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Author Topic: Bilge Keel placement?  (Read 1678 times)

tonyH

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Bilge Keel placement?
« on: July 21, 2019, 03:16:46 PM »

Sorry, but it's one of those questions that probably has no answer but here goes!
When the Admiralty took trawlers into the fleet in WW1 they added 9" bilge keels onto existing hulls and updated the spec for the commissioned ones to match. I imagine because it would create a more stable gun platform.
Is there a common angle, e.g.45 degrees, that they are likely to be set at, since that would vary substantially depending where on the curve of the hull they sat and is there a "normal" percentage of the length of the hull?
Cheers
Tony




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Capt Podge

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tonyH

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Re: Bilge Keel placement?
« Reply #2 on: July 21, 2019, 04:15:37 PM »

Thanks Ray,
I'd had a quick search but what I found was somewhat later and designed in. That said, the post from Colin gave reason for the location on the turn and one, from BB I think, gave the 1/3rd 'ish length so I've got a basis to work on......unless, of course, someone knows different!
Cheers
Tony
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Akira

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Re: Bilge Keel placement?
« Reply #3 on: July 21, 2019, 06:26:22 PM »

I learned the following technique a while back and it has served me well.Using a stations plan, determine the fore and aft stations on the hull for the forward and aft ends of the bilge keel.Using the station plan and a seamstress tape( one of the flexible plastic or clothe tapes) and measure from the ship's keel center-line to the bilge keel on the station of maximum width. The measurement is now transferred to the hull at a number of points between the fore and aft ends of the bilge keel.  Draw an line thru all points and it should give you the mounting line for the bilge keels. The keel should make a straight line when viewed along it's length. From the profile it will appear to curve. I hope this makes sense.
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tonyH

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Re: Bilge Keel placement?
« Reply #4 on: July 21, 2019, 09:44:25 PM »

I'm working on a fibre hull with no plans so it may be a bit of trial and error but it makes sense to me. Cheers :-))
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Akira

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Re: Bilge Keel placement?
« Reply #5 on: July 21, 2019, 10:45:07 PM »

Tony, Even without plans, you can make a go of it. Find the maximum beam of you hull. Estimate where you think you bilge keel would look good at that point. Measure as I described and mark your hull accordingly. The fore and aft end points are up to you as well. If you wanted to, you could install interrupted bilge keels the same way.Best of luck. Please post your results
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tonyH

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Re: Bilge Keel placement?
« Reply #6 on: July 22, 2019, 08:50:18 AM »

Will do Akira :-)) and thanks.
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ivorthediver

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Re: Bilge Keel placement?
« Reply #7 on: May 03, 2020, 04:04:12 PM »

Well I must admit my bilge keels were fitted by eye [ not that is any recommendation ] but it was on the same basis as already outlined previously , working on the basis that if it looked right it would work .


As a rough guide though it was on the radius of the turn of the hull and where the hull was consistently wide and the ends where tapered and the mating surface where it met the hull was shaped so that they were pointed downwards at approx 35 degrees


These can either be fitted by fitting brass pins into both the hull and the Bilge keel  and glue -or as I do... use a two part resign putty which adds the benefit of a shouldered joint and can be easily shaped by wetting lightly and running your finger along the mating surfaces prior to letting it dry .........works well for me on 6 models and never lost one yet  OK
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