Hi Mike
?
First, thank you Brian and David for your insights. I appreciate this very much. This is what a forum, group should be about. I as a designer biased of course. I like them all, otherwise, I had not designed them.
?
Very short, all boats you are interested in have more or less the same stability characteristic. The sail area should be decreased above 20 knots. I add the ECO 6 stability diagram to see the stability characteristic of this boat.?
As mentioned by Brian. The lower CE of a biplane rig plus the possibility to shorten sail very fast is a big safety factor. It is the quickest way to shorten sails.
?
Masts. The windsurf masts for the DUO 480 are a more European solution. Here in France, we get them now in the Winter from Euro 50,- onwards. I admit it is the minimum solution. Brian's masts are the real good solution. Lucky he lives in New Zealand where carbon tubes can be obtained for good prices. I was surfing in Alibaba. Found 80mm diameter carbon tubes for 35,- $ per 1m. So one mast would cost 227,5 $. The bad thing, the transport costs 135 $ to the USA or Europe are the same. Total is 590,- $.? But overall a reasonable price.?
?
Building your own boat has many advantages. We have here some very interesting solutions. One of them is the gaff rig from David and the Dyneema rigging. By using an Al tube as a mast. Hu, a gaff rig? where is the difference between the popular fat heat sail and a gaff sail There is none. But the costs for the total rig were kept down without sacrificing sail quality.
Weight, having a light multihull is a safety factor.? The defense is a fast accelerating, principal, running away from the wind and reducing in this way the force of a gust. By the way. If this happens, do not luff up, bear away and loosen the main sheet to lessen the rotational effect.
Construction time is a controversial issue. It is individual.? For example, the beautiful ECO 55 as built in New Zealand by Hamish was taking two years. Martin in Nicaragua built his boat in 600 hours including the Gunter rig ( see some clips in this video:? https://www.youtube.com/watch?v=ioKESt3xtUU. In Russia, the boat was built in 3 weeks by three men. See photos (Economy cruiser pictures). Take your pick!
To stay in the size range. Brian mentioned it already. Look at the?
KD 650.
I hope this helps you a bit to make the right decision for you
Bernd Kohler