Subject: Re: : Re: [harryproa] Re:: Flat Bottom Harryproa
From: "Rick Willoughby rickwill@bigpond.net.au [harryproa]" <harryproa@yahoogroups.com.au>
Date: 3/26/2015, 5:56 PM
To: harryproa@yahoogroups.com.au
Reply-to:
harryproa@yahoogroups.com.au

 

Arto

I have not looked at the James Brett work.  I have seen quite a variety of stabilised monohull.  That is the concept behind my pedal boats.

I took a video of a friend at the local lake to show how the stabilisers should ride the diagonal wave off the bow:
https://www.youtube.com/watch?v=F5nMkikOM88
About 3:30 in the water is mirror smooth and it shows how the majority of the stabiliser sits above the water.   I show this to people so the know to set the stabilisers correctly. 

When the boat has fixed stabilisers there needs to be some ability to trim aft down in light boat situation to get the aft end of the stabilisers on the water to avoid flop roll.  

I can also do the wave analysis on the hulls to work out the best place for the stabilisers to give the required stability while having minimum wetted surface:
http://www.rickwill.bigpondhosting.com/V16_9m_Underwater.jpg
This is the underwater view of a 9m boat with 3m long stabilisers in its wave train at design speed and design displacement.  The two small triangles are the wetted portion of the stabilisers.  That is all that needs to be wet to get the KMt higher than CoG.

With the models I posted earlier the fishing boat has design weight for scale but C0G is higher in scale than it would be full size.  The runabout is heavy in scale so its stabilisers are more immersed than they should be.

Rick
On 26/03/2015, at 6:46 PM, "Arto Hakkarainen ahakkara@yahoo.com [harryproa]" <harryproa@yahoogroups.com.au> wrote:

Rick

Thank you for posting these very informative and inspiring posts. I guess you are familiar already with the work of James Brett http://www.brettmarinedesign.com/designs.htm and especially his Eagle 4.6 power trimaran=

Arto
 

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Posted by: Rick Willoughby <rickwill@bigpond.net.au>
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