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Author Topic: R/C or leave as static model  (Read 2764 times)

Damien

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R/C or leave as static model
« on: May 06, 2009, 07:31:03 AM »

I was given this small static model for my 50th b/day several years ago, it has sat collecting dust since then my brother inlaw, who's into model yachts challenged me to R/C it.
I have stripped the crab/lobster pot and net from the hull, my wife confiscated them for a kitchen wall in one of her Doll's houses.

It's pretty good for an elcheapo ornament. Hull seems sound and fully sealed, I'll resin the insided to be safe.

Boat dimensions are
Bow to stern 430mm 
Beam 180mm
Keel to mast top 465mm
Bottom sail boom 250mm
Upper sail boom 180mm









Questions
1/ Will ballast within the hull be sufficient or
(a) cut off the existing lower keel off and replace with a lead replacement.
or (b) modify existing keel to accept a fin with bulb weight.

2/ Is there any real need to fit sail control ?

3/ Any suggestions for housing the radio and or adding boyancy, short of enclosing the hull i'd like to keep it looking as a fishing sail boat, with perhaps the oars also visible.

I have some 9g micro servos that will work for the rudder and AAA nimh cells for a micro battery pack.

Thanks Damien.
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tigertiger

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Re: R/C or leave as static model
« Reply #1 on: May 06, 2009, 08:21:10 AM »

Nice model.
She is big enough to convert to RC easily.

I am no expert, but in answer to your questions.

1/ you will need external ballast, some sort of fin keel would be advisable.
Modifying the keel to take a fin with a bulb weight may be easiest.
You will get lots of advice on here about placement of the fin, if that is what you want to do.

2/ Sail control is not essential, I have sailed boats with no RC sail controls, the sails were permanently set halfway out.
The only difference is you will not be able to sail her as far into wind, and you won't get maximum speed at most points of the wind.
Also it is a bit boring, just point the boat using the rudder IMHO.

3/ I have seen complete radio strays, including sail winches, hidden under model fish boxes. The only give away was the sheeting (control lines) but once 20 foot out in the water they would not be noticed much.
4x AA size cells will give you 4.8v of 6v which should meet your needs, so fairly small, and give you several hours sailing
(I get 8 hours out of a set of Duracell on a 31" hull).

Bouyancy you may have to relly on the gods. If she is well ballasted, with a fairly long fin keel she should not heel over too far. Alsoby reducing your sail plan (fitting smaller sails) you can also reduce healing forces. Until you see how stable she is it might be worth only sailing her in light winds.
I suppose you could glue in some blocks of polystyrene disguised as fish boxes, or under a tarp, where they will not foul the sheeting.

A micro server for the rudder may not cut it. You will need to increase the size of your rudder maybe by as much as 200-300%. This is because the density of the water does not scale. You can design this as a balanced rudder to reduce the amount of torque needed to turn it. But as I said, I don't think a micro-servo will have enough torque to turn a rudder through water.
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Proteus

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Re: R/C or leave as static model
« Reply #2 on: May 06, 2009, 08:23:13 AM »

How about making a rowing mechanism for it, and have a nice action man rowing it.


Proteus,
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John C

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Re: R/C or leave as static model
« Reply #3 on: May 06, 2009, 09:57:38 AM »

It's do-able
Here's one I did earlier at 14" about the same size, although not a sailing version. I also used resin to make sure it was water tight, the worst part was deconstructing it of all the tat they glue onto these souvenier boats.
Have you seen the mirror dinghy kit where the sail controls are contained in a removeable box?.

John C
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Vintage

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Re: R/C or leave as static model
« Reply #4 on: May 06, 2009, 06:16:24 PM »

Hi Damien

That's a sweet little boat.

I think you'd be best fitting some form of weighted dagger board to keep the weight as low as possible should you wish to sail her & just rig up some form of simple servo rudder control rather than worry about controlling the sail.

So far as buoyancy is concerned - maybe construct some form of small sealed foredeck packed with a two part foam just in case...

I've often thought about the possibilities of putting rudimentary r/c in this Adamcraft dinghy pictured below, it's a similar size, built circa 1949 & designed to actually sail.

The photos should give you an idea for the brass dagger board which actually retracts in this case & also the sealed compartment in the bow.

Hope this helps, let us know how you get on & good luck.  :-))

Mark.

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Damien

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Re: R/C or leave as static model
« Reply #5 on: May 07, 2009, 03:43:40 AM »

Thanks for the replies guy's.
I'll go with a weighted fin i think 30mm x 3mm thick should do ok, i have some 1/16th alluminium sheet i'll laminate 2 together.

Any ideas for depth of the fin please?  

The main sail measures 190mm on mast edge, 245mm on main boom, 190 mm on upper boom and 250mm on the free edge.
Not a very big sail area and the Jib sail is about 1/4 the main sail area.
This pic will show sail size.

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Vintage

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Re: R/C or leave as static model
« Reply #6 on: May 07, 2009, 03:38:41 PM »

Damien

If it's a help - the model in the photos I've posted is 460 mm bow to stern x 185 mm beam.

The brass dagger board / fin is made from 5 mm brass, is 100 mm along it's leading edge & weighs 180 grams.

Mark.
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