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porpoising and chine walking.....what cause's it??

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Old 01-02-2003, 05:47 PM
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When a boat is chine walking the boat is basically falling off the pad. When it hits the running surface additional lift is produced and the boat is thrown to the otherside. It sets up a repetitious motion that will continue until there is steering input, the boat is trimmed in or the throttle is pulled back. Often the boat will want to fall off to the right. This is due to the torque of the engine and prop weighting that side of the boat. The solution can be as simple as moving a couple of bodies or ballast around or as complicated as repairing the steering system or reducing lift. The slop in the steering will amplify a prexisting problem. The problem is also amplified or reduced by the propellor selection. An example would be comparing a Bravo1 to a Hydromotive. The Hydro's are well known for their positive handling-despite the fact that they reduce bow lift.

If the boat is loose, then the driver must pay attention. Watch the bow closely. When it starts to wander, a quick twitch of the wheel will throw the boat back up right. The driver must be in synch with the boat as a mistimed correction may result in a loss of control. In the right hands a boat that is prone to chinewalking can be a very controlled ride.
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Old 01-02-2003, 06:06 PM
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Personally, I think a Top Gun cruising with a little porpoising looks Bad Ass ..... after all, it's not a cruise boat, it's a HiPo MoFo

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Old 01-02-2003, 06:14 PM
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I have noticed on Wed. and Sat. mornings, trash days, when I roll one of my garbage cans out to the curb it starts chine walking to the point I have to stop, let the can settle down, and the start to get rolling again. But when I bring my empty can in, it doesn't do it ??? Any help would be appreciated, Thanks, Dr. Phil...... Wardey
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Old 01-02-2003, 06:16 PM
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Wardey-the solution is perfectly obvious: you need to have the little woman take the trash out for you.
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Old 01-02-2003, 08:16 PM
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The 388 Slingshot was not re-tooled for the Shott Brothers. They themselves eliminated about 12" of the inboard strakes to settle the boat down as it would chine walk at 140 mph. Others have since tried the same remedy.

The original bottom is still made today, maybe it should have the strakes removed in the same area that the Shott brothers did theirs then again maybe not as they have these boats running today without as much problems as some here state.

Majority of these boats come with stock 500 efi engines and the problem does not exist that badly at the speeds they reach. Now if they all ran over 100, maybe Hustler would change the bottom to accommodate the boats faster speeds?

All the Fiore boats have wide strakes which produce a lot of lift, if the CG of the boat were lower, they would probably not chine walk as much.
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Old 01-02-2003, 08:20 PM
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Quote:
Originally posted by cigarette1
Personally, I think a Top Gun cruising with a little porpoising looks Bad Ass ..... after all, it's not a cruise boat, it's a HiPo MoFo


Yeah..........real hot.......more like cute!
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Old 01-02-2003, 08:53 PM
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Default Hey Cord

I got the little lady to mow the grass, but she just won't take out the garbage, she says thats my job, I hate my job, it just don't pay enough but I only have to work 5 minutes a week.

PS, I felt so bad, her pushing that old mower around, I got her a new big wheel self propelled jobbie.
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Old 01-02-2003, 09:21 PM
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Cord is pretty much right on. My 98 MPH 21' Baja is solid as a rock when I am at the helm. I have let a few of my friends drive and they have a hard time getting 85 out of it before it gets a little hairy. They normally over correct with the steering. My steering is tight and full hydraulic. Very small corrections will stop the chine walking. Bobby Daniels is right about to much lift, but bow steer is a dangerous condition that occurs from not enough lift and high speeds. Ideally in a v hull you want the boat to run dry and flat with the bow slightly up. If that attitude cannot be maintained there is likely a set up problem and that includes porpoise. Tabs may fix it but will probably slow the boat down.
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Old 01-02-2003, 10:49 PM
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porporsing cans

Quote:
Originally posted by Wardey
I have noticed on Wed. and Sat. mornings, trash days, when I roll one of my garbage cans out to the curb it starts chine walking to the point I have to stop, let the can settle down, and the start to get rolling again. But when I bring my empty can in, it doesn't do it ??? Any help would be appreciated, Thanks, Dr. Phil...... Wardey
with weight in the can this causes the ripple in the side of the can to flex and bounce back causing garbage can porporsing with the weight removed this creates additional trash can lift DR,Phil full of trash
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