If this may help in the discussion let me share the decisions I made when discussing my 860Open with Bernd.
1) sacrificing some cabin space was not an issue because I am not planning to sail overnight with many people on board.
2) I will be sailing mostly in warm waters so I will be spending more time outside than inside. In the design process: a bimini right after the front beam for passengers and another bimini aft combined with the davits for sheltered navigation. At anchor, a tarp can be drawn between the mast and turn the whole space into a very large tent.
3) the open deck makes for a huge cockpit well protected between the two hulls, the front beam and the rear beam so very safe for everybody on board.?
4) the bridge deck on the 860 is very low and I am 1.92 so I will get very annoyed by the lack of headroom. If I was building a bigger boat, I would have got a covered bridge like the Duo1000 with removable canvas windows for weather protection
5) It is an "ode" to people who have sailed open deck catamarans on long distance for centuries. My second choice beside Bernd designs was the Wharrams which are all open deck, sometimes with a kind of shelter at the center of the bridge. Those are very well regarded long distance, albeit minimalistic, catamarans.
6) I choose the biplane rig because
- it offers redundancy in case one mast breaks
- there is no stays so less failure points plus there is not limitation to the angle of the sail
- with the wishbone it is super easy to manage. It is self tacking so minimum work on the sails even in tight corners. Reefing is straight forward and fast at any point of sail.
- with lower sails, the center of effort is lower which reduces the risk of capsizing
7) It should be lighter and it should sail well in light winds despite the lower sails. With less interior space there is less temptation to cram more things inside so it will help keep things light!
8) the bridge clearance is increased from 500mm to 600mm
9) it will look very different from anything floating nearby so it could be a good ice breaker to make new friends ;-)
And then I got good news: I found a buyer for my home with completion at the latest early May and I got a 20-year visa in Thailand. So, the build should start mid 2024 with target to hit the water in May 2025 for my 60 year old birthday.
Alain Dupuis