Gooseneck on wing mast

If I remember, some Formula 40 tris used boom gooseneck on the deck. If you dont use gooseneck aft the mast you will lack forward compression to induce mast rotation with aft mainsheet, you will need a mast rotation control lever forward the mast.

 

What about attaching it to a beefed up rotator plate so it rotates with the mast ?

 

Simple, no forward spanner to tangle sheets, no gap distortion (contrary to deck stepped boom) at sail base with mast rotated, allows boom to apply pressure to push mast to correct position.

 

I like the reduction in sheet loads. My way was to use a full wishbone, which I still love 21 years later. I think the engineering of the system would easier with the gooseneck on the deck. The sides of the boom will have to be strong in compression up at the top flanges. The good thing about your system is that you will have proper vanging on the main even when fully eased. Most travellers only get a cruising cat's main out to the correct position for a beam reach. But a very broad reach or run requires you to fudge something. Your solution would be good at vanging at deep angles. As well as being more efficient, it really seems to protect the sail from chafe and flogging. My laminate main is 21 years old and has done 4 trips to the reef and a trip to Tassie and huge amounts of day sails and still looks good up to 15 knots true. I think a lot of that is to do with the wishbone keeping the sail tight in all dimensions when hoisted, the thing is very placid.

You could put the wishbone on the end of this boom, or halfway down the boom and attach it to the aft edge of the mast. A version of this is done on some 14 metre cats to get the vanging effect (but with a normal wishbone attachment at the front of the mast)

Freeflow 46 Freeflow 46: Sailing Catamaran for Sale | Composite Sail Boats | Boats Online | Queensland (Qld) - Bunbury Region Mooloolaba QLD https://www.boatsonline.com.au/boats-for-sale/used/sailing-boats/freeflow-46-freeflow-46/254186

and some of my thoughts on an old thread

Questions Wishbone - Birig, Rotating, Unstayed Wing Masts - Catamaran https://www.boatdesign.net/threads/questions-wishbone-birig-rotating-unstayed-wing-masts-catamaran.59913/page-2