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Schaf
08-19-2006, 11:10 AM
I went out this week and most of the day I had problems getting my 22 to ride calm. She kept bouncing. Drove me crazy. I don't fiddle much with the trim tabs unless my side to side weight needs to be compensated. Does anyone have any suggestions? Thanks.

Pismo
08-19-2006, 11:33 AM
Thats the ever famous Donzi Classic porpoising, very common. Trim all the way down, some tabs will stop it. Over 40ish it seems to stop. Hull likes 60 about the best. Some recommend Turbo props to solve, havent tried yet. Less gas in the tank seems to make mine do it less. Search porpoising, porpoise.

undertaker
08-19-2006, 11:35 AM
Do a search a lot of information on this subject...:) here is my SHORT opinion, you need to use your trim tabs more on the 22 classic, you need to do some prop testing, and get some seat time....Good luck:) :)


Undertaker:pimp:

Schaf
08-19-2006, 03:14 PM
I appreciate your time. I have a mirage plus 23..

undertaker
08-19-2006, 04:13 PM
I am assuming you have a small block in your 22 I do not remember, but I would go with a Turbo prop Poodle can get you one and he can recommend the right pitch for your set up. Seat time is very very important in these boats so take your time learn your boat. Good luck


Undertaker

Carl C
08-19-2006, 05:33 PM
I wouldn't be too quick to ditch the Mirage prop. Porpoising is normal around 40 mph but you should be able to control it with a little neg. trim and a little tab. Try to avoid that speed; after 50-55 mph all should be OK. Don't try to turn with too much neg trim; the boat will roll onto its side. Part of the reason these boats porpoise is that there is no hook built into the hull (at least on the later models) and that is a good thing!:alligator

undertaker
08-19-2006, 07:56 PM
Yes the Mirage prop is the fastest prop for 22 classics with 496 MAG HO'S which I don't think you have, but for all around performance IMO the turbo gives it to ya. Like I said get seat time, do some prop testing and do what feels good for YOU because every boat is different.....:) :) :)


Undertaker:bonk: :propeller

yeller
08-19-2006, 08:17 PM
The Turbo prop is popular, as is the Hydromotive. Lots of places will let you test different props before buying. If you can find one close to home, that's a big bonus.

BUT.....keep this in mind.

....every boat is different..... Truer words were never spoken. :biggrin.: :wink:

Schaf
08-21-2006, 01:32 PM
I have the 496 Mag not HO if that makes a difference.

undertaker
08-21-2006, 03:17 PM
Give Poodle a shout he will get you the right pitch Turbo prop to run...Good Luck:)


Undertaker

Last Tango
08-21-2006, 03:31 PM
"Tiggers luv to bounce!"

Trim tabs, maybe, but try putting the trim tabs full up, and bringing the drive trim down a bit until it stops, will cover most porpoising problems. As speed increases the porpoising decreases. It is very speed dependent. What others have said about hull sppeds and planing speeds is very correct. Under 40 MPH and your 22 (or 18, or 16) Classic just isn't happy without lots of negative drive trim and even some trim tab down. But as you increase speed, bring the tabs up first, and then the drive up slowly. Seat time will tell you where the drive should be. Over-trimming the drive up is not the answer either. Your Classic is like a light aircraft and needs constant attention to trim and tabs.

joseph m. hahnl
08-21-2006, 05:30 PM
I went out this week and most of the day I had problems getting my 22 to ride calm. She kept bouncing. Drove me crazy. I don't fiddle much with the trim tabs unless my side to side weight needs to be compensated. Does anyone have any suggestions? Thanks.





Don't go wasting money on props:bonk: ,Use it for Gas:yes:

Trim in ,tabs down.


Carl is dead wrong:boggled: , trim all the way in, will power the boat thru the turn with out cavitating. Also Cavitating is the reason for porpoising not a Hook. I also noticed that the surface tension of the water induces porpoising. It will start bouncing even before it contacts a wave.
My point is it can be the conditions, not your set up.

The tabs are the key to a smooth ride .In a slow tight turn
put them up.

joe

blackhawk
08-21-2006, 05:59 PM
Don't go wasting money on props:bonk: ,Use it for Gas:yes:
Trim in ,tabs down.
Carl is dead wrong:boggled: , trim all the way in, will power the boat thru the turn with out cavitating. Also Cavitating is the reason for porpoising not a Hook. I also noticed that the surface tension of the water induces porpoising. It will start bouncing even before it contacts a wave.
My point is it can be the conditions, not your set up.
The tabs are the key to a smooth ride .In a slow tight turn
put them up.
joe

I would NEVER go into a turn with my drive in full down(negative) position. Carl is not dead wrong, you can push a boat on it's side attempting this. Porpoising is nothing more than the prop being unable to carry the bow. At these slower cruise speeds the prop tries to carry the bow(bow goes up) and fails(bow goes down) tries again and fails, etc, etc. At higher speeds with more power at the prop it is now able to suck the stern down and carry the bow. Hook in a hull raises the stern and lowers the bow. So, boats with hook will porpoise less at mid-range because they don't try to carry the bow as high. And at high speeds they run flatter(and usually slower) because they carry the stern higher and th bow lower, making them run "wetter".

I always drag a little tab to stop porpoising but that's not saying that is the "right" way to do it. Others trim all the way down. I don't like the feeling of cruising with the drive that negative. Do what your comfortable with. Lowering the tabs and/or tucking the drive in will both help get rid of porpoising.

Get some good seat time and figure out which way you like to control it.

blackhawk
08-21-2006, 06:02 PM
On a side note, I would think that the 23 that came on the boat is too small. If I remember correctly the non-HO should run at 4800 rpm. A 24 or maybe even a 25 pitch would probably be a better choice for speed.

slapshot11
08-21-2006, 06:23 PM
Schaf,
My 22 came with the same Mirage Plus prop as yours. I replaced it with a Turbo (25P) from Poodle and things improved dramatically. There is still a slight porpose at lower speeds but nothing like with the Mirage. It can easily be corrected with the trim. I also picked up a few MPH on the top end. I'm always adjusting the trim but use the tabs very little except when the boat is fully loaded with passengers. With the Turbo prop, I can adjust the trim way up at WOT. It's a great feeling. You can literally feel the boat lift up and "unstick" itself from the water.
I also think that seat time helps control the porposing as well.
My advice, call Poodle.

Donziweasel
08-21-2006, 06:32 PM
My 16 porposes like and SOB between 30 and 40 mph, then flattens out, and I have a hook. Just put on tabs and hope this will calm it down. Engine is out, but hopefully next weekend will have engine back in and can try the tabs.

Poodle, would a Turbo help a 16 as well? Probably going to need a new prop with the new ponies in the engine. Can ya help me out?

joseph m. hahnl
08-21-2006, 06:43 PM
I would NEVER go into a turn with my drive in full down(negative) position. Carl is not dead wrong, you can push a boat on it's side attempting this. Porpoising is nothing more than the prop being unable to carry the bow. .
Well I don't seem to know what your talking about:boggled: . I do it all the time .
maybe the Minx out handles the 22? I not getting in a pissing match:wink: . drive the way you want. Do what works for you:bonk: .
I have to admit though, I am impressed with all the physist who own Donzi's:eek!: .
porpoising is caused by Cavitation of the propellor:yes: . The prop slips and then the boat falls down. That is why the four blade don't porpoise they have less cavitation. Also porposing is not restricted to Just Donzi's Allmost every boat with the trim or tilt up will porpoise:eek!: .
The only Reason I ever put the trim positive is to cavitate the prop to gain RPM, speed, and lighten the bow. All the way up to air her out for top speed:yes: .
But for the most part it's down (in) and I turn her 45 mph on a Dime:boat: .
Joe

Pismo
08-21-2006, 06:47 PM
I think Blackhawk is right on with his not carrying the bow statement. Lots swear by the Turbo prop to help pospoise. One likes the Bravo 1 4 blade labbed, I have one but have not tried it yet. My biggest problem with the Turbo is that I am already on the rev limiter with a 25" Mirage Plus so I will have too many revs with a 25" Turbo and a 27" will be too much. So I will try a 26" Labbed Bravo 1. We'll see. Its a boat so endless tinkering and tuning.......

Schaf
08-21-2006, 07:11 PM
I appreciate everyones advice. I always start out with the drive down all the way. I raise it slightly at higher speeds so the bow lifts out and I get less friction with the water. I might be miss understanding but some of you start your hole shot with the drive up? Also why would donzi put a prop on the 22 that made it porpoise? As far as turns I couldn't imagine turning with the drive up. I usually trimm the side down that I am turning towards. Otherwise it seems like the boat is going to flip. I hate that. I do appreciate everyones comments.

tiger lily
08-21-2006, 07:15 PM
i just use the throttle to fix mine throttle up, it goes away, who wants to go slow anyways :)

Donziweasel
08-21-2006, 07:15 PM
My, this thread is getting testy. Maybe we should talk about something calm, like Middle Eastern Politics:) :) :)

gold-n-rod
08-21-2006, 07:19 PM
All the way up to air her out for top speed:

Joe, you may want to clarify this statement. I know what you mean, but others might mis-understand.

:wink:

undertaker
08-21-2006, 07:42 PM
Schaf,
My 22 came with the same Mirage Plus prop as yours. I replaced it with a Turbo (25P) from Poodle and things improved dramatically. There is still a slight porpose at lower speeds but nothing like with the Mirage. It can easily be corrected with the trim. I also picked up a few MPH on the top end. I'm always adjusting the trim but use the tabs very little except when the boat is fully loaded with passengers. With the Turbo prop, I can adjust the trim way up at WOT. It's a great feeling. You can literally feel the boat lift up and "unstick" itself from the water.
I also think that seat time helps control the porposing as well.
My advice, call Poodle.


Well said....:) :)

Undertaker:yes:

undertaker
08-21-2006, 07:43 PM
I would NEVER go into a turn with my drive in full down(negative) position. Carl is not dead wrong, you can push a boat on it's side attempting this. Porpoising is nothing more than the prop being unable to carry the bow. At these slower cruise speeds the prop tries to carry the bow(bow goes up) and fails(bow goes down) tries again and fails, etc, etc. At higher speeds with more power at the prop it is now able to suck the stern down and carry the bow. Hook in a hull raises the stern and lowers the bow. So, boats with hook will porpoise less at mid-range because they don't try to carry the bow as high. And at high speeds they run flatter(and usually slower) because they carry the stern higher and th bow lower, making them run "wetter".
I always drag a little tab to stop porpoising but that's not saying that is the "right" way to do it. Others trim all the way down. I don't like the feeling of cruising with the drive that negative. Do what your comfortable with. Lowering the tabs and/or tucking the drive in will both help get rid of porpoising.
Get some good seat time and figure out which way you like to control it.


Well said again.....:) :) :yes: :yes:


Undertaker:boggled:

undertaker
08-21-2006, 07:51 PM
Beleive me I am just a newbie to the 22 classic but I have owned and driven a 28ZX, 33ZX, 22 classic and they all drive and ride differently soooo IMO get the feel for your own boat.... try some props, install some bling:) and more importantly have fun:) :) :)


Undertaker:bonk:


PS Did I mention call Poodle.....:) :) :) :) :bonk: :boggled: :yes:

blackhawk
08-22-2006, 01:06 PM
I appreciate everyones advice. I always start out with the drive down all the way. I raise it slightly at higher speeds so the bow lifts out and I get less friction with the water. I might be miss understanding but some of you start your hole shot with the drive up? Also why would donzi put a prop on the 22 that made it porpoise? As far as turns I couldn't imagine turning with the drive up. I usually trimm the side down that I am turning towards. Otherwise it seems like the boat is going to flip. I hate that. I do appreciate everyones comments.

Yes start with the drive all the way down. I also start with the tabs all the way down as well so I can baby it up on plane. Once on plane I raise the drive SLIGHTLY then I start raising the tabs. If cruising(which I rarely do :D ) then I bring the tabs up to just under halfway then trim up to speed. Not saying this is the RIGHT way but it's how I do it.

As far as going into corners with the drive tucked in ALL THE WAY I have been in boats that rolled on their side and seen it happen a few times. I would guess that it is possible for some drives tuck into a greater negative position than others. Maybe the limit switches work both ways? Propshaft depth would also play a part in this. The deeper the propshaft the more leverage it has and the greater the chance to push the boat on it's side. My Volvo would go into negative big time.

Schaf
08-22-2006, 10:36 PM
Does anyone else bring there drive up when they make turns? THe 22 is new to me but in the past with other boats I never raised the drive to turn.

RedDog
08-22-2006, 10:44 PM
Does anyone else bring there drive up when they make turns? THe 22 is new to me but in the past with other boats I never raised the drive to turn.

In a Classic it probably is not so crucial either way. In a stepped hull, like a ZX, my understanding is that the drive MUST be trimmed out at higher speed turns

Magicallbill
08-22-2006, 11:55 PM
Classic 18 Scorpion Pak.
When I go into a tight turn with positive trim, the boat starts jerking/porpoising.With full neg trim, I go thru the turn smoothly.
My boat jumps at low-to-mid planing speeds if the trim is out any. To stop the porposing, I trim in,and it goes away. Every time.
At speeds above 40-45, I trim out, the boat breaks loose..life is good.
I know we're talking about a 22..Is an 18 that different?

MB

Lenny
08-23-2006, 01:21 AM
In a Classic it probably is not so crucial either way. In a stepped hull, like a ZX, my understanding is that the drive MUST be trimmed out at higher speed turns

RD, don't you mean "IN" against the transom ???

Schaf
08-23-2006, 08:51 PM
Just to make sure. Positive trim in drive up and neg trim is drive down?

MOP
08-23-2006, 09:31 PM
Yes Pos Up & Neg Down or tucked.

Schaf
08-24-2006, 11:37 AM
When you trim the drive up or pos trim it how much do you trim? Just a little very much slightly ect......

yeller
08-24-2006, 09:48 PM
When you trim the drive up or pos trim it how much do you trim? Just a little very much slightly ect......
Hey Schaf,
Here's some advice from another relative newbie. I just went through the problems your having. I can't take credit for anything I give you...it's what I was given from more experienced people here.
Before you know what is neg/pos trim, you have to locate neutral position first. I took a 4' level to the bottom of the boat and adjusted the trailer jack until it was level. Then I took a 1' level and put it on the drives' cavitation plate. I adjusted the drive until it was level. That is neutral position. I marked this position on my trim gauge with a piece of silver tape. Anything below this point is negative and anything above is positive.
My boat porpoises HUGE!! Up to about 50, I generally run with the drive in neutral position (or very slightly positive i.e.: the trim needle is less than 1/8" above my tape) and control the porpoise with the tabs. Higher than 50 it's tough to say what I do because different conditions may mean more neg trim and less tabs, or vice versa, or more/less of both. I porpoise well into the 70's, so I almost always use some tabs, but I can usually get away with pulling the starboard tab all the way up.
I have about 40hrs driving time on mine and I am just now starting to get comfortable with it. It's always going to be a pita, but you learn to correct it quicker with more seat time and it becomes less and less of a concern.
And as others said, I alway start off full neg trim and tabs fully down. I had automatic retract on my tabs, but I disconnected it because it was a pita to have to drop them from the full up position everytime I started the boat.

Schaf
08-30-2006, 11:02 AM
Thanks for everyones advice. It seems like when i turn sometimes the boat seems like its going to roll over. It can be a little scary at time.

CHACHI
08-30-2006, 12:26 PM
Thanks for everyones advice. It seems like when i turn sometimes the boat seems like its going to roll over. It can be a little scary at time.How fast are you going? At slow speeds I find that to be the feeling, same as the Minx. Ken

Sofa King
08-30-2006, 12:54 PM
I have a lot of bouncing to between 2000-3000 rpms. I hope my new Turbo 1 prop 25 p will cure this. I'm putting it on tommorow. What kinda tool and size do I need to remove my old Mirage +?

TY
Sofa King

Schaf
08-30-2006, 07:25 PM
Its at all speeds. Not going to slow.

Pismo
08-30-2006, 07:30 PM
Seat time..........These are all normal things for a Donzi.

Carl C
08-30-2006, 08:02 PM
Seat time..........These are all normal things for a Donzi. Yes and they are why we (I) love Classics. You can dip the rubrail in a slow tight turn and, just as the boat starts to roll harshly onto it's side, give it some quick positive trim and straighten the wheel and she'll settle smoothly onto the bottom. Bouncing is easy to control with a little negative trim and a little more speed and rarely a little tab may be needed; at least on my boat. Classics are not for beginners or casual boaters. They are a drivers boat and I love driving mine; especially 70+ in 2-3 foot chop which requires constant tweaks of trim and tabs as conditions vary fast at that speed.:boat: :yes:

BUIZILLA
08-30-2006, 08:23 PM
especially 70+ in 2-3 foot chop you sure about that... :wink:

Sofa King
08-30-2006, 08:36 PM
I don't use my tabs over 50, can't imagine using them over 70.

Carl C
08-30-2006, 08:43 PM
you sure about that... :wink: I really try to not exargerate waves and I think I'm sometimes too conservative. 3 ft chop is easy at speed. honest four foot rollers can be taken head on but 4 foot washing machine chop must be taken slowly. 5-6 footers are too much for planing speeds. This is what I've learned this summer! Remember that this is a touchy subject........like milk:wink: Sofa, just a little tab will help keep the boat level while skipping over the top of the chop when it gets rough. I don't like to run much neg trim; it plows the bow and makes the boat feel unsafe and increases the chance of a stuff. Again, just my personal technique.

Schaf
08-31-2006, 09:58 AM
this is all great feed back. I need to take tight turns on certain lakes due to the fact the lake is not big enough to make a wide turn. I can't believe you dont use much tab action. Do drive with the boat full or passengers or just yourself? I think it makes a big difference.

MOP
08-31-2006, 10:35 AM
I boat on two big shallow bays that build a nasty close chop, hopefully it is a head or following sea. I do my level best not to air the drive, when I am in a chop I use moderate tabs just enough to keep the bow from getting to high but also add enough trim to keep the light so the bow does not slam. Another thing I have found is when throttling back when riding on top of a chop is to turn into the troughs it does away with the slam the hull gets when stopping straight on. This has worked very well on both my 16 and now on my 22, I do appreciate the 22 a lot more. Don't just sit there and get flogged experiment, as long as the sea is not to big you can find a happy medium.

Carl C
08-31-2006, 02:07 PM
:yippie: I've gotten out of shape a few times but not quite that bad!:eek!: :crossfing

DonCig
08-31-2006, 07:07 PM
Your Classic is like a light aircraft and needs constant attention to trim and tabs.
__________________

Mark
Supreme SEADOG

Tborisch
04-12-2010, 09:58 PM
how do I get in touch with poodle?

Thanks,
Tom


Schaf,
My 22 came with the same Mirage Plus prop as yours. I replaced it with a Turbo (25P) from Poodle and things improved dramatically. There is still a slight porpose at lower speeds but nothing like with the Mirage. It can easily be corrected with the trim. I also picked up a few MPH on the top end. I'm always adjusting the trim but use the tabs very little except when the boat is fully loaded with passengers. With the Turbo prop, I can adjust the trim way up at WOT. It's a great feeling. You can literally feel the boat lift up and "unstick" itself from the water.
I also think that seat time helps control the porposing as well.
My advice, call Poodle.

Dr. David Fleming
04-12-2010, 10:34 PM
Well you guys covered most all aspects of trim and hull except that "weight" also affects the whole equation. Change the gas in the tank, get a crowd in the cuddy and the whole trim equation needs to be redone. basically a boat heavy in the ass will need more negative drive and tab to lift the back of the boat. Get the crowd forward and it is reverse, positive drive trim and less tab to get the "weight" in the bow lifted out of the water.

The donzi 22ZX with the step hull is famous for "stuffing" with negative drive trim. What is stuffing? Well its like a spin in a car. the whole boat pivots at high speed around the bow which becomes stuck in the water so to speak. This is highly dangerous and can kill. Last year a guy on this site was clowning around with turns at 35mph and drive trimmed in - tabs down. The boat spun and threw him into the windshield which busted. He was in the water while the boat slowly did circles and he tried not to drown. The 22ZX has a sticker on the dashboard which says "do not remove trim limiters." But they never tell you what they are. In 1999 they were two black aluminum blocks that were placed on the trim cylinder inner bolt. THey stoped the drive from coming into negative position. This was a safety thing and later Merc went to inserts used inside the trim cylinders.

All of this danger should not alarm you, if you took your car stearing wheel and gave it a violent yank at speed, you would spin out the car. IF you violently stomped on the brakes at speed you might get rear ended and spin the car. You just take these dangers for granted - you will get used to your boat trim also. Buy Donzi not Toyota.

DC18
04-12-2010, 11:42 PM
I appreciate your time. I have a mirage plus 23..
Had a Mirage 23+ on my 18. Boat porpused between 25 mph up to arround 40mph. After that, no problem. Switched to a Hydromotive (from the cleaver, was hitting rev limiter) and no more porpusing. Boat is rock solid. Am still testing. Mirage is a good prop, but have heard that they usually need to be "tweaked" for most applications. I DO NOT have tabs.