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Author Topic: Would this need a false keel?  (Read 3453 times)

das boot

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Would this need a false keel?
« on: November 20, 2009, 08:04:14 PM »

If I convert this to r/c, do you guys think I'd need a false keel?


Rich


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Vintage

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Re: Would this need a false keel?
« Reply #1 on: November 20, 2009, 09:15:51 PM »

If I convert this to r/c, do you guys think I'd need a false keel?

Hi Rich

Yes - you'll almost certainly need a weighted keel.

There was a thread earlier this year where a similar boat was discussed -

http://www.modelboatmayhem.co.uk/forum/index.php?topic=16782.msg166256#msg166256

Hope this helps

Mark.
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Reproduction wooden stands for the full range of vintage Star Yacht models are available from Vintage Pond Yachts

das boot

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Re: Would this need a false keel?
« Reply #2 on: November 20, 2009, 09:34:35 PM »

That's exactly what I wanted Mark...now why couldn't I find that post? Doh!!!

Marvellous, thanks ever so much for that, much appreciated.


Rich
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Greggy1964

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Re: Would this need a false keel?
« Reply #3 on: November 21, 2009, 02:05:14 PM »

Hello Rich

The sailing canoe I built a few years ago and converted to RC is here.

http://www.modelboatmayhem.co.uk/forum/index.php?topic=19576.0

and a video of her sailing here.

http://www.youtube.com/watch?v=AfiAmpvd-GA

She has a pivoting dagger board and rudder blade and is ballasted with lead under the floor boards.

Unlike your dinghy, she has side decks which means she can take a higher angle of heel before becoming swamped. O0

She has water tight bulkheads fore and aft so that if she does get swamped I can sail her to the pond side for a bail out. :-))

I have a 2 channel radio set up, one for rudder and one for sail control.

I converted and old acoms servo to a sail winch found here.

http://www.modelboatmayhem.co.uk/forum/index.php?topic=20883.0

Hope this all gives you food for though for your sailboat project :-))
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das boot

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Re: Would this need a false keel?
« Reply #4 on: November 21, 2009, 02:34:24 PM »

Now that's nice, I like that...I have another one of these boats which I converted to to use a small outboard motor and r/c, so this time I fancied using wind power for a change.

My usual sailing lake is fairly small and quite shallow and sheltered, so it should be an ideal little project for sailing there.

Thanks for the help...much appreciated.


Rich
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das boot

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Re: Would this need a false keel?
« Reply #5 on: November 26, 2009, 04:02:29 PM »

Any ideas as to how I go about calculating the amount of lead needed in the keel? I take it that the keel goes under the centre point of the mast? Or does it go on the C of G on the boat?


Rich
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Bradley

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Re: Would this need a false keel?
« Reply #6 on: November 26, 2009, 04:44:26 PM »

Hi Rich,
Things can get complicated here with 'centre of effort' of the sails and 'centre of lateral resistance' of the hull which would have to be calculated for a full size yacht {:-{.  However, with a model you may be able to get away with the positioning of the keel with a bit of guesswork - the keel needs to be aft of the mast and the ballast below the cg of the boat (approx).  You can calculate the ballast by loading lead in small quantities into the boat itself and when she is nearly down to the waterline that is the amount you want on your keel (allowing a little for the weight of the keel itself).  This all sounds rather hit and miss but with a little care (and a little bit of luck) you should be able to get it right :-)).
Hope this helps. ok2
Derek.
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das boot

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Re: Would this need a false keel?
« Reply #7 on: November 26, 2009, 07:01:32 PM »

Hi Derek,

Yes, that's given me something to think about...I understand what you mean, so I'll work from there and see how we go.

Thanks for your help, much appreciated...


Rich
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Jimmy James

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Re: Would this need a false keel?
« Reply #8 on: November 26, 2009, 10:32:11 PM »

I did a boat like that some years ago but sold it off and don't have any photos but this is the way I did it
 1)The after seat was boxed in and a carved block of foam fitted inside for floation
 2) The steering servo was mounted on its side between the aft and centre seats with the arm moving fore and aft and connected to a brass arm on the rudder by a brass rod the arm was camouflaged with lobster pots ( because the servo is moving fore & aft in a vertical plan it only needs a narrow slot to work in.
 3) the sail servo was mounted under the centre seat through a hole in the seat the black servo arm was mounted on top of the seat ( from two or three feet away you could hardly see it
 4) A flat 4 AA battery box was fitted on the bottom boards just forward of this and covered with fish boxes
 5) a removerable triangle box (Bait ditty box)was fitted forward of the mast (filled with foam) as foreward floation
 6) the fin keel was made of 1/16 ply  5" x 2 1/2" with 4 bits of flashing lead bolted on and faired in with P 38
 She sailed quite well in up to a force 3
Freebooter
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Brooks

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Re: Would this need a false keel?
« Reply #9 on: November 27, 2009, 04:13:48 PM »

Can't tell the size of your ship, but if it's a foot long, a footy keel would probably work. There are posts and plans here and elsewhere on the web. That size keel would be about the width of your jib's foot, and a foot deep. I generally make my keels wider, say 2/3 the width of your main boom. But my boats sail slow, and don't generate the lift that a fast moving Footy racer generates. The wider the keel, the better you'll work to windward, but the surface area will slow you down in a light breeze. It's perfectly acceptable to have more than one keel, for different wind conditions.

For testing ballast, I use a small pill bottle taped to the bottom of the keel, filling it with lead shot or pieces of automobile wheel weights.  At a minimum, there should be enough righting force to bring the boat back up if she gets knocked down (sails flat on the water). If your sails are cloth, there will be a surface tension suction, so you will need more weight than you'd see just testing the boat on land.

The deeper the keel, the more righting force the lead will have. So, if you find, by experimen,t that you need more lead than you want (due to buoyancy problems), deepening the keel will let you reduce ballast.

Adding styrofoam blocks to ensure she won't sink if knocked down is a good idea, especially while you are testing. Tape them to the floorboards for testing (use waterproof tape, of course...electric tape is not waterproof, at least here in the US). Boats have sunk on their maiden voyage, so be cautious.
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