TW28

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kiwi
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Post by kiwi » Mon Nov 14, 2005 4:24 am

:!: set mode to envy...

Tony
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tech_support
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Post by tech_support » Mon Nov 14, 2005 7:05 am

Looking good, thank youfor the pictures. Great work space too :D

Steve in Spring Hill
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Post by Steve in Spring Hill » Mon Nov 14, 2005 8:38 am

Wow seeing my dream boat in progress, looking great.

Later............Steve

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jasonmcintosh
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Post by jasonmcintosh » Mon Nov 14, 2005 9:04 am

Fantastic! Thank you very much for the pictures.

So, the keel is hollow? I imagined it to be solid. Will it be filled with ballast when done? What kind of ballast goes in there?

Jason

PS: Fantastic...
Hopefully fishing from my GF18

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Lackofdistinction
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Post by Lackofdistinction » Mon Nov 14, 2005 10:08 am

Must be difficult to work in such a cramped space!
:lol:
"Off Fighting Windmills."

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jasonmcintosh
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Post by jasonmcintosh » Mon Nov 14, 2005 8:20 pm

I'm still curious about the keel.

How big of a prop goes on it? Isn't the keel's width pretty wide and will interfer with the water flow around the prop?

Jason
Hopefully fishing from my GF18

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Jonnas
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Post by Jonnas » Tue Nov 15, 2005 5:31 am

jasonmcintosh wrote:I'm still curious about the keel.

How big of a prop goes on it? Isn't the keel's width pretty wide and will interfer with the water flow around the prop?

Jason
From the study plans:

"One particularity of this design is the relatively wide box keel somewhat in the style of the Jersey skiffs. W. Atkins was a great believer in that feature and we have used it on long range sailboats between 32 and 65 feet.
That keel is a NACA profile and has very little drag. It is easier to build than a keel with outside ballast and allows us to install the engine very low. This gives a shallow shaft angle which is more efficient and the low engine installation angle gives better lubrication, extends engine life. Plus, it lowers the engine weight and gives easy access to trim ballast.
Access to the shaft coupling and stuffing box is also much easier than on most boats."
JG

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Post by Macca » Tue Nov 15, 2005 6:10 am

jasonmcintosh wrote:I'm still curious about the keel.

How big of a prop goes on it? Isn't the keel's width pretty wide and will interfer with the water flow around the prop?

Jason
Hi Jason,

I brought a Vetus 42hp and requested Vetus to specify prop size and pitch. They came up with a 18" dia prop with a 11
deg pitch. They also suggested that a cruising speed of around 9kn would be achievable based on the hull design. 7kn or 9kn I don't care, I'm not in a hurry.
As for the keel width the boys from Bateau used a NACA profile which is also used to design rudders. After a bit of research I came to the conclusion that it acts a bit like a wing on a plane. Although it doesn't create lift it does create a push effect as water passes over the widest part of the keel resulting in very little drag. As this design (NACA) is not new I feel confident it won't interfere with the flow of water around the prop.

Macca

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jasonmcintosh
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Post by jasonmcintosh » Tue Nov 15, 2005 9:05 am

Macca wrote:As for the keel width the boys from Bateau used a NACA profile which is also used to design rudders.
The profile looks great to me. What I was wondering about is how wide the keel is just infront of the prop. I was thinking that it continued to be wide all the way back and your pictures didn't show it from an angle so I couldn't tell. But the study plans show some framing that has it narrowing again before you get to the prop. I'm not questioning the plans so much as trying to understand the boat.

Looks like you're doing a fantastic job. Please keep the pictures coming, I think we all REALLY appreciate them. I'd also love to hear about how you're handling the size issues in building a very big boat. Can't wait to see how you flip it.

Where do you plan on using it? Any lengthy voyages planned?

Jason
Hopefully fishing from my GF18

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