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Old 11 January 2011, 15:27   #1
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Xs rib chine walking

I have an Xs Ribs 600 with a opti 150. Over 37 kn it all gets a little lively, and damn scarey at 42kn does anyone else get this or could it be the the set up of the boat?
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Old 11 January 2011, 16:10   #2
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I'd say that's pretty normal for a 6m rib. Mine used to chine walk at those speeds, especially when trimmed up. I changed my 3-bladed prop for a 4-bladed Cyclone and this helped significantly. I also got better acceleration and slightly better fuel economy.
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Old 11 January 2011, 17:30   #3
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I don't really agree that it's normal for general 6m RIB to chine walk at any particular high speed. It all depends on set-up, HP and hull design (some being better than others).

Does your XS Chine walk all the time or are there occasions were it is better ie: Heavily loaded/lightly loaded? When you trim in does it improve?

You might be able to make some subtle changes to weight distribution that would see chine walking disappear.
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Old 11 January 2011, 17:41   #4
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most likely when sea is flatter perhaps ?
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Old 11 January 2011, 17:53   #5
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most likely when sea is flatter perhaps ?
And trimmed out.
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Old 11 January 2011, 18:03   #6
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Originally Posted by Hightower View Post
I don't really agree that it's normal for general 6m RIB to chine walk at any particular high speed. It all depends on set-up, HP and hull design (some being better than others).

Does your XS Chine walk all the time or are there occasions were it is better ie: Heavily loaded/lightly loaded? When you trim in does it improve?

You might be able to make some subtle changes to weight distribution that would see chine walking disappear.
I meant it's not unusual. I didn't mean to imply it's acceptable.
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Old 12 January 2011, 06:30   #7
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Had this with a boat I worked on a while ago, it was about an 8.5m boat that had twin 150hp but hopefully the theory should stand.

The boat was fine up to about 40 knots but chine walked above about 42, sometimes quite violently! We were advised by a reputable outboard dealer/installer to try ballast and let him know how we got on. I put about 100kg in the bow, I used lead shot so max weight minimum space, difference was instant, much improved. He then advised us to raise the motors about 2" if possible. It wasn't without transom work so we used the ballast for a month or so then altered the transom and raised the motors to the advised height.
No more need for ballast and no more chine walk...

I'm not a Naval architect but this worked for us. Hope this helps as the ballast thing is very easy and cheap to try.
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Old 12 January 2011, 09:14   #8
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I get chine walking starting at about 45kts when the boat is light, it is considerably better when the boat is reasonably laden with people and dive kit, also very rarely blast about at this speed so I have never bothered with trying to raise the engines on the transom. I suspect that you would be looking at a combination of raising the engine and putting in some ballast.
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Old 12 January 2011, 10:39   #9
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Suffered it in my old boat, which was poorly balanced and rather stern heavy. The balast idea is a good one and easy to try.
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Old 12 January 2011, 11:31   #10
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So this all seems to suggest it's a lack of lift at the stern or too much lift at the bow that causes chine walking. I would have guessed it being the other way round
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