Reply
 
Thread Tools Search this Thread
 
Old 19 September 2011, 18:38   #1
Member
 
freyaflys's Avatar
 
Country: UK - Scotland
Town: Fort William
Boat name: Ibis West
Make: Solent
Length: 5m +
Engine: Etec 115
MMSI: 235091448
Join Date: Aug 2011
Posts: 14
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.
__________________

__________________
freyaflys is offline   Reply With Quote
Old 19 September 2011, 18:42   #2
SPR
Trade member
 
SPR's Avatar
 
Country: UK - Scotland
Town: Central Belt of Scotland
Boat name: Puddleduck III
Make: Bombard
Length: 5m +
Engine: 50 HP
Join Date: Mar 2009
Posts: 2,066
yes ...
__________________
SPRmarine / SPRtraining
RYA Training Courses & Safety Equipment Sales
SPR is offline   Reply With Quote
Old 19 September 2011, 19:05   #3
Member
 
Country: USA
Town: Seattle
Boat name: Water Dog
Make: Polaris
Length: 4m +
Engine: Yamaha 60hp
Join Date: Apr 2007
Posts: 1,152
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.
__________________
captnjack is offline   Reply With Quote
Old 19 September 2011, 20:04   #4
Member
 
Hightower's Avatar
 
Country: UK - England
Town: Fareham
Length: 6m +
Join Date: Sep 2003
Posts: 7,855
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?
__________________
Andy

Looks Slow but is Fast
Member of the ebay Blue RIB cover club.
Hightower is offline   Reply With Quote
Old 20 September 2011, 02:04   #5
Member
 
Country: UK - Channel Islands
Town: Jersey
Boat name: Archangel
Make: Ribcraft
Length: 6m +
Engine: ETec 225
MMSI: 235063789
Join Date: Sep 2008
Posts: 1,005
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.
__________________
www.flickr.com/photos/gj0kyz
GJ0KYZ is offline   Reply With Quote
Old 20 September 2011, 02:24   #6
Member
 
Country: UK - Scotland
Town: Aberdeenshire
Boat name: Kikican
Make: Vipermax 7
Length: 7m +
Engine: F250 / FT9.9 Aux
Join Date: Nov 2006
Posts: 250
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.

Richard
__________________
Richard Selman is offline   Reply With Quote
Old 20 September 2011, 03:57   #7
Member
 
kubcat's Avatar
 
Country: Australia
Town: Sydney
Boat name: Lunasea
Make: Ribtec 890SX
Length: 8m +
Engine: Yamaha ME 421STI x 2
Join Date: Aug 2009
Posts: 470
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.
__________________
kubcat is offline   Reply With Quote
Old 20 September 2011, 04:35   #8
Member
 
Country: UK - Scotland
Boat name: Wildheart
Make: Humber/Delta Seasafe
Length: 5m +
Engine: Merc 60 Clamshell
MMSI: 235068449
Join Date: Apr 2007
Posts: 4,610
Quote:
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:
__________________
9D280 is offline   Reply With Quote
Old 20 September 2011, 04:45   #9
Member
 
Leapy's Avatar
 
Country: UK - England
Town: Sheepy Parva
Boat name: Sadly Sold
Length: no boat
Join Date: Sep 2008
Posts: 1,728
Quote:
Originally Posted by 9D280 View Post
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
__________________
Leapy is offline   Reply With Quote
Old 20 September 2011, 05:27   #10
Member
 
Country: UK - England
Town: Northampton
Make: RibTec
Length: 5m +
Engine: Outbaord mariner 75
Join Date: Apr 2011
Posts: 506
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.

:-)
__________________

__________________
jezza2011 is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 12:19.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.