What do you do with a bargain basement priced 35 year old Tornado sailing catamaran when its sailing days are past? I had a couple of choices. I could restore and reinforce the hulls, buy new sails and rigging, and sail it like the designer intended, but somehow I could not see myself righting that 27' rig after a capsize. I could have used the two hulls as amas and built a longer center hull to make a small cruising trimaran. This has been successfully done by others.
Or I could make it into an outboard powered fishing and day cruising boat. The last choice seemed the easiest because not only do I already have a yard full of sailing canoes but I had a 9.9 hp Honda outboard and was interested to see how fast I could drive these hulls.
I tried to keep everything as light as possible while still spending the minimum amount of money. There are four hollow plywood girders bridging between the two original aluminum crossbeams. The deck is 9mm (3/8") Meranti ply. The sides and seats are all 6mm (1/4") ply.
I had to do some test runs to get the motor height just right. You can lose a lot of speed if the prop is too deep and it will ventilate if it is too shallow.
My GPS read a maximum speed of 13.8 knots (25.5 km/h).
Future work will involve reducing the spray from the engine that hits the aft crossbeam and possibly fitting a dodger/awning for sun and wind protection.
And in true outrigger style, the entire platform is lashed to the crossbeams with polyester line.
I have to admit that I was partially inspired to do this by Russell Brown's "Skeeter", although his is designed for rougher conditions than mine.