I asked John M. about the rig; here's his response:

<JM>"The yard is set about mid-height to avoid any vertical loads at the tips. Dividing the luff length is an advantage, making them easier to control (no collapse when luffing, like a spinnaker). Also, the head and foot apexes will have little tip losses, causing the sail to be more efficient. A conventional sail with a long foot has a large loss of lift from air escaping under the foot of the sail and increased drag from the vortex it creates.

The COE may be marginally higher than a marconi rig, but you have full control of the amount of sail - if the boats heels too much, roll up a little sail until it is comfortable again. Unlike conventional reefing, you can "dial in" the amount of sail.

I have tested the model with a number of rigs and this produced to best performance. It is very close winded and fully balanced on any point of sail. It requires no deck lines, winches, lead blocks and other clutter. And there is excellent visibility since no sails sweep the deck. It was also the smallest sail area of any of the rigs tested, so I think the sail is more efficient.

I would love to build a full-size demonstration rig on a 30' boat, but financial support for the project is lacking. The major cost is a carbon mast and yard. All the other equipment is largely off-the-shelf gear.

This rig design was part of an autonomous boat project (computer operated) for ocean racing. Only two control inputs; sail size and trim, simplified the programming and improved reliability. It has uses for cruising boats as well - what I call the "the ultimate geriatric rig". " </JM>

I'd also thought about lowering the yard to lower the COE, but I've got to say the video of the test rig is impressive as is.

The Outrig site is worth joining; I'd be way more paranoid about joining Yahoo or Google (who does sell your affinity information) than what seems to be the best multihull history site, and they actually care to ask what you'd like to see.

http://www.youtube.com/watch?v=QzIjO4A9nXE

http://www.youtube.com/watch?v=Ufgn8IP4tFQ

http://www.youtube.com/watch?v=J8aHw0PcVPw

Mike

On Oct 26, 2011, at 3:27 PM, sfbaysailingdad wrote:

> I agree the sail area looks to be fairly high up, but imagine the yard only 1/3 of the way up the mast. The trick with the proa is to make it easy to shunt, and this rig is built for shunting. Pretty sure I don't like the idea of relying on electric motors for trimming and furling, but that is likely just an option.
>
> Is the rig optimal? nope - I'd want some sort of wing for that - but wings have other issues. Like having to take them down after every sail.
>
> As to signing up - the only email I received was a "welcome - what would you like to see on this site in the future". wasn't too offensive.
>
>
> --- In harryproa@yahoogroups.com.au, "sfbaysailingdad" <mitch.sailing@...> wrote:
>>
>> Might be a pretty good fit for a proa - if you watch the video you'll see that it requires wearing-away when "tacking". Sortof like a fully balanced Balestron rig, with the boom higher and sail below the boom.
>>
>> You might have to sign up to see the video
>>
>> http://outrigmedia.com/outrig/uncategorized/2011/10/19/diamond-rig-designed-by-john-marples/
>>