Prop Selection for Mercruiser 3.0 at 5000-8000 Feet Elevation

[jedfish]

I have a SeaRay 160 with a Mercruiser 3.0 135hp i/o and need to choose the diameter and pitch for a new prop this season. Last year I ran a 14.5D x 18P and could hardly get a skier out of the water. It would max out around 3800RPMs, with ideal WOT at 4500RPMs.

The lakes I frequent are in Idaho between 5000-8000 feet in elevation, and I have been told I need to lower my pitch. I am thinking about dropping it down to a 15P or 16P. Any recommendations on diameter and pitch would be greatly appreciated.

Thanks!

 

[jestor68]

Re: Prop Selection for Mercruiser 3.0 at 5000-8000 Feet Elevation

The Mercury prop selector says a 15 X 15.

A Solas would give the most bang for the buck.

 

[dazk14]

Re: Prop Selection for Mercruiser 3.0 at 5000-8000 Feet Elevation

A 15" pitch would probably run around 4600 and be nice with a skier.

Select a lower diameter prop(of available choices) that will likely be 15"(14's good). Avoid the higher diameters...15-1/2 up(not for a 16' boat).

A 15 x 15 Solas Amita is a good prop for $112 here on iboats.

 

[fishrdan]

Re: Prop Selection for Mercruiser 3.0 at 5000-8000 Feet Elevation

You need 1000 RPM to hit the engine's top end of it's WOT RPM range, so I'd definitely go with the 15x15 suggested by others.

The 15P prop should put you at the bottom end of the WOT RPM range, more pitch would drop the engine out of the WOT RPM range..

 

[Sea Rider]

Re: Prop Selection for Mercruiser 3.0 at 5000-8000 Feet Elevation

Don't know about Merc Inboards, but on outboards running at high elevation is a combination of less diam carb jets + less prop pitch maintaining same diameter to deal with best lost rpm and overall performance.

Happy Boating

 

[fishrdan]

Re: Prop Selection for Mercruiser 3.0 at 5000-8000 Feet Elevation

running at high elevation is a combination of less diam carb jets + less prop pitch

Leaning out the carb is a good suggestion, if he's running at high elevation all the time.

 

[Sea Rider]

Re: Prop Selection for Mercruiser 3.0 at 5000-8000 Feet Elevation

Leaning out the carb is a good suggestion, if he's running at high elevation all the time.

Yes, all the time at a given fixed boating location. Probably not applicable if running at two different 5000-8000 Ft height locations with such a small height difference. In that case just play with prop pitch as recommended.

Happy Boating

 

[Starcraft5834]

Re: Prop Selection for Mercruiser 3.0 at 5000-8000 Feet Elevation

The Mercury prop selector says a 15 X 15.

A Solas would give the most bang for the buck.

I have one of these in 4 blade... as dazk14 said too........

 

[fishrdan]

Re: Prop Selection for Mercruiser 3.0 at 5000-8000 Feet Elevation

Probably not applicable if running at two different 5000-8000 Ft height locations with such a small height difference.

I was thinking of going from lakes at 0-1000' then up to lakes at 5000-8000, then back down again. I have this scenerio and re-jetting is kind of a pain, but I do it if being at altitude for more than a day.

If the OP is running at high altitude of all the time, jet for the lowest altitude and leave it there. (Just be aware the carb will need to be re-jetted for low altitude usage.)

 

[jedfish]

Re: Prop Selection for Mercruiser 3.0 at 5000-8000 Feet Elevation

Thanks, everyone! I'll try a 15x15 and let you know how it goes. Still have a couple of months before the lakes thaw out though...

Cheers,

Jed