18' Classic Handling Question

[Ranman]

I have noticed that my 97' 18 Classic MAG 350 / Bravo One likes to seriously chine walk at top speed. If I let off for a second it will stop, but when I hammer down again it will start all over. I've heard that this may be due to loose steering (the drive fishtailing in the water at speed). I've noticed that I can grab the outdrive while the boat is on the trailer and move it from side to side rather easily. Whan I do this the steering wheel also moves, but this did not happen on my Alpha boat. There doesn't seem to be much slop between the drive and the wheel (1/4" - 1/2"). Is this normal? Can it be adjusted? Thanks for the help.

[PaulO]

Ranman,
As this has been explained to me, sloppy steering may contribute to the problem but, the real source is the hull design. It seems that as speed and trim increase, less and less of the boat is in contact with the water. You end up riding on the last foot or two of the deep v section of the hull. Because of the deep vee, the boat is unable to balance itself well on that wedge shaped surface and tilts from side to side trying to find a balance. This is why Steve Stepp was motivated to develope the "pad" (flat section) at the aft-most section of the keel. This, in effect, gives the boat a false chine and flat bottom to balance on. Interestingly, people erroneously attribute the stepped hull design to Steve Stepp probably because of the name.
PaulO

[Ranman]

PaulO, Good info. I'm assuming that you are saying that this is somewhat inherent to Donzi's. I have an interesting thought though that contributes somewhat to my Stern Jack post too. The Land-And-Sea Stern Jack is supposed to provide more lift due to the increased leverage from the prop setback. Wouldn't this cause a boat to chinewalk more since you are lifting even more boat out of the water? What effect does the Stern Jack have that offsets this tendency?

[rayjay]

I have been interested in what, if anything, the Stern Jack will do. According to Land and Sea the jack will help a deep V by letting the prop get closer to the surface of the water without being trimed at an excessive angle upward which tends to make the bow rise and the boat porpoise. They said it would help get the whole boat to run higher in the water, not just the bow. This would give a less bow high angle which would help the chine walk somewhat, at least acording to them.

Makes sense, but has anyone used a Stern Jack? rj

[RickSE]

Got some info for you guys.

Recently I had the chance to drive a new 28ZX Scorpion with one of the test drivers from Donzi. This boat really liked to chine walk with all that power. Ted the driver showed me that when the boat starts to chine walk you could drive out of it without getting off the throttle(s). Although I don't suggest you do this I'll tell you what he said, maybe you already know though. For example when the boat starts to dip to the left nudge the steering wheel a little to the right, forcing the boat to roll in the opposite direction. In the 28 the chine walk was gone as soon as you gave it one or two little nudges. The chine walk would soon return though, you just had to stay on top of it and not let it get out of control. I know this doesn't really answer your question but I've been dyeing to tell this story.

[DFLOWER]

Ranman,
If you can stand behind your boat and wiggle your stern drive around, while idling through a channel your constantly playing with the wheel to stay straight and at high speed your all over the place! It could be your stern drives gimbal ring.

I had this item replaced this past winter "expensive" in my 95 16' because of the above problems. Now there is no play in my drive, I cant move it at all from side to side and now all the above problems have been solved.

I asked if this part should be worn out in a five year old boat? I was told that with a V-8 and a good beating it can happen. I am the third owner of this boat so who knows. I was told also that it is a safety issue also as if it let go at high speed who Knows?

Good Luck!

[Barry Phillips]

Ranman: I have a 98 18 with a Brovo I
and my drive dose not move. Chine
walking is not a big problem eather.
I've only noticed it when I am really flying
the boat trying to get that last bit of speed
out of her, and more in glass calm
conditions. In a light chop the boat is
completely stable. Dee vees tend to
hunt from side to side by nature, I have
noticed that I compensate constanty
at low speeds and at top end, maybe I
am compensating for the chine walking
to. I would have the drive checked, and
I would consider a steering stablizer
if you think it is the drive, but vee bottoms
will hunt from side to side .
SO-SLO

[GeneD]

I wonder...
I've been avoiding this issue, and it comes up often. Thing is, I've never experienced the chine walk. Sure, I used to get it all the time on my Checkmate, but never in the Donzi.
I think it's the deep V going all the way to the transom that keeps my boat from doing it. It seems like all the guys with the late models, that have the rounded transom, have this inherent problem. Perhaps the fact that the lower strakes go all the way back too has something to do with the stability I enjoy.
Anyone out there with the V going all the way to the stern experience chine walk?
And yes, the way to get out of a chine walk is to work the steering wheel back and forth. It takes a bit of a knack, but it does work.

------------------
GeneD
007
Melbourne, Florida