Prop for 3.0 135hp Mercruiser on Sea Ray 180BR

[rochester]

I bought my 2001 Sea Ray 180BR with the 135hp 3.0 Mercruiser 3 years ago. It only had 50 hours on it! What a deal! The boat had a J14.5x19P prop on it. There are a lot of areas I go into that are Slow/No Wake for extended distances, and it helps a lot if I get weight into the bow with respect to steering and getting the stern up because it is also very shallow. I hit a rock and dinged up the prop... not terrible, but I thought it should be fixed. I took it to a prop repair shop, and bought a new Mercury prop J14.25X21P, because that is what the Mercruiser recommendation is.

I have some friends who are pretty big, and it took forever to get on plane with the 21P prop. I dinged up the 21P prop very minor, and put the 19P prop back on after repair. I like the 19P a lot better. I'm thinking I should get the 21P prop fixed, but was also thinking about getting the pitch changed from 21P to 19P. (BTW, these are both aluminum props.) However, it seems like by the time I get it repaired and have the pitch changed, I could almost just buy a new 19P prop. I wish I knew who the mfr. of the 19p prop was... but I don't.

My question... I hardly ever run the boat WOT. If I do, it would be for a few minutes. I don't really care about the loss of top-end speed. What I really want is a prop that is going to give me the best hole-shot, and plane at the minimum speed. Also, even with the 19P prop, the boat porpoises if I trim it up much when on plane. It is fine if I trim it all the way down. I'd like a prop that is going to get the stern up as much as possible. I don't want stainless steel. I'm wondering if a 4-blade would be better than the 3-blade 19P, or would I not notice much difference? If I went with a 4-blade, would I want a 17P? Would there be a downside to a 17? Any brand recommendations? The Solas Amita 4 looks like it's popular here... I'm hoping someone has a similar boat and messed around with some different props...

Thanks for any feedback you could provide...

 

[steelespike]

You should read the stickys at the top of the prop forum.
Marine motors work very hard,like pulling a trailer up a never ending hill.
A 21 on your boat is like overdrive in a car.
Your motor needs to be able to rev freely within its recommended rpm rating.4400-4800 rpm.
Your 19" may be close to what you need.
If you do a lightly loaded wot (wide open throttle) test run with the 19" get us your rpm and gps speed.
Once we know your numbers we can tell if your setup works.
You can run at what ever speed you like once we have the motor propped within its rpm range.

 

[Scott06]

Try a 4 blade 18" pitch like Michigan vortex. Did the same on my 3.0 sea ray 170, better holeshot, planed slower much better stern lift, but lost 3 mph top speed. Really performed well for the uses you are looking to improve

 

[rochester]

I finally got out and got some information. At WOT, with the J14.5x19P prop, I am running at 38 mph and 4500 rpm. As a reminder, what I really want is a prop that is going to give me the best hole-shot, and plane at the minimum speed. Also, even with the 19P prop, the boat porpoises if I trim it up much when on plane. It is fine if I trim it all the way down. I'd like a prop that is going to get the stern up as much as possible. I don't want stainless steel. I'm wondering if a 4-blade would be better than the 3-blade 19P, or would I not notice much difference? If I went with a 4-blade, would I want a 17P? an 18P? Any brand recommendations?

The Mercury prop selector showed two 4-blade props based on 38mph @ 4500 rpm, a Spitfire 14X19p or an Alpha 4, 14.5X18p. Is one of these better than the other? What is comparable from other manufacturers?

 

[steelespike]

The 4 blade has a reputation for quick hole shot, ability to stay on plane at reduced throttle,handle better in heavy seas and usually will handle better
around the dock.If you are going from a 19 it usually is suggested to reduce pitch 1".
The Spitfire is said to give good results without messing with pitch.

 

[Scott Danforth]

planing speed is a function of the hull and weight carried and not the prop. you can reduce the throttle to maintain planing speed with some props, or by adding trim tabs, however if your goal is to stay on plane at 5mph, not going to happen.

regarding the prop, I would be running a 17P prop myself based on your 4500 rpm and 38mph, especially if your desire is better hole shot you may actually pick up a bit on the top end too as the motor will run up to the upper end of its range. does your local prop shop have demo props to try?