Posts: 96
Location: Eden Prairie, Mn. | Kevin,
With the new info. provided we can go to work.
Manual trim bar- all the way in
Motor mounted at top hole- lowest mntg. position
New /undinged alum 12 1/4 x 15 prop
A tachometer will make testing extremely easy !!!
Lets start with the spare 17 pitch prop - the motor will never 'pull' the prop, not enough horse power. It's your
'get home' prop. No amount of tweaking will get you enough RPM to make the prop work.
The 15 pitch is your runner-
First - move the trim bar out one hole. Ck. speed, general handling and load carrying.
If faster and the boats handling is the same or improved - good.
Step 2 - Raise the motor one hole. Ck speed, handling and load carrying. pay attention to 'porpoising' lift/drop of bow.
Ck. speed, general handling and load carrying
Step 3 - If not move trim bar back in original position -
Did perf. drop or increase or remain the same ?
Step 4 - If it dropped, go back to the second trim position and raise the motor to the next hole (2nd hole)
Ck speed,handling and etc with the motor in the second hole up and trim bar out one hole from original position.
Step 5 - If worsened or same, move trim bar in to original position.
Ck speed, handling etc.
Step 6 - Move trim bar to best position.
Step 7 - Buy a performance mid-range HP SS prop or the a Hustler perf. Alum. prop and start testing all over.
You will gain top-end by systematically tweaking to find the 'sweet spot' but,
I feel that you may have rough water cavitation troubles and hi-speed turning issues with your alum. prop.
I had a '87 40HP Johnson on a 16' LUND Rebel Pike Special, It spun a almost the same prop you have and I raised the
the motor 2 holes and made a custom 'trim bar' for half way between the fisrt hole and the second hole. The trim
adjustment bar from one hole to the next was just too much for my boat/hull design. That was 8 years ago, before
I knew much and it taught me a lot about fundamental motor height, trim, props;load capacity, hull and balance.
I was able to get her to almost 35mph !!!! running with a light load.
Mother |
