Yep, another prop question!

[tonyjh63]

Just curious what prop y'all would think I'd need. I have a 19'6" bowrider, 2830 lbs, 4.3 Mercruiser with 4bbl. Currently have a Nemesis 14x17x4 (8M0055534) on it. Any idea what kind of performance I should get from this setup? (It might be a while before I can get out on the water and do any testing). It's a newly installed remanufactured engine from Michigan Motorz, so I haven't been able to do much testing yet. Thanks!

 

[Scott Danforth]

once you break in the engine. then take it to WOT to see what it does.

 

[Scott06]

It is so hull and how you want to use your boat specific that it is hard to answer with out any WOT rpm info. Likely the boat will hit mid 40's maybe a hair higher, but likely will want to optimize the prop when you get it broken in.

I'm assuming since you have a 4 blade your primary use is watersports/towing skiiers?

Do you have a local prop shop or marina that will let you trial props?

 

[airshot]

Yep it will push your boat quite well thru the water, without much more info it is only a guess

 

[mvn]

When you can, provide the following info.....
1. Wide open throttle rpm as indicated above
2. Drive ratio
3. Intended use/desired qualities
4. Gross weight, typical/max

Once you've got that, there are numerous online calculators available that can narrow down the optimal prop.

 

[QBhoy]

It’s almost certainly going to have the rpms through the roof, if it’s the usual outdrive ratio. Bet my life on it.

 

[tonyjh63]

It is so hull and how you want to use your boat specific that it is hard to answer with out any WOT rpm info. Likely the boat will hit mid 40's maybe a hair higher, but likely will want to optimize the prop when you get it broken in.

I'm assuming since you have a 4 blade your primary use is watersports/towing skiiers?

Do you have a local prop shop or marina that will let you trial props?

Yes, I often have a number of guests on the boat, and pulling a tube is one of the things we do.
Unfortunately, I don't know of any shops in my area (NW Georgia) that loan out props for testing.

 

[Scott Danforth]

Yes, I often have a number of guests on the boat, and pulling a tube is one of the things we do.
Unfortunately, I don't know of any shops in my area (NW Georgia) that loan out props for testing.

Until you get a WOT run, you don't have a starting point. When you get the motor broken in. Change the oil and then go for a WOT run. From there you can dial in the prop and not before

 

[QBhoy]

Until you get a WOT run, you don't have a starting point. When you get the motor broken in. Change the oil and then go for a WOT run. From there you can dial in the prop and not before

Excellent point… but I’m sticking with him needing more inches on the pitch for sure. Not sure I’ve known a boat similar with a 4.3…and only a 17” pitch. But never know. Depending on the ratio and hull…usually be 19-23”. I’d be starting with a 19”. Also tough to start off and know where you are, with a 4 blade like that too, I’ve found. Hard to reference for what you need next, unless going like for like

 

[tonyjh63]

Excellent point… but I’m sticking with him needing more inches on the pitch for sure. Not sure I’ve known a boat similar with a 4.3…and only a 17” pitch. But never know. Depending on the ratio and hull…usually be 19-23”. I’d be starting with a 19”. Also tough to start off and know where you are, with a 4 blade like that too, I’ve found. Hard to reference for what you need next, unless going like for like

I have 21" 3-blade SS I'm going to try come spring...I guess I'll start dialing it in from there. The reason for the 4-blade 17" is that I often have almost a full boat, and like to pull the young-uns on a tube. And, while breakng in the new engine, I just figured it'd be better on the engine to be under-propped, rather than lugging the engine with too big of a prop - makes sense? Also, according to a bit of anectodetal testimony, Bryants benefit from the additional lift that a 4-blade provides (even more so than most other boats).

 

[QBhoy]

I have 21" 3-blade SS I'm going to try come spring...I guess I'll start dialing it in from there. The reason for the 4-blade 17" is that I often have almost a full boat, and like to pull the young-uns on a tube. And, while breakng in the new engine, I just figured it'd be better on the engine to be under-propped, rather than lugging the engine with too big of a prop - makes sense? Also, according to a bit of anectodetal testimony, Bryants benefit from the additional lift that a 4-blade provides (even more so than most other boats).

I get it. No doubt. Although there is an argument for not being underpropped for breaking in. Thought I’d mention.