New to the Forum and Prop Question

[powderhoundbrr]

Been around engines my whole life (sleds, dirt bikes, trucks) but I am new to this boating thing so I have a prop question. I recently was given a boat with a 1992 Black Max 135 Outboard. It is on a 18 foot Maxum bow rider of the same vintage.

Took it out for the first time over the weekend and it sucked getting out of the hole. There was just no get up go with the boat although when it eventually got up on plane my top speed was almost 45 mph at 4500 rpm. I am wondering if a lower pitch prop would help with getting me out of the hole faster to pull up skiers and wake boarders.

It has a 17 pitch prop on it right now and from what I have learned this is already a low pitch for the engine? Can I go lower as I don't need the top speed I just need some low end grunt?

Or should I be looking at the engine and checking compression and that sort of thing?

Thanks everyone, looking forward to getting in this forum and contributing soon.

 

[QC]

Re: New to the Forum and Prop Question

Sounds a little like the boat is heavy. Yes, could be engine condition, and certainly lower pitch would help, but does seem a little sick although 45 MPH is not slow. I would:

1) Verify tach
2) Check compression for good measure.
3) Throw everything out of the boat except one anchor, and a life vest and retest.

Do you know how to use the trim? In (down) for getting out of the hole, and out for top speed. Need data with best conditions possible to start although ultimately you should prop for an average load. I am worried about soaked foam flotation. Any soft spots in the floor?

Make any good eights this season?

 

[emilsr]

Re: New to the Forum and Prop Question

Or should I be looking at the engine and checking compression and that sort of thing?

You MAY have too much prop, your rpm's are too low, but start here. Make sure it's running right first before you start playing with props.

 

[steelespike]

Re: New to the Forum and Prop Question

I do suspect a motor problem;but we need to double check your numbers.
With a 17" prop 45 mph would make about 6,200 rpm The motor is only rated for 5600.
I think you would be able to tell if it is turning 6200.4500 would produce about 32 mph.
I do suspect either the tach is low or the speed is too high.If the tach is accurate at 4500 you can't make up the difference
of 1100 rpm( to make 5600) with a prop.
A gps will check the speed. In the mean time you could check the compression and check that it is running on all cylinders.
Probably can check just by pulling them and noting the condition keep track of where they came out of.
I'll bet it was sitting a long time; most likely you will have to go through the fuel system.

 

[QC]

Re: New to the Forum and Prop Question

BTW, I have confirmed that a free iPhone GPS Speedo is accurate. Been playing with one a lot in cars with known good speedos and against other GPS systems. The one I am using is called Speed Box and despite a few annoying things it is pretty dern good for free. Just need to give 30 seconds or so to settle down and I trust it.