Rudder Servos

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Rudder Servos

Postby RRoush » Thu Jul 09, 2009 8:14 pm

What is the best rudder servo product for the EC12?
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Postby Capt. Flak » Fri Jul 10, 2009 10:08 am

Well I like the Futaba S3802. It has more torque than you need for any wind and the slower speed feels more like a big boat and prevents over steering the boat. It is still fast enough to get you out of trouble, but I think Gerhard Kelter will tell you otherwise.

If you have been sailing with a fast rudder servo, it takes a little getting used to. Of the 8-10 guys I have talked into using it, only one (that I know) has gone back to a faster servo. That was John Bottensek.

It is also a good choice for a jib trim servo.

OK, now let's hear from all the guys out there who think I am nuts for using it. ...Gerhard?!?

Joe Walter #24
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Postby RRoush » Fri Jul 10, 2009 7:23 pm

I'm using the Futaba S3010 for the rudder and a Futaba S3802 for the
jib trim.

Does this sound about right?

Bob Roush #1938
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Postby RMDJBD » Fri Jul 10, 2009 9:02 pm

I use the Futaba s9351 for rudder and s3305 for jib trim. I also use the same on all boats I build.

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Postby The OZ » Sat Jul 11, 2009 10:05 am

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OK, to be different, I use a Futuba S9350 for rudder servo and a Futuba S3004 for jib trim. On rudder TX I sometimes use the Aileron D/R in the UP position to give me a faster rudder response, with a DX6 Spektrum radio. Dick Reinke EC12-1936
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Postby Bob Wells » Tue Jul 14, 2009 11:16 am

Ive just been researching what servos to purchase and Joes idea of a slow rudder servo caught me by surprise. To put some numbers to servo speed:
Slow = 0.56 sec/60 (very high-torque analogue)
Fast = 0.18-0.21/60 (high-torque analogue)
Fast = 0.10-0.13 sec/60 (high-torque digital)
Ive been away from EC-12s for awhile, but my experience from the 90s leads me to continue with the fast that Im familiar with. Fast servos in light air doesnt sound like a good thing? Im curious what the top finishers in the class chose for rudder speed?

Ive also read Rick Wests consistent recommendations on torque for rudder servos that Ill note below for reference:
1.) 100-140oz-in. in Ordering Sheet 2/8/07. (He used 100oz-in. in his 07 boat.)
2.) 133oz-in. in Heavy Weather section 2/19/02.
3.) 100-135 oz-in. in Rudder Servo Assembly 12/15/02.
My past experience suggests that this is high, but in Seattle it is mostly lighter wind. Control downwind in heavy weather is the test. Does anybody else want to weigh in here?

Bob Wells
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Postby Rick West » Tue Jul 14, 2009 10:59 pm

Hi Bob,
Good to hear you on this forum again.

I am still doing the same thing but the model numbers change. In O7 I canned Hitec analogeand went to the Futaba digital 9350. There were not a lot of choices with this brand in digital. This servo is 139 torque and .12 seconds at 6v.

Servo selections are more specific now because most of us have exponential control of the servo speed. Using this feature gives you both worlds; minute rudder input within 5 degrees deflection and emergency speed in one package. I would like to have had something slower than .12 but it was not significantly slower in the torque range desired.

To be honest, these servos are rarely needed during the season. I have gone all season with no B rig needed even for a few heats. However, a powerful rudder servo will extend the use of an A rig as the pressure ramps up. That and good windward heel control can push an A rig into 12mph where needed on a course that is not fully enveloped.

The EC12 is overpowered and unstable on a run in a fresh breeze. The leeward mark is a heart pumping maneuver. Control here is worth the servo.

I see no benefit to half second servos because of the exponential control.

From experience I found this servo could not handle 20+ air at the leeward mark with a B rig in NZL during the 2006 Worlds. Twice I could not turn left for the reaching leg and choose an immediate 270 to the right to be on my way. The rudder was losing but would go right a bit for the long way around. Hence, I do not feel that too much torque for the majority of the time is wasted. If you want to be in the top of the fleet, one needs to be prepared for all conditions including the extremes like the Worlds which could be anywhere like Charleston in the spring.

...94 [8D]
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Postby tag1945 » Wed Jul 15, 2009 5:58 am


Here is another servo that I have been using with good sucess:

SSV-9784HMG / Extra Torque Servo w/ Metal Gear

Weight: 53grams / 1.66oz.
Dimensions: 40.5 x 20 x 40.5 mm / 1.60 x 0.78 x 1.60 in.
Input Voltage: 3.6V ~ 6.0V
Torque At 4.8V: 11.8kg/cm , 158oz/in
Torque At 6.0V: 13.6kg/cm , 187 oz/in
Speed At 4.8V: 0.16sec / 60 deg at no load
Speed At 6.0V: 0.13sec / 60 deg at no load

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Postby EC1210 » Wed Feb 24, 2010 5:07 pm

Hi all, Just looking to see if anyone else has had this problem and can offer what to try next?

I brief background as follows:
Was getting a rudder twitch. and loss of control.
Changed the batteries, as was told at a regatta, maybe have a bad cell
changed the rudder servo
changed the receiver
changed the receiver location and antenna
changed the transmitter
changed the crystals.
checked the wire diagram as stated on page 8 of RMG manual
This weekend set the hull on the work bench and was ok, went to the Lake Sunday, got ready, hull in stand, batteries in and switch on, all was ok, until I went to the sail box. Once I touched the rig/sails and went near the boat, not touching the hull, just within a few feet the twitch would start. even had someone else hold the rig, to see if I was giving off a electric charge, or bad vibes.
Any help or advice you have would be helpful.
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Postby s vernon » Wed Feb 24, 2010 6:31 pm

If the radio is close to the boat the servo might twitch like mine does sometimes. If it does not twitch when the radio is farther away from the boat then you do not have a problem. If it does then you do have a problem. At least that is something to consider.


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Postby Doug Wotring » Wed Feb 24, 2010 7:26 pm

I have been using GWS servos for several year without a failure.

and as a bonus they were about 1/2 the cost of a Futaba or hightec at the time I bought them
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Postby EC1210 » Wed Feb 24, 2010 8:02 pm

Thanks, I tried, doesn't make a difference<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by s vernon</i>

If the radio is close to the boat the servo might twitch like mine does sometimes. If it does not twitch when the radio is farther away from the boat then you do not have a problem. If it does then you do have a problem. At least that is something to consider.


<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
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Postby Chuck Luscomb » Wed Feb 24, 2010 8:11 pm

Hi Earl,

Sounds like you are using an AM or FM radio. If so, it is possible to have conflict with another radio at the pond on a different channel. We discovered in the 914 class that if two radios were 23 channels apart, they could interefere with each other. Check what channel you are on, add and subtract 23 channels and see if anyone is on either one or both of those channels at your pond. If so, that may be the problem. Also, it does not matter if the other person is on AM or FM(75mhz). You could also try changing crystals/channels on your radio to see if you have any changes.

Hope this helps,

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Postby EC1210 » Wed Feb 24, 2010 8:24 pm

Has done the same at two different Lakes, and at home in my workshop with no other known radio within miles.
Thanks anyway, will keep trying
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