See this. http://www.storm250.com

http://intheboatshed.net/2008/05/13/104-year-old-norfolk-broads-cruiser-maidie-gets-a-carbon-mast/

I can recall him doing the CYCA winter series on Sydney Harbour charging past the leading 40-50 footers of the day downwind. It was a much bigger mod than you are thinking of doing but it did show that the hull isn't too slow!

On the other hand, will the stock foils handle the extra sideload of a much bigger rig? Perhaps if you were pimping a FF you could find an old keel and fill in the hollow on the trailing edge to give you more lateral area without introducing problems in getting the boat to fit on the trailer, and getting the keel to fit on the boat.

I also seem to recall a FF fitted with wings and/or skiff rig that I raced against once or twice on my stock FF years ago. It was quite slow, which may indicate that a conversion has to be done well, or it may be very tweaky.

Down here in Oz there's a mini tradition of converting inshore racing keelboats to offshore racers, with a fair amount of success. I have flirted with the idea of doing the same thing to a FF; not so much to race offshore (although that could be fun) but to compete in races that are only open to trailerable cabin yachts.

Now that is fantastic! In style (although not design) it reminds me of a varnished 30 Square Metre (or 40 Square) that was fitted with a different rig, wings and traps and used to race on Lake Garda with the Libera Class "giant skiffs".

This thread has given me ideas about a project boat for my own club (located 120km inland on a small lake) but it will have to wait a few years until other projects get finished.

Provided you don't increase the righting moment with racks or trapezes, increasing the rig size would actually decrease the sideforce when fully powered up, as you'd have the same heeling moment generated by a smaller force with a longer (higher) lever arm!  You could actually increase the righting moment and then with a higher rig generate the same sideforce higher up.  But where would be the point?

I'd suggest that what you're looking for is a rig that generates more thrust for the given heeling moment, and that is a bit of an ask, given the highly developed state of the ff rig.  I am not convinced that the modern generation of fat headed rigs are so much more efficient compared to the pin-heads - the Fireball is startlingly fast to windward in a blow given its hull and available righting moment.

What would be nice would be a lighter, carbon mast, although the benefit on an ff would be limited given that they are best sailed upright.  But at least you might be able to flatten off the sail better, and it would spill more automatically in gusts, so you might, on average, get a bit more thrust.  Most likely the biggest gain would be in the ease of stepping the mast!

But whatever, you'd need a pretty well-sorted rig to beat the existing highly developed sails.  I wouldn't expect a mix up of mast from this boat and sails from another class to be much, if any improvement.

Now, if you're talking trapeze (surely a good idea on an ff?) we have a different scenario.

Edit: caveat: my remarks about sideforce are based on the fully-powered up situation. In less wind the boat will be quicker for sure with a bigger rig, but you wouldn't need to wait long before you got overpowered!  The extra speed would generate more lift off the foils too, so the keel should suffice, except maybe in manoeuvres when the speed was low - you need to sail for speed initially after tacks, but that's true of other, more modern boats with their minimal 'boards.