I have not done the numbers, but the answer is not much weight or cost. Probably less than the weight of the beam mounted rudder which was pretty heavy for a variety of reasons. On my Sol (single beam), the rudder is mounted on a 100mm/4" dia fibreglass stub beam which sits on the deck, which I think is a better solution than the horizontal flanges as it allows the rudder to kick up in both directions, and a shaft rudder to be used. Also allows it to be supported fore and aft.
<<If this was raised, the loads go up, so the spray is a tradeoff with strength and weight. >>This brings up a question that's been brewing in my mind for a little while now: very roughly, how much weight and expense would this involve when raising the rudder box up, say, half a meter?
Is it another $100 of carbon and 5 kg per rudder? Another $500 and 10 kg per rudder? Is the issue not as much in reinforcing the rudder as in reinforcing the attachment point?
I'm just curious. I know that increasing the height increases the forces, which increases expense and weight. I'm just trying to get a ballpark feel for how much. Perhaps visionarry-strength rudders and supports on a harry-size proa wouldn't be that bad. Or maybe it's worse than that.
- Mike
Rob Denney wrote:Excellent advice, Carlos, and I intend to do just that at some stage. At the moment, though, I am just really pleased that the boat is working and that Henny, Nol and co are making the videos for us all to watch, warts and all. A person (or 2) lying in the bunks and 6 or so sitting in the cockpit would be great, if you get the opportunity.
Herb,The rudder spray is mostly off the reinforcing on the sides of the rudder box. This could be filled in with foam and glassed, or 2 pieces of ply could be joined at the leading edge and folded around the box to fair it. There is also some spray from the horizontal bracket which is close to the water surface. If this was raised, the loads go up, so the spray is a tradeoff with strength and weight.
rob