prop help request

NHGuy

Captain
Joined
May 21, 2009
Messages
3,631
Hey,. I've been lurking for a couple of months and I'm ready to ask for a little input.
Boat is a 1988 Baja Sunsport 196 with a 5.7L, 260 HP, 4 barrel Rochester carb, Mercruiser Alpha 1, 1.47 ratio, 14.5 x 19 Michigan wheel Vortex prop. I get 51 MPH at 4800 RPMs.There is more throttle available, I just won't run past 4800 RPMs. I weighed it with full fuel (27 gallons) but I do not know the trailer weight. Trailer is a Shoreline single axle galvanized with rollers, no brakes and manual winch. The trailer axle weighed 3660 lbs and the tongue is about 175 lbs. My inferred boat weight is 3000 to 3200 lbs. Boat is 19 foot 6 inches long, 20 degree deadrise vee bottom with no pad and I do not remember width. I normally have 400 to 600 lbs aboard in live weight.
When I go out on my home lake I can't exceed 45 MPH due to local speed limit. But it is a trial rule and may be allowed (I pray) to expire. We are at 500 feet above sea level.
It hole shots fine, I full loaded it one time and it went to a plane darn well. No issue tubing the kids. I almost took my old bones out and water skied the other day, but it didn't happen. Probably better for my over-50 back and knees.

The boat goes a bit nose high when running slowly, just before plane. I know, they all do.
Should I look at a 4 blade prop, maybe 20 or 21" pitch? I might go for that if it can be reasonably expected to lift the stern a bit. Do higher pitch props improve fuel use while cruising? Or should I just bring money? I really kind of want a big prop so I can be cool like the big blocks and high powered outboards!
There will be lots of times I want to putt along below planing speed. Our lake can be choppy and my wife can't take the beating sometimes. Should I save my money for tabs? Or should I look for a stern lifting prop. The prop seems like a cheaper, quicker solution.
Thanks for reading my ramble.

Noob.
 

rndn

Commander
Joined
May 20, 2007
Messages
2,323
Re: prop help request

I had a 1989 Baja Force 216 with the same motor and drive. I also had the same issues with bow rise, except I also had a slow out of the hole issue. I went to a 22 inch Stiletto 4 blade SS prop and it made it an entirely different boat. It actually launched out of the water and topped out at 64 mph using a handheld GPS.
The only issue I didn't care for was it would kind of float a little back and forth at full throttle because the boat was just about out of the water. Just a tiny bit so you didn't even need to adjust steering, but you could just tell it was floating.
 

hwsiii

Commander
Joined
Jan 25, 2009
Messages
2,639
Re: prop help request

Noob, you can stop the high bow rise during transition to plane, go faster at the same RPM while cruising, have a better hole shot, cruise at slower speeds, be able to plane at a lower speed and your fuel use will go down as well, because you are showing a prop slip right now of 13%. The 4th blade will decrease your prop slip thus giving you a little more speed and will lower you RPM about 300 RPM because of the extra blade and will raise the stern for less bow lift. Just stay with the same pitch you have now. Here are my numbers for prop slip.


Prop Slip

NHGuyPropSlip-1.jpg



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Add Amita Aluminum Propeller 1513-143-19 To Your Cart

Propeller Specifications:
SKU:#1513-143-19
Manufacturer: Solas
Brand: Amita
Material: Aluminum
Diameter: 14 - 1/4?
Pitch: 19?
Blades: 4
Rotation: Standard (Clockwise)
Usually Ships Within: 1 Business Day


This is the prop I feel you need for the aforementioned results.


H
 
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