TERBObob

My Feedback: (21)

Good day all ,
First , let me say that I am out of my territory ( so to speak ) here and was looking to find a cheap sail servo . Can anyone tell me either where I can get them from , or , how to possibly ( if it can even be done ) convert a 1/4 scale high torque to a sail servo ?
My need is for a sail driven ice boat that I am making .

ANybody ?

LtDoc

T.'Bob,
It depends on how large your sail is, and how long the 'arm' on the servo is. If either is very large/long, then a 1/4 scale hi-torque servo probably won't do the job. I wish there were a way to 'convert' smaller servos to a 'sail winch', but I sort of doubt that there is. It's an odd thing when the servo costs more than the boat, but that's the way it goes (LOL).
I'm using a 1/4 scale servo as a sail winch on a boat, but the boat isn't a large one. It works okay in all but a high wind. Not as good as a real live sail winch, but also not as costly, and I can live with it...
- LtDoc

ballgunner

My Feedback: (1)

The Futaba sail arm servos are usually what is recommended most. As far as I'm concerned they also cost the most. Hitec makes a sail arm servo as well, a few bucks cheaper. When you are really flush with cash try for a sail winch servo. Some of the experts prefer a winch. I always use the arm type. The use of a 1/4 scale servo will be just fine if your yacht and sail are small enough. The main difficulty is getting enough throw. The Futaba 3801 and 3802 have
140 deg. of throw. When you are trying to run wing and wing you will need the extra throw to get the main boom out 90 deg. to the hull. Realizing that the Futaba is a bit more costly do not spend a dollar to save a dime. Frustration at the pond just isn't worth it.

TERBObob

My Feedback: (21)

Ballgunner ,
This is actually a "project" that I am attempting ( Ice sailboat ) .
The sail is gonna be estimated 4.5 sq ft . I was thining that a servo torque of around 160 would be enough .... Am I on the right track , or is that too little ?
BTW - thanks for all the help and info do far ....

Bill McW

Ballgunner.

The Futaba S3801 sail servo produces almost 160 oz/in of torque at 4.8V and over 190 oz/in at 6v.
Seawind sailboats use the S3801. It is more than adequate for it's 605 sq. inch sail plan. The sail plan you are contemplating is 648 sq. inch. The numbers suggest it would work. However, most ice boats have a mono sail rig instead of the main/jib rig found on most sloops. I don't know how the larger main sail would effect my math.
I'm also playing around with the idea of building a land sailer. So far, I plan to get a mast, boom and standard "B" sail for a Laser. That combo will run about $80. The Hitec sail winch servo that has proved itself as more than adequate for the Laser costs an additional $70. I'm now looking for tires and a steering set up. It is clear that my project is likely going to cost over $200-probably more being "RC". Couple the cost with this time of year and I revert back to the financial comfort of just considering the idea.

Bill

ballgunner

My Feedback: (1)

Never having owned or sailed either a land sailer or iceboat I'm may be out of my league. I'm sure I read somewhere that both types sail close hauled on most points of sail. If that's the case a 1/4 scale servo would only have to hold the boom in place and the degree of rotation is not quite so important. It would still require pretty high torque to move the sail but I'm not sure about the slippage. I have had some slippage with a sail as small as 600 sq. inches even with a so called sail servo. I notice too that most iceboat and land sailers give great advantage to the sheets by double or triple blocking for leverage. That might require less power to hold the boom. Sort of like putting the servo in low gear.

bogordoug

There has been quite a lot of discussion in the IOM discussion groups about using the HS 5735 digital servo as an arm winch. Also if you want a traditional drum winch, look at from cheapest to most expensive: Hitec 725, Futaba 5801, Whirlwind (Atlas, Tensor, Olympic), or the RMG sailwinch 360, 260DL.

wolff2000

Forget all other suggestions. Buy a tower hobbies TS-80. 343 )0z-in Torque and only about $40.00! Cases Closed!

ballgunner

My Feedback: (1)

Not quite closed. You still have to consider the maximum rotation of the arm. Most regular servos have a 60 deg. rotation which is adequate for aircraft but not enough for a servo sail arm. Unless you can get into the gears and redo the stops to increase the rotation you'll have that 60 deg.. I've found that the stop is usually only wide enough to allow another 4 or 5 deg. at the end of the arm. If the land sailer or the ice boat sails mostly close hauled and by the quarter boards off the wind the travel doesn't become quite as important. For a regular yacht the ability to go wing and wing when off the wind depends on being able to pay out to almost 90 deg. or preferrably a full 90. and that requires travel of the servo arm much more than 60 Deg..