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Some help and advice needed please


Old 04-12-2013, 01:30 PM
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Default Some help and advice needed please

I will start with some background. I am an experienced builder and pilot of planes. I am retired and live full time on a sailboat and will be in Grenada in the West Indies when I am thinking about building a RC model boat.

I thought about buying one of these nearly ready to sail kits. You know shake the box and go sailing but I know that I won't get much satisfaction from that. I don't need the instant gratification. I sit out hurricane season in Grenada and will have time on my hands once the boat jobs are done.

But for 200 euros I can get a 45 inch monohull with all the bits and pieces.

For a bit more I can get the Thunder Tiger Trimaran and that is a little more appealing.

However I think I want to scratch build from a plan or maybe build from a kit. I have downloaded and worked my way through the US 1M construction tips guide and I don't see anything that I can't cope with.

My first question is I will be sailing the model in the anchorage and most times there is a degree of chop there. Nothing that bothers my 44 ft boat or the 9 ft RIB tender but I suspect it will affect the model. My gut feeling is that it will upset the tri more.

So what kind of model boat will handle the chop best. Mono or Tri? I am thinking about something 45 to 48 inches long.

If I go the mono hull route I might go for a something that will look like the J class Endeavor when sailing but will have a deep fin keel with torpedo bulb ballast. Is this stupid? I suspect that the fine bow and stern lines may make this a bit of a semi submersible. Is it like the beginners in RC flight with Spitfire dreams.

Next question. If I go the scratch build route I am thinking about carving the shape I want out of urethane foam. I wood start with the deck shape with a cutout for a equipment box and the side view in light ply with a slot for the keel and a tube for the rudder. Glueing on foam blocks then insetting some wood for attachments. Covering it with glass cloth and epoxy. I am not worrying about meeting class rules or a super dooper finish. My aim will be something that sails well and not going for a concours d'elegance prize. This is a method that I have used before when making 12th scale combat models.

Are there any problems in using this method for model boats. Is there any online site giving an idiots guide to things like keel attachments and hard points for rigging.

Next question. I suspect that with the chop I will be sailing through there will be splash coming over the deck and a need to keep the RC gear dry. Any watertight box will have the rudder link and the sail link which must move. Is there an easy way of sealing those two things.

Mast sails and rigging. I was looking at an old fishing rod [ fibreglass or carbon ] for the mast. I can get SS wire from a fishing supplier That should do for the rigging. The sails I will make from spinnaker cloth. I have looked at the guidance notes from RCSails which suggest mylar. Is there a big difference. Mylar might be hard to locate down here although I can order it from the USA I guess but it will be rolled. Any problems there?

For the rudder I would use a 40 oz inch servo and for the sail a large ΒΌ scale servo at 300 oz inch. Would those do the job or do I need a sail winch?

Finally is there anything I have overlooked.

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Old 04-13-2013, 02:00 AM
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Default RE: Some help and advice needed please

A lot depends on the strength of wind and size of chop generated, but provided that all of the bits are strong enough, the plan is sound.  What you are planning sounds a bit like a slightly shortened Marblehead, but probably built a bit more solidly and therefore heavier.  You are looking for pleasure over the years to come rather than racing and repairing.  Its a good idea to combine the mast step and fin box into one strong unit - thats where most of the forces go.  Thinking back, at one of the world championships held at Fleetwood back in the late '80's, there was a competitive boat called "Odi" with much the same construction as you have described.
Sealing the rudder linkage exit is easy - you can buy soft plastic bellows to do that exact job.  Sealing the running rigging line exit is less easy because of the large travel needed coupled with the need for it to be free running so that it can pull out in light air.  Perhaps a prop shaft going through the watertight bulkhead with a pulley on the end instead of a prop?  Thats assuming a winch.  A motor/gearbox and ESC would probably serve better than a big servo.  Think cordless electric screwdriver.
Your servo choice would work, but is overkill.  A standard servo will do the job.
Carbon rod blanks have been used successfully for masts, as has aluminium tube from the hardware shop and dowel from the same sort of place.
If the sails will never be stowed folded or rolled, mylar is great.  Otherwise, cloth is the thing.  Once rolled or folded, mylar remembers the unwanted shape for a long long time.  You might want to consider a simplified, self tacking rig rather than a full on J class type rig.  If you are doing your own designing and developing, large plastic bags opened out combined with Sellotape are good for experimenting cheaply to determine your favoured size and shape.  A heavier boat, unless it has a much longer fin, will be a deal more tender than a modern racer, it will therefore need to run a smaller rig in any given conditions.
For standing rigging I like venetian blind cord, available in various weights and colours, running rigging I prefer salmon backing for its flexibility and very low surface friction.  That, and I was given a reel of it many years ago.
Quite possibly you will find a shop that sells stainless steel shark trace.  This makes excellent linkages and rigging hooks.  Fishing tackle shops are also good for swivels.
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Old 05-07-2013, 06:38 AM
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Default RE: Some help and advice needed please

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Each time I build a boat I think I should have made it bigger. I don’t know what’s wrong with me. Even the largest boat way out on the lake they look so small.

I have built a 2 meter multihull and am trying for crowdsourse funding to build a three meter R/C sailboat. Hopfully people will donate to my project. I have plans for 3M boat on my site - http://rcspeedsailing.com/index.html

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