Jackplate setting and Prop Selection 92 Glasstream 17V

[JgarrettS86]

I just purchased a 1992 Glasstream 17V Fish and Ski. The boat has a 98 115 Fast Strike Johnson with a 6" manual jackplate, also a 13.5x22P Raker prop. The boat gets on plane very fast and tops out at 53mph @ 5900 rpm or so. The propshaft is set at 7.5" below the pad of the boat, which seems to deep to me. I raised the jackplate to where propshaft is 4.5" below pad of boat and top speed fell of to 49mph @ 6000 rpm. Can someone explain to me why the boat has abetter top speed with the prop so deep in the water??? Also I was thinking of trying a 13.5x24P Raker prop because the motor runs threw the 22p so fast and is very high in the motors rpm range at wot. Any answers and suggestions would help. Thanks Garrett

 

[steelespike]

Re: Jackplate setting and Prop Selection 92 Glasstream 17V

Can't tell you exactly why you lost speed. Though most likely the prop simply can't hook up well at that height.More than likely the po had it setup best for his purpose.
If you want to take advantage of the jack plate go back to the 7.7" and lower it another 1/2" to an inch lower it till performace fades.Then raise it a little at a time to the point performance fades. Somewhere in there will be the best spot.In the old days we used to raise 1/4" at a time
to get the sweet spot with smaller motors.

 

[JgarrettS86]

Re: Jackplate setting and Prop Selection 92 Glasstream 17V

Ok im gonna put it back to the setting where it was when i got it (7.5") and adjust from there. But what about the prop? I can get my hands on a 13.5x24 raker pretty cheap. Like I said, im running a 13.5x22 raker right now and it has tons of low end and will get on plain from a dead stop in like 5 seconds flat! The motor is in no real strain at wot and the rpm are high as well. So would the 24p raker be a good thing to try? Im tryin to squeeze 60mph out of the lil ol boat. Hull weight is around 1050lbs i think.

 

[steelespike]

Re: Jackplate setting and Prop Selection 92 Glasstream 17V

I'm a little surprised at your prop size and top speed with a 115.
Typical props run about 17-19.
The setups I've seen running around your speed usually run about 20" props boats about 1000-1100.running over 50 at about 5600 rpm.I supose if the Glassrtream is a really fast hull you might run a 24" prop but I wonder if your tach may be a little optomistic.
Even the Etec 115 ho only runs a 20 on an 1400lb bass boat at 5700 and 53 mph.

 

[JgarrettS86]

Re: Jackplate setting and Prop Selection 92 Glasstream 17V

Yeah I read up un the boat before I bought it and from what i found out it is a high performance style hull. And like i said it will jump on plane fast and top speed gps is 53 with me and gear @ about 5800-5900 rpm. I know it sounds hard to believe, but it dont act like it even know the 22p is back there! I will try a 24p just to see what happens. Thanks for the input.

 

[Dhadley]

Re: Jackplate setting and Prop Selection 92 Glasstream 17V

A great question with a real simple answer. The early generation Rakers had great lift. The faster you went the more lift you got. When they lift the boat they also lift the motor which lifts the prop. On some performance hulls with hydraulic jackplates it's not unusual to drop the plate as you increase speed.

 

[JgarrettS86]

Re: Jackplate setting and Prop Selection 92 Glasstream 17V

That makes alot of sense, and also explains why it has better top speed at a deeper prop setting! I have an early style raker on the way just like the one I have now but a 24p. Is 60mph gonna be a posibility???? Thanks

 

[steelespike]

Re: Jackplate setting and Prop Selection 92 Glasstream 17V

A great question with a real simple answer. The early generation Rakers had great lift. The faster you went the more lift you got. When they lift the boat they also lift the motor which lifts the prop. On some performance hulls with hydraulic jackplates it's not unusual to drop the plate as you increase speed.

It pays to have someone really in the know.

 

[steelespike]

Re: Jackplate setting and Prop Selection 92 Glasstream 17V

That makes alot of sense, and also explains why it has better top speed at a deeper prop setting! I have an early style raker on the way just like the one I have now but a 24p. Is 60mph gonna be a posibility???? Thanks

I think 7 mph when your allready over 50 is asking a lot. But nothing ventured nothing gained.
Looking for your report.

 

[JgarrettS86]

Re: Jackplate setting and Prop Selection 92 Glasstream 17V

I should get the 24 Raker by Friday and do some testing over the weekend. Ill post the results when I do.

 

[JgarrettS86]

Re: Jackplate setting and Prop Selection 92 Glasstream 17V

55mph @ 5600 rpm with the 13.5x24 Raker, Jackplate still set at 7.5" below the pad. I havent had time to make any adjustments from that point yet.. Gonna try 6.5" below pad and see what happens.