mercruiser 3.0 propeller questions

[tka77]

Brand new to me 2006 sea ray 180 owner with prop questions, I have the 180vsport with mercruiser 3.0 alpha one with a 14.25x21pitch black diamond (mercury/) propeller. Ive had luck seeking collective wisdom of enthusiast before, those who might know this boat or the 3.0 engine, and interested in sharing their experience.

question one, when does one need to replace a propeller- again first boat/newb question for sure, I ran into a shoal on the third trip out, there is a chunk out of the aluminum 3 blade prop about half the size of a dime- how much does this affect efficiency in this engine and relatively lightweight boat? There does not seem to be any other damage to the lower unit I am aware of.

2-any propeller suggestions- interested in mid performance, some knee board or tubing with kids, but mostly just enjoying the boat and efficiency again, It seemed to top out at around 35mph per the gauge- thought this should be faster, sorry don't have a record of the rpms at wot, again first couple times on a boat/new boat. Considering turning point hustler14x21, vs solas amita, vs another black diamond mercury propeller. Not interested in stainless as I expect to run into something else on the lakes.

 

[Scott Danforth]

first, welcome aboard

second, get your prop serviced. besides the chunk missing, you now have an imbalance, and you could have a bent blade

third, with a 3.0, you may need multiple props to do water sports. on my 3.0 powered boat, I kept a 15p, a 17p and a 19p. there is not enough motor for low-end grunt requiring sports like skiing

with your current 21 pitch, are you actually getting to full WOT RPMs of 4600?

 

[Scott06]

I would second all the comments Scott made above.

For years I had a 3.0 in a Sea Ray 170 (1991). Nice fuel efficient little rig I ran two versions of 4 blade Michigan Vortex props depending on use. General cruising and tubing an 18", water skiing a 16". They were relatively cheap and easy to swap for different uses.

I would definitely verify the tach vs a shop tach and check you speed with gps app on phone. In dash speedos are normally inaccurate. Normally a lightly loaded 3.0 in a boat this size will be like 38-40 give or take top end.

Find out what you are currently taching at WOT and that will determine what pitch to try

 

[QBhoy]

Hi
totally agree with all said above. But I also knew of an identical boat that managed to run a 21” high 5 well in most areas and surprisingly even did 40 mph with it. Same boat also ran 43 mph with a 21” laser 2 but was not as impressive on holeshot. Another similar boat I know also did almost as well as both the above, just with a 21” ally black max.
All said and done, I reckon if you have a boat load most days and want all round...a 19” black max or 19” spitfire would both do well...but watch the rpm when light.

 

[tka77]

Thank you all for the advice. I ordered a 14x21 since that’s what the sea ray manual says, and an 19 to see what difference there is, and if the 19 helps with the porpoising At higher speed. I’ll make sure to find some other project soon for the boat.

 

[QBhoy]

If it’s porpoising then trim down a little or ask the passengers to sit further forward