[Jimboat]

Originally Posted by Sonar

What are the symptoms of chine walk ?? what happens when chine walk ??

Originally Posted by Sonar

...just seen something about chine walking that's bothering me a little now as I fitted a large planing pad...I was hoping porpoising and the walking would be out of the equation.

sonar - chine walk is pretty common on performance hulls, particularly vee hulls. As the hull accelerates, lift increases and the wetted running surfaces that are required to support the hull are reduced (more Speed = more Lift = less Surface). As the speed increases, the hull often gets to a point where the lifting surfaces become very much reduced and the hull is now "balancing" on a small area of the vee-portion or the "vee-pad" of the hull. When that surface becomes sufficiently small, it becomes very tricky to "balance" the hull on its vee or pad. The result is a dynamic unbalance and a rocking of the hull from side-to-side. This rocking can tend to get a little more extreme with each motion, and so the "balancing" must then be provided by additional driver input (steering/throttle/trim) in order to maintain the hull in a balanced state.

check this thread for more on chine walk.

and check out this magazine article on chine walk.

Porpoising is pretty common...any vee hull (or tunnel hull) can be susceptible to porpoising, depending on design and setup. Flatter bottom vees are more prone to porpoising than steeper deadrise vee hulls, but there are several contributors to the occurance and any vee hull can find the problem caused by dynamic instability. Adding a pad can often make a hull more suseptible to porpoising.

here is a reference for more info on porpoising

Also, have a look at this article on "Hump Zone/Why does my Boat Porpoise?

and check here for how to consider whether your hull will be susceptible to porpoising