

Pete wrote:

What's the advantage of a rotating mast - is there more to it than aligning the mast section relative to apparent wind?

How different would the 15 be if the mast didn't rotate?

What would be the optimum mast for the 15 beam/loa plan?
(Talk about daydreaming!)

Keith in Hong Kong replied:

You don't get out much do you.....it could be argued why don't most dinghy masts rotate........it just makes sense......uniform mast bend characterisitcs at all sail angles, easier rig tension control, more robust hound fittings......etc.

Apparently not getting out enough! replied:

So what you're saying Keith is that cats and the odd dinghy (Taser, laser, topper & others) actually have an efficiency advantage over all those dinghies and boats with lids whose masts don't rotate? So all the hardware you see on, say a 505 or an International Canoe, is just so much extra weight to try and overcome the disadvanges of a non-rotating mast?

Keith in Hong Kong replied:

Well we're not comparing like with like here.....unstayed rigs are a different bag of spanners anyway. All that 'extra weight' is there of course to keep the stick up, and control/define bend and pre-bend. Simpler dinghies like the Laser have a mast that gives no advantage/disadvantage in aerodynamics because the mast is round...so it can rotate. If it didn't rotate the sail would tie itself in knots each time you gybed. I guess the reason for Dart mast to rotate is to take the minor advantage that it can having no complicated arrangements of spreaders and diamonds.

My old Magnum 8 Moth was a nightmare to get setup correctly due to the fixed prodder and the rotating mast, and diamonds, but at least the spreaders weren't trying to poke through the sail.

I guess the other point is that with a fully battened sail, without batten cars, the batten ends would suffer too much going downwind/gybing etc.

Anyway......I think we've exhausted that one...it rotates

Bob Carter replied:

The rotating mast is a big advantage. The sail is designed for it. The mast effectively become the front of an aerofoil section with the sail blending in behind. If you do not believe it, try sailing a Dart 15 without the mast rotating (it happens if you have the rigging too tight).

Simon replied:

Hadn't noticed before this weekend but when I'd rigged up my Dart the (single piece) mast had a definite curve to it.

The curve was not front to back (like a windsurfer mast) but looking from the front 'C' shaped (that is a huge exaggeration but you idea!). The curve would flip over to the other side when the sail rotated to the other side.

Is this how it should be or, as my guess would be, I've put far too much down haul on?

Regards,

Simon.