Tell me about T foil rudders.

Originally posted by Daniel Holman Yes you have to be chest deep and holding the boat singlehandedly into a big shore dump to slot the tfoil in from underneath.

Yes, If the rudder blade and the foil are a unit construction, but what if the horizontal foil were part of the gantry and fixed to a forward only direction?

Originally posted by iGRF Originally posted by Peaky Foils at the bow, like canards, are destabilising. if the bow lifts it will continue to lift, and if the bow goes down it will continue to go down. Makes you wonder how submarines ever surface when they reverse the bow plane?

because submarines surfacing or diving is only marginally impacted by the attitude of their external fins and a lot more about bouyancy....

Originally posted by Daniel Holman Yes you have to be chest deep and holding the boat singlehandedly into a big shore dump to slot the tfoil in from underneath.

I first remember T foils appearing in moths. some of the later Magnum designs. These I think were fixed to try and reduce nose diving. I remember Simon Nelson trying a moth one on a N12 back then.
I think there is a big difference between N12 and I14 use of T foils. On the DCB we tended to have it switched on almost all the time. It did control pitch very well and you could induce a bow up position especially to get the nose over small waves before then going for more lift for a faster more level planing mode. This reacted very much in the same way as outboard trim on a RIB.
Once going it was just a case of sitting as close to the rudder a you could. As a result we moved back earlier. The boats with less rocker would need to back off of they had a nose diving tendency.
The dihedral swept back and up foil induced stability in a similar way to light aircraft. It also reduced the weed issues as a wiggle got rid of any. The N12 foils are set closer to the surface than I14, and I think at lower speeds the stern wave effect is important.
We rarely got to the point we needed to back off on the foil, which is not what I hear from I14 sailors who with greater speed can generate more lift. I wonder if the t foil reduces the extreme wheelies you see in 18’s
To get an idea of loads we were breaking fittings with about 500kg rating and the ones we ended up with were about double that.
We certainly got on the plane earlier and got longer than non t foils. It also allowed heaviier teams to be a little more competitive.

Andy

Originally posted by iGRF Originally posted by Peaky Foils at the bow, like canards, are destabilising. if the bow lifts it will continue to lift, and if the bow goes down it will continue to go down. Makes you wonder how submarines ever surface when they reverse the bow plane?

Could give a long answer to that, but this ain't the place!