will this prop be OK on my boat

[1216bandit]

I have a 22' Starcraft Islander with a 4.3 engine and hit some submerged debris the other day damaging the prop to where it cant be repaired. The prop that was on it had these numbers 48-78120 -19 and I was very pleased with it. A friend has a prop that he as given me with these numbers 48-78122-21 and I am wondering how this will work on my boat. What will I gain or loose with this prop?
Thanx for any advice...Dan

 

[Maclin]

If your boat was propped correctly before with the -19 (19 pitch) then the -21 (21 pitch) will be a little too much prop, or over-propped. When over-propped the take off is slow and the engine feels sluggish and cannot reach top RPM, lugging it which is hard on engines.

If you were underpropped before, meaning the engine cold rev past the top RPM, then the 21 pitch is a step in the right direction.

We need to know the top RPM your engine could achieve at WOT (Wide Open Throttle) with moderate load with the 19 pitch prop. That will give clues as to what the 21 pitch may or may not do for you.

 

[1216bandit]

I believe I was getting about 4600-4800 rpm. The boat got on plane very quick which I really liked. I am not sure about top speed and that is not really a concern as I normally cruise at about 3600 to 3800 rpm. Now that I think about it I may put this prop on temporarily and get something new in 19" pitch. I have never replaced a prop before and really unsure about what too look for in a decent affordable prop. The boat is a fishing/pleasure boat and with that being said would something like the solas amita 3 be a good choice???

If the 21 is too much prop what would I see as far a rpm at wot...in other words, if I could see 4400-4500 would that cause stress on the engine if only used for a short time?
Thanx...Dan

Edit...what diameter is the 19 pitch prop?? From what I read some say 14" and other say 14 1/2???

 

[steelespike]

If the prop is intended for your outdrive the diameter should be right.The 21 may be slightly less diameter to the 19, that would be considered normal.
The 21 will probably knock 300 or 400 off the rpm.If your at 4800 now that would still put you within range.4400-4800 Hole shot may be slower,
it may be more sensitive to added weight,it may be more fussy at slow planing speed but could be faster.

 

[jestor68]

You were running a Merc 14-1/2 X 19. A Solas 14-1/2 X 19 will work even better.

Solas also offers a 15-3/10 X 19 aluminum prop that runs 100 rpm slower than their 14-1/2 X 19 prop, for better economy. There is hardly any difference in acceleration.

 

[Maclin]

Definitely try the 21 pitch, well, if it is a free trial anyway It may work out well. Most times though the best top speed is from the prop that lets the engine get to the top RPM specified for the engine's RPM range. Looks like good advice from experienced boaters regarding fine tuning the 19pitch props.

 

[1216bandit]

Thank ya kindly for the quick replies. The 21 pitch will be going on tomorrow. Unless anyone can suggest a better prop for the money than the aluminum solas, I will order one of those in 19 p later in the week, and keep the 21 as a back up.

 

[Maclin]

Sounds like a good plan to me :thumb:

 

[Sea Rider]

That's why always tach engines with current delivered prop and lightly loaded boat. In case prop is shot and was delivering near or top wot rpm will surely go for same new one. If not that rpm pleased, will know from where to start and move to +,- pitch.

Happy Boating

 

[Chris1956]

I like the Turning Point Hustler props. They are a bit higher performance than standard aluminum props.