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Author Topic: please advice once about the keel and bilge keel..  (Read 2569 times)

rathikrishna

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please advice once about the keel and bilge keel..
« on: January 11, 2012, 05:47:52 PM »

Friends..i started working on a big TUG, inspired by a tug, named BRYN FOSS..she is in to 3 feet, and 11 inches wide..i saw a long knife like structure just under the keel, in a straight line, up to stearn end..will this affect the directional control..?  and is the bilge keel affect the speed..? please advice me once..i am planning to complete her, with real river crossing ability..so even a tiny improvements, that helps for high performance is needed..Veterans..please advice me once..its a kind request..
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wartsilaone

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rathikrishna

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Re: please advice once about the keel and bilge keel..
« Reply #2 on: January 12, 2012, 06:09:37 AM »

Hai good morning respected Modeller..thanks for the link..it shows this makes some resistance in directional motion..so i have to avoid adding the keels..a million thanks again...
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barryfoote

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Re: please advice once about the keel and bilge keel..
« Reply #3 on: January 12, 2012, 07:29:04 AM »

The keels also help to add stability to the hull, so do not be too quick to dismiss them from your model.
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rathikrishna

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Re: please advice once about the keel and bilge keel..
« Reply #4 on: January 12, 2012, 02:19:22 PM »

Sir..i am holding the work..still waiting for a rethinking...she is more than 3 feet long..so..in a confusion..because it is designed to cross real river, from the home of my Friend,other bank, to the pavement to this bank..here the hull basic structure..
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barryfoote

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Re: please advice once about the keel and bilge keel..
« Reply #5 on: January 12, 2012, 04:14:54 PM »

I assume that if it is going to cross a flowing river it will be crossing the direction of flow. that my well cause instability. I would certainly add two bilge keels to help reduce this problem which could lead to capsize. Put them on. if after trials you are not happy with them you do have the option to remove them! :-))
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rathikrishna

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Re: please advice once about the keel and bilge keel..
« Reply #6 on: January 12, 2012, 05:24:11 PM »

thank you Sir..i am on the mark..will add bilge keels..
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farrow

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Re: please advice once about the keel and bilge keel..
« Reply #7 on: January 29, 2012, 01:31:21 PM »

Hi Krisna, is the tug you are building a tractor tug, that is fitted with a propulsion at one end with 360 degree of thrust. As the centre keel you describe sounds very much like a keel fitted to tractor tugs, because they have no rudder and rely on a fixed rudder/keel for directional stability, as the propulsion units turn for the direction of travel by the tug.
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rathikrishna

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Re: please advice once about the keel and bilge keel..
« Reply #8 on: January 29, 2012, 05:20:00 PM »

Dodes..thanks for the valuable advice..and at first i was thinking about the propultion as you mentioned, means a thrust vectoring system, but i couldnt find some apropriate bevel gears to make a 90 degree shifter for the units..so, at present, i have fixed two reworked motors, and willing to add one more at center, and as conventional method, as she is intended to cross real rivers..with ease..so, i added two bilge keels to stable her..i am taking alittle time to finish her, as i am working on lots of my crafts..thanks once again.. :-)
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tugnut

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Re: please advice once about the keel and bilge keel..
« Reply #9 on: January 29, 2012, 05:51:15 PM »

Hi Krisna i would definatly fit a keel for stabilaty,plus make the hull a bit deeper.
Take a look at MMB hull hope this helps
regards John
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rathikrishna

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Re: please advice once about the keel and bilge keel..
« Reply #10 on: January 30, 2012, 04:52:49 AM »

Good morning Tugnut..and the picture of the awesome craft.. :-))  i will add more depth, as the basic structure is under work..at present i am working on its motor, rewinded, and waiting to dry the insulation..i am adding one more motor at center, as a reserve power, to overcome any current and wind issues..bilge keels are added..but i think the turning radius became more vaster..so working on a thrust vector pump..at bow..a million thanks for the advice..
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tweety777

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Re: please advice once about the keel and bilge keel..
« Reply #11 on: January 30, 2012, 07:03:27 AM »

A keel majorly helps to keep the ship on course.
A ship this broad really needs that, as it naturally wants to make turns.
The drag you'll have from it will be such little that you really won't notice it at all.
The added stability only applies when sailing, the weigh is to small to get the centre of gravity down, but it does make it harder for the water to flow from port to starboard side, thus acting as a "dam".
The same applies to bilge keels.
A hull this wide probebly won't really need bilge keels, though it really won't hurt to add them at all, as again the drag will be so little that it won't noticable decrease the topspeed.

Greetings Josse
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rathikrishna

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Re: please advice once about the keel and bilge keel..
« Reply #12 on: January 30, 2012, 10:38:49 AM »

thank you Tweety..i am working on it..so happy.. :-))
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