Yes the DS16 is definately intended to be F16 complient. However, at present it is being designed for sailing single handed. By this I don't just mean sail shapes and systems etc but the actual hull form is designed for one person only.

Thanks, that is really great!

Altered was also a dedicated on-up rocket. Will be very interesting to see the result from your hand.

Altered is definately the closest comparison. However I suspect it suffered from being cut down and operating at a higher than designed displacement. A one up boat will definately look more A class inspired than the current boats.

T-foils may/do help to prevent pitchpoles but the question relates to the comment about increasing the effective waterline length claim for T-foils.

Waterline length really only helps for vessels in the displacement speed regime. ie. for a 16 foot boat that is speeds less than about 5.5 knots.

To clarify, I believe the claim about T-foils near the surface increasing the effective waterline length is too simplistic. A shallow T-foil will have these influences:

- Change the wave pattern around the transom
- Change the vessel trim (which will also change the wave pattern generated by the boat)
- Add drag
- Increase pitch, heave and roll motion damping.

When the 14's were moving to t foils (as against T foils) Bieker who pioneered these foils argued that the foils effected the flow at the transom which was like lengthening the waterline. I've never really looked to closely at it but if you could lengthen the "hole" left by planning this might result in a boat the acted like it had a longer waterline, it would definately increase the "hull speed"

What I have seen in practice is that the boats are generating lift with the rudders up wind and as a result the crews are standing well back. This then allows the bow to become finer and therefor faster through the water. Down wind the finer bow isn't the risk it used to be beacuse the foil can be used to keep the bow up. This is why the foils (or the cases) are made adjustible, so you can get lift upwind (and in low wind down wind) and down force in a blow.

Cool, very cool indeed.

Look forward to seeing another F16 in Aus.

But they are generally operating well beyond their hull speed.

That is my understanding of the adjustable t-foil usage on the 14s also. Generate lift upwind and in light airs and generate suction downwind. It makes the boats faster, more controllable and docile according to general opinion. I'm not convinced this can be attributed to "increasing the effective waterline length" entirely, there's a lot of other stuff going on at the same time.

You'll have to be patient Tony, it won't be this summer

You have watched the progress of my boat.

I have lots of patients.

the I14 foils sits below the waterline.. So doesnt increase the actual waterline length.. what it does is theoretically reduces the stern wave..
but how effective it is is debatable.

True, the I14 foils are just below the waterline; but point is they are designed to alter/modulate/modify the hull-induced wave pattern. I don't think it's a stretch to envision a design where a long gantry and specialized foil on a rudder can make the water think the boat is longer than it is. I find the concept intriguing. Question is whether on not the class wants to allow boats to go in that direction. And of course how effective such designs are on sailing around a course fast is debatable.

Hi,
The bieker foils sit about half way down the rudder. So a reasonable distance under the water surface. Not surface skiming nor "just under".

All well designed foils are designed to to modified waterflow. But I understand your concerns. Just dont think they are founded. But I will ask the I14 boys to see what the latest state of play is with their rudders. Then get back to you with real world experienced results.

Stewart

There are two schools of thought on rudder foils in regards to long thin hulls ( unlike dinghys skiffs with fat short hulls ), one being any foil in the water is drag and is simply countering a poorly designed hull. The other is that the foil is stabilising the boat and thus allowing the boat to be more longitudinally stable enabling the gorilla on board to sail the boat better. Having a gantry simply, by a longer leverage, allows a smaller foil to have a greater effect.

So far the jury is out on both counts, as a development class we should be encouraging this sort of development as it may ( or may not ) lead to an easier to sail boats.