Futaba 2.4 Ghz SAILBOAT winch problems? Solutions? - Page 3 - RC Groups
Thread Tools
Aug 10, 2017, 09:29 PM
Registered User
As you have found using a 4 cell alkaline pack ie 6v is quite sufficient to power your yacht. Using 5 x NiMh batteries will give you a nominal 6V. A NiMh cell straight off the charger will have a voltage of approx. 1.25V. The recommended minimum is 1V. So for a 5 cell pack you have a nominal range of 5V to 6.25V. Assuming you bought some decent mA rated batteries you should get hours of sailing out of them. If the Rx voltage telemetry has a low volt alarm set it to 5V and you will have plenty of battery reserve to get back to shore from way out.

If the 2.4G system looses transmission between Tx and Rx they take a short time to reconnect unlike am sets which were instant. This is where fail safe can work for you.

Running any Rx/Servo combination on less than 4.5V is asking for trouble. As was pointed out previously the instantaneous current draw of a winch servo under load can be amps which will cause the voltage to drop to below what the minimum voltage for the Rx. This would lose your transmission link and by the time it re-establishes your servo could have done anything. Not sure if fail safe works in low volt condition its mainly designed for loss of transmission I understood.
Sign up now
to remove ads between posts
Aug 10, 2017, 10:03 PM
Registered User
Tugboat 2011,

Sounds great. Best news I have had all day. Fail safe is set up now as well as RX telemetry to report RX battery voltage! I have to confess right here that I did not know for sure if this Futaba 6TK was really a telemetry ready radio as delivered to me, but after I read all the 159 pages of the manual it turns out that it is. So now I have rcvr battery voltage displayed right on the TX screen as well as a fail safe system and voltage minimums will set off alarms in the TX. Really quite a radio if it works in practice.

As an option you can purchase an upgrade rcvr and another adapter accessory cable and get the option to monitor the winch battery as well. I don't think this is really needed, but it would be a nice option to have. Sometimes you can make it back on rudder only if the wind is right. (should sail into the wind going outbound anyway)

I don't know if too many skippers go that two battery route or they have an on board voltage regulator and just run off of one battery? Are you an IOM guy or a sail boat racer?

I was put "into that boat" by the winch servo having to have it's very own voltage source.
The heavy duty servo is pulling too many amps under load to be powered thru the rcvr, so it has it's own source by default.
Aug 10, 2017, 10:26 PM
Registered User
I am just a casual sailor and have yachts from 600 -1800mm. Don't have an IOM as such but do have some with HD winches. I would think most skippers only use one battery. The Rx as such does not actually switch any current. The battery plugs into the Rx as do the servos. All the +ve pins are commoned together as are the -ve pins on the Rx circuit board. This allows the servos to be powered with easy plugin wiring. ie the power from the battery is fed directly to the servos through the Rx pins. The only out puts on the Rx that are individual are the signal pins.

On one of my yachts I use a winch servo that is rated as 7.4V so I use a single battery NiMh 6 pack (7.2V) and use a BEC to power Rx and rudder servo.

The really good HD winches like RMG only use a single battery pack on board.

But you are the skipper and what ever works for you is the best way to go for yourself.
Aug 10, 2017, 10:48 PM
Registered User
That BEC may be an option for me If I get into racing a bit. The one battery pack would save about 110 grams off the total weight. The IOMs are rated for 4Kgs minimum and most of the home built boats are closer to 4.5Kgs so if you are racing against a factory boat it makes it kind of tough. But I dont know if a single battery pack would last for a whole race or just how long it would last. The batteries I bought are rated at 6 Volts and 2300Mah which should be plenty, but who knows? I don't think you can bank on getting 2300 Mah out of 5 cells of anything that small, but it might work.

The old Nicad rcvr battery pack that is on it's last legs is rated at 800 Mah and 4.8 volts, so 23oo ought to outperform it by quite a margin. maybe it would last a couple of hours if I could get the boat to track in a straight line! LOL!
Aug 11, 2017, 12:20 AM
Registered User
I looked up the Hitek Hs 785HB and it is lighter and smaller than the Futaba, but much slower.

I'ts listed as 60 degrees per 1.68 seconds at 4.8Volts or 6 times that long for a full revolution which is 10 seconds and one full rev gives you 4.3 inches of string in 10 seconds. So it's too slow for a 1:1 situation. Torque is 152 in/oz at 4.8v and 183 in oz at 6 v.

The futaba is 8.8 oz of weight, but it pulls 21.8" in 3.8 seconds at 122.3 in/oz at the same 4.8 volts. So thats about five times more string in i/3rd of the time.
Aug 11, 2017, 01:51 AM
Registered User
Under test the Hitec HS-785HB gave me these results at 6V.

500gm constant load

76mm/sec (6.7sec for total rotation)

Stall load was 6.3kg at 1.6A.

Not the fastest out there but a reasonable winch though. And you normally would not need the full rotation as it is too much line for most yachts so time would reduce depending on % reduction.
Aug 11, 2017, 03:57 AM
Registered User
Any circuit designed to behave in a set way for a specific range of voltages can reasonably be expected to behave differently outside those limits. It is generally forgotten that in the transmitter, receiver and servo, however "digital" they claim to be, there are analogue components that rely on voltage that is both within limits and stable. This is to create the timing pulses that the servo or speed controller uses to figure out what position it should be in.
Going over the voltage limits lets the magic smoke out. Going below the minimum results in either no, or unpredictable, action. A battery, not in good condition, running at or very near the lower limit, might, under a varying load, have brief excursions below the limit, shifting the reference points that everything relies on. The electronic bits are usually based around CMOS technology, and three and a bit volts was, and probably still is, the lower limit.
I am used to running on a nominal 4.8 volts of NiMHs, so normally sluggish action is the sign that voltage is getting low. Time to return to base.
I have seen that there are receiving end systems (receivers, servos etc) that work on a 1S Lipo, about 3.7 volts, but usually a Lipo system incorporates a vow voltage alarm. I suspect that the 3.2 volts mentioned is around or below that.
Aug 11, 2017, 09:17 AM
Registered User
The ones I have looked at have had 3.3V regulators. So your minimum voltage has to be about 0.6v above that for it to maintain regulation. Anything below 4V is asking for trouble. As I suggested I would use 5V as the minimum on a 5 cell pack. This gives you most of the pack and the last % of the pack the voltage drops fairly rapidly. A 2000mA pack will give you hours of sailing with a 1m yacht. If you require more up the capacity of the pack or buy a second one.
Aug 11, 2017, 10:49 AM
a.k.a. Bob Parks
My DF95 uses a 700 LiFe and I can get five hours of sailing easily, with plenty left over, usually putting in about 480mah.
My Seawind has a 1200 LiFe and lasts a full day.

BP


Quote:
Originally Posted by Tillerman6
That BEC may be an option for me If I get into racing a bit. The one battery pack would save about 110 grams off the total weight. The IOMs are rated for 4Kgs minimum and most of the home built boats are closer to 4.5Kgs so if you are racing against a factory boat it makes it kind of tough. But I dont know if a single battery pack would last for a whole race or just how long it would last. The batteries I bought are rated at 6 Volts and 2300Mah which should be plenty, but who knows? I don't think you can bank on getting 2300 Mah out of 5 cells of anything that small, but it might work.

The old Nicad rcvr battery pack that is on it's last legs is rated at 800 Mah and 4.8 volts, so 23oo ought to outperform it by quite a margin. maybe it would last a couple of hours if I could get the boat to track in a straight line! LOL!
Aug 11, 2017, 11:24 AM
Big Boats Rule!
boater_dave's Avatar
Really large winches may have separate power supplies. Most boats, certainly in the 1M range, use just one pack. Hooked up to the winch and then back feed the rx possibly, but still only one pack. I like the LiFE packs because you can charge them way in advance of use and they hold their charge. That solved my problem of wanting to sail during a short break in working around the house, but having to charge batteries for a half hour first. My 54" Frer has a Robotzone servo powered winch and I can sail for hours on 2400mah. That's 1300 sq in's of sail area (same as an EC-12). A 1M only has about 600 sq in's.
Look in the threads for all the current 1M setups. I bet they are split between drums and arms. Arms are faster, drums are more powerful. RMG's ($$$) at the top level. Your S10 is a bit of a dinosaur. Even more so if it requires special power.

Dave
Aug 11, 2017, 11:27 AM
Registered User
The math I did was at midnight and I wasn't all there, but for 6 volts the specs say 1.38 seconds for 60 degrees of rotation. That makes a full revolution 1.38 times 6 or 8.28 seconds. The spool they supply is a 1 3/8" diameter giving 4.3 inches of line travel in 8.28 seconds. On my boat the line needs to move 9 1/2 inches full in to full out, so I would need 2.2 revolutions which would take 18.3 seconds to complete. That would be pretty slow at the down wind mark if you were racing. I could get my full sized Tornado to round the mark much faster than that and I'm an old geezer.

My Futaba winch (I'm not bragging or anything like that) goes from full out to full in in about 4 seconds. Of course it cost over a hundred bucks and it weighs 8.8 ounces and is twice as big, and they don't make them any more, but there you go.
Aug 11, 2017, 05:55 PM
Registered User
Dave,

Yes, I would have to think you are right about the larger winches. The Futaba 110 is a bit oversized for the IOM, but I already burned up two smaller Futaba winches in the same boat, and this one has lived thru it all, so yes, it's an antique, but I can't find anything in my price range to replace it or do any better. With the width of the hull there isn't much room for a sail arm winch, I have to pull at least 9" of string full out to full in, so I don't know of an arm winch with that kind of range that will fit inside a hull that is only 7" wide at the widest point. In addition, there is already a push rod going back to the rudder, so that too cuts down on the available space for an arm type winch.

I suppose it would be possible to do a 2:1 reverse leverage situation and put a pulley on the end of the arm winch. That might give enough travel, but then the servo would have to have some real torque available to make it work properly.

I'm just a little tempted to try and build something from scratch. Maybe some kind of linear actuator if it could be made light enough. that would be the kicker.

How do I find in the threads people talking about the IOM's and winch types they are using?

Thanks for your insight, and glad you joined the thread here!
Aug 11, 2017, 06:54 PM
Registered User
Crunchy Frog's Avatar
I use an arm winch on my IOM. It's setup at 1-2 ratio, so pulls double the arm length. I use a Hitec HS-7954 SH. It's blindingly fast, and has gobs of torque. The only challenge is that, with an arm winch, you usually have a bungy-return-cord, and so you are always pulling. This means the servo will eventually slowly eat itself.

I used to buy a new one every year. However, in my new boat I set it up so that, when fully sheeted, the sheets run straight across the centre of rotation to the end of the arm. That way the load is down the arm, and it doesn't load up the servo as much. With this setup I'm on my 3rd year with the same servo.
Aug 11, 2017, 07:12 PM
Registered User
Crunchy Frog,

That is interesting. Could you do away with the bungee cord if you ran an endless loop of line for the traveling part of the sheeting? That is what I am doing with my winch setup. I have a U shaped track on the foredeck and I also keep a loop of bungee to tension the loop when I need to work on the servo or re-calibrate the drum starting point (which is way too often) That way the servo is not fighting with any one way bungee tension, and the bungee is only there to assist with the loop tension which is balanced and controlled by sliding a pulley in the fore deck track until it is tight enough. then you cinch it in place with the pulley hardware and your loop is ready to rock.
Aug 11, 2017, 07:20 PM
Registered User
That servo is selling for about $100.00 which is an improvement to the RMG winches for sure.
Did you have to buy the programming gear as well to get it to behave in the boat? And do you have any pictures of the installation? The 330 In / oz torque is at the end of the arm? Or at the output shaft? What voltage are you running? and any Voltage regulator?

And only the one battery in the boat? and how is the battery compartment set up?


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Massiv Problems with Corona 2,4 GHz Futaba Modules Rudi HobbyKing 1 Nov 15, 2015 07:15 AM
Discussion Older radio converted to Futaba 2.4 GHz - ESC and servo reverse problem bossee Radios 14 Feb 14, 2012 04:03 PM
Discussion 2.4 Ghz Futaba FASST with 2.4 Ghz Video Transmission BlizzardWhite FPV Talk 17 Nov 06, 2011 12:19 PM
Help! Problem : Phoenix RC and Futaba T12FG 2.4 Ghz not working Solal Simulators 11 Nov 30, 2008 04:36 PM
Discussion Spektrum DX7 2.4 ghz or Futaba 7C 2.4 ghz? Da Kine Batteries and Chargers 1 Nov 16, 2008 09:55 PM