Futaba 2.4 Ghz SAILBOAT winch problems? Solutions? - RC Groups
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Aug 08, 2017, 11:01 PM
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Futaba 2.4 Ghz SAILBOAT winch problems? Solutions?


I am new to the 2.4 Ghz radios, but I just installed a new Futaba T6K system in my old Nimbus IOM. Prior to that it was a JR 622 FM system.

The FCC changed the rules a while back on the use of the 72Mhz frequency, and I decided to switch the boat to a legal freq being the good citizen that I am. I do live in a fairly remote area, but rules are rules. Anyway, The T6K radio has been a problem since day one. I am not sure if the problem is the 2.4 new receiver or the winch servo. The winch servo will all of a sudden take off on it's own and run the winch line in or out. Sometime this is with the transmitter sitting 10 feet away from me on the ground! Usually this is not all the way to the trim limit, but sometimes this too is exceeded.

The first time this happened was before I ever launched the boat, so it was no big deal. but with the winch servo running a spool of string, it did eventually hit the string dead end and tried to keep going. On this boat there is always the tape over all the hatches that has to be carefully removed and replaced whenever you have to access the winch servo. This is now about the 20th time I have had to remove the cover, and the whole process is getting pretty old.

At first, I associated this problem with low receiver voltage and have been troubleshooting with a freshly charged 4.8 Volt Nicd battery, but the problem re-occured today when the receiver battery was still up to 4.6 volts. I don't know if the receiver battery is getting "noisy" but it is several years old, and that is where I am going to try replacing it first.

I contacted Futaba, and they suggested that I should connect both the winch battery ground to the Rcvr battery ground. I did this mod today, but the symptoms just changed a bit to a situation where the winch will still take off without a command at random times, but it can now be "re-captured" by cycling the throttle stick all the way forward and back one time. The winch is happy again for a few minutes, and will then take off again for no reason.

The rudder seems to be un- affected by all of this, and the rudder servo is running off the rcvr power only, so I'm thinking that something may be wrong with the winch servo itself.

The winch servo is also Futaba and has it's own DC supply from 4 AA alkaline cells in series.

The Futaba literature seems to suggest that the new R3006 rcvr (2.4 Ghz) which came with the T6K is a "high voltage" rcvr ?? Any thoughts on any of this?

Also, my sailing area is within 1/2 mile of a cell phone tower and direct line of sight, so I don't know if this could be a factor or not, but when the 72Mhz radio was in the boat (temporarily) I never noticed that the winch servo would go crazy like it does now with the 2.4 Ghz rig. The rudder would occasionally flip a few times but self correct and never seemed to be much of a problem.

What am I doing wrong? Any suggestions?

Thanks in advance!


When the rcvr battery was at 3.4V, there was noticeable cross talk between the rudder and the throttle channels, and I had to re-spool the winch drum several times because of this.
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Aug 09, 2017, 02:15 AM
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Cell towers don't broadcast on 72MHz. They do use the 2G4 part of the radio spectrum.
I've had similar problems when the transmitter battery was getting a bit low and put it down to a temporary loss of signal followed by the receiver going through a fail "safe" condition and then going back to working properly when it gets a proper signal again.
Is the receiver aerial above deck? I can't see it in the picture. In theory, 2G4 is happy with it anywhere above the waterline if there is nothing to deflect or absorb the signal. In practice that means that if anything metallic is between the transmitter and receiver aerial, signal is interrupted.
Aug 09, 2017, 08:20 AM
Big Boats Rule!
boater_dave's Avatar
I'd bet the biggest issue is your 4 cell rx pack provides too low a voltage, even when fully charged. Get 5 cells, or a 2S LiFE pack and retest. The manual for your tx says voltage requirement for rx starts at 4.8 volts. Voltage will dip when the big sail servo has a load as well.

Aug 10, 2017, 01:14 AM
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Unfortunately the rcvr antennas (2 each) are below the deck. The deck is wood and tape, but the antennas for 2.4 are pretty short anyway. And they want to be at 90 degrees from each other which is a bit difficult in an IOM hull because they are about 6" long (each). I don't know if any of you guys have a sucessful plan or idea to get this to happen?

Right now I have stuffed the front end of the boat with packing "air bags" which are plastic bags filled with air in the event of a hull breach. I don't think this would mess with the rx signal, but who knows?

The thing is that the rudder always works unless the rx battery is at or below 3.2Volts and the Winch servo has it's own supply which has never been below 5.2V.


Seems as though most of the problem is only the winch servo but it must be RX related somehow. I ordered a 5 cell NiMH battery pack today and I will let you guys know if the extra voltage helps the situation or not. I think 6 volts would not do the servos any harm, and the side by side 5 cell NiMH packs will still fit into the battery "jar" .
Aug 10, 2017, 01:19 AM
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Also I could not figure out a way to put the short 2.4G antenna leads above the deck and not have them fouling something /getting we/ letting water in. The old 72Mhz system had an antenna about 3 ft long, so it was easy to snake it out the stern and up the back stay. Range = 1 mile ! but the TX would eat AA batteries up pretty fast. Also not legal now.
Aug 10, 2017, 03:37 AM
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If its a wood deck, just taping them to the underside will be fine. Or, since nobody can see it, a blob of Blu-Tak is probably easier to handle out of sight. As long as the aerials are above water, they should not be the problem. The very short "active" bit of the aerial wire is very easy to mask, as opposed to the long length of a 27/40/75MHz one. Hide an inch of one of them, nobody notices. Lose an inch off a 1" long one, it's all vanished.
Several years ago I got a second hand boat that sort of worked, but needed more power for the sail servo. I got a high torque type to replace it. Using this rapidly highlighted the need for a new battery. Then a new wiring harness. The increased demand found all of the weak links in rather rapid order.
Aug 10, 2017, 03:45 AM
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As stated try a new battery pack.

Swap the winch to another channel and see if the problem still exists. If the rudder channel works fine use that as a known. The winch maybe faulty. What type is it?

The 2.4G aerial is only the last approx. 30mm of bare wire at the end of the lead. The rest is just co-ax cable to allow you to position them. They don't need to be outside the hull/deck. just tape them up under the deck so they are above water level.

I have used small diameter plastic tubing to keep them in the correct orientation.

The voltage of the Rx is 3.5 to 8.4V so yes it is rated as HV. Most Rx are rated at 4.8 to 6V but newer ones are increasing the high voltage to suit LiPo's
Aug 10, 2017, 07:10 AM
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Should have added you cant just use a HV Rx by itself, you need to upgrade the servos to HV also unless you are going to run dual battery systems.
Aug 10, 2017, 09:56 AM
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Resurgam's Avatar
If possible, try plugging the winch into different receiver channel; if the problem goes away, then there's likely something wrong with the receiver.
Aug 10, 2017, 11:31 AM
a.k.a. Bob Parks
For the 2.4 antennae, only the 32mm on the end is the active part. The rest is shielded wire. Just keep them up near the deck and there should be no problem, unless you have a metal hulled boat!!

Aug 10, 2017, 11:34 AM
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Originally Posted by Resurgam
If possible, try plugging the winch into different receiver channel; if the problem goes away, then there's likely something wrong with the receiver.
I will try that today! The problem has been repeating pretty consistently as of late. Last time it happened I was all buttoned up and I wanted to show my in laws the boat really bad, so I changed the trim limits on the TX and that re-centered the winch drum position long enough to go sailing one more time, but I know it didn't fix anything.

If moving the winch servo lead on the receiver to another channel( or the rudder channel) does not show any glitches, (and this is a very good idea by the way) it does point to the receiver as the culprit.

I have not received the new batteries or the charger yet, but I rigged up some alkaline cells to test with.

Thanks for the suggestion!
Aug 10, 2017, 11:37 AM
a.k.a. Bob Parks
Do you have travel limits on the new tx?
Are they set to allow the winch to go too far out?

Aug 10, 2017, 11:39 AM
Registered User
I have to try one thing at a time, but I am learing a lot about 2.4 real fast. It's extremely new to me, so I guess there is going to be a steep learning curve associated with the new radio.

I didn't know that the antenna wires were just stripped off coax. If that is the case, then there is a possibility that the center lead is touching the metal braided sleeve or is intermittently touching it. I will take a much closer look today.

Thanks for the reply! I will let you all know what I find! The channel swap is the first test I guess.
Aug 10, 2017, 11:44 AM
Registered User
The travel limits were too far out at first, but then I figured out how they work in relation to the throttle stick position. After that they were set to 50 -50 with the correct "close haul" position being where the stick was all the way down. The total travel is about 6" overall.

And FYI you can still re calibrate "on the fly" if you have to just to get the string close hauled positon back to "normal" even if the throttle position limits are something other than 50-50.

The only other way is to use the digital trim or remove the winch servo hatch tape and physically re-calibrate the close haul position manually.
Aug 10, 2017, 11:54 AM
Registered User
I am running dual battery systems right now.

Cost- These winch servos can run into the hundreds of dollars even if they are not HV versions. So I am hoping that this one is still OK.

Availability - I don't know if there is even any HV winch servo version available anywhere? Futaba is not making this winch ( FP-S 110) any more, and I don't think they make a HV winch servo either. There are HV servos yes, but they are not Winch servos which is a breed all of it's own as you may know.

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