As is well known by now I'm a big fan of T-foil rudders; especially when I can get these on my Taipan F16. I really do believe that these T-foils are one of the parts that will make the F16 platform "complete". The short hull length and large width do make pitching on the F16's an issue especially when singlehanding with an aluminium mast on the relatively confused North Sea.

Up till now I had 2 major issues with the T-foil designs as they stand now.

-1- The were fitted to non-kick-up rudders or when they were they would really slow down the boat when the rudders were kicked-up and dragged behind the boat.

-2- The are relatively hard to adjust to the sailing conditions.


Point -1- is a major concern as the surf at Zandvoort is often big enough to destroy major parts on your boat if you catch a breaker at the wrong time. Speed and manouvrability are paramount. Dragging the little winglets through the water perpendicular to their plane is not an attractive option. Neither are rudders that slide up and down.

Point -2- is important on my boat as you likes different attitudes in different sailing conditions. In light winds and flat water she like to sail on her bows, in rought weather or at speed she like to ride more on her sterns. The semi planing Blade design will probably show a similar behaviour. It is too much effort to pack the pintles each time you go our sailing.

I also wanted a setup that I could remove from the rudders entirely and that I could adjust on the water between races or even during a distance race like the 3 hour long NAM-REM race.

And of course it need to be simple and relatively inexpensive.

Basically what I've come up with it this :




The rudderboard is cut off at the bottom to get a flat surface. Half a circle is cut out there as well. This will take the axis (a tube) that is laminated into the T-foil. The T-foil is jammed between this cut-out and a plug that is screwed to the rudder (and the T-foil) from beneath. The T-foil is now fully secured but can still rotate its trailing edge downward and also a little bit upward but not by much. Just behind the opening in the T-foil that exposes its axis, a nut is laminated into the foil. This nut connects to the threaded rod that runs through the rudderboard in a relatively wide canal (some laminated in pvc or glass tube). On top of the rudderboard there is a little plate. On top of the threaded rod a nut and a winged nut are welded. These are spaced sufficiently far apart so that the little plate will just fit between them. The little plate is screwed to the top of the rudderboard and hold the threaded rod in place. Now by turning the winged nut the whole foil is adjusted in its trim. The rod is by far long enough to bend a little inside the tube so it can align itself properly to the nut in the foil even when angled. The kick-up rod of the rudderboard can still pass over the winged nut and so there is no interference with that mechanisme. Actually the rod will most likely act as a security against the wingnut/rod getting "undone". Nice double function of the rod !

A single turn of the winged nut will adjust the angle of attack of the foil by about 1 degree. Meaning that when you using half turns you get a range of 8 settings covering 0 to 4 degrees of trim. 16 if you count trimming the foil the other way as well.

How to beach and land ?

You simply unlock the rod of the kick-up system and turn the winged nut till the rod is detached of the foil. The foil will as a result have a couple of degrees upward trim. It will try to lift the sterns a little, but that is acceptable as you will be sitting far back on the boat with relaxed sails anyway when you get in through the surf. The foil is now free to rotate its trailing egde downward. The rudder stays down due to friction in it housing. You sail through the big breakers and at the first sandbar the rudder is un-jammed of its stock, the rudder will move back and up and the T-foil will automatically align itself to the flow of the water. As the axis is back from the leading edge the foil will also move clear of the rudders leading edge and thus prevent the foils from scrapping along the bottom.

When going out this procedure is covered in reverse.

During sailing the trim can be adjusted by quickly unlocking the kick-up rod (but leaving the rudderboard itself down) and turning the winged nut. This can easily be done between races. For long distance races with very long downwind legs, this can also be done. You take a 15 seconds hit but recover that on the way down.

I would prototype this setup using Catamaranparts rudders myself but I'm too much strapped for cash (when is that going to end ?) and so anybody may run with this and tell us all on the forum how it works. I'm seriously considering it for when I have play money again myself. I really do believe it will work well.

Wouter