Haddanuvva breakthrough …
Long ago in the mists of time, two posts went up on biplane cats:
The main two reasons I shelved the idea were:
1. I went tri, not cat
2. I read a report on a hi-tech model which flipped when a sudden gust came down off a hill. I started to wonder why and then it became clear.
If you put one mast and sail in each hull, then a wind coming in obliquely is going to hit the windward sail first and the only way then for that hull is up and over, especially if there is a board down from the lee hull. It’s a fulcrum.
There is also the question of blanketing or wind shadow.
There is also the issue of the area being split equally in half and so that’s still a massive area up on the windward hull, which is already struggling to stay in the water. Therefore, I decline to use a biplane arrangement.
Run six sails, not two, on unstayed masts embedded through the hulls, which might seem counter-intuitive at first and seems to compound the issue:
1. 100 sq ft is vastly easier to handle for an ageing man.
2. That area allows for dinghy sized masts [14′ x 3″] and other rigging.
3. Each mast is in a separate compartment, so that if there is a sudden squall, a mast causing damage does so in one sealed compartment. Yes, there’s always the chance they’d all break at the one time.
4. Removing the masts from the cross beams of a cat removes stresses but does transfer such stresses to the hull, which is more readily braced inside. It’s assuming unstayed masts here.
5. The added weight of six small masts is better placed on/in the hulls, not on the beams. Cats of this size need weight in the hulls to resist capsize.
6. Using modestly cambered junk sails takes advantage of the instant reefing. Junk sails are heavier with those battens and once a halyard is released, they come straight down into cradles, something which can be done from the cockpit.
7. Six sails give an enormous number of permutations on each point of sail. You might run one windward sail and three leeward upwind, you might use five or six downwind. There’s a rule of thumb that it’s better to have the area forward going downwind in big seas, hence many of the old ships ran their square sails from the foremasts. You can partly reef each sail to fine tune the centre of effort against the centre of lateral resistance as you go. And so on.
8. For an approaching storm, the masts lift out and are lashed to the cross beams, which gives added strength anyway. Each of these masts is about 18 feet long by 3 inches all up – a job for two crew.
In that situation, a 7′ x 3″ stayed staff does go up on the centre beam for the storm jib.
Redolent of but not the same as this: