A few years ago I got into the habit of locking down the windward rudder to the up position. On my G-Cat the rudder in the up position is at a higher angle than horizontal so waves don't hit it. It has lighter helm feel, less drag and makes alignment issues moot. I've noticed I'm the only one around that does this. I know there must be a down side, but what is it?
Downside is the time spent raising and lowering the windward rudder. IME, it isn't worth it for shorter Windward-Leeward races. Likely worth it in a longer race. If you notice a change in helm feel, it is worth verifying the blades are aligned and the blade rake within the cassette is the same side to side.
The more modern boats don’t seem to do this, but Hobie racers do it all the time for the reasons you mentioned. If your boat has really efficient, low drag blades, raising and lowering them on each tack probably isn’t necessary.
The downside upwind is that tacking can be quite difficult because you need to add locking down and raising tbe rudders to the tacking process - it makes it much more likely to blow the tack. Also, if you’re pushing the boat really hard (example, if you’re trying to pinch high upwind), the extra load on a single rudder can actually cause it to stall out. If this happens, you have to ease off the mainsheet and bear off far to reattach flow. In a race that will cost you a lot of distance.
Downwind, there’s basically no downside since raising and lowering the rudders doesn’t really hamper the jibing process. The only time we tend to leave both down is when it’s quite windy so drag isn’t really an issue and the main focus is on maintaining control.
I've run some distance races with one rudder and to me the helm feels sloppy. I have found the weight of the raised rudder puts a weird feel on the helm. I have not found flopping to the back of the boat getting the rudder up and down was worth it. I have worked away from people who fiddled with their rudders. It's a personal preference. It would be interesting to run some vmg numbers to see the benefit.
Prindle 18-2 Mod "FrankenKitty"
Tornado Classic "Fast Furniture"
Prindle 19 "Mr. Wiggly" - gone
Nacra 5.8 "De ja vu"
Tornadoes (Reg White)
if your tow in and other angles isn 't spot on, on a g-cat with the hull shape you are probably more efficient with one up.
g-cats (stock) come with a plastic snap that holds your rudder up or down - this is kinda unique in the beach cat class and works well until it breaks (cracks)
some other cats have a notch in the castings that holds the rudder up. this is not very secure and often i will have a rudder drop and drag on the water surface from that "up" position. that is certainly not fast and if you need to steer sharply/quickly - that can cause issues
Edited by MN3 on Dec 09, 2020 - 10:06 AM.
The olympic tornado class explored this decades ago, and found that raising one rudder only helped if your rudders were already problematic from mis-alignment, etc. They found no benefit to eliminating one finely tuned rudder's influence on the water, and it's use fell out of practice across the class.
They did document the advantage to bringing up dagger/centerboards to half profile when sailing off wind, providing the drift (side slip) was advantageous to your destination.
Prindle 18-2 #244 "Wakizashi"
Prindle 16 #3690 "Pegasus" Sold (sigh)
AZ Multihull Fleet 42 member
(Way) Past Commodore of Prindle Fleet 14
Its an old "trick" especially for low wind conditions. Dart 18 sailors are especially aware of this advantage since rudders are hallow and designed to take in water which helps keep them down/ and therefore provide stability allowing skegs and weighted down with water&very secure(system far superior to eg prindle 16,P18, which will pop up in seaweed conditions and require constant adjustment and replacement of springs,etc) rudders obviate necessity for daggers , but of course adds weight & slows boat speed. Dart sailors with our very small square footage of sail will sail "one up" until wind exceeds 10 ks. Also Dart 18 rudder very fast to raise and lower even when single handing cat; But i used same 1 up procedure when sailing my P16s ,H16s,H18,N5.2,N.5 N5.7 & N570, even sailing in the ocean where the waves/rollers are larger. I also went 1 up when i surfed P16s, h14(in Hawaii)H16&H18S on to the beach while flying a hull while surfing in & as a precaution since at worst you could only "snap off"/lose one instead of 2 rudders(P16s rudders popped up so u you probably wouldnt lose one). one other observation , when towing at higher speeds 2 down creates more stability and cats are very stable when towed even, at 20mph with 2 down