New rudders for the Banshee

[Banshee36]

Finally got around to getting new rudders for my rig. The originals I think were a bit on the small side for the re-power. Our local OC diver made these for me out of SS. I cannot wait to run the boat, perhaps now my autopilot will keep a straighter course.

 

[Mike36c]

Wow, I bet she will turn on a dime now. Post the trial run results and I might be interested in your old rudders for spares. Mike

 

[REBrueckner]

Great photos..the new look great. Good luck with all!!!!

Were the (more square_ bottom forward corners on your new rudders a conscious design change to add more area?? What's the blade area of old vs new and how did you choose the amount of increase...

I would have expected your autopilot to "learn" (during "setup" the rudder characteristics of your boat...Or is your autopilot an older model without that capability?

It will be interesting to see if you get a straighter course.....was that a problem only in waves or also in calm water? If the former, you may have to switch to a rate compass if not so equipped. My Simrad Robertson doesn't track all that well in big seas, but I always steer by hand in those conditions anyway...but nowhere near your speeds...so I never upgraded to a rate compass which all reports say tracks much better in big seas....

 

[Banshee36]

I will post my results when I sea trial her. I will splash her tomorrow and then motor her home to the slip, its a short slip.
These rudders are Branch's design. If you notice the top forward part of the rudder is parallel to the hull, supposedly this is in clean water and hill have the ferrarri effect on turning at cruise, meaning hold on!!! The overall width is the same as the old rudder then it tapers to just past the center of the shaft.

My probelm with the AP , was that the STB rudder was bent about 2 inches to the port, plus the fact that I never could get the electronics gurus to dial itin right. That will happen in the next week, it should track spot on with these babies.
JW

 

[REBrueckner]

The "ferrari" effect sounds like more than a few square inches of area can deliver, but then what I know about rudder design is even less than what I know about most subjects. But the deeper foot will certainly turn you faster.

I am now confused about one subject: As boat speed increases effects of turning due to faster passage of water... momentum....also increases...so needing larger rudders at higher speeds seems odd... Slow trawlers, and displacement hulls for example, routinely have "barn door" rudders due to limited volume of passing water.

 

[Banshee36]

I think the small original rudders were fine when the boat was 16kts cruise. I really wanted a longer rudder rather a wider rudder. I really wanted the 31 bertram oversize rudder, but too much of a PITA to change everything over. The new rudders are about 4 inches longer than the old one.
Any how I will see, should track great.
JW

 

[jim rosenthal]

JW, does this increase the loading on the rudder gear when turning at speed? I would think it does. I find my boat turns fine at speed, it's at lower speeds I wish I had bigger rudders.
You'll have to tell us if you can walk the boat sideways at low speeds with these; I have never been able to.