Regarding board length on F16's and the F16 class rules.

In the beginning the daggerboards in the F16 class were largely left unregulated. Basically, each F16 had to have none or a pair of them and no part of the daggerboard may be angled to more then 6 degrees of the vertical when the boat is laying flat.

Everything else is allowed. For example canted boards are NOT included in the overall platform width rule.


A few year later some clarifications were issued but left the spirit of the daggerboard rules in tact.

Now we are face with a development in both the F18 and A-cat classes with respect to very high aspect daggerboards ( > 7 ) and their associated high costs and additional skills in handling them.

In that light I would like to provide the following points.


In the beginning, I analysed that there was no meaningful gains to be made in the drag to lift coefficients of a daggerboard beyond an aspect ratio of 5. From my experience with the FX-one I knew that oversized boards are rather a detriment to performance then a boost. So this made for a framework where the total area of the boards were limited and no real gains were to be made with higher aspect ratio's. I envisioned this framework to be self regulating and expect all board designs to end up somewhere around aspect ratio's of 4 and an area of 0.15 ( = mainsail area / 100 as is typical on performance beach cats)

This seemed to coincide with what could be done with modest use of carbon cloth, thus making the daggerboards performant but not overly expensive.

Additionally, experience with the first Stealth designs and comments by its designer (an established sailor and Olympic hopeful) suggested that short and wide boards (aspect ratio 3 and lower at the time) did NOT suffer in light winds or strong winds. The main benefit to long and narrow boards were found in the medium winds section. Additionally, long narrow boards made the craft hard to control at low speeds and on the start line. Loosing the start is about as bad as lacking 5% speed on the course. So by going to aspect ratio of around 4 we could strike a good optimize between costs and sufficient overall performance in all wind conditions and at the start.

I still hold to much of this viewpoint but with one important exception. I overlooked the importance of very skilled semi-professional sailors with respect to driving developments in this area.

Indeed, long narrow boards are just as much a disadvantage as they are an advantage but very skilled sailors with lots of practise time can overcome the drawbacks and make the advantages count. This is all good for the top of the fleet of course but the payback is spiralling cost over the whole fleet and not just the top. This aspect of the framework is sadly not self-regulating as we see in the F18 class.

This would all still be very acceptable if the long narrow boards (> aspect ratio 6) were not so expensive and driving up overall cost of the boats. A single F18 daggerboard is now twice as expensive as the bare aluminium F16 mast section and that is not right. Also remember that there is no top if there is no fleet (of amateurs swelling the numbers). A balance must be striken between the desires of both ends of the pyramid, if indeed the class is to be healthy.



I feel the time has come to limit board depth under the hull in the same way as we've limited the mast height in the past. For two reasons, to keep sailing of F16's accessible to amateurs in the way of handling and to increase our financial attractiveness with respect to the F18's and A-cats. The latter two are spiralling up in costs and here we have a chance at fixing our cost price while maintaining an excellent and generally acceptable performance around the race course.


My data suggest that the Viper is currently the F16 with the deepest boards at 0.85 mtr. Can Viper, Falcon, Aqua-cat, Stealth, Nacra etc owners please check this ? We are talking about wetted length here , that is the length of a fully extended board from the keel line to its very tip.

If so then the Viper board has an area of 0.180 with a wetted length of 0.850 this implies an aspect ratio of 4.01. Data taken from the ISAF SCHRS rating measurement sheet.

My own Taipan 4.9 boards are the smallest in the class at 0.162 sq.mtr. area and 0.56 mtr wetted length. They have an aspect ratio of 1.93 and pulling them up in any wind condition is bad. As a result Taipan sailors always keep these down and the Taipan is still surprisingly quick with them in both light and strong winds. Not so much in the medium stuff however.

Currently ISAF SCHRS handicap system quotes for the F16 daggerboards. Area = 0.200 with a wetted length of 0.900 mtr = aspect ratio of 4.05

A 0.1445 sq. mtr daggerboard with a wetted length of 0.85 mtr will have an aspect ratio of exactly 5. Such a board will have a width at its root of about 0.175 mm. This appears as the optimal F16 daggerboard when going on the math numbers.

When this board is pulled up by 0.15 mtr it will still have a good aspect ratio of 4. If it is raised by 30% or 0.255 mtr then it still has an good aspect ratio of 3.53. When in nuclear conditions it is raised by 50% or 0.425 mtr it will still have an acceptable aspect ratio of 2.58. Remember, low aspect boards maintain good performance at high speeds.

Therefore I personally feel that limiting the wetted surface area on the F16's to the largest curently in the fleet (= 0.85 mtr. I believe) to be a reasonable compromise to maintain sufficient performance but avoiding excessive costs. Also in comparison to the A-cats and the F18's !

Basically, we allow just enough inward canting and a high enough aspect ratio to cover our bases with respect to very high aspect boards and lifting foils. So, yes both F18 and A-cats may have an edge over F16's under some narrow set of conditions but not very much and we maintain a very competitive cost-to-performance ratio. Of course, a newbie will never tap into the additional performance provided by the extreme go-fast specs of an A-cat, a modern F18 or curved foiled cat. But he can tap rather quickly into the performance of the F16's. I feel that that is a better position in the market place.

With kind regards,

Wouter Hijink