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Old 19 September 2011, 22:38   #1
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Chine walking

Hi to all, new to the forum but enjoying the site. Excellent place to learn. Can anyone explain the term chine walking? Read it recently and assume it means a form of loss of control of the boat. Recently accelerated quickly (no passengers) up onto plane and boat started to skip side to side at stern. Quickly reduced revs to get control back. Did I experience chine walking?

Thanks or any responses.
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Old 19 September 2011, 22:42   #2
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yes ...
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Old 19 September 2011, 23:05   #3
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The side-to-side wagging of the stern would be chine walking. When it becomes extreme, the boat walks sideways so far momentum of the boat causes it to flip/roll.
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Old 20 September 2011, 00:04   #4
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You might have been trimmed out too far, try trimming in to eliminate it. If you can't get rid of it though trimming another area to explore in identifying why it's happening could be worn steering or that you have reached the design limit for you hull. Weren't the Selva's designed for light two stroke outboards?
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Old 20 September 2011, 06:04   #5
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Did you kak your pants? If so, you were almost certainly chine walking; welcome to the club. Quick solution: buy and fit a four-bladed prop. It'll minimise the panic attacks and may even save some petrol.
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Old 20 September 2011, 06:24   #6
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How would the number of blades change the situation? My old boat had 6 and would chine walk a bit when flat out until I put on planeing pads.

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Old 20 September 2011, 07:57   #7
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The number of blades and the shape of the blades changes, amongst other things, the stern lift. We chimed walk less with a 4 bladed prop, but it was still there.

The most effective change we made on the race boat was moving the driving position forward and having a lower profile fuel tank. The change in balance reduced it considerably, but it is still there.

You may find you had gear in the boat loaded differently to normal if you have never felt it before.
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Old 20 September 2011, 08:35   #8
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Originally Posted by kubcat View Post
The number of blades and the shape of the blades changes, amongst other things, the stern lift.
Uh. Oh..... Prepare for heated discussions!


Back to the original question......

Fistly, Freyaflies, welcome to Ribnet!

To put this in "layman's" terms, chine walking is essentially when the boat lifts too far out the water & "falls over".

Picture the scene at rest. Whole hull (& probably your toobs) are in the water. Nice & stable. Start moving, you are in "displacement mode", pushing lots of water out the way & making big waves. The bow lifts mostly down to the force of the passing water against the shape of the hull. As you speed up, the whole hull is lifted out by the pressure of water on the bottom of the hull due to the movement and you get up on the plane, where you are essentially skimming over the top of the water instead of ploughing through it. The V shape of the hull has an upward force proportional to the speed through the water. So, the faster you go, the further out the hull comes.

Now imagine you have somehow managed to sit the boat on a bowling green and perfectly balance it on it's keel. you can imagine it won't take much for it to fall over. The faster you go, the more the hull lifts out, and the nearer to that bowling green scenario you get. Eventually gravity takes over (or a small wave unbalances it slightly) and it goes one way. Toob then hits the water & gets an instant lift that throws it the other way......

You know the rest!


As an aside, you don't get chine walking on flat bottomed things like Dorys 'coz once they're up they're up and sat on an essentially flat surface. This, as some of us know has some major dissadvantages too.... :smiley with missing teeth, sore @rse, rolling eyes & dazed stars around top of head:
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Old 20 September 2011, 08:45   #9
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Quote:
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As an aside, you don't get chine walking on flat bottomed things like Dorys 'coz once they're up they're up and sat on an essentially flat surface. This, as some of us know has some major dissadvantages too.... :smiley with missing teeth, sore @rse, rolling eyes & dazed stars around top of head:
Been there, remember it well but not fondly
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Old 20 September 2011, 09:27   #10
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excelent description of chine walking 9D.
this is why I like my old Ribtec as its got a shallow V so doesnt chine walk as badly as say a osprey with a full V.

:-)
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Old 20 September 2011, 09:35   #11
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I like my old Ribtec as its got a shallow V so doesnt chine walk as badly as say a osprey with a full V
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Old 20 September 2011, 09:54   #12
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9D280 , +1 on the excellent description.
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Old 20 September 2011, 10:07   #13
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chine walking

Thanks for all the input. Makes for fascinating reading on the subject. Think I must have experienced the very early stages. Dont like the thought of the ultimate consequence captnjack!!
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Old 20 September 2011, 10:22   #14
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Linky 1 Link 2
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Old 20 September 2011, 10:42   #15
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LOL @ Leapy
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