Radical Bay style Bipod but with jibs only?

I wonder if anyone has seen something like this done, - or even planned? Just two sails, based on jib furlers, in order to achieve as much ease as possible in terms of handling the sails. Yes, I know that this is neither the optimal solution vs. performance nor the cheapest one etc. but are there any other pro's or con's besides the obvious ones?

Radical Bay 800 Catamaran | Schionning Designs International https://schionningdesign.com/radical-bay-800/

 

Depends on what you consider obvious. There are the drawbacks of any furling jib only rig:
1) You get decent sail shape only for a narrow range of courses close to the wind, unless you can move the sheeting point out as you fall off, which makes things more complicated.
2) To keep forestay sag from the pull of your large jib within acceptable limits, you need a lot of forestay tension, putting a large load on the rest of the structure.
3) As you furl the sails, the centre of effort moves forward a lot, and also up.

Then there are the issues specific to a catamaran:
4) Even on the wind, you may have to move the sheeting point on the leeward hull outwards.
5) The biplane rig with mainsails is well suited to unstayed masts, but those don't play well with foresails. I am pretty sure the foresail flown by the Radical Bay 800 is a light wind sail, with a modest wind speed limit. You would need shrouds, and not having much of a staying base, you would probably need to stay each mast to the opposite hull, and put a compression post between the masts, like on Parlier's catamaran Mediatis Region Acquitaine, or on the Trifoiler. Then your masts are no longer independent; if one falls, the other will, too.

If you are willing to accept some performance loss for simple sail handling, and you want a biplane catamaran, I recommend looking into a modern junk rig, such as a split junk, or a soft wing junk.

 

As above, the main problem is forestay tension. If you want a jib only rig, use a stayed center mast and two jibs, one to each bow.

 

Photos

 

Excellent points, many thanks Robert. It's kind of interesting that the second option I've been thinking about is indeed a biplane junk sail, -or even a lug sail, which I'm for the time being having as an alternative in my daysailer. The lug sail I have is now a kind of modified standing lug with a jib type of boom, instead of a real boom making it a balanced lug. Something like that might help also with those biplane furlers, regarding the sail shape. But as you said, the mast construction may become too complicated.

 

Thank you Rumars, possibly a A-shaped mast might work, with two jibs as you said.

 

Many thanks for the photos, Triroo. No bipod but indeed two jibs and apparently without problems in terms of mast related tensions. Is this a one-off or a production model, would you happen to know?

 

Finby: That is John Hitch's Exit (Xit?) designed and built by himself. She is currently for sale.The twin jib rig was proven on his Hitchiker range of designs, many of which are still cruising.
Google "John Hitch catamaran" and settle in for a long read.

 

Many thanks for the reply and the good reading suggestion, Burger!

 

Not exactly a bipod but looks pretty interesting anyway:

https://www.hopyacht.co.za/