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-   -   Arm vs. Drum - sorta (https://www.rcuniverse.com/forum/rc-sailboats-89/874975-arm-vs-drum-sorta.html)

RobStagis 06-18-2003 06:53 PM

Arm vs. Drum - sorta
Arm winches work well, though now we're entering the realm of probably the oldest debate in R/C yachting :). You either need less friction - or more power :)

My first boat, a Victoria, came with (from the guy I bought it from) a Futaba FPS25 arm winch. It's a stout, though old, servo. I go sailing, right? And the danged thing wouldn't pull the sails in. Huh, says I. That's a pretty strong servo.

I installed blocks in the arm (instead of the metal ring) and the back of the cockpit. I replaced the blue string with spyderwire. Much better. Then I installed a block on deck at the jib sheet and separated the sheets, though still using a single-sided arm. Better yet.

Then I installed a 5-cell battery. All fixed. This wasn't a major project - just a scratching the head while sailing project, and every change improved the boat.

Talk to me about the Dumas 3701 arm:) I just installed one modified by my buddy into a proportional servo. Let me tell ya - if a frame gets in the way of that arm? No more frame. If a sheet hangs up? You're gonna pull the rig down.....

I just modified my dad's original open-ended drum setup in his EC12 into a closed loop system and he couldn't be happier. He's probably sailed it 20 hours or more this year, in spite of the weather, and hasn't had a hang-up or a snarl. The open-ended one probably could've stood some improvement, but hung up so often that we didn't even consider fixing it.

Dave Lilley 06-20-2003 01:31 PM

Arm vs. Drum - sorta
I like the close-loop drum setup, but I cannot bring myself to drill holes in my boat, yet. (It would also have to be an external setup, since there is no access to the front of the boat, internally.) I will try the arm setup first, and then move to a drum if it doesn't work well. (I used a HS-815BB, which has 275 ounces of torque on 4.8v and 343 ounces on 6.0v.)

RobStagis 06-20-2003 01:50 PM

Arm vs. Drum - sorta
Maybe a helpful tip if you want to try a drum setup someday: Mount a long arm to the front of your radio board. This arm will hold the other end of the closed loop. Mock up an arm with your radio board and a stick or something. Trim/bend/tweak/snip until it'll go into the boat and the radio board will screw down again. Now pull it out. Set up your closed loop on the bench! This is a really nice setup, but the arm has to be pretty stout.

It allows you to setup the winch and loop on the bench. Also - since the loop is basically clear of any blocks since the winch is in back and you have a clear shot all the way to the bow, you can put rings on both the 'to' and 'from' lines on the loop and run your mainsail off one and your jib off the other - no turning block!!!

bogordoug 06-23-2003 07:23 PM

arm vs drum
I am not taking sides in this debate since I have successfully (?) used both arm and drum winches.

At the recent IOM world championships two of the top finishers used arm winches. It appears they used Hitec 5735 digital servos with a custom carbon fiber arm with a pekebe block at the end. The servo was modified using the HFP-10 servo programmer to change the standard swing from 90 degrees to what looks like 120 to 140 degrees. The lines were configured in a double purchase arrangement to get the necessary travel

Yes arm servo's tend to use a lot of current, especially in high winds, but they are faster than drum winches.

Doug Hale

Dave Lilley 06-24-2003 02:10 PM

Arm vs. Drum - sorta
I am using a Hitec HS-815. It has 275 to 343 ounces of torque (depending on cell count), and 140 degrees of throw. It uses a Y connector on the servo lead. The battery plugs into one fork in the Y and the servo goes into the other, and the "bottom" of the Y goes into the receiver's controlling slot. (I use channel 3.)

I actually had to limit the throw using the end point adjustment on my radio. (I think I could also put in new holes closer in on the arm, but the EPA works well.)

wismerhell 07-12-2003 04:14 AM

Arm vs. Drum - sorta
well i would say : drum is more precise
arm faster

now its up too u
i use drum in low wind and arm in strong wind..but i still pefer the speed of an arm:D


Trombe 07-14-2003 09:50 AM

Arm vs. Drum - sorta
I agree with the speed in the arm :)

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