Rudder camber/cant ?

One of those days where I can't work on 'time on the water' and I was letting my mind drift a minute.. Watching Volvo 70 boats... you know just one of those things.


So when measuring the toe in the other day I happened to notice that they measure about an inch or so wider at tip of the rudder than they do at the head of the rudder. on the trailing edge.

I imagine withing just the manufacturing tolerances of the various parts their could be a small range of 'adjustment'.

Is there any advantage to running a little 'negative' camber, or is the goal to have them as parallel as possible?

I can't recall ever hearing anyone discuss this. probably because within the range of adjustment there ain't much to be had.. but still?

They need to be parallel to no more than 1/4" toe in for best performance. We set them at about 1/8" toe in. What model boat? Most have adjustable tiller crossbar lengths. Wave and Getaway do not, but maybe a tiller arm is bent.

_________________
Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)

I think the OP is referring to parallel in the vertical axis. I.e., how close to “plumb” should the rudders be if the boat is sitting level side to side?

sm

_________________
Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)

hmmmm rudder camber. Maybe? it's complicated? Sometimes?

More negative camber would...
reduce vertical lift
increase lateral resistance (very slightly)
Reduce the rudders tendency to pitch the bows down when falling off/coming away from the wind.
Reduce the rudders tendency to pitch the bows up when coming into the wind. A couple of times I have dug my bow free by steering hard into the wind. This only works if you are heeling a lot.

Weighing everything out, I suspect there isn't an advantage. When sailed at their best, cats don't heel much. Monohulls heel enough to make it worthwhile to add cambered rudders.

Ahh.. yeah.

Now I see... he was looking at Toe and then saw the vertical difference.

_________________
Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)