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building an rc sailboat from scratch, HELP ME

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Old 02-05-2011, 06:58 PM
  #1
fpob
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Default building an rc sailboat from scratch, HELP ME

hey guys, i am a Jr. sailor (i race optis, if you know what they are). my coach let me borrow his mold, it is 30"X4.4"X2.5" and has a 12" keel, and a 55 or so inch mast. i have a couple of questions tho before i start laying glass.

1. is a standard servo strong enough to pull in the main and jib, or do i need a high power servo?
2. how do you build the rudder/ servo assemby whith it still being watertight?
3. how do you attach the keel and ballast to the hull?
4. what do you use for your ballast, and how do you attatch it to the keel?
5. how do you make/ atach the deck and have hatches in it.
6. how much ballast do you think ill need, my oach has 3 pounds, but his boats not stable when the winds get above 10 or so knots

thank you so much,


opti boy
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Old 02-05-2011, 08:20 PM
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Default RE: building an rc sailboat from scratch, HELP ME

While Iam in no way an expert, Iwill offer what Ihave figured out so far.
For sail servos you will need something big. If you go for a winch type setup they have servos built just for that. If you choose to use a sail arm you need something heavy duty in the standard servo range. Hitec has some nice ones for a reasonable price usually. The kkel rudder assy, I am working on now with my first non-kit based boat. I am copying what Ican from the kits Ihave built and using tubes epoxied into the hull to bring the openings well above the waterline. The keel and the ballast depend on how you want to use it. Do you want it remobable or not? If not, just build it into the hull mould. If you do, use tubes and a box, to give it a good base and bring the attachments above the deck. Ballast material is up to you, lead shot epoxied together or melted lead. Google itt some and see what looks like it will work for you. Once Iattach the deck to mine Iwill let you know how Idid it lol. Not quite sure on that part myself, but Ihope Ihelped you a little.
Opti's are a nice boat, good luck on the build up and post pictures if you can.
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Old 02-06-2011, 10:51 AM
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Default RE: building an rc sailboat from scratch, HELP ME

thanks so much, and honestly, optis are not fun, can weight till i get to lasers, thanks tho.

also, what did you mean by "I am copying what Ican from the kits Ihave built and using tubes epoxied into the hull to bring the openings well above the waterline."

my dad said to just epoxie it on and then screm it on with some 3" wood screws, also, what are you making the keel out of? i was thinking wood, and then glassing it, would that work?


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Old 02-07-2011, 03:07 AM
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Default RE: building an rc sailboat from scratch, HELP ME

A common way to fix a fin is to have the fin extend into the hull - best is up to the deck level.  This part of the fin sits in a box as a tight fit.  The fin handles all of the power generated, a surface join is the surest way of losing the fin in the shortest possible time.  Instead of a box, some have a pair of threaded rods coming out the top of the fin, which go through matching tubes inside the hull.  For convenience, these are usually fixed by nuts at deck level.
The rudder will usually be on a rod which fits into a tube that goes up through the hull and has a tiller arm at the top.  This gets a wire linkage to wherever the steering servo has been mounted.
A winch is good, but can be very tricky for a beginner.  A arm type (look for 9Kg in the spec as a minimum pull) is much simpler to make reliable.
Fixing the deck is a matter of fixing inwhales (google is a help here) around the inside top of the hull to make a narrow shelf.  I have used thin wood strips epoxied to the hull, and repeated until I thought the top surface was wide enough, then the deck beams can be fitted, and the deck skin glued over them.  
Size and place of holes and arrangement of coamings and covers is up to you, but you need to be able to remove and refit the equipment you put in there through them.
3 pounds sounds about right - with real boats, if the wind is too strong, you shorten sail.  On a model, you put smaller sails on.
Remember that all the power generated by the sail is transmitted via the mast and its mount, through the hull, to the fin, so that path needs to be strong enough.  It also transmits through the line to the sail servo and its fitting to the hull, so this set of fittings needs to be strong enough.  There is also considerable force going through the rudder and its mount.  
At the same time, construction needs to be light, otherwise it will perform like a log.  This is what makes sailboats so interesting.
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Old 02-10-2011, 04:54 PM
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Default RE: building an rc sailboat from scratch, HELP ME

thank you for being so quick, I really needed some help. my only remaining question is about the rig. how do you attach the back stay, i know theirs a little piece that sticks backwards off the mast, but what are they made out of, and how do you attach it. also, could I make my own servo arm, and how do you make one?

thank you so much for your help

"if its esey, you ain't doin it right!"
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Old 02-14-2011, 08:19 AM
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Default RE: building an rc sailboat from scratch, HELP ME

Howdy

The thingo that extends the masthead aft is called a crane. Your current boat's pretty small, so it shouldn't have any extreme amount of stress on it and most materials should be fine. That being the case, I'd make it out of something that goes well with the materials of your mast.

If you're using a wooden mast, I'd make the crane out of plywood slotted into the mast. If you're using a an arrow shaft or hollow kite spar, I'd go with a fiberglass crane you can either make a flat one yourself or make it out of a short piece of spar material. Either way, I'd notch it into the masthead and epoxy it in place.

BTW, there's an old saying that goes "Love the boat you're with." Optis may not be the most exotic thing on the water, but they're pretty well standardised and you get to sail them single handed, so win or lose, YOU earn the credit for every bit of performance that boat shows. You're right about something: Lasers are a ball to sail... I was a Force5 guy myself and I certainly understand the excitement, but the real fun of it was sailing with (or against) friends in similar boats so until your friends move up to something like the Laser, there's a lot you can learn in the "pram" and you really wouldn't have had much fun sailing a Laser against Optis anyway. Bottom line There are millions of starving kids in Africa who don't have a sailboat, so the Opti may be "just" a junior's boat, but it's a good one. Enjoy it while you can!
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Old 02-14-2011, 10:55 AM
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Default RE: building an rc sailboat from scratch, HELP ME

I made a lot of parts following a trip to the local home improvement store.  In particular, an aluminium shelf bracket was a source of  T section raw material for years.  Amazing what you can do with a vice, a hacksaw and a file.  And a bit of practice.
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Old 02-14-2011, 05:04 PM
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Default RE: building an rc sailboat from scratch, HELP ME

thank you guysfor you help, i will post some build pics, hopefully next week when i get started. and you know, optis aren't that bad, we just like to complain about them because where teenagers, thank you again for your help.

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Old 02-14-2011, 11:56 PM
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Default RE: building an rc sailboat from scratch, HELP ME

I have another option for you as well. At the R/C Expo last weekend in Monroe, there was a booth that was taken by Tippecanoe Boats, an R/C sailboat kit manufacturing company. You might give them a call and see if they can hook you up with either a sailing club, a sanctioning organization or at least others that, like you, do the sail thing that might be able to help you out with your questions
Their phone number is 1-800-206-0006 and web site is http://www.modelsailboat.com and, what makes this company really good for you is they are located in Everson WA
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Old 02-15-2011, 06:43 PM
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Default RE: building an rc sailboat from scratch, HELP ME

thank you, i was able to get in contact with my coach tho, and he told me everything. the Tippecanoe boats are really cool, but the boat I'm building is a little more race oriented then those. my coach actually modified his boat, it now has a 20" keel, and 1.7 pound wheight. alot of the kids on my race team have also made boats, nd we have organized a system of handicapping the fast boats, so there pretty much even. the only official club in my area races the thundertiger victoria boats, and i wanted to build my own, so i think this is the best option. thanks to all of you who helped me on my way to building a cool boat. also, i hacked my servo, so now its a winch. there's a ton of info on the web on how to do this, so insted f getting a 50$ winch servo, you get an 8$ stranded, and just cut some wires and your done! i will tell you all how this works out.
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Old 02-19-2011, 05:34 PM
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Default RE: building an rc sailboat from scratch, HELP ME

ONE MORE THING. all the arm servos i have found have arms that are to big, but i do not want a winch. should i buy a large scale servo, and make my own arm, or should i just cut the tip of the arm off a regular arm servo. the hack didnt work, so i need an arm servo.
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Old 02-19-2011, 06:44 PM
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Default RE: building an rc sailboat from scratch, HELP ME

Even for an RG65 (which is a little smaller) I think a standard servo can have too little power for sail control on the wind. BUT, they're very chep and you may have some already, so...

If it were me and I were stuck using an arm servo, I'd shorten a regular servo arm as needed and give it a try if it isn't doesn't have enough power, then you can go with a higher power servo I think that the higher power servo I have for my RG is about a 120 in-oz servo and I got it for around $20. If that would handle your sails, it may end up being a good way to go.

In any case, cutting a servo arm or making one is an easy thing to do and I would recommend trying it.
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Old 02-20-2011, 02:48 AM
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Default RE: building an rc sailboat from scratch, HELP ME

If a servo arm is too long to fit in the boat, it is a simple matter to shorten it.  It then becomes a matter of matching the travel available at the servo arm to the travel required at the sail boom.  The longer the arm, the greater the travel, but you get less torque.  The bigger the sails, and the more wind, the more torque needed.  Like Al Stein says, if the standard servo is not strong enough, there are higher torque versions available that are the same dimensions.  They do need a power supply in very good condition, though.
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Old 05-27-2011, 10:09 AM
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Default RE: building an rc sailboat from scratch, HELP ME

Check out this link.

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

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Old 05-28-2011, 09:24 AM
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Default RE: building an rc sailboat from scratch, HELP ME

that was helpful thanks, pics are cumming!
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