Interestingly enough the F16's were designed for 142 kg crewweight. I know because I was the one who proposed the class rules in cooperation with Phill and Kirt.

I was the one who proposed to follow what Bethwaite calls the cube-square law. Or at least I learned later that he had given it that name. I arrived at this law myself because I was looking to use F18 hull development to kick start the the class what would later be called the F16's. I was looking to combine the benefits of the AHPC Taipan with the class structure of the F18's and the possibility of viable singlehanding with the same platform.

I like to play with calculators and punched in the scaling factor that was needed to scale down a F18 hull to F16 length and started playing with it. The Taipan was 4.95 mtr long but I rounded that off to 5.0 mtr. F18's are max 5.52 mtr long.

5.00/5.52 = 0,905797

I wanted this scaled hull to sit at the same waterline as the F18 hull and so I calculated its new displacement where I knew that 155 kg was considered ideal F18 weight at the time.

(0.905797)^3 * (180+155) = 248,96 kg or indeed 249 kg.

At the time the Taipan was 102 kg and my own spinnaker kit weighted just under 5 kg. This lead to the following calculated ideal crewweight for the new F16.

249 - 107 kg = 142 kg


Using the same ratio to determine equivalent mastheight and sailarea's would have produced the following measurements (followed by the measurements we settled on for the F16's)

Mainsail area 13.95 sq.mtr (15.0)
Masnsail luff 7.79 mtr (8.10)
Mast length 8.15 mtr (8.5)
Jib area 3.40 sq. mtr (3.70)

Of course the Taipan already had 14.58 sq.mtr mainsail with a 8.02 luff on a 8.47 mtr tall mast and an overlapping jib of 4.18 sq. Mtr. I wanted to grandfather this boat so I maxed the specs to at least enclose the Taipan. I also wanted a selftacking jib so I ran the numbers on a jib size that would allow that.

Over time we tweaked the specs so that the 1-up and 2-up versions both had a rating equal to eachother and the F18's where I was happy to put some more power in the rig to cater a little bit for the heavier then 142 kg crews as indeed I too am a large male from north-west Europe weighting in at 85 kg.

Some more calcs showed that 2.5 mtr width (Taipan 2.35 mtr) would work best with the larger rig when looking at overall righting moment. Mind you the cube-square law pedicted equality at 147 kg and 2.5 mtr width when using the smaller rig. Basically by opting for the larger rig specs I overpowered the boat for a 147 kg crew by 112% in relation to a 155 kg crew on a F18. The new F16 rig would need a crew of 169 kg to establish parity with the F18 crew in the ratio tipping moment to righting moment. We could then have made the boat wider, but noticed that alot of nations limit maximum trailer width to 2.5 mtr and we really didn't want to go past the ratio of 2 between length to width for fear of loading the bows up too much. The italians wanted A-cat width of 2.34, the europeans at least 2.60 mtr and the aussies 2.5 mtr. A decision had to be made and politically the 2.5 mtr could be justified due to the legal implications of overstepping the max trailer width. So we settled at 2.5 mtr. accepted a boat that is a bit overpowered in the rough stuff.

In fact , I bought improved light air performance against having to depower a little earlier. additionally, some drag factors didn't scale down by 0.905797 so I needed some extra sailpower to correct for that.

With this in mind I find it a little bit peculiar that a F16 is said to be underpowered. It is in fact more powered up then the F18's and even more so with respect to the Tornado. In truth, it is one of the most powered up 2-up catamarans right after the F18HT for example. This is part of the reason why the initial F16's were easy to put nose down. I don 't recall anybody calling the F18's or Tornado's underpowered, so why this claim with respect to the F16's ?

I feel too many people look at the name F16 and feel that thus hull length number says all one needs to know about these designs.

Making the nacra 17 even more powered up doesn't appear to me as a sound decision. Let alone the fact whether this in in fact at all needed. Afterall, the nacra F16 crews have just found out that their sail cut is lacking power in relation to the Vipers. So they are not even getting the max out of the F16 specs currently.

Wouter