NEW RUDDERS

Post your photos of Repairs and/or Outfitting projects

NEW RUDDERS

Postby GB42-267 » Tue Apr 07, 2015 3:49 pm

I have been dissatisfied with my rudder response or lack thereof during low speed and docking performance for quite some time. I designed a set of larger balanced rudders a few years ago, but never got around to actually make them since it was so far down the list to really seriously consider going forward with it. For some reason, this project made its way to the top of the list earlier this year. I was actually working on the installation of a new auto pilot and I believe this revitalized my desire for new rudders.
The new design gives approximately 40% larger rudder surface than the original ones and are balanced for less stress during hard turns at higher speed. Once I have these mounted I should notice an improvement in low speed and rudder response during maneuvering. Since I can do only approximately 9 KN or so over water at full speed, they will not cause excessive stress on the steering or be too responsive to cause problems (I have no desire to repower for more speed :) ).
The new rudders are made from 316 Stainless Steel and the shaft split and flanged for easy removal without having to disconnecting the tiller arms. The flange has a machined register and doesn’t solely rely on the bolts for rudder stock alignment. I still have to cut the upper shaft to size and machine the keyway, but that will have to wait till next haulout when I will mount them.
I will post an update after they are installed and tuned in, but that will have to wait till later this summer.

I'm more than happy to share the full dimensioned drawing if anyone is interested and have access to AutoCad.
Bjorn M
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Postby Bob Lowe » Tue Apr 07, 2015 5:58 pm

Very nice, Bjorn! Looks good!

Please keep us up to date with installation and performance, photos and all. :)
Good luck,
Bob Lowe
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Postby Stretch Head » Fri Apr 10, 2015 8:46 am

What a great idea. Mine have been a problem for too long but when I changed the shaft log I bought some time. I will watch for your updates.
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Postby Keith Morris » Fri Apr 10, 2015 10:03 am

I have a question. The leading edge of the stock rudder is swept back. The only reason I can think of for this is to help seaweed, stray lines or debris from getting hung up on the rudder. If that's the reason, is it worth the effort to do the same with the new rudders or is it really going to matter?
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Postby GB42-267 » Sat Apr 11, 2015 4:45 pm

I have a question. The leading edge of the stock rudder is swept back. The only reason I can think of for this is to help seaweed, stray lines or debris from getting hung up on the rudder. If that's the reason, is it worth the effort to do the same with the new rudders or is it really going to matter?
Having a curved edge will probably aid in dislodging weeds or other flotsam that may get picked up, but in reality it doesn't matter since the prop wash will disperse it anyway. actually, a wide upper and a narrow lower part will reduce the rudder efficiency. The most effective part of a rudder is the lower 35% and for optimum performance it would be of benefit to have it wider on the bottom than the top.
an even more effective design would be an articulating trailing edge. This is most beneficiary during maneuvering and especially noticeable in a single screw, single rudder configuration. One can also add a center rudder or flanking rudders to improve maneuverability, which is quite common in older tugs. I'm just looking for some improved performance and if I can improve slow speed maneuvering by 20% - 30%, I'll be happy. I'm quite sure I will notice an improvement, but since I don't have access to model testing, I went by some general rules of thumb. The only way I will know is to install at next haul out later this year and give them a real test.
I realize this is not an exact science and only an approximation, but all elements of naval architecture is based on compromises and approximations. I wanted a simple palmed rudder design with easy installation and the possibility to remove the rudder blade when needed for shaft extraction.
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Postby Keith Morris » Sat Apr 11, 2015 8:42 pm

Thanks for the response. Appreciate it
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ss rudder

Postby andy vouras » Tue Nov 17, 2015 6:38 pm

My gb42 came with new ss rudders.
I read some articles that said that it should not be painted at all, even with bottom paint.
They indicated that sealing the ss will cause it to lose some surface oxidation that helps prevent corrosion. My plan was to put bottom paint on them just as I painted my trim tabs with no bad effects.
What do you think?
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Postby GB42-267 » Tue Nov 17, 2015 7:06 pm

I read some articles that said that it should not be painted at all, even with bottom paint.
They indicated that sealing the ss will cause it to lose some surface oxidation that helps prevent corrosion.
This is true for Aluminum and Stainless which needs exposure to oxygen to develop a protective layer of oxidation to prevent corrosion. This is the total opposite to regular carbon steel which needs to be painted or otherwise coated to protect it from corrosion.
However, I coated the rudders with AF in order to protect them from being a breeding surface for barnacles and mussels (these buggers loves bare steel, your shafts are prime examples of this). There is really no concern for corrosion since they are plainly visible and any corrosion problem is easily detectable and in plain view. I am more concerned with the rudder shafts being exposed to crevice corrosion since they are exposed to stagnant oxygen starved seawater.
I have a 1/4" of reinforced solid 316 SS plate rudder blades and I'm not too concerned of having them waste away anytime soon. The 4 bolts holding the rudder blades to the rudder stocks are 16mm 4 x 316 SS and they will have to be pulled for inspection once every 5 years or so and inspected for crevice corrosion since they are partially hidden and are suspect to corrosion.
I'm sure there are several different opinions on this subject and until I'm proven wrong, this is my take on it. :wink:
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Re: NEW RUDDERS

Postby Mike Massingill » Wed Jul 03, 2019 9:23 pm

Have you installed the new rudders yet?
I am thinking the same thing, but I want to go Articulating for extra maneuverability.
Did you consider this?
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Re: NEW RUDDERS

Postby GB42-267 » Thu Jul 04, 2019 12:39 pm

Yes, I installed them a few years ago and I’m very happy with the result. Since I have twin engines, I still use the engines as a primary means of docking. Articulating rudders would have added to the complexity of the whole setup, but If I had a single engine, I would definitely have considered an articulated rudder design.
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