Z-25 top speed and prop selection

[duckkilr]

I have an '87 Donzi Z-25 with a 454 HO engine. I was wondering what kind of top speed I should have and what size prop I should use?

Thanks in advance!

------------------
'87 Donzi Z-25
454 HO
Alpha

[Steve Smith]

I'm running a 23" Mirage 3 blade on my 1988 with 1993 454 Mag. On a cool day with less than 1/2 a tank it will run 60 on GPS (57-58 on speedo--I may own the first boat in history with an actual speed in excess of speedometer). I have a 25" Mirage that we use on boat trips (much better mileage).

[Donzigo]

I have a1987 Z-25 and run the EXACT same set-up as Steve Smith. runs perfect and at the same MPH as Steve's. I have 1998 454 MPI Merc w Bravo outdrive.

[johndmay]

My '88 Z-25 went 62 on the gauge, which was probably about 57, with the 454 Magnum and 23P prop. I installed a new 550 HP 502 and it went 67 on GPS with a 26P. It now has a 1998, 415 HP 502 MPI with the 23P back on, and runs at 63 on the GPS. Biggest problem I had with the '88 Z-25 was porpoising.

------------------
John D. May
Manotick, Ont.
www.jackmay.com

[PachMan]

johnandmay- Did you ever try blueprinting the hull like you were talking about in your posts from last year?

I was considering buying an '86 Z-25. What is holding this boat back speed-wise? Too heavy? Hull design? Is porpoising a common problem?

[johndmay]

Hi Pachman,

I came close to getting the hull done, but the logistics were getting way too weird. Then I lucked out on a '98 28ZX with a single in it-perfect for the new 502 that was wasting it's time in the Z-25. So now I have two Donzi's, the '88 Z-25 with a two year old 502, 415HP MPI, and a '98 28ZX with a new, built, 502, 550HP.

Both boats run the way they should now. The 28ZX does 70 on GPS. I added an extension box to it when we installed the big mill. Not bad for a 28 footer with a single. And the Z-25 does an honest 63 (but still bounces). With the tabs down, it runs flat and still holds onto about 60-61.

Anyways, as georgeous a boat as the Z-25 is, I've learned that hook and rocker are pretty common for that era. And the tabs do manage to settle it down, but it's like driving a corvette pulling trailer.

If I'd had the facilities to flip the boat, I'd have done the blueprinting, cause I hate to give up on stuff like that, but when that nearly new 28ZX showed up, I jumped ship, so to speak.

[PachMan]

So are you saying that the Z-25 molds had some hook or rocker built in, or did quite a few of the hulls simply come out "imperfect" resulting in hook or rocker? I know this is a donzi board, so I will get biased opinions, but I'm deciding between a Sea Ray Pachanga 22 and the Donzi Z-25, trying to assess what will make a better budget sport boat, and which will respond better to future mods.

[Montauk Crossbow Z33]

I've had my Z-25 for 2 years and I never had any porpoising problems , in fact every time I'm out with my friend his formula 242 LS seems to porpoise like crazy ,as far as the tabs go I never seem to have a reason to use them.

[Frank Civitano]

Pach Man. I dont want to sound bias. When you talk performance boat. Pachanga doesn't count. My freind has his for sale and the boat is not that fast he has a 454 with a 330 hp. Paid a ton of money for it and cant get rid of it. The boat is still a Sea Ray . When you think of a Performance boat, Donzi,Cigarette,Magnum,Formula,Hustler,Outerlimits ,Baja and so on. Sea Ray Bayliner Cobalt,Mariah they are family oriented boats. You will Never get the reSale value from a Pachanga like a Donzi. Name reconition is one. Everyone in the boating world knows what a Donzi is. Because every kid wanted one! Sea Ray is a good boat in the family world of Cruisers not performance. Best of luck in your choice.

------------------
Frank Civitano

[Steve Smith]

I agree with my northern bretheren. I have owned a Z-25 for four years and have loved every second. The only porpoising I have ever experienced has been at WOT and it has been negligible.
As for value, I can think of no other boat that would come near to the "bang for the buck" that I have received from my Donzi. Yes, I am one of those who grew up drooling over the sweet 16 that regularly ran up and down our lake and when I finally had the chance to upgrade to a "real" boat, I went for the Donzi. From the spacious engine compartment (I'm 6'4" and every bit of 300 lbs and I can crawl inside and work on the engine) to the rock solid construction and attention to detail, I have found absolutely nothing about my boat that I can criticize.

As for resale value, I sadly/happily am in the process of getting ready to go to Houston to work a trade for a 272 Formula and will end up recouping most if not all of my initial investment.

Sea Ray builds a great boat--my parents have a 23' that they love. It is beautiful, stable, easy to drive, easy to maintain and is just a great boat. They also used to own a Caprice Classic which was a great car for the same reasons. Great car, but I had a lot more fun in my '69 VW bus as I ever had in the car. Not that the Donzi is a VW, but they're both classics to me.

Buy the Donzi. I guarantee you'll never regret it.

------------------
Steve Smith
Cullman, AL
scsmith@hiwaay.net