What is Chinewalking?

bernithebiker · 30 August 2006, 14:34

Hi - new Ribster (Capelli 4.7m, Yam 60hp 4 stroke) and I read quite a bit here about chinewalking at max speed.

As my engine is only just run in, I haven't really maxed the boat out yet, so maybe then I'll see this 'chinewalking'!

But so as to know what to expect, what is it?!

And how does one relieve it? Trim down or up?

To get on the plane, I trim right down, then raise it slightly to position 2 or 3 (out of 5) to maximise speed. Hope that's right........!

Also, how easy is it to flip a RIB? Putting aside, large shorebreak type waves, is it possible to flip a RIB like this in a moderate sea, (eg. Force 4 to 5)

Thanks!

Biggles · 30 August 2006, 15:03

Bernithebike,

Chine walking can be quite scarey. But I don't think it happens with every boat.

Happened to me because I put a new engine on an old boat. I was used to the old engine and that didn't cause chinewalking. When I opened the new engine up it just about threw me and my son in the water. The power went straight off I can tell you.

My words of advice are that when you take your new boat out for a thrash accelerate slowly. If your going to suffer chinewalking then you can easily back off.

Seems that if you have the engine trimmed right in this gets rid of it but then you lose speed. As you trim out it becomes apparent. I think an early sign of chinewalking is that the steering seems to be very light.

Therefore it seems to be caused by a combination of engine trim and speed.

A little trial and error should get you sorted.

Biggles · 30 August 2006, 15:04

With regards flipping a RIB.

Its not something I'd want to do so I always steer clear of breaking water.

le_forban29 · 30 August 2006, 15:18

Chinewalking is more likely to happen on a deep V hull with an engine mounted low, at speed and trimmed out. If you trim in (down) and/or reduce speed, you'll find it stops.

It may start like this: Propeller torque sends your port tube/chine down to hit the water. The tube bounces back and you're in for a dance when it bounces so much as to send the starboard tube hit the water in turn

. Some boats will never experience it. Mine does when I'm alone on board and maxing out everything in a light chop.
My $0.02

spence · 30 August 2006, 15:22

Chinewalking causes the hull to roll quickly (and violently) from port to starboard at certain high speeds in certain wave conditions, usually when you are fully trimmed out (i.e. the outboard in a high trim position) and running at full throttle.

My previous boat was a Ring 18 with a 175 merc and that would chine walk violently at high speeds (>60 mph) if I had too much weight aft. The throttle was a foot throttle so it was easy to back off and re-adjust the trim etc before it got too scary!

Normally you can move weights around in the boat (e.g. anchor & chain, spare fuel, the wife?) etc to minimise the effect of chine walking. Or reduce the amount of trim you apply in that particular sea condition. Or check that the outboard is not mounted too high on the transom.

You may never experience chinewalking, but if you do slow down and sort it out.

Matt · 30 August 2006, 16:25

And sometimes, despite the best setup, it just happens. In this case, you need to learn to drive to control it.

Lostboy · 30 August 2006, 16:37

DON'T try too hard to correct it! Nice easy turns and "tack" along with it.

Rogan · 30 August 2006, 17:55

Our little 4.4m Zodiac Hurricane would start chinewalking at just under 40mph. Easy to control and back off unless it was very choppy. She tried to eject me at 38mph once. The GPS mount kept me in the boat and I still have the scar to show for it. Got some sport trim tabs and the proplem is almost nill. Can hold the throttle all the way open, trimmed all the way up, with one person on board now. The trim tabs have changed the whole character of the boat. When we leave the water after a wave she hooks up right away and we can keep moving. Can also maintain slower speeds on plane which is awsome for extreme conditions. The boat feels more planted and generaly takes a lot more to upset her.

BogMonster · 30 August 2006, 21:30

Would it be reasonable to say it happens only at or near the maximum speed of a hull i.e. with a large engine on the back?

My Humber doesn't show any signs of it even solo (even when trying to unsettle it which I have done just as an experiment) but it only has 115hp on the back and I think it is rated to 150 - so I guess it's just too slow!?