Correct Prop - 1988 Harris Flotebote Classic 240 - Mariner 45

athelu

Recruit
Joined
Jul 11, 2017
Messages
5
I purchased this boat and it feels slow to accelerate and just kind of slow in general. I know it is a pontoon, and am not expecting speed boat speeds out of it, but it really seems to labor if i get more than four people inside (says rated for 2600lbs or 16 persons). I looked through the forums previously and saw the recommendations about getting a tacho on the boat to make sure it was operating within specs.

I have finished setting up the Tacho and a speedometer, as well as using a GPS speedometer to try to validate things. All of the numbers will be from my typical boat experience which is my family of 4.

existing prop
Size perhaps 9 - 9.5 inches
only numbers i see are Michigan 189m
Idle @1000rpm
In gear @900rpm
Top speed 12mph @ 4200rpm

New Prop
Solas 1311-122-08
12.5 Inch
Right Hand
Pitch 8
Idle @1000prm
in gear @950rpm
Top Speed 16mph @ 5000rpm

I do not recall the site i used to make the new prop selection (unfortunatley).The new prop has much better acceleration - but i am worried about the RPM range at the top end.

I have not been able to find a manual for my motor. i am not sure what the deal is, but the serial number for the motor does not seem to fall within the range i am seeing posted for manuals

Mariner 45
assuming 1989 (based on boat year and mariner 45 production run)
SN#: 0B109573
 

QBhoy

Fleet Admiral
Joined
Mar 10, 2016
Messages
8,286
What size is this boat ? Presumably not 24ft the model number makes me think it might be ?
if it is...then a 40hp ain’t going to do much at all.
 

ahicks

Captain
Joined
Sep 16, 2013
Messages
3,957
That new prop is fine. Really makes no difference what boat it's on, the numbers show that the new prop is close enough for casual pontoon boat cruising.

Top rpm, without digging around looking for it, is probably 5500 - 6000. If you MUST have a prop that will allow maximum speed (maybe 1-2mph more tops) or max pulling power, you could probably go with a little less diameter to raise the rpms. With only 8" of pitch, I would not go with less pitch. My opinion anyway.
 

athelu

Recruit
Joined
Jul 11, 2017
Messages
5
What size is this boat ? Presumably not 24ft the model number makes me think it might be ?
if it is...then a 40hp ain’t going to do much at all.

Yes - this is actually a 24ft boat. 30 years ago i guess they did not want to pull skiers. The sticker says it can support a 90hp. but i paid for the boat/motor what the motor is probably worth on its own so, not looking to sink more into a larger motor (yet).
 

athelu

Recruit
Joined
Jul 11, 2017
Messages
5
That new prop is fine. Really makes no difference what boat it's on, the numbers show that the new prop is close enough for casual pontoon boat cruising.

Top rpm, without digging around looking for it, is probably 5500 - 6000. If you MUST have a prop that will allow maximum speed (maybe 1-2mph more tops) or max pulling power, you could probably go with a little less diameter to raise the rpms. With only 8" of pitch, I would not go with less pitch. My opinion anyway.

Thanks. In my initial research i knew the existing prop was really undersized for the application. The pitch is what i was unsure of. wish i could recall the site that cave me the 8" pitch recommendation. I did find a site that claims to have the manual for my motor (or at least the same manual seems to apply to all makes of my motor) that i think i will order just to be safe.
 

QBhoy

Fleet Admiral
Joined
Mar 10, 2016
Messages
8,286
Ok so I wouldn’t worry too much about it then. It’s not going to plane with a 40hp really. Maybe just take it easy and enjoy. All the best.
 
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