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Old 07-22-2016, 08:35 PM   #1
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Scaled Hull Models

Anyone know where you can purchase scaled hull models for water testing? I have a few ideas I would like to test myself (in the pool) by modifying a purchased hull. Thanks

John T.
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Old 07-22-2016, 09:00 PM   #2
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What sort of boat, what scale and what time frame? If you are testing a hull alone it will need to be properly ballasted to sit on its lines. I was/am? a custom model builder and might be able to help you.
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Old 07-22-2016, 09:06 PM   #3
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"in the pool" ...
Sounds very controled.
Testing hull form?
I'm listening.
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Old 07-23-2016, 03:52 PM   #4
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Hull Models

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Originally Posted by TDunn View Post
What sort of boat, what scale and what time frame? If you are testing a hull alone it will need to be properly ballasted to sit on its lines. I was/am? a custom model builder and might be able to help you.
Thanks for reaching out to us. I'm just starting to think about the idea of playing around with a scaled hull which I can add different types of stabilization ideas. These are very uncharted waters for me and I'm not looking to prove anything to anyone but rather confirm in my own mind a few "what ifs" on a gross scale. We are not sailors but last year when we went out a 45 Sailboat (first time) I was very impressed with the reduced rolling motion even without sails up. I attributed this to the long keel and low profile salon. It was like the wind just went over the top of the boat and felt very different from our previous tall Nordhavn's.

Regarding size I'm thinking around 1/20th scale (40' hull equals 2' model). I'm not sure that scale will even replicate how the hull shape would really perform but if it is close I'm happy.

I'm looking for a traditional mono-hull sail boat style hull with a removable keel. From there I would build different style stabilizers and attach to the hull for testing.

For testing we are looking at very primitive (in the pool) style testing. We would do this on a very hot day so if the hull sinks at least I can enjoy the water as swim down nine feet to retrieve it. Fortunately our pool has a beach entry, is 50' long and has various waterfalls so we can create all types of conditions from dead calm to significant size beam seas. (ha ha) .

I thought about just purchasing a plastic model sailboat then realized I need a more precise weight distributed hull to help with the testing? I'm not even sure what type of material I would use. Any thoughts? Thanks

John
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Old 07-23-2016, 04:11 PM   #5
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I have built a number of radio control models from 1/16" balsa. I glass the hulls inside and out with 6 oz fiberglass cloth set in epoxy. It is easy to add weight to trim the hull to sit on its lines. Actually the mast on a sailboat provides a lot of the roll damping. That is very obvious if you go out on a sailboat without the mast stepped.

I have plans for about 125-150 different sailboat hulls as well as plans for a number of powerboats ranging from deep V to full displacement designs.
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Old 07-23-2016, 06:17 PM   #6
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TD,
Are you a NA or have you studied at Westlawn .. or equivalent?

I designed one boat. I built a bulsa model .. Varnished it. Then I built a 28' plywood proof of concept boat. Hard to call a 28' boat a model. One of the most rewarding things I've done.
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Old 07-23-2016, 07:05 PM   #7
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Eric, I took a series of naval architecture courses during my senior year at the UW. After college I worked as a very junior "Naval" architect at PSNS in Bremerton for two years before I went back to Grad school. So no I am not a naval architect, but I know how to design boats and do all the calculations. I am a retired physical science professor and have taught grad level fluid dynamics. In my model business I have drawn many sets of hull lines and applied my NA knowledge. I have built three fiberglass boats and am a reasonably skilled amateur shipwright. I restored and repowered my 1936 woody completely by myself.
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