Dec 09, 2012, 05:49 AM Registered User Joined Sep 2010 137 Posts Question digital servo Hi all was wondering if you can use a hitec 5755hs digital servo for a sail winch and what drum would fit ? has anyone had any experience with doing this ?
 Dec 09, 2012, 08:36 AM Registered User Blackpool, Lancs Joined Feb 2006 2,845 Posts If it's a lot like this - http://www.servocity.com/html/hs-5755mg_servo.html it wouldn't use a drum. Just fit an extension to the horn supplied to make it the right length to give the throw required. Is there a pressing need for a digital servo as opposed to a normal heavy duty one?
 Dec 09, 2012, 08:38 AM Registered User Canada, BC, Maple Ridge Joined Jul 2011 461 Posts That servo would normally be used as an arm winch, programmed for 180 degrees rotation. It can be modified for continuous rotation and a drum added, but why do that extra work? The drum dia will depend upon the length of sheet line that you need to move, and the number of turns you want, More turns allows a smaller drum and more torque, but increases travel time. Note that the servo uses the large 'D' size spline. You can calculate the length of main sheet to be moved by the winch. Assume that the boom going from close hauled to full out to the shrouds, creates a 90 degree angle, then the length of the sheet line is the hypotenuse, and the base and side are the distance from the goose neck to the main boom attachment point - call it L. the diameter of the drum is square root of (L squared*2) divided by Pi- divided by number of revolutions desired. For example, Gooseneck to main sheet attach point L = 200mm, Three revolutions required L squared (200*200) = 40000 times 2 = 80000 Length of main sheet movement is Sq root of 80000 = 282.8mm Divide by 3.14 =90 Divide by 3 revolutions = 30mm So the diameter of the drum is 30mm John Last edited by hiljoball; Dec 09, 2012 at 10:22 AM.
 Dec 09, 2012, 03:11 PM Registered User Joined Sep 2010 137 Posts sounds very complicated
 Dec 09, 2012, 05:31 PM Registered User New Zealand, Northland, Kerikeri Joined May 2011 22 Posts Have a look at the" Drum for Hitec Sail Servo 67F" by Sailsetc
Dec 10, 2012, 02:54 AM
Registered User
Blackpool, Lancs
Joined Feb 2006
2,845 Posts
Quote:
 Originally Posted by darynxbcoupe sounds very complicated
If it was simple, everybody would have one.
 Dec 10, 2012, 08:26 AM Registered User USA, LA, Mandeville Joined Feb 2005 885 Posts I have a HS-5755 in an IOM, as a sailwinch. It is not a drum, but an arm about 2.75" long. It works fine. Let me know if you want photos
Dec 10, 2012, 03:10 PM
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Joined Sep 2010
137 Posts
Quote:
 Originally Posted by hew565 I have a HS-5755 in an IOM, as a sailwinch. It is not a drum, but an arm about 2.75" long. It works fine. Let me know if you want photos
thanks but i dont have the room i think i might get a rmg thanks all
 Dec 10, 2012, 03:39 PM Registered User Australia, TAS, Penguin Joined Mar 2012 461 Posts RMG sailwinch is bulky, heavy and expensive if that matters. It is also FAST and STRONG - watch you dont fold the boat in half.....
 Dec 11, 2012, 12:18 AM Registered User Perth Western Australia Joined Jul 2009 1,094 Posts Wrong quote
Dec 11, 2012, 12:19 AM
Registered User
Perth Western Australia
Joined Jul 2009
1,094 Posts
Quote:
 Originally Posted by darynxbcoupe thanks but i dont have the room i think i might get a rmg thanks all
Darryn,

Whats the winch going into?
Dec 11, 2012, 01:11 AM
Registered User
Joined Sep 2010
137 Posts
Quote:
 Originally Posted by 8387mike Darryn, Whats the winch going into?
A tri i just built i had a cheap one from hk it worked great till the other day it just stopped working and i have read that they dont last