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 ?

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?

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

sounds very complicated

Have a look at the" Drum for Hitec Sail Servo 67F" by Sailsetc

Originally Posted by darynxbcoupe

sounds very complicated

If it was simple, everybody would have one.

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

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

RMG sailwinch is bulky, heavy and expensive if that matters.
It is also FAST and STRONG - watch you dont fold the boat in half.....

Wrong 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?

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

Is that a water bottle on top?

Originally Posted by northernmike

Is that a water bottle on top?

yep so when it tips it doesnt go right over in the process of making something nicer