Pepin,

There are different ways in measuring platform stiffness.

The way we (in F16 land) do it is to lay the boat up on its sterns (check it is perfectly horizontal in both planes) and then lift the boat by one bow only. At some point the other bow will loose contact with its support. When that happens lower the boat a little bit till the bow hanging down is just above its support and then measure the difference of the raised bow above its support.

In the past this measurement was performed by F16 enthousiasts for a series of boats. All the gethered data is useful because we used the exact same procedure for each boat.

The boats were : Hobie Tiger, Nacra F18, Reg White Tornado, Taipan 4.9 (both homebuild and AHPC), (Homebuild) Taipan F16, prototype Blade F16, Blade F16 (both VWM and Aussie), Stealth F16.

Interesting detail here is that the Taipans all flexed by as good as the same amount (only a difference of 2 mm over an average of 64 mm). Therefore my WIDER homebuild F16 flexed by the same amount as the AHPC build standard (narrow width) Taipan 4.9. My boat has only modest reinforcements at the beam landings (a few carefully placed strips of carbon fibre cloth) and a 80x2 mm rearbeam instead of the square rearbeam of the Taipan. That was enough to compensate fully for the "loss of stiffness" that is normally related to making a platform wider (30% stiffness loss). Additionally, my set of beams weight a a fraction less then those on the standard Taipans. The prototype Blade F16 used 2 80x2 mm beams and its set of beams was significantly lighter while also achieving noticeably better stiffness (by 33%) then the Taipans (both versions). A similar improvement was again had by redesigning the F16 beams (used on Aussie Blades and Falcons). 1.5 kg increase in weight against additional 40% stiffess. ... etc.

In the end, it is all about careful engineering. Any knucklehead can make a stiff boat by adding 10's of kg's to the beams. A true boat designer does it by careful analysis and being smart.

Wouter