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Eco 520

When I compare fast sails on good performing multihulls with the SMG 50 example, I am a little confused. It is a beautiful boat but the mainsail seems far too full for a multihull especially in the photo looking aft from the foredeck. This is something that has confused me about most boomless rigs. I know they work well on beach cats that always have the apparent wind far forward. I have rearely seen larger multihulls with boomless rigs with good sail shape. When beating they seem to have inadequate sheet tension making the sail too full.? When reaching, they don't usually have the traveler to leeward far enough and have inadequate sheet tension again making the sail too full. When broad reaching, they run out of traveler and thus the sail is too full and the sheeting angle is incorrect. On the boomless version of Bernd's Duo 480, this also seems to be the case. Am I missing something?

Hi Domenico
Yes, we are doing very well over all, thank you.?

Your drawing looks similar to what is in the plans, so it looks ok to me. It is a big thing to be an experiment, though. Of course the wood needs to be stiff enough to hold itself up while you put the glass and carbon on. Like a permanent mold. Will you put carbon on the interior support structure as well??

I found a company that makes aluminum airfoil shapes. Perhaps one would be strong enough for the legs of the A. I have not contacted them or made an inquiry into cost or length.

@catamaniac:?I have researched a bit the issue of battened main vs furling main. It seems, that there is no conclusive answer to which is better :-) It all depends on intended use of a boat. Of course Voyager with battened main will be generally faster -> larger sail area. But for singlehanded sailing furling mainsail seems to be more desirable in terms of ease of handling. Also, I came across other drawbacks of a mainsail, please check this quote:

"...I was always a huge fan of the full batten main...that was until I started sailing long distance across rolling seas with light breeze. Rolling seas and light breeze cause main sail slatting. When you head out across the pacific or down to Mexico, these conditions will dominate your sailing experience…so be prepared. Slatting is when the roll of the boat overcomes the fill pressure on the sail and the sail pops back and forth as the boat rolls with the sea. Long periods of slatting the main sail result in batten chafe which ultimately results in battens being spit-out in the middle of the night and difficult to repair holes in your main. In addition, slatting also causes excessive wear of goose necks, bat-cars and tracks. Being able to reduce sail area and pull the main flat greatly reduces wear in these conditions. Because the battens are there to produce curvature, they also amplify the pounding of the sail during slatting conditions. It is our opinion that battens are not worth the trouble for blue water cruising..."

So, in my opinion, You should choose carefully, minding where You'll sail Your boat and with what crew :)

I also consider building KD122, but that A-Frame mast worries me in terms of me being able to build it / buy it with reasonable amount o money :)

Hello Domenico
It might be good to make the top the same as the bottom, not smaller, as it will need to be just as stiff as the rest. Will you add carbon or just glass? What will you use for the cross pieces??

Patrick

Yes, he does. ?But I think there was some issue with the stiffness at the top if you use tapered flagpoles as your base material. I decided on a center mast, so Bernd drew me a center mast instead and I stopped following the flagpole based A-mast development.?

Aluminum would work if you could get your own custom extrusion, but that is not easy. Two normal masts meeting at the top would be a bit heavy, and custom carbon would be nice. If you could find an aluminum extrusion that was very long fore and aft (10 or 12 inches) and very narrow side to side, that would be just right, I would think. But I could not find one before and I needed to move forward on the boat. So a center mast it is.?

Patrick