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Author Topic: help on sail boat..  (Read 2475 times)

Krishna

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help on sail boat..
« on: June 25, 2015, 07:08:51 AM »

Friends.. after looking in to an article of sail boat, i am in a deep excitement to make a sail boat.. and sure, not new to me, but sure again new in sailing it.. and can anyone guide me, that how can we control it without power..  is it possible to drive the craft against wind..? it will be so helpful to me once.. at present i am planning to add a good brush less motor to it, fix sails and runs when no wind is there.. million thanks in advance..
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malcolmfrary

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Re: help on sail boat..
« Reply #1 on: June 25, 2015, 10:20:16 AM »

A fore and aft rig with the sails pulled in so that they are a little off the center line will go forward at about 45 degrees from the wind provided that the sailplan is balanced to the underwater parts like the fin.  No yacht can go directly upwind, they all have to tack first to one side of the wind direction, then to the other.
When I built my first yacht from my own half-baked ideas, about half way through the build I decided that I really knew too little about sailboats, so I dumped the idea and built it with a motor.  I later bought a kit and learned a lot from that.  Have lots of fun learning.
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tigertiger

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Re: help on sail boat..
« Reply #2 on: June 26, 2015, 02:19:23 AM »

What do you mean when you say, 'without power'?
You will need power for the motor.




I would tend to use a brushed motor. Brushless are too fast for this kind of boat.


Before the days of RC, model sailing boats used Braine gear http://www.vmyg.org.uk/pages/resources/plans/braine.htm and there is a lot of information about this on the Web. Before Braine gear boats had manually adjustable rudders, and manually adjustable sails. You would set the boat up, depending on the wind and where you wanted to go, and then release the boat to sail across the lake. You would then walk around the lake, recover your boat and then adjust the sails and rudder for the next leg of the journey.
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Krishna

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Re: help on sail boat..
« Reply #3 on: June 27, 2015, 07:31:56 AM »

thank you malcom, and tiger..


so its sure.. we must need a motor in it.. and before starting, i must learn well about this one's nature well.. thanks for the web link.. thanking you once again..
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malcolmfrary

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Re: help on sail boat..
« Reply #4 on: June 27, 2015, 09:05:39 AM »

Provided that the sailplan and underwater hull balance their efforts properly, then steering, tacking and all of the other maneuvers work without extra power, assuming that there is enough wind to drive the boat, and not so much that the boat becomes uncontrollable.  My comment about my first home build getting a motor was supposed to indicate that I discovered that I knew so little about designing sailboats that I dropped the idea of a sailboat and built it as a motor boat, not as a sailboat with an auxiliary motor.
Steering is by rudder and servo, only it usually needs a larger rudder than a powered boat, since there is no propwash, having a winch (and I expect to see some of your ingenuity here) to adjust the sails helps a lot.  As TT mentioned, before radios, there were the self steering systems.  These were good on waters with all-round access, but only tried to keep the yacht on a set heading to the wind after much adjustment.  Even after you got it right, there was always the chance that a shift in the wind would give a new and unexpected course.
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tigertiger

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Re: help on sail boat..
« Reply #5 on: June 27, 2015, 09:30:20 AM »

Krishna
Most sailing models have no motor propulsion.
But there is power to the Rx, rudder, and sail servo.
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roycv

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Re: help on sail boat..
« Reply #6 on: June 27, 2015, 02:14:30 PM »

Hello Krishna.  Forget putting a motor and propeller on the boat.  Make sure it is big enough for radio control and then show us how you fabricate a sail winch out of nothing!

If the boat gets stuck anywhere then use one of your other RC boats to recover it.  If not she will drift in with the wind and if there is no wind I would not bother making a yacht in the first place.

I like what you did with plans I sent you for Mistral.

Good luck,
Roy
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Krishna

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Re: help on sail boat..
« Reply #7 on: June 30, 2015, 04:25:26 AM »

Friends.. i started working on sail boat.. with provision of a powerful motor.. 2.5 feet long.. 3 inches high.. 8 inches beam extreme.. need some trail and errors.. some rework.. going on.. making sail from Georgette shawl, and height will be determined after some trial and error.. hope it works.. sure, have enough wind here.. i must try.. thanking you all once again..
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malcolmfrary

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Re: help on sail boat..
« Reply #8 on: June 30, 2015, 07:33:39 AM »

How deep will the fin carrying the ballast be?  Fitting a "powerful motor" might not be a good idea, since it and its battery is a lot of weight where it is not wanted, inside the hull.  The only weight in the hull should be that needed for strength, what weight there is should be as low under the hull as possible, for stability when the wind hits the sail.
Before committing to cutting up what was probably a perfectly good shawl, do your experimenting using thin plastic sheet, like that used for shopping bags.  Edges that need extra strengthening (typically, the edge nearest the front of the boat) to prevent stretching can have it provided with very ordinary self adhesive tape from the stationary shop.  This is a low cost way of going through the trial and error process.
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Krishna

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Re: help on sail boat..
« Reply #9 on: June 30, 2015, 07:00:17 PM »

Malcom.. it will be 12 inches down.. and i am waiting to turn a metal rod, in to egg like shape to form ballast.. or try to search parent home, for some older weights from wooden kits, that i discard.. the motor will be out runner, and the battery will be 800 mAh, LiPoly weighing about 60 grams.. and will add a dent under belly, for holding battery.. and re sketching lots now.. almost satisfied.. have to work again.. and thanks for the guidance to make sail.. i must try.. thanks once again..
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malcolmfrary

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Re: help on sail boat..
« Reply #10 on: June 30, 2015, 10:20:57 PM »

For satisfactory working, the side area of the fin should be 5-10% of the sail area.
If you don't mind looking at a plan of a sailboat about the size you are aiming at that is known to work very well, have a look at http://www.sealevel.demon.nl/english/indexXL25modelyacht.htm and look for the download section.
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Krishna

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Re: help on sail boat..
« Reply #11 on: July 01, 2015, 05:33:09 AM »

Goddess.. million thanks Malcom.. its great helpful.. so my doubts are cleared.. wow.. time to go ahead.. million thanks once again..
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