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powerplay230
08-31-2001, 01:22 PM
Does anyone have any experience with sternjacks? Have a 23' Deep Vee with 502/Bravo1 that doesn't go fast enough and have seen the ads for the stern jacks and their supposed 5-10 mph increases and wondered if someone has tried with or without success.
Thanks!

Cyrus
09-10-2001, 11:32 PM
Originally posted by powerplay230:
Does anyone have any experience with sternjacks? Have a 23' Deep Vee with 502/Bravo1 that doesn't go fast enough and have seen the ads for the stern jacks and their supposed 5-10 mph increases and wondered if someone has tried with or without success.
Thanks!
Hi,
the sterjacks are working fine. We had good results here in Germany, The reason is that the Drive isn´t so deep in the water at the same trim agle. I wondn´t buy the Land & Sea Jack because it stesses your Transom. Go for the Imco with external steering.
Cyrus
Germany, Hamburg

powerplay230
09-15-2001, 03:43 PM
Hi thanks for your input. Few more questions from the peanut gallery. What size/weight of hull did you use on, and with what type of power did you get what results?
Thanks,
Rich

CHUCK
09-20-2001, 10:21 PM
Originally posted by Cyrus:
Hi,
the sterjacks are working fine. We had good results here in Germany, The reason is that the Drive isn´t so deep in the water at the same trim agle. I wondn´t buy the Land & Sea Jack because it stesses your Transom. Go for the Imco with external steering.
Cyrus
Germany, Hamburg
I have a sternjack on my 23Donzi classic,454 bravo-12mph(gps) gain + much improved handling

Slick
09-26-2001, 09:42 AM
I read an article where they slapped one on a Couger 20.5 open bow. There was zero performance gain and, if I remember correctly, handling suffered as a result of it. They attributed this to the fact that the Couger hull was so dialed in as far as the bottom design and engine package that Stern Jack actually raised the prop too high and too far away from the stern. Or something like that. Nevertheless, I believe they guarantee to take the system back with full refund. However, I don't think that includes labor.
Anyway, Good luck,
Slick

Infomaniac
10-03-2001, 07:16 AM
I put a land & Sea model on my 21' Seebold. It made it porpoise like crazy. I am sure they probably improve some boats. It depends on how well the boat and outdrive setup is. The better the boat is dialed in the less you will gain from a sternjack.

OotB
11-12-2001, 10:23 PM
Interesting the Stern Jack made your 21' Seebold Porpoise. I have a 26' Seebold and I think the X dimension is too high as mine porpoises until you get to about 35mph and it blows out in turns. I was thinking of installing a stern jack as I figured that would give it more lift as well as down force. I am running a 23" Mirage. Anyone else have any ideas?

Infomaniac
11-13-2001, 06:49 AM
OotB: I was lucky if it just porpoised. A lot of the time it chimed hard. The x-dimension on mine is pretty high. I am running an Alpha SS drive, it is really short. It has never turned well, if it is trimmed any at all it porpoises like crazy. I have to trim the nose in to get it to turn. At top speed on the pad it barely turns at all.

Racing Ray
11-13-2001, 08:16 AM
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[This message has been edited by Racing Ray (edited March 12, 2002).]

OotB
11-13-2001, 09:49 PM
Infomaniac: My Seebold slides in turns. Doesn't bite at all. However, it does quit porposing at speed and flys pretty good when you get on it. No chine. Stable. Am I wrong to think I can get more lift or more tuck under with a stern jack?

Infomaniac
11-13-2001, 10:05 PM
OotB: Sorry I dare not answer that one. I can only give the input about my experience. It is a bit of work to install one. If you are willing to take it back off if it does not work, it cannot hurt to try it. The only thing is you will have to buy new trim cyl rods. You have to cut the old ones and weld in extensions as part of the installation.
My application was quite a bit different.
I was turning a blueprinted 27 pitch mirage prop, the Alpha SS outdrive ratio is 1.3:1 and the engine RPM was 5,200. It would GPS at 93 MPH. Not bad for a blown small block Chevy with one carb.
My 21 footer was their factory demo boat at one time. It has the kevlar option. It is light as a feather. Hard to compare with a larger boat.

OotB
11-14-2001, 08:05 PM
Well, I think the first thing I am going to do is try a new prop. My mechanic swears by the 4-blade hydromotive. He has test props so I think I will try a few pitches and see how they affect performance and handling. If I do a stern jack I won't be installing it myself so I need to be sure that is what I want to do. I shredded my coupler this summer and am still reeling from the cost of repairs. But, being in the Midwest, it will be a few months before I am back in action.

Stroker
11-18-2001, 05:00 PM
I had a SternJack in conjunction with an Alpha SS on my last boat (18' Python Vyper which is similar to the 18 Donzi Classic) and the SternJack made a very big improvement in handling and added a few miles an hour top end. The SternJack all but eliminated chine walking at top speed (just under 80 w/built 383 cu.in. smallblock). I could drive with two fingers, whereas before, it was all hands on deck to keep the boat stable. The other variable is the prop. I found best top speed with a Mercury Lab Finished 25" Laser II, but it porpoised at midrange. I tried Mirages and Hydromotives, but the surprising winner was a Turbo Vector 25". Its blade shape and diameter is similar to a Mirage, but the handling was amazing. With this prop I only adjusted the trim tabs when I wanted a full speed run, otherwise I didn't touch them, and trim angle was likewise totally forgiving. Never a problem with blowout or turning either. My boat was much smaller than yours, but thought my experience would be interesting. One last thing, driving in rough water with the SternJack is also much safer. The prop hardly breaks free and the landings were better. The boat acted like it was at least a foot longer. Granted, the Alpha SS drive is approximately 2 1/2" shorter so the drive is naturally very high.

OotB
11-19-2001, 08:34 PM
What about the claims that the added length of the drive with a stern jack puts undue stress on the transom. Those of you that have installed the Land & Sea Jack, did any of your mechanics say anything about this?

Stroker
11-22-2001, 03:27 PM
My concern wasn't with the transom but with the gimbal bearings and the steering. My solution was to add a Drew Marine steering stabilizer which is a form of shock absorber. I didn't observe any difference in handling, nor did I expect any. I was only seeking additional relief for these bearings and the peace of mind that came from knowing shock loads from going over wakes were being absorbed by more than the drive and the short tiller arm on the steering. If I had gone all the way, I would have installed hydraulic steering, but felt the steering stabilizer was sufficient. I trusted Land & Sea on this one.

sea buddy
11-26-2001, 07:29 AM
Hey, all Donzi classic and knock -offs--a QUESTION.
Donzi 18' classic the best boat to go 80 mph in a stiff chop?
How much slower with full versas empty fuel tank?
Same two questions for you 22' owners.
Thank you very much.

Stroker
11-26-2001, 07:11 PM
I found a light wind chop was best for top speed. The 24 degree hull is terrific for taming rough water but not at my 79-80 mph top speed. I never ran a comparison between full vs. empty gas tank. My speed runs were typically with about half a tank.

sea buddy
12-29-2001, 11:33 AM
Thanks for your honest info. How about anyone else?

slowride
01-02-2002, 12:36 PM
After I bought my sternjack I was informed
in the instructions that they recommend a
high performance gimbal ring. I Don't
remember the cost. It was not cheap. Just
something to check out. Hope this helps.
Slowride