Performance numbers

[sniper222]

New to the board, have been reading non-stop for 2 days, so much info looks like a lot of great people, hoping I can help out when I know the answers to the questions. To start with, I have a question of my own.

Have a 1997 ZX 185c with a 150 ProV, Tempest A40 25P. I am only getting about 57MPH top speed (GPS) at about 5100-5200 RPM with me and gear. I don't really know motor height, as I don't know exactly how to measure it. Another stupid quesiton, how are you adjusting motor height, I assume using a floor jack or is there a better way?

My prop does have a couple nicks on it that need to be worked. Others seem to be getting as much as 10MPH more than I do with similar prop, at higher RPM.

Would like to get more out of it if possible. I am going to get a new prop, just as a spare, should I stick with the tempest A40 25P or should I be looking at something else to increase performance and RPM? What should my RPM's be without blowing up the motor.

Any advice appreciated

[Rodney Bledsoe]

First off WELCOME why did you wait 2 days

1- I'm not sure but do you have a jack plate on the between the boat and motor. if you do you'll need to raise the motor there.
2- motor heights is the distance from the middle of the nose cone to the bottom of the pad on the boat.
3- you will loose speed with a dinged prop. Almost every one on BBC sends there prop to Marks High Performance Propellers for repairs, he is a BBC sponsor and the prop forum moderator.
Also if the prop has hit something hard enough to put dings in it the prop shaft might be bent.
By no means am I an expert, sometime I can be a good listener I'm sure some with better knowledge of your boat spec will chime in soon.

http://www.bassboatcentral.com/marksprops1.htm
Here is a link to Marks prices and address if you chose to send the prop to him.


Modified by Rodney Bledsoe at 5:04 PM 7/11/2008

[Blanked Again]

I would think that you would need a 23 pitch prop. Check out the skeeters owners list. It will have other boats similar to yours with what they are running with the numbers.
http://www.bassboatcentral.com/skeeter2.htm

[Olddawg]

I'm getting almost 66 (GPS) with a 24P Tempest 2 @ 5600 RPMs. 6" Jack plate set @ 3 1/4" below the pad. This is with a 96 Mariner 150 Magnum lll on a 96 Skeeter ZX 180. I feel you would be better off with a lower pitched prop and at least a 6" jack plate.

[sniper222]

I do have a jack plate, after reading more I assume I need ot measure it as they come in different sizes, my rough guess would be about a 6 inch jackplate.

I assume I can put a floor jack underneath, loosen the bolts and raise the jack and re-tighten or is that a stupid idea/assumptino?

[sniper222]

After looking what other's use on pitch, am I correct in assuming I am trying to get my rpm's up by changing the pitch. Other than buying or letting Mark modify, it seems a lot like trial and error, are there prop shops that let you borrow in larger areas like Atlanta to find the right prop?

[Rodney Bledsoe]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sniper222 &raquo;</TD></TR><TR><TD CLASS="quote">I do have a jack plate, after reading more I assume I need ot measure it as they come in different sizes, my rough guess would be about a 6 inch jackplate.

I assume I can put a floor jack underneath, loosen the bolts and raise the jack and re-tighten or is that a stupid idea/assumptino?</TD></TR></TABLE>

Jack plates should have 2 bolts on each side, loosen them. Looking down between the transom and the motor there should be a long bolt. Screw it down it should raise your motor.
You water pressure should be something you watch closely. You will loose pressure the higher you raise the motor. Don't let the pressure be lower than 12 psi at wot.
One thing I did while messing with my jack plate was take a pencil and mark my start point for reference, and every increment you move it maker it. So when you find out where raising it too far you'll loose performance and hole shot, it's easier to get back where it ran the best. When you find the sweet spot all the old marks will erase.
I'd only raise it in 1/4" increments.
Raising the motor will increase RPMs some, but smaller prop pitch will get more.
Make sure you get a new prop or the damaged one fixed. you will not see real results on a damaged prop. If you prop is damaged makes sure you check out the prop shaft see if it's bent. A slightly bent shaft fill damage the lower unit.
If you have a shop that let's you try out props sizes that'll be a great help before you drop $$$$$$

[-BjBnet-]

Sniper that's too much pitch....go to a 23-24 to bring up the rpms...your motor is thristy for more revs...
Listen to the guys here.....play with your j/p height and make sure you take notes (on paper!!) everytime you go out....rpms, water pressure, j/p height, even air and water temp can make a difference, note how much fuel you have so you can compare with roughly the same weight, wind .....

You can often get a good tempest prop for cheap on ebay, that's where I got my 23 and 24 Tempest and 23 Trophy.
Good Luck

[sniper222]

Thanks, good advice

Is there an RPM range I should be shooting for or a Max

[Bass Junkie]

You need a 23p prop, adjust plate, and shoot for the 5800 range with a full load. Although, you might not see 5800 right now in the heat of the summer, expect an increase of 150-200 rpms in the cooler months.