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-   -   Sail Winch Newbie ?? (http://www.rcuniverse.com/forum/rc-sailboats-89/3839448-sail-winch-newbie.html)

spindrift 01-29-2006 10:46 AM

Sail Winch Newbie ??
 
New to the RC sailboat scene. I am putting together an old RC boat that has been sitting in the garage for many-many years. Plan on using it for casual - recreation sailing. The sail area rough calcs to around 1200 in2. I have no plans for RC gear install so I am currently trying cardboard mockups of what the servo installation tray needs to look like to work properly.

I was thinking about using the Hitec Mega Sail Arm HS-815BB with the 4" arm but I cant seem to get the sheet travel (even at 1:2 on the main) that I would like. Looks like I can get more sheet travel with the Hitec Winch although its slower with a lower torque rating. I seem to remember (maybe incorrectly) that loads attached to drums decrease the torque required to pull a load (as compared to the lever arm).

My questions:
Will the Hitec Sail Winch Servo HS-785HB be able to handle that size sails?
If not, will the winch work if I dont sail with the windspeed above _____knts?
Whats the longest arm that I can put on the 815 without over-torquing the servo (not planning on sailing it on windy days anyway)?
If the winch or mega sail arm wont work - is there an alternative servo that anyone could suggest?

Thanks in advance for any help you could provide,
spin

Midget 01-29-2006 08:47 PM

RE: Sail Winch Newbie ??
 

ORIGINAL: spindrift


I was thinking about using the Hitec Mega Sail Arm HS-815BB with the 4" arm but I cant seem to get the sheet travel (even at 1:2 on the main) that I would like. Looks like I can get more sheet travel with the Hitec Winch although its slower with a lower torque rating. I seem to remember (maybe incorrectly) that loads attached to drums decrease the torque required to pull a load (as compared to the lever arm).

the reason why your most likely not getting enough sheet travel is because maby the servo horn isn't long enough

spindrift 01-29-2006 09:26 PM

RE: Sail Winch Newbie ??
 
agent,
Thanks for your response..... I thought about making the arm longer but I was afraid that with the larger sail area that it will overload and damage a servo. Since I am new to sail winches I figured that I should ask someone before I purchase and modify the servo. From my internet searches it seems like many rigs are <1000 in2 so I was looking for some tips from anyone using larger sail areas with these servos.

At this time I have been using cardboard mockups and trying the sheet travel setups for a stock 4" arm. I have seen instructions to modify the servo from 140* travel to 180* but with the 4" arm its still a bit too short.

Making the arm longer will get me more travel but, what limits should I impose on the length so it works reliably?

Thanks again,
spin

LtDoc 01-29-2006 09:42 PM

RE: Sail Winch Newbie ??
 
spin,
The limits on the length of the control arm is usually determined by how much room you have in the hull. Got room enough for a 12 inch conrol arm, then why not? (That's sort of a 'stretch' but I'll bet you see where the idea is going.)
- 'Doc

Midget 01-29-2006 09:47 PM

RE: Sail Winch Newbie ??
 
do you know if you can get some pics of the boat,
than that will give me an idea.

thanks

spindrift 01-30-2006 02:45 PM

RE: Sail Winch Newbie ??
 
Agent,
Sorry I cant get pics. The boat is 5' long, 13" beam and the mast is 69" off the deck. From what I have seen on the web it appears somewhat similar to an EC-12.
With cardboard mockup and the servo located fully outboard I can get an 8" arm to fit.

LtDoc,
With an 8" arm it looks like I can get the travel I need. However I am still concerned that by doubling the arm length I am doubling the torque loading of the servo. In your experience is the 8" arm on that 815 servo not a problem considering the size of my sails?

Does anyone have info on estimated loads created based on sail area and wind speed?

I am trying to get this thing sailing without breaking the bank (too many hobbies) thats why I am looking at these hitec servos. Im not sure I can justify the cost of the big winch servos that I have seen. But if thats what I have to have - Ill try to figure out a way to get one - maybe used.

Thanks for all the help - I really appreciate it,
Spin

Mike Denest 01-30-2006 05:00 PM

RE: Sail Winch Newbie ??
 
Why not check out a local club? You can look at boats and get an idea of what you would need to do. There also plenty of help here: http://www.amya.org

LtDoc 01-30-2006 05:27 PM

RE: Sail Winch Newbie ??
 
spin,
Wish I could answer your question but never had a boat that that long of an 'arm' would fit in - lol. I'm not sure by any means that doubling the work the servo has to do would really harm it. I have used a servo too small for the sail, and changed it out. Didn't hurt the servo, just couldn't change sail in too much wind. (Wasn't a Hiteh' servo, but doubt if that had anything to do with it.)
- 'Doc

spindrift 01-30-2006 06:00 PM

RE: Sail Winch Newbie ??
 
Mike,
Thanks - didnt consider checking for a local scene - Ill search that path. The amya site has been very helpfull - plenty of info to be read. Ill definately spend some time diging through more of it and the other links referenced.

Doc, Thanks for the help - I guess it doesnt have to be a hitec servo - its just that they are readily available, the price isnt that bad and I picked up a hitec 2 channel, 2 stick surface transmitter for next to nothing. I really dont know much about servos at all. My problem is sometimes the right brain gets me thinking too hard and I struggle with technical details.
If all that happens with too much load is the servo just cant pull the sail in then - what the heck - I should just give it a go.

Thanks again everyone .........
spin

wismerhell 01-30-2006 06:40 PM

RE: Sail Winch Newbie ??
 
http://www.onemetre.net/Build/Servo/Servo.htm

spindrift 01-30-2006 08:47 PM

RE: Sail Winch Newbie ??
 
Thanks for the link wismerhell,
Lots of info for that right brain of mine...:D

I feel like such a knucklehead. I was doing the cardboard linkage thing really late at night. Just now thinking --- why does the 8" arm at 1:1 work when the 4" arm at 1:2 didnt. Light Bulb comes on - shouldnt the travel be about the same. Went back and measured the 4" arm I was using - great - I somehow put the 4" mark at 3" location (you know - used the tape measure but its more accurate if you start at 1" and then add the 1" to your desired length.....) [:@]

Now that I have it at the correct length I think Ill be fine with a 4" arm for starters and I can make one maybe an inch longer later if I need it.

While trying to figure this out I learned a bunch reading these and other forums. Still on the steep part of the learning curve.

Thanks to all who helped me out -
Im off to order the servo and make a servo tray....

Measure twice, cut once I always say (just dont forget where you started with the tape measure) :)

Thanks again -
spin

Mike Denest 01-30-2006 08:53 PM

RE: Sail Winch Newbie ??
 
Spin,
http://www.ec12.org website has links to an extensive build site, http://www.ec12.info. You will find an extensive build site, including winch set up. Since you said that it might be a 12, are there any identifying stickers in the hull, like a registration number?

Midget 01-30-2006 09:33 PM

RE: Sail Winch Newbie ??
 
this is the servo (http://www2.towerhobbies.com/cgi-bin...&I=LXGZU2&P=RF)i have in my northwind
and it seems to have plenty of power and its cheep

spindrift 01-30-2006 09:34 PM

RE: Sail Winch Newbie ??
 
Mike,
Its not a 12 - in doing my web search I found that the 12 has similar measurements but is a bit different. I'll spend some time on the sites you linked - thanks.
I referenced the 12 since I thought anyone with experience in that size would know how to answer my servo questions.

Markings - In the hull it says Regatta Yacht #73 by RC Model Sail Yachts - Div Tech-Aero Products from Burbank, CA.
All my web searches for Regatta Yacht, Div Tech-Aero, etc came up dry -- however through the AMYA manuf links I found a link http://www.pondboats.com/6-Meter.htm Thats the boat. I figured it was old but wouldnt have guessed its from the 60's... I emailed them with a few ?? and have not heard back.

Thanks to all...
spin

Midget 01-30-2006 09:36 PM

RE: Sail Winch Newbie ??
 
just to let you know that your link didnt work spindrift
it says that it cant be found

EDIT:but it worked when i just typed in this http://www.pondboats.com/

wismerhell 01-30-2006 09:56 PM

RE: Sail Winch Newbie ??
 
http://www.pondboats.com/6-Meter.htm

60 inches!!WOW>>>no even that expensive...thx, very interesting

spindrift 01-30-2006 10:48 PM

RE: Sail Winch Newbie ??
 
wismerhell,
Thanks for fixing the link. I went back and edited my post.
It is a classic looking boat. Ill be curious to see how it sails. If its anything like full scale boats with similar lines and a full keel it will heal over a bunch and the turning radius will be quite large.

spin

spindrift 01-30-2006 10:56 PM

RE: Sail Winch Newbie ??
 

this is the servo (http://www2.towerhobbies.com/cgi-bin...&I=LXGZU2&P=RF)i have in my northwind
and it seems to have plenty of power and its cheep
Agent,
I looked at that one - thanks for the heads up. I think that the HS-815BB has almost twice the torque as that one. I think with the size of my sails I may need it.
Thanks again...
spin

wismerhell 01-30-2006 11:31 PM

RE: Sail Winch Newbie ??
 
might drop an email to Larry and ask him!

http://www.ludwigrcyachts.com/MAINPAGE.htm

he builds BIG

spindrift 02-13-2006 04:01 PM

RE: Sail Winch Newbie ??
 
Update...
I went ahead and purchased a Servo City / Robot Zone Power Gearbox and a Hitec 815BB. Someone here I think mentioned it in another thread. Should be more than enough power and easy (I think) arm linkage sheet control setup. Its big but so is my boat - luckily I have the room for it. They do make a smaller version that takes standard sized servos so the footprint is smaller.

For those of you interested in the Power Gearbox but have not seen it I give it a thumbs up. All the parts went together as advertised. The manual and directions have detailed, step by step pictures. You will need to open your servo and do some cutting, soldering and drilling. Once I got over that anxiety about possibly destroying the servo and remembered how to solder it all went smooth.

Probably enough torque to break a boom (or finger) .........

Thanks for all your help,
spin


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