This is my second A-class with spi, and this time I wanted it to be optimal for the A-class. I got a snail from Marstrom designed for the smaller A-class spi of around 18 m2 together with a 40 mm spi pole and nice carbon struts.

I've been out sailing a couple of times and max speed so far is 20.6 knots. The curved centerboards makes a big differance in higher speeds, it lifts the bow nicely and you can get the boat to take off on the centerboards if you stand far back.

Check the link below for pictures.

http://www.webbo.dyndns.org/a-cat_sailing/spi_mk2/


hakan

Pretty sweet.
How do you get the halyard from the luff track to the front of the mast, without going over the top?

Håkan,

with the halyard running inside the mast and exiting at fixed positions, will not mast rotation be hindered?

There is a tube going from the front of the mast and back to the mast track. In the tube there are two sheaves so the halyard can run inside the mast track up to the tube, over the sheave, through the tube, and then over the next sheave and out on the front of the mast. The tube is glued water tight to the mast, it was rather tricky to glue inside the mast track...

/hakan

The rotation is no big problem since the exit point is so close to the rotation point of the mast and that the block svivels around the mast base. In the gybes you might have to help the rotation a bit to get it fully rotated.

I added a picture on the wepage with the mast rotated.

My biggest problem is to stop the spi sheets from dragging in the water when going upwind, you can of course make a knot to tighten them but that takes time....

/hakan

Do you have a full tube going all the way down inside the mast for the spi halyard?

No, the tube goes horizontal from the front of the mast to the mast track. The halyard runs in the mast track down sharing the space with the luff line of the main sail. Works great!

/håkan

Hm, perhaps something to try on our F16s also
Since you say it works great it must mean that friction is no problem when hoisting/dousing either.

Your work is impeccable as always. Keep up the good work!

Thats unbelievably simple, thanks for sharing

Hakan, a number of the F16's have a small line ( about 300mm on my boat )from the clew to a small metal ring, the retrieve line then goes though that. When you douse the spinny the sheets then get dragged back in further than normal. Adjust the length dependant on the sheet lengths. Have a search on the F16 Forum it has been well documented and photoed.

Hey Håkan,

I hope will give us your impression on sailing with curved daggerboards when you feel you have enough experience with them. Very interesting development..

I'm not getting this fully. Your pic's show a hole at mast base. Then another with sheave in the mast track, but up from the base several feet. Are you saying there is a tube between those points (i.e. diagonally from base to sheave)?

Then Halyard goes up mast track with the mainsail luff bolt rope. But how are you going from the track to the mast leading edge at the top point? Another tube horizontally with a sheave at each end to turn the halyard two 90 degrees turns? Have you considered making a strop & bail setup like most other spinny setups to decouple load on halyard from de-rotating the mast?


How does your halyard cleat release work? Your pic seems to show a line that pulls one side of the cam cleat open. Does this mean you must hold that trigger line tight all the time while dousing the sail (to keep the cam pulled off the line)? Did you consider a SpinLock instead of camcleat here? Once open via a trip line, it would stay open on its own.

The pole stays look trick. But for practical reasons I'd prefer spectra. One good bump at a mark rounding/startline or at the dock and your day/wallet is done!

Mike.

The mast is not waterproof all the way down, only to the point of the exit block where you insert the sail in the mast track. There is no tube there due to that reasone, just a line running down to the mast base.

The volume in the mast is so large compared with the boat weight that it is very hard to get the boat is mast down position. I managed a couple of years ago, but only when the mast was broken...

A line is cheaper and more roboust but you need lines instead to keep the pole in position and since it is a uni rigged boat with twin forestays it is more tricky than a normal sloop rigged boat.

You guessed right, there is a tube going horizontally with a sheave at each end to turn the halyard two 90 degrees turns. I haven't had any major problems with the mast rotation so far and I don't have any space left between the sheave and the top of the gennaker.

The halyard trigger line is connected to the block on the tramp. When I pull the line to take down the spi hard enough it will pull the line that the block is connected to, trigger the cleat and after that the force in the block is high enough to keep the cleat open during the "take down" process. When the spi is down the cleat will close by it self and be prepared for the next hoist. A spin lock requires a manual interaction to trigger it for the next hoist.

I agree that the poles a fragile, but repairing them is quite easy. I haven't broken any one yet....but I will sooner or later!

Cheers
Hakan