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tdonily
06-18-2004, 09:04 PM
Hey all. I know it's probably been asked several times over, but how do you know how much sail winch to put with a certain sailboat. I've looked through the various classes that the AMYA sanctions and others but am not knowledgable enough to know how much winch you need with a given sail area. Thanks for your patience with us "newbies"

Travis

Don't forget to have fun!!!

wgorgen
06-19-2004, 01:45 PM
The best way to select a winch for a boat is to find out what the other skippers in that class are using. If your boat is unique, then look at classes that are similar in size and sail area.

If you describe the boat you have, it's likely that someone on this forum has a similar boat and can tell you what winch they use.

- Will

Will Gorgen

tdonily
06-19-2004, 01:56 PM
I was working over the idea of a 10-rater sized boat. Having a set of line plans from MY, I was thinking up a "supply" list of items needed. With the winch being the biggest in question for me.

Travis

Don't forget to have fun!!!

tdonily
06-19-2004, 08:11 PM
So do you just set the sails about the mid-point of their travel? I could possibly see how this would work.

Travis

Don't forget to have fun!!!

Ed Morales
06-20-2004, 05:56 AM
HITEC HS 815
Is there anybody in this forum who has tried using this sail arm servo? I would like to use this in my new IOM hull that is currently being moulded. I saw a picture of a sailarm setup at http://thesailor1.tripod.com/id297.htm showing a digital hitec hs5735 sailarm servo. i would like to try using a non digital sail arm servo in a similar layout but i am not sure if this has been tried before and if the HS 815 can handle the top of a rig conditions. any help will help.
ed

Larry Ludwig
06-21-2004, 02:11 AM
This is actually being asked on one of the other boards... I forget which one... but the old 815 is not a great choice. It has reasonable torque, but will creep under load.

I am using one right now for a rudder servo and it seems to be doing OK.

Ed Morales
06-21-2004, 02:30 AM
isnt the hs 815 bb a bit too big for a rudder servo? it's more powerful than the futaba s3801. oh, and that was me asking in the other forum
ed

Rcher
06-21-2004, 01:14 PM
Travis, the winches usually have a rating for sail size ie the Hitec 725BB is rated for 1000sq in sails. So once you know what size your sails are, then you can fit your winch to your sail size.

tdonily
06-21-2004, 01:30 PM
I've been looking for that kind of info, but where is it listed? Is it in the manufacturers instructions? In addition, how do I come up with how much force my sails are putting out? Thanks for bearing with me...

Travis

Don't forget to have fun!!!

wgorgen
06-21-2004, 01:50 PM
Rcher, travis,

The holding power of an arm winch can be dramatically influenced by how you instal it. If you rig the winch so that the arm is aligned with the sheets at closehauled (the sheet will be positioned directly along the arm from the axis of rotation to the point where the sheet is attached. Then the torque on the winch is 0 for any load on the sheet. Small angles aff of this position will produce small torques for large forces. If the sheet is at a 90 degree angle to the arm, then a large torque is required to react a large sheet force. So the amount of force the winch can impart into the sheets is not constant for a constant amount of torque. If you take advantage of this in your instalation, you should be able to get substantial holding force at close hauled....

- Will

Will Gorgen

Rcher
06-21-2004, 01:54 PM
Travis, The force that your sails are putting on your winch is usually dependent on your setup. I have a Marblehead which is relatively smaller sailboat than a 10-rater so I can already tell you that the Hitec 725BB that I'm using may not be big enough for your 10-rater. ( Is there any reason why you can't gang two Hitec 725BBs?)

So if I were you, I would plan on getting a RMG winch ( http://www.users.bigpond.com/rmgsw/ )for your sailboat. I don't know if there is another winch on the market besides the Whirlwind (which is not made anymore).

Peter _Birch
06-21-2004, 05:41 PM
I have reported previously that there is a guy over here in australia that converts HS805BB servo's into sail winches. The torque of this winch is high. It can easily handle the sail area of a 2meter multihull.
The price is around $169:00AUD.

Just another idea.

Peter

Larry Ludwig
06-22-2004, 04:53 AM
ED, nope it works well on the rudder of a J boat. I lose no sleep on being able to apply the "force". Since the design is such, you have to go with the class. If you could put a balanced rudder on it you could turn it easily with 1/4 the force.

Ed Morales
06-22-2004, 06:00 AM
larry,
sorry.i thought you were using it on a smaller boat

wgorgen
06-22-2004, 10:34 AM
Larry,

I used to race on full sized IOD class boats which are basically a scaled down J boat:

http://www.internationalonedesign.org/

http://www.iodfleet.bm/Worldsphotos/100-0010X_640.JPG

Like the J (full size and model) the classic 6, 8 and 12 meters (and the EC12), these boats have long overhangs, narrow beam, long heavy keels with an integrated rudder. The boats are sailed with a lot of heel.

Anyway, the skipper of the boat I crewed on was 9 time world chapion of that class and was considered to be one of the fastest sailors. If the race came down to a boatspeed drag race, he would most likely win. He had a feel for the boat that allowed him to sail very fast.

I sailed with him for about 5 years and learned a lot about what it takes to sail that classic style of boat. The most important thing I learned is that if you have any helm at all, the boat is slow!

It was not uncommon for my skipper to announce "I am getting some windward helm, lets make a change to the sail trim." He would then work through a list of changes. He had a specific set of measurements of sail shape that he used. For example, when laying on the floor of the cockpit, if you extend your arm and sight past your fingers to the gap between the leach and the backstay, you could measure the twist of the sail in terms of finger widths. so the first question he would ask is "what is my leach?" to which the mainsail trimmer would reply "you have a 3 finger main." My skipper would then make a change to that depending on the conditions. He might ask for a 4 finger main or he might decide that the traveller needed to be dropped down. You get the idea. Then, as is the case with heavy boats, he would wait. 10 to 15 seconds would go by before the boat would have fully adjusted to the change. Then he would re-evaluate the situation. Did the helm get better or worse? We would use paralax to judge our boatspeed relative to other boats. Were we moving faster or slower? Pointing higher? Etc.

The bottom line is that on these types of boats, you do not want any helm at all. You should be able to drive a classic 12 Meter with your finger tips on the tiller.

If you need a massive servo to keep that boat sailing straight, then more than likely you are not sailing fast. It is not a matter of having a balanced rudder. The rudders on these classic designs are really little more than a tab off the back of the keel. If your boat is balanced, then that tab of the back of the keel will be balanced. You should not need such a big servo to drive that boat.....

- Will

Will Gorgen

greg V
06-22-2004, 11:21 AM
......... if only you could have a crew on these RC boats to do that kind of work, but you don't. So many times you need to use a heavy tiller to correct a J boat especially when you are in puffy conditions, not to mention quick maneuvers.
I used a Futaba 3801 on my J.

Fact is that there are always forces on these rudders and we can't feel them through the Tx/Rx. A small servo on any boat is usually a big mistake.

Larry Ludwig
06-22-2004, 11:35 AM
Yeah that would be the way to do it, but unfortuantely even with back stay and vang I am limited in my controls and even more limited in what my sail trim is when the boat is 200' away from me. More importantly.. when I am headed by a gust that in scale would be about 90 kts I need to do something with the boat... and watching your rudder authority diminish as the winds increase just flat sucks.

Everything you say is completely true, and I have seen it on the ocean. Basically this is something I have going on the EC-12 board right now about rudder size and shape, that being I am not convinced that the larger rudder is all that great because of the braking action created.

When I started racing as a kid I was told quite simply that everytime I touched the tiller I was going to slow the boat down, and my reason for doing so would need to be I was creating a better speed than the one I had. The temptation to move that stick just has to be resisted.. but when it is time to move... by golly.. it's going to move.