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slapshot11
07-31-2005, 04:43 PM
I've now got about 20 hours of seat time in my 22' Classic so I've become somewhat more comfortable with it's handling characteristics. I've replaced the Mirage Plus prop with a Turbo and almost eliminated the purposing issues. :jestera: At WOT I can now feel the boat "air out" when I trim it up. That's kind of amazing. Anyway, at WOT, with the trim up a ways and no tabs, the boat begins to chine walk. Would a little tab help or is that just a consequence of being so much out of the water?

boatnut
07-31-2005, 04:51 PM
I've now got about 20 hours of seat time in my 22' Classic so I've become somewhat more comfortable with it's handling characteristics. I've replaced the Mirage Plus prop with a Turbo and almost eliminated the purposing issues. :jestera: At WOT I can now feel the boat "air out" when I trim it up. That's kind of amazing. Anyway, at WOT, with the trim up a ways and no tabs, the boat begins to chine walk. Would a little tab help or is that just a consequence of being so much out of the water?

interesting, did you have similar (chine walking) with the mirage? I am thinking of going from a Bravo 1 (4 blade) to a turbo--- I get what seems to me to be excessive porpoising but I haven't noticed chine walking yet -- maybe I haven't been trimmed out enough to get it as I just got the boat and don't much time in it yet.

joseph m. hahnl
07-31-2005, 05:01 PM
I've now got about 20 hours of seat time in my 22' Classic so I've become somewhat more comfortable with it's handling characteristics. I've replaced the Mirage Plus prop with a Turbo and almost eliminated the purposing issues. :jestera: At WOT I can now feel the boat "air out" when I trim it up. That's kind of amazing. Anyway, at WOT, with the trim up a ways and no tabs, the boat begins to chine walk. Would a little tab help or is that just a consequence of being so much out of the water?

what ever you do you'll cut down on the top end. i would think the tabs would help stabalize it. but you would be forcing the bow down. sinking the power trim down. will also force the bow down. my minx wiggles just a little full up tabs and trim not enough to scare me. you just need to play withit to see where your comfort level is.
joe

blackhawk
07-31-2005, 05:51 PM
I don't have my Donzi any longer but I tried a couple Turbo props on my new boat and they all chine walked pretty bad. To me it felt like the Turbo 1 lifted the stern too much and made it walk.

blueliner
07-31-2005, 05:51 PM
i put a post up a couple days ago regarding wot and chine. how did you manage to keep your tabs all the way up??? i had a listing problem to the left, and had to keep my left tab down in position 6(according to the tab indicator) so the boat would stay level. i was experiencing so chine walking as well as i was lifting the leg out. when it got too much i would back her down a notch and she was fine. what was your top speed and what engine do you have???


thanks for the info

slapshot11
07-31-2005, 08:56 PM
My power is a 502 with a Bravo 1. In terms of speed, I'm embarassed to say that my speedo is still broken so I really don't know. I do know that I feel like I've entered a new dimension of speed with the Turbo prop. The purposing is gone and the boat feels "lighter" and rides higher out of the water when trimmed up. The boat doesn't feel like it's stuck to the water any more. I do know that I've picked up between 300 and 400 RPMs but still not at the rev limiter.

Magicallbill
07-31-2005, 09:20 PM
I have an 18 '02 with the 377 Scorpion Engine..
It dances at high speed better than some of the patrons I play music for in the clubs.
I am not qualified to talk about a 22 with different prop combos,but I can make a blanket-generalized statement..
While chine-walking seems to be a part of high-speed Donzi operation,after a couple summers in the boat,I and my son am getting much better at controlling it. At first,it's pretty wierd,but with some "seat time,"as they say here on the board,you figure out how to steer out of it and get her running level.
While on vacation last week,I had mine to 72 . Mild walking,maybe,but nothing unnerving.
There are lots of experienced high-speed drivers here who could offer more on this, I'm sure..
MB

pmreed
07-31-2005, 10:18 PM
See this thread for a recent discussion that touched on this subject, though the main area of interest was porpoising.Porpoising (http://www.donzi.net/forums/showthread.php?p=328873#post328873)

I stand by my post in that thread.

Similar set-up, '99 22 Classic w/502. Came with the 25 P Mirage +. Fun prop, and I could stop it propoising at cruise by tucking the drive way down. Flat out was where it was fun; put the hammer down and keep trimming up 'til it flies. Watch Chromey's avatar for the look. Fun, but loose; and it had a tendency to chine walk passing through the high 60s. You really had to pay attention, as you were on the edge. Put on a 25 P (now a 26 P) Turbo and the handling became benign. Much less tendency to porpoise and no significant chine walking. Flatter ride at speed and just as fast. If you get a chance to try one, do it; you won't be sorry.

ps: about the only time I use my tabs is to adjust roll for load, wind, seas or a combination of the three.

Phil

blackhawk
07-31-2005, 11:58 PM
I have an 18 '02 with the 377 Scorpion Engine..
It dances at high speed better than some of the patrons I play music for in the clubs.
I am not qualified to talk about a 22 with different prop combos,but I can make a blanket-generalized statement..
While chine-walking seems to be a part of high-speed Donzi operation,after a couple summers in the boat,I and my son am getting much better at controlling it. At first,it's pretty wierd,but with some "seat time,"as they say here on the board,you figure out how to steer out of it and get her running level.
While on vacation last week,I had mine to 72 . Mild walking,maybe,but nothing unnerving.
There are lots of experienced high-speed drivers here who could offer more on this, I'm sure..
MB

MB, 72 is smokin! Is that on GPS? Isn't it amazing how some seat time gets us to figure this stuff out? I can drive my boat SO much better now compared to the beginning of the summer! And my passengers are extremely happy that I finally figured it out! :D

And I'm not knocking the Turbo Props at all. Every boat is different and IMO you should try as many props as you can. I'd actually like to try one again now that I have learned how to drive the boat a lot better.

Magicallbill
08-01-2005, 04:00 AM
Blackhawk;
No... 72 is what the Gaffrig said,so I'm not sure how accurate that is. I need to buy a GPS and get with the program,but just haven't done it.
I turn a 25P Mirage prop that came standard with the package. The engine turns 5000,and I use tabs only for load-leveling situations.
As I've mentioned previously,my son Jason's 18 with a 350 MAG 300HP Alpha rig goes almost as fast as mine,and chinewalks much less. I attribute my boats squirreliness to the extra weight aft and the Bravo.
Hope the rest of your summer goes well,

MB

DonCig
08-02-2005, 11:30 PM
I am no expert on chine walking, but based on my own experiences, here is what I have learned:

Chine Walking is a matter of degrees:



1st degree, the chine walk is like a steady rhythm that keeps you on edge but never reaches out and bites you. (Remember that we are driveing narrow beam boats.)



2nd degree, the chine walking is pronounced and ready to bite you, but not at every moment.



3rd degree, the chine walking will bite you on the third cycle and has you reaching for the throttle on the second movement.



I have experienced all three degrees. I found that I enjoyed the 1st degree. It was with a prop that was not on the top of the list of recommended props, but it was the fastest, the best hole shot, and the most stable at WOT.



Enjoy the pursuit, and learn to enjoy the controlled waggle. Also please try and avoid the progressive 3rd degree waggle.



DonCig

cigarette30
08-03-2005, 08:02 AM
Chine walking is a result of a rounded V bottom, running on a limited amount of surface remaining in the water, thus it is tring to fall to the sides, and strakes with more surface contact. After severial 22' and 18' classics, this was always one of the more enjoyable traits to overcome (most pronounced over 70 mph) Anytime tabs are used, you are "scrubbing" speed by having more wetted surface. There is nothing wrong with this practice however, & aditional peace of mind, and safety factor. However, for true top speed, the chine walking can be driven out, in fact once you get past the first few "phases" the boat actually settles down IMO. Take your time, raising the tabs easy, along with the drive, first in smooth water with no wakes, while compensating for this "rocking" by counteracting the steering wheel toward the side of the fall. This is dificult to explain, it takes a quick motion, and just really needs to be learned. BTW, speed particulars ....... 496 HO, with Imcoand labbed prop, 68-70 with heavy tabs, 72-74 some tab, little "light", 74 - 78.4 (GPS, can post pictures) with tabs up, trimmed out. Last point, fuel and passenger load greatly affect these speeds, and the amount of chine walking, ie" more wieght, the more hull in the water" I lose 4-6 mph with full fuel and 2 more people.

blackhawk
08-03-2005, 08:13 AM
Chine walking is a result of a rounded V bottom, running on a limited amount of surface remaining in the water, thus it is tring to fall to the sides, and strakes with more surface contact. After severial 22' and 18' classics, this was always one of the more enjoyable traits to overcome (most pronounced over 70 mph) Anytime tabs are used, you are "scrubbing" speed by having more wetted surface. There is nothing wrong with this practice however, & aditional peace of mind, and safety factor. However, for true top speed, the chine walking can be driven out, in fact once you get past the first few "phases" the boat actually settles down IMO. Take your time, raising the tabs easy, along with the drive, first in smooth water with no wakes, while compensating for this "rocking" by counteracting the steering wheel toward the side of the fall. This is dificult to explain, it takes a quick motion, and just really needs to be learned. BTW, speed particulars ....... 496 HO, with Imcoand labbed prop, 68-70 with heavy tabs, 72-74 some tab, little "light", 74 - 78.4 (GPS, can post pictures) with tabs up, trimmed out. Last point, fuel and passenger load greatly affect these speeds, and the amount of chine walking, ie" more wieght, the more hull in the water" I lose 4-6 mph with full fuel and 2 more people.

I totally agree, chine walking can be driven through! My boat has no tabs and I basically "bump" the steering wheel to the right every few seconds before the walking starts to counteract it. I don't even think about it anymore.

Tabs work but scrubs speed. Trimming down works but scrubs speed. Drive through it!!! :yes:

cneidhart
08-03-2005, 09:23 AM
Has anyone changed the angle of the trim tabs?
Instead of running stock location, an inch above the hull. Remount them to the location on the ZR's, flat with the water.
This was suggested by a experienced Baja Owner. He claimed it improved the beam wakes.

cigarette30
08-03-2005, 12:06 PM
I totally agree, chine walking can be driven through! My boat has no tabs and I basically "bump" the steering wheel to the right every few seconds before the walking starts to counteract it. I don't even think about it anymore.

Tabs work but scrubs speed. Trimming down works but scrubs speed. Drive through it!!! :yes:


Now there's a person that likes to roll! :wavey: As I said, it is hard to explain how to "drive it out", but you are correct, it's a "bump" one just learns ..... and enjoys! Another note, seems the quicker (after practice) you get through the first indications, (by trimming quicker) the easier is it to reach the "sweet spot".

blackhawk
08-03-2005, 12:21 PM
Also agreed! For the first time ever I actually use the trim gauge on this boat. When I drop the hammer I look at the gauge and keep in the trim til it's where I want it. When I first got the boat I would keep trimming up slowly and it made the walking much harder to deal with!

It still walks ever so slightly, but it's actually kind of fun! Remember, as Harry Hogge once said, fast is loose and on the edge of out of control! :biggrin: :yes: