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 Post subject: Re: First test run.
PostPosted: Sat Jul 23, 2011 6:02 am 
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Joined: Sat Jun 17, 2006 2:21 pm
Posts: 2126
Location: Toronto, ON, Canada
Mattias Bjorkman wrote:
Bruce!

thanks.

I have spent hours on your site to get were i'm right now.

/ snip /


Best regards / Mattias



It is great to hear that you got value from the content on the site. I don't think I ever publicly thanked Mr Hot Rod for hosting that site for me, and for the many hours he spent assisting with loading and organizing the content... Thanks, Paul!

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Bruce.

~~ Do what you love, and love what you do. ~~
~~ To me - only my boat is not yet perfect. Everybody else's is to be admired for I know the path they have walked (Dave Lott, 2010) ~~
Dow's Monaco Project


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 Post subject: Re: First test run.
PostPosted: Mon Aug 01, 2011 3:14 am 
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Joined: Wed Sep 03, 2008 10:55 am
Posts: 22
Location: Mjolby sweden
:mrgreen:


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File comment: Speening at "Göta Kanal"
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 Post subject: Re: First test run.
PostPosted: Mon Aug 01, 2011 3:17 am 
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Joined: Wed Sep 03, 2008 10:55 am
Posts: 22
Location: Mjolby sweden
have a look at 5.16 :

http://www.youtube.com/watch?v=uaw6NZFguTQ

Nice sound!


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 Post subject: Re: First test run.
PostPosted: Mon Aug 01, 2011 5:04 am 
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Joined: Sat Jul 04, 2009 3:50 pm
Posts: 3653
Location: Branson, MO
What a great picture of your boat. It looks like a lot of folks in your area build their own boats.

At what speed did you experience your porpoising?

dave

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My Riviera build - the Midnight Cry Project

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Few things in the world measure up to the thrill and satisfaction of boating in a boat that you built.


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 Post subject: Re: First test run.
PostPosted: Mon Aug 01, 2011 2:20 pm 
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Joined: Wed Sep 03, 2008 10:55 am
Posts: 22
Location: Mjolby sweden
about 35 knots on that video.


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 Post subject: Re: First test run.
PostPosted: Mon Aug 01, 2011 7:45 pm 
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Joined: Sat Jul 04, 2009 3:50 pm
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Location: Branson, MO
Ok, you might want to contact Bruce Dow and discuss with him the solution he came up with. You have a lot more top end you can experience if you get rid of the bounce.

dave

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Dave

My Riviera build - the Midnight Cry Project

Video of Midnight in Action
Blog

Few things in the world measure up to the thrill and satisfaction of boating in a boat that you built.


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 Post subject: Re: First test run.
PostPosted: Tue Aug 02, 2011 8:40 am 
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Joined: Wed Sep 03, 2008 10:55 am
Posts: 22
Location: Mjolby sweden
I just had about 3400 RPM at that speed so the boat is faster than that. But the river is not that wide and i had no beer, so i did'nt floor it :-)

But kan someone tell me more about Bruce idea?

Best regards

Mattias


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 Post subject: Re: First test run.
PostPosted: Tue Aug 02, 2011 12:16 pm 
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Joined: Sun Sep 06, 2009 2:55 am
Posts: 995
Location: Co.Dublin, Ireland.
Looks and sounds great, Not sure if this is any help to you with the porpoising but if someone can work it out it might be :D
http://illustrations.marin.ntnu.no/hydr ... index.html

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 Post subject: Re: First test run.
PostPosted: Tue Aug 02, 2011 7:12 pm 
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Joined: Sat Jul 04, 2009 3:50 pm
Posts: 3653
Location: Branson, MO
Hot Rod - Why did you not come up with that chart. Slacking off on us?????


Regarding the porpoising. My studies suggest the boat pushes a small wall of water ahead of itself. As the boat goes fast it climbs up the wall causing the bow to drop. The bow drops and bounces off the water allowing the next wall of water to form under the bottom. The faster you go the larger the oscillations. The remedy is to reduce the angle the boat moves over the water so that the wall of water is not being pushed up.

With an inboard, the process to lower to bow and thus lesson the angle of attack can be achieved in two ways:
a. The rake of the prop can be changed to a more forward rake. This causes the bow to drop. Bruce Dow had good sucess with this
b. A small ( I mean small) trim tab can be fastened to the bottom of the boat at the transom forcing the bow down. This is what I did. My tab is a wedge is only 5 inches long, 3 inches wide and at the thickest edge only 1/8" thick. I have one on both sides of the prop even with the transom trailing edge and under the motor stringers.
c. Well there is a 3rd - mount hydraulic trim tabs on the transom. I prefer to leave that to the speedsters such as Hot Rod and V-driver.

Good luck. Porpoising is common with us newbies that want to power up hulls designed 50 years ago with smaller engines. So you are not alone in this area.

dave

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My Riviera build - the Midnight Cry Project

Video of Midnight in Action
Blog

Few things in the world measure up to the thrill and satisfaction of boating in a boat that you built.


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 Post subject: Re: First test run.
PostPosted: Sat Aug 20, 2011 2:59 am 
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Joined: Mon Apr 11, 2011 8:39 am
Posts: 196
Location: Abu Dhabi, UAE
Gorgeous!! Congrats :D


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 Post subject: Re: First test run.
PostPosted: Tue Sep 13, 2011 10:29 am 
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Joined: Mon Apr 11, 2011 8:39 am
Posts: 196
Location: Abu Dhabi, UAE
Btw... is that teak on the deck?


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 Post subject: Re: First test run.
PostPosted: Tue Sep 13, 2011 12:11 pm 
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Joined: Fri Jun 09, 2006 4:28 am
Posts: 629
Location: Dublin, Ireland
Now that's just sweeeeet

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