1860 w/ 50HP motor - appropriate propeller pitch?

[nathanralph]

Well, I have a flat bottom 1860 john boat. The prop it had when I bought it was this stainless steel prop that says 10.50x12. I'm assuming this is a 10.5" diameter prop with 12" pitch. As far as I can tell, this is probably not the prop that came with the motor, but when I first got this boat I didn't know anything about pitch (and still know very little).

Now, the motor is a 50HP I believe, but I can't remember what brand - I think it's a Johnson. The guy painted it all camo (used to be a duck boat) and I couldn't find numbers under the hood anywhere.

This prop setup has pushed us pretty well for a few years before the hub spun out. Now, I need to get this rebuilt and probably grab another prop as a backup.

So my question is 2 parts -

1) Is this diameter/pitch combo probably appropriate for my setup? I run LEDs (for bowfishing) and a 101 troller so I usually have 10-12 deep cycle batteries and 3-4 grown men on the boat, plus bows (and hopefully fish).

This is no race boat, so hole shot isn't really important - I'd rather have top speed and stay in a safe RPM range.

2) Does anyone recognize this engine off-hand?

Not sure if it's relevant: the prop is 13 spline.

 

[steelespike]

Re: 1860 w/ 50HP motor - appropriate propeller pitch?

The prop size and being a black 4 cylinder I'm guessing a merc . There may be some numbers somewhere on the mounting bracket.
Is the boat a bare bones 1860 or does it have a floor,live well lots of batteries gear etc.
We need the lightly loaded wide open throttle rpm and gps speed., You can get a new hub pressed in the prop.
Get us the performance numbers. If a change is in order you can keep the prop as a spare or sell it.
An induction tach will get your rpm.For best performance its best to be sure the motor is able to operate within its rated wot rpm.

 

[steelespike]

Re: 1860 w/ 50HP motor - appropriate propeller pitch?

The prop size and being a black 4 cylinder I'm guessing a merc . There may be some numbers somewhere on the mounting bracket.
Is the boat a bare bones 1860 or does it have a floor,live well lots of batteries gear etc.
We need the lightly loaded wide open throttle rpm and gps speed., You can get a new hub pressed in the prop.
Get us the performance numbers. If a change is in order you can keep the prop as a spare or sell it.
An induction tach will get your rpm.For best performance its best to be sure the motor is able to operate within its rated wot rpm.
The stainless prop is worth getting fixed and appears to have been on the boat for some time.

 

[nathanralph]

Re: 1860 w/ 50HP motor - appropriate propeller pitch?

The prop size and being a black 4 cylinder I'm guessing a merc . There may be some numbers somewhere on the mounting bracket.
Is the boat a bare bones 1860 or does it have a floor,live well lots of batteries gear etc.
We need the lightly loaded wide open throttle rpm and gps speed., You can get a new hub pressed in the prop.
Get us the performance numbers. If a change is in order you can keep the prop as a spare or sell it.
An induction tach will get your rpm.For best performance its best to be sure the motor is able to operate within its rated wot rpm.
The stainless prop is worth getting fixed and appears to have been on the boat for some time.

I'll definitely be getting it fixed, as a spare at the very least. I just figured since I'm changing it out I'd check and make sure the pitch is OK and maybe buy one better suited for the boat.

I guess I need to get a tach so I can figure it out. I stripped it completely and built a lightweight aluminum bowfishing deck on the front. The weight comes in the 10 or so deep cycle batteries (for 36V troller, 24V LED lights and backups) and 3 or 4 guys.

I'll check around the mounting bracket today.

 

[phillnjack2]

Re: 1860 w/ 50HP motor - appropriate propeller pitch?

gfet a 10x14 and vent it. then you can have same pull away maybe a touch more and definitely more top end.
once up on plane the vents don't make any difference but the power will now be on tap already due to spinning up and let the prop run.
But by having 3 big blokes and all those batteries it wont be a race boat, youl be lucky if it hits 30mph.
you would probably find your prop spun do to not getting going enough from the pull away and biting but struggling on the bush.
or you hit sand or mud with it. ?

phill

 

[Frank Acampora]

Re: 1860 w/ 50HP motor - appropriate propeller pitch?

That is a later model four cylinder, twin carb, oil injected Mercury. Be certain to keep the blue colored plastic oil tank on the front of the engine full with TCW-3 oil OR--if you disconnect the oil injection system, run 50-1 gas-oil mix. Michigan and mercury offer a wide range of props for that engine. You can buy a new one on iboats store or a used one on the auctions.

 

[nathanralph]

Re: 1860 w/ 50HP motor - appropriate propeller pitch?

gfet a 10x14 and vent it. then you can have same pull away maybe a touch more and definitely more top end.
once up on plane the vents don't make any difference but the power will now be on tap already due to spinning up and let the prop run.
But by having 3 big blokes and all those batteries it wont be a race boat, youl be lucky if it hits 30mph.
you would probably find your prop spun do to not getting going enough from the pull away and biting but struggling on the bush.
or you hit sand or mud with it. ?

phill

We definitely hit sand with it in 2012. It spun at the end of 2013 and probably was just worn out. We used it a lot.

Thanks for the help, folks!