How to Extend Transoms

[thinwater]

Many multihulls drag transoms, in part because designers try to put as much accommodation as possible in a given length as possible and in part because after that, the marketing department adds more accessories. A little extra length often solves the problem, plus adding speed and better handling. Often, like Seawind and Stiletto, these extensions lead to a permanent change for the better.

This post summarizes my reasons.
Sail Delmarva: Better Boarding--Extended Transoms

This post describes the process.
Sail Delmarva: Extended Transoms: The Process

[James S]

Very nice looking job.
Any noticeable difference in performance...like speed...balance?

[thinwater]

Speed. + 0.2 knots motoring full throttle (7.6 knots vs 7.4 knots), measured 2 ways over the same course I use every time I paint the bottom or tune an engine. About what 2 feet of water line would project.

Balance. Nothing significant. Maybe it tacks a little faster (even with the length, she is going faster AND the profile of the stern as it slews out is smoother). Maybe it pitches less.

Backing. Noticeable improvement. Faster and smoother turns. Nice, since I dock stern-in.

But all of these changes are minor. The real improvement is dingy and kayak boarding, plus hanging your feet in the water.

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This sort of thing is going to be very boat specific, benefiting those who's transoms are under. Also, there are boats who's transoms only go under at speed, when the boat sinks in its displacement hole.

[James S]

Interesting...I didn't even consider it would improve performance backing up...

[simonmd]

Interesting, a friend of mine has extended transoms on his FP Mahe 36 (now 37 lol) and it certainly makes them much more usable.

[Abaco]

Strips of 2X2's will create a mold that you can lay glass to create the extended scoop.