BACKGROUND
After Booth successfull rebuilt of the M18 I'm thinking about adding a second trapeze, a bigger mainsail and spi to my Marstrom A-cat. I know that Booth didn't win but my interest was focused on the fact that the boat could handle the extra loads without any failures!

Booth used the M18 with 330+ lbs of on the wire and used a main beam that had a weight of 110 lbs instead of 11 lbs. The reason for the heavy mainbeam was to reach the minimum weight of 286 lbs. Booth used a cut down M20 mast, I will try to use the A-cat mast as it is.

Should I do it?

THE PROJECT

Crew
It will not be designed for "Team beef" but for teams around 286 - 308 lbs, same as Hobie 16.

Sail
The area can be increased from 148 sq.ft to maybe 176 sq.ft by adding more roach area to the main sail. The spi should be around 180 sq.ft.

PROBLEMS
Mast
The top of the mast may be to bendy for the bigger roach and increased loads. The performance to windward in medium winds could suffer from this.
Increased compression of the mast by 30%, reason higher sheet load and another crew on the trapeze.

Main beam
Increased load on the mainbeam by 40%, reason higher sheet load and double trapeze. Booth had 50-60% more load on a WIDER main beam.

Hull
The hull needs to support 480 lbs instead of 363 lbs which means that the hull will be 1.5 inches lower in the water. The hull on Booth F18ht supported at least 616 lbs and that hull was probably 4 inches lower in the water than normal.

Performance
The boat is narrower than the F16 and 55 lbs lighter but the sail area will be lower, 176 sq.ft instead of the F16 192 sq.ft. The lower sail area will be compensated a bit by a 3 feet higher mast compared to the F16 and uni rigg instead of main+jib.

/hakan