Anti-Diving Foils

Caution: some of the information given here was also given under another topic, probably in the multiONE class, in response to a question. It is impossible now to locate that topic. If you would like to avoid anything that might be repetitive please don’t read this.

Modelers interested in the concept of using ADF for the prevention of diving downwind might be interested in the very rare photo provided in todays Scuttlebutt showing the application of anti diving foils on a full size monohull.See: and look down a ways for the article on Grundig and her Sydney-Hobart preparations; a link to a picture is provided at the end of the article showing the bow mounted anti-diving foils.
I’ve used ADF on a 36/600 successfully and they can be used in some classes legally. Two things are important: 1)- that the foil doesn’t hit the water going upwind, 2)- that it is at the correct angle of incidence. A close approximation of that is: if you push down on the bow of the boat until the stem/deck intersection just touches the water the angle to mount them on the boat is 5 degrees above the level of the water with the bow down. You can mark the depressed waterline and use it to reference the foil mounting angle.(Back end of foil should touch the line; front end should be up by 5 degrees)
It is important to note that these will not be legal in every class or even desirable since the foils stick out and in close proximity to another boat could cause damage. But in mutihulls the foil could be placed just on the inside of the outside hulls so that couldn’t happen.
Area of two foils total for a 36/600 is aproximately 4 square inches…

Doug Lord

High Technology Sailing/Racing

A direct link to the article Doug mentioned is here:

Will Gorgen