Replacing the prop

[mclark1989]

I have a 1990 Dynasty challenger boat that's 17 foot weight is somewhere between 2500-3000 pounds if I were to guess. The engine is a inboard outboard Mercury mercruiser 3.0 140 hp I just had the stern drive replaced and need a new prop. What is my best bet we use it for fishing and pulling tubes just would like good overall performance. Thanks Michael

 

[Sea Rider]

Could check with old stern drive which prop was there as a starter and go from there to suit your boating needs and applications. It's impossible to dial best prop in first blind purchase. Anyway will need a tach to tach down new prop to see if inside wot rpm range for that combo.

Happy Boating

 

[steelespike]

Do a lightly loaded wot test run,get us the prop size(under the prop nut) rpm and gps speed.
Boats like yours wot would usually run ABOUT 4800 rpm and ABOUT 40 mph.Your actual results would
deprend on your typical load, activities and condition.
Without a baseline performance I would suggest a 19" prop as a starting point.

 

[mclark1989]

If I have the old prop how do I tell what kind and size of it? I'm new to all of this and to winterize my boat just drain all the water correct?

 

[Scott Danforth]

all props have either a part number, or the diameter and pitch marked on them somehere. for your 3.0, it will be under the prop nut.

unfortunatly with the 3.0, power is not in abundance, you may need to have two props - one for higher top end (higher pitch), however sluggish holeshot to get from fishing hole to fishing hole, and one for more low end grunt (lower pitch) for tubing/watersports

I had both a 19Pitch and a 17 Pitch on board my old 3.0 powered boat.

regarding winterization, read the stickies at the top of the mercruiser forum.

in general
run motor for a bit on muffs
change engine oil
change gear oil in drive
lubricate all points
pull drive for inspection of bellows/u-joints
drain water from 3 ports (probe drains with a wire or screw to get the gunk out of the way)
drain the big hose on front of motor
drain the hose from the drive to the motor
replace drive
store with drive down.

 

[Sea Rider]

Is old prop compatible with new sterndrive ? if number around prop can't be found will need to take prop to a prop shop amd have it measured to know your prop starting point, provided that OB and prop are healthy tach it at wot on flat no wind water cond to know if inside safe wot rpm range for that OB. Can go from there maximizing pitch to suit best your boating needs.

Happy Boating