Rudder depth

[Niantic Mike]

My situation:

My slip is very shallow so when I come back to dock, I usually need to use my motor to steer which is difficult due to the boom gallows.

Are there any replacement rudders that don't extend below the keel?

Or, is "shortening" the rudder by cutting it back an option?

[bruce]

One of the nice features of the Com-Pac catboats is the use of a high aspect rudder (long and narrow) compared to the low aspect barn door rudders typically found on catboats (short and wide). The barn door rudders display significantly more weather helm.

Before replacing your rudder, I would experiment with bringing your rudder up some, with the existing uphaul and pivot clamp annoyingly located underwater, enough to be usable. The rudder won't feel right, mushy is how I'd describe it, but it will allow you to steer. If the rudder in its partially deployed state is OK, then I'd look at ways of locking the rudder angle that are more convenient to do from the cockpit.

Here's a photo of what I did on my PC. Eventually I foiled the rudder too, but earlier versions were done with just the stock blade as shown in the link. I wasn't having problems with water depth, I just wanted a better system for raising the rudder.
https://cpyoa.com/forum/index.php?topic=11630.msg87413#msg87413

[Niantic Mike]

Thanks Bruce! Is your rudder cut? Looks significantly shorter than mine.

[bruce]

No, I used the same dimensions for the foiled rudder as the original aluminum plate.

This is on a Picnic Cat though, so apples and oranges. We don't have a stub keel, the CB trunk is flush with the hull, but the rudder does extend 16" deeper than the fully-retracted CB so in that way it's similar. The barn door rudder on a traditional catboat doesn't typically draw much more than the hull.

I would still try raising the rudder you have to see if that's a reasonable work around, before you start altering things or try to design a new rudder, which may not be as simple as you expect. I'm assuming you're able to sail with the rudder you have, it's just the shallow berth that's a problem, so some issues with rudder performance around the dock could be OK.

The stock rudder uphaul and tensioning pivot are similar on the two boats. A version of my system would work, but there are others ways to do it of course.

[Niantic Mike]

Ah you mean like having the rudder halfway up, so it's extended outward rather than down. I have tried that, it is ok but not very reactive at slow docking speeds

[bruce]

No, but no rudder is very effective at low speeds. The flow over the rudder is critical.

I'm all for experimentation. If you do want to try a shorter rudder, I'd encourage you to use new stock, aluminum or otherwise, and keep the stock rudder for comparison or restoring the original configuration if it doesn't work out. I've had good luck on eBay for King Starboard and aluminum in sizes I've needed at less than normal retail.

[Niantic Mike]

Good talk, thanks!