c3opti

I have a basic question but I am very confused on it so any help is appreciated. Basically I am building a volvo open 70 model and I need a sail servo with torque of about 20 kg-cm and it must be reasonably priced. I was thinking the HS-815BB but if it only has 140 degrees of rotation how will it trim in the sail all the way or am I missing something? What is the difference between sail arms and winches, how much rotation do I need from either I winch or arm to fully trim the sail? Any help/ references is greatly appreciated.

c3opti

PLEASE HELP!

Islander51

Look in the R/C section here:

http://www.onemetre.net/Build/Build.htm

This site has the information you need. Also

http://www.theamya.org/hints/sailservo.php and

http://www.theamya.org/boats/us1m/us1mcons.php

These sites are for the IOM and the US1M, but the basics are the same for all fractional rig yachts.
You double the sheet travel by adding a pulley to the end of an arm,attaching the end of the sheet to the boat, but lose some torque.

You don't say what size your boat is, but if you measure from the sheeting post to the mast,take that out sideways,then measure from that point back to the sheeting post;
this is the amount of sheeting travel you need.

Have a look here at the build logs, the ones by Claudio always have plenty of Pics.

http://www.rcsailing.net/forum1/foru...ca-s-Cup-Boats

Edward.

Captain MacGyver

Hi Captain MacGyver here,
A servo is around 140 degrees of swing. The winch on my Sanibel turns 360 degrees 3and 3/4 times stop to stop. I hope this helps you.
I live on a 43 ft. Sail boat in the center of Morro Bay I have posted a few of my Boat on you tube they have a GoPro camera on them.
To see these videos go to YouTube and type in W6FOG (this is my ham call sign)

boomer1

My Feedback: (1)

These sites can be of value in your research: http://www.servodatabase.com/ and http://www.servocity.com/html/servos___accessories.html
Servo City can help you select a good servo for your boat. Worth a few minutest to check out these sites.

On a personal note, setting up a winch system correctly requires knowledge. Setting up a sail servo using a servo arm requires less engineering and is much easier. There are many very popular rc sailboats using winch set ups, my point is when done correctly they work great.

There are many boat sold using a single double track drum set up, but those are not true winch systems - I posted photos of DENNIS DESPROIS' Gambit (one of thefinest rc racing yachts ever build)with a properly set up winch system. Hope this provides youwith an idea of what is involved.

Dennis is a well know RC sail maker and boat builder (and Champion sailor.) http://www.ddesprois-rc-boats.com/Site/contact.html
I am sure he'd be happy to give you some insights on your project.
Boomer

mainiac68

Did you get your problem solved? The 815BB should have all the power you need. 140degrees may be enough depending on how long your sail winch servo arm is/ how much haul you need/ and if you use single or double purchase method of hauling sheets(lines). A simpler solution if you need 180 degrees of travel is to buy a servo stretcher ($20 at ServoCity)
http://www.servocity.com/html/hs-815..._sail_arm.html

http://www.servocity.com/html/180o_servo_stretcher.html
Hope this helps.