Guys,

We have a choice to make I'm afraid.

I won't go into details right now but because of the short hull length this F12 will have a more narrow crew weight range then larger catamarans. We need to decide where to place this range.

I worked out the underlaying scalings law and as such can give you all a feeling of what we are talking about.

As the reference I put forward an F18 sailed from 115 kg to 180 kg, with 155 kg being optimal. Lets assume that all F18 crews in this range are more or less competitive and experience enjoyable sailing, meaning, neither heavily overpowered nor sluggish and underpowered.



If the F12 is exactly 12 feet long = 3.66 mtr then its characteric weights (similar to F18 above) are :

range = 31 to 50 kg with 43 kg optimal


if the F12 is 3.90 mtr long then its characteric weights (similar to F18 above) are :

range = 49 to 72 kg with 63 kg optimal.


if the F12 is 4.00 mtr long then its characteric weights (similar to F18 above) are :

range = 57 to 82 kg with 73 kg optimal.


All above boats have been scaled to not perform worse then the F18 when not looking at the other issues associated with scaling like the pitching moment problem (= dive happy).

Additionally, from the point of drag it is always better to sail an boat underweight then overweight. Meaning that being 10 kg overweight is just as bad as being 20 kg underweight. The overweightness just hits harder.

Be sure to note how only 0.1 mtr (= 4 inches) difference in hull length, (from 3.9 to 4.0) moves all characteristics weights up by 10 kg's ! 0.1 differenc in length is nothing on a F18 but it is the world on a F12.

The point of this post is that we need to decide what the F12 should carry in crew weights a choice here will have a direct impact on the required MINIMAL length of the hulls.

Please everybody give your opinions on this, I'll provide my own opinion at the very end of the discussion.

Wouter