Reply
 
Thread Tools Search this Thread
 
Old 24 September 2011, 11:28   #1
Member
 
Country: Other
Town: Malta
Boat name: DeltaBay
Make: DeltaBay
Length: 5m +
Engine: IHonda BF90D
Join Date: Sep 2011
Posts: 72
Rib lose control at 30knots

Hi all i am new here and i donít know if this is the right place to ask you if you could help me with my problem.
I own a maxxon rib 4.80mtr and powered with a mercury 60hp 4 stroke all bought new this year when i try to reach high speed the rib at 30knots lose control and start swinging from rear and it becomes very danger and will have to slow down. What i have been told to do is to rise the outboard but this didnít help. some told me it is over power but i donít think so. Total weight of the rib is approximately 400kg. What do you think ?.Thanks Jason
__________________

__________________
Jason calleja is offline   Reply With Quote
Old 24 September 2011, 11:42   #2
Member
 
Country: USA
Town: Oakland CA
Length: 3m +
Join Date: Feb 2005
Posts: 6,653
Swinging from the rear? Or rocking violently from side to side?

From the lead-up to the problem, it sounds like a case of chine walking. Do a search on this site, and you'll find a substantial amount of information on what it is.

jky
__________________

__________________
jyasaki is offline   Reply With Quote
Old 24 September 2011, 13:52   #3
Member
 
Country: Other
Town: Malta
Boat name: DeltaBay
Make: DeltaBay
Length: 5m +
Engine: IHonda BF90D
Join Date: Sep 2011
Posts: 72
yes that is the right description. thanks for your help
__________________
Jason calleja is offline   Reply With Quote
Old 26 September 2011, 07:20   #4
Member
 
Country: Other
Town: Malta
Boat name: DeltaBay
Make: DeltaBay
Length: 5m +
Engine: IHonda BF90D
Join Date: Sep 2011
Posts: 72
Hi and thanks for your information as it was very helpful. Last Saturday i went for a ride with the rib and tried to see if the chine walking was less after i raised the motor by 1” and what i noticed that when i was at W.O.T at about 32knots and was steering to starboard the rib was very stable and good running trim all down but as i steering straight it to trim it out it started cine walking violently. Now i have to ask you what is the best way to try eliminating the chine walking i have read a lot of things here that can cause chine walking. What i have noticed on my steering that it has a little clearance from right to left it has about Ĺ” on both sides. Will this affect the chine walking. Do i have gust to add weight or install a jack plate or hydraulic steering. Thanks to you all again and your help will be appreciated. Jason
__________________
Jason calleja is offline   Reply With Quote
Old 26 September 2011, 08:28   #5
Member
 
Cookee's Avatar
 
Country: UK - England
Town: Salcombe, Devon, UK
Boat name: BananaShark
Make: BananaShark
Length: 10m +
Engine: 2xYanmar 260 diesels
Join Date: Mar 2003
Posts: 4,225
Quote:
Originally Posted by Jason calleja View Post
What i have noticed on my steering that it has a little clearance from right to left it has about ĹĒ on both sides. Will this affect the chine walking. Do i have gust to add weight or install a jack plate or hydraulic steering. Thanks to you all again and your help will be appreciated. Jason
1/2" will make it difficult to stop the chine walking - take out the play and the boat will behave much better. Hydraulic steering can also have play if not maintained properly but is generally considered to be better other than by the purists.
__________________
Cookee
Originally Posted by Zippy
When a boat looks that good who needs tubes!!!
Cookee is offline   Reply With Quote
Old 26 September 2011, 09:28   #6
Member
 
Country: UK - England
Town: NW& wherever the boat is!
Boat name: depends on m'mood!
Make: Humbers/15-24m cats
Length: 6m +
Engine: etec130/big volvos
MMSI: many and various
Join Date: Nov 2001
Posts: 1,815
I see its only a 60hp outboard. Is it power trim or not? Would suggest the trim angle is too high so perhaps try 1 hole "in" if manual or just trim down a bit if power trim.
__________________
Dave M
www.wavelengthtraining.co.uk
wavelength is offline   Reply With Quote
Old 26 September 2011, 10:45   #7
Member
 
Country: Ireland
Town: Castlebar
Boat name: Clewless
Make: Valiant DR 490
Length: 4m +
Engine: 60 hp ETEC
MMSI: Awaitng one
Join Date: Oct 2007
Posts: 1,240
RIBase
32 kn is a good speed for a hull of that size. I would say you are trying to squeeze too much out from the hull
__________________
two stroke mick is offline   Reply With Quote
Old 26 September 2011, 12:20   #8
Member
 
Country: USA
Town: Seattle
Boat name: Water Dog
Make: Polaris
Length: 4m +
Engine: Yamaha 60hp
Join Date: Apr 2007
Posts: 1,152
Quote:
Originally Posted by two stroke mick View Post
32 kn is a good speed for a hull of that size. I would say you are trying to squeeze too much out from the hull
Agree. Trimmed all the way down you are keeping hull in the water, raising the trim is raising the bow. With less wtted surface the chine walking starts. 30knts is about all that hull is going to do with stability.
__________________
captnjack is offline   Reply With Quote
Old 26 September 2011, 14:26   #9
Member
 
Country: Other
Town: Malta
Boat name: DeltaBay
Make: DeltaBay
Length: 5m +
Engine: IHonda BF90D
Join Date: Sep 2011
Posts: 72
Yes it is power trim and when it starts chine walk it is trimmed all down and the other thing is i know another person that has same rib with same outboard it is identical with mine and he is doing 40knots with it and had never chine walked and my brother has a 14ft rib that weights 250kg including outboard and it has 50hp tldi on it and never had problems like this i can’t understand what does my rib could have i will try eliminate steering clearance then i will see if it will reduce the chine walking. Thanks all for your help. Jason
__________________
Jason calleja is offline   Reply With Quote
Old 26 September 2011, 15:25   #10
Member
 
Country: UK - England
Town: NW& wherever the boat is!
Boat name: depends on m'mood!
Make: Humbers/15-24m cats
Length: 6m +
Engine: etec130/big volvos
MMSI: many and various
Join Date: Nov 2001
Posts: 1,815
trimmed in? at full speed? Why?
try trimming out gradually as you speed up-you are trying the equivalent of pushing a weathervane the wrong way into the wind and obviously if the pressure one side of the bow is stronger than the other it will try to whip round. Get the bow up.. with the limiting factors being either the prop will draw air and the motor will over rev OR the boat will become unstable again. Our 4m searider was good for well into the thirties with no problems...our 4.3 humber assault was also ok with the proviso it needed a bag of sand in the front for balance-but both still had to be trimmed out.
__________________

__________________
Dave M
www.wavelengthtraining.co.uk
wavelength 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 15:57.


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