Need higher pitch please take a look tell me what you think

[Mike82]

This is my setup:

Prop ss 48-16988-18 I think it has a 13.5in diameter
1998 115hp mercury 2+2 max RPM 5250
1998 lund pro v 1775 32 gallon gas tank don't usually run full though
Maxxum 101lb
3 size 30 deep cycle batteries
1 cranking battery
8hp kicker motor 73lbs
3 bank onboard charger
Plus 2 live wells one usually full when fishing
usually fish with 1 other guy 240lbs or so

After I added the trolling motor and the 8hp my RPM's are way too high. At the moment I can't even have the throttle all the way down and I'm over max rpm that's without even trimming it up. I know if I trim it up I would be over 6000 RPM's easily but don't want to try. What would you guys recommend going to I'm looking to drop around 800 RPM's or so.

 

[Mike82]

Re: Need higher pitch please take a look tell me what you think

I forgot to add my speed which is around 30 at 3/4 throttle because if I go full throttle I hit around 5700 to 5800rpms. Before I added the trolling motor and kicker it would go around 40 but even then with this prop I could not trim at all without over revving the motor.

 

[steelespike]

Re: Need higher pitch please take a look tell me what you think

We need to confirm your tach is accurate before any prop selection.
Really can't make head or tail out of your numbers Without a wot properly trimmed rpm and gps speed.
When the rpm goes up when you add weight makes the tach suspect.
A 18" pitch is certainly in the ball park.

 

[Mike82]

Re: Need higher pitch please take a look tell me what you think

We need to confirm your tach is accurate before any prop selection..

How would i go about testing my tach to see if it is wrong? It seems to work at idle at around 1000rpms.

 

[Mike82]

Re: Need higher pitch please take a look tell me what you think

So if my weight goes up my rpms should go down and not up?

 

[steelespike]

Re: Need higher pitch please take a look tell me what you think

If you have a regular marina you might be able to borrow a shop tach or have the tech go for a quick ride.
There may be a switch on the back of the tach sometimes you can note the position and operate the switch to clean the contacts.
You could get a Tinytach about $47 will work on most any motor now or in the future.Can be hand held or installed.