This would be a huge undertaking, and I couldn't recommend you to take it on without working up to it with one or two smaller rigs. It's going to have to be rigged as a three masted junk, similar to the larger Colvin boats, but even so, the mainsail is going to be vast, and making it is something that I myself would view with great trepidation, with the experience of a number of sails of 600 sq ft behind me. Making the mainmast by any glued construction is going to be a similarly large operation, not to be undertaken without gaining experience on smaller masts, so a grown mast is the only sensible option - the boat can carry it.

The big junks went up to much bigger sizes than your MFV, but remember that they had big crews as well. You would have to replace all those chinese seamen with powered winches for the halyards and sheets.

I've just bought a Danish oak ex MFV, which has since proved to be engineless. I've been curious about the feasibility of using a junk rig to propel her and it has now become a more urgent consideration. The boat is large, 19m, deep draught, probably in the region of 75T. Am I deluded to even consider this as an option, or is there a designer out there who could come up with some ideas?

Many thanks, Simon.