Piece of rigging.

[Vara]

A not particularly good pic of a large wooden boat in Dover.

Whats the wishbone affair between the two masts, and how does it work?

 

[Poignard]

The mainsail is triangular and the wishbone is its boom. The wishbone boom is pivoted at its forward end, its after end is controlled by a sheet leading down the mizzenmast.

http://en.wikipedia.org/wiki/Wishbone_rig

 

[Vara]

Thanks for that, I can usually work these things out, but that one had me beat. Googling without the right search terms didn't help either!

Clever idea, but must be very difficult to manage safely.