Propeller Pitch Selection

[bmason0517]

I have a 2010 Bayliner 195 BR and swapped out my Mercruiser 5.0L TKS for a Mercruiser 5.7L MPI (so much better). I'm finding it underpropped with the 19P X 14" prop that is currently on the Bravo 1 leg. The engine warning comes on as it reaches it's maximum rpm's (4600 - 5000) that it gets with that prop and looking for suggestions at what prop (pitch or diameter) I should try. I don't seem to have a dealer local enough for me to test out a few although that would be ideal.
Given this new higher HP engine is unique to this size of boat as Bayliner never put it in, they don't have any recommendations themselves
I'm still getting up to almost 52mph but would expect more with the new 300hp engine,

 

[alldodge]

Welcome
Look for a local prop shop, many will trade props after you buy first one

If that is not available then try Hill Marine
Hill will trade props with it just costing you return shipping

 

[airshot]

You need to know what rpm that prop is turning at wot. Then adjust the pitch until you get max engine rpm at wot. If you think the current prop is under pitched, then beg, borrow or steal a higher pitched prop so you can get that important max rpm at wot. Do you have a friend that might let you borrow his prop for a run? Otherwise, be prepared to spend money on guesses.

 

[JohnSz]

I'd agree that you are running slowish for 300hp, comparing to my 1997 2050 Capri w/5.7L - 280hp@prop. It could touch on 60mph with a 14.25X21P Black Max. It would probably get a few more with the right SS prop. It had an Alpha G2 1.47 gear ratio. My hull is narrower and has more V than yours, too. Mine would start to chine walk at 55mph. Smart Tabs brought it back under control.

A 14.25x21P is a very common prop, that shouldn't be hard to find/borrow. A 23P, a little harder to find/borrow, but with those two, should get you in the ballpark.

 

[bmason0517]

I'd agree that you are running slowish for 300hp, comparing to my 1997 2050 Capri w/5.7L - 280hp@prop. It could touch on 60mph with a 14.25X21P Black Max. It would probably get a few more with the right SS prop. It had an Alpha G2 1.47 gear ratio. My hull is narrower and has more V than yours, too. Mine would start to chine walk at 55mph. Smart Tabs brought it back under control.

A 14.25x21P is a very common prop, that shouldn't be hard to find/borrow. A 23P, a little harder to find/borrow, but with those two, should get you in the ballpark.

Thanks, that's a good comparison to go with and more what I'd expect.

 

[QBhoy]

Just be aware, that you sound like you don’t have a 1.47 ratio. More likely a 1.6 I’d think. I don’t think you’re too far off though. A few more mph from her yet…I’d go for a good 21” 3 blade…won’t be far wrong with that I’d say…

 

[jlh3rd]

You need to know what rpm that prop is turning at wot. Then adjust the pitch until you get max engine rpm at wot. If you think the current prop is under pitched, then beg, borrow or steal a higher pitched prop so you can get that important max rpm at wot. Do you have a friend that might let you borrow his prop for a run? Otherwise, be prepared to spend money on guesses

this is the spot on advice. It doesn't matter what a gear ratio is or anything else.
You have a starting point and should just go from there.
You didn't say if you had a 3 blade or a 4 blade, that makes a difference also in rpm's with everything else being equal.
Increasing pitch, diameter, or blades decreases rpm's. And stainless steel vs aluminum gives different rpm's with everything else being equal....

 

[bmason0517]

this is the spot on advice. It doesn't matter what a gear ratio is or anything else.
You have a starting point and should just go from there.
You didn't say if you had a 3 blade or a 4 blade, that makes a difference also in rpm's with everything else being equal.
Increasing pitch, diameter, or blades decreases rpm's. And stainless steel vs aluminum gives different rpm's with everything else being equal....

it's a 3 blade

 

[QBhoy]

I'd agree that you are running slowish for 300hp, comparing to my 1997 2050 Capri w/5.7L - 280hp@prop. It could touch on 60mph with a 14.25X21P Black Max. It would probably get a few more with the right SS prop. It had an Alpha G2 1.47 gear ratio. My hull is narrower and has more V than yours, too. Mine would start to chine walk at 55mph. Smart Tabs brought it back under control.

A 14.25x21P is a very common prop, that shouldn't be hard to find/borrow. A 23P, a little harder to find/borrow, but with those two, should get you in the ballpark.

That’s a hell of a performance you managed there. Amazing. I know well, the same boat, but with a 4.3 in her. She has about 190/205hp through an alpha gen 2. Can’t remember the ratio, but she will run a touch over 40mph gps any given day and maybe nearing mid 40’s running light. Runs a 19” laser 2 fairly well near the top of the rpms.
I was extremely impressed with that hull those particular models have. Very capable deep v. Very good in rough water I thought. Very unlike any other bayliner open or cuddy hull close to the size for sure. Couldn’t quite get why such a difference between that and the others around the model in the range…then I came to the conclusion that the hull was the same hull used in the same size trophy model they do. Not sure I’m definitely correct, but sure looks like it and might explain things.
Would take serious power to get that heavy capable hull…towards 60 mph for sure. Great going.

 

[JohnSz]

That’s a hell of a performance you managed there. Amazing. I know well, the same boat, but with a 4.3 in her. She has about 190/205hp through an alpha gen 2. Can’t remember the ratio, but she will run a touch over 40mph gps any given day and maybe nearing mid 40’s running light. Runs a 19” laser 2 fairly well near the top of the rpms.
I was extremely impressed with that hull those particular models have. Very capable deep v. Very good in rough water I thought. Very unlike any other bayliner open or cuddy hull close to the size for sure. Couldn’t quite get why such a difference between that and the others around the model in the range…then I came to the conclusion that the hull was the same hull used in the same size trophy model they do. Not sure I’m definitely correct, but sure looks like it and might explain things.
Would take serious power to get that heavy capable hull…towards 60 mph for sure. Great going.

The oem motor was the 5.7L 2brl, 210HP at prop. If I recall correctly, it touched on 51mph. I added vortec heads, dual plane, 4brl. GM/Merc roller cam, etc. I figured it was equivelent to the 5.7L EFI Gen+. Sold it last year and replaced it with a pontoon boat. 1st grand child was born. Now my top speed is 30mph.

 

[Scott06]

What is the drive ratio? I think with a boat that light will need a 1.47 drive and probably a 21" pitch or maybe a tad more pitch.

As outlined you want to find a prop shop like Hills or I think Prop MD does pitch exchange. Just need to find someone who will work with you to try before you buy...

 

[QBhoy]

The oem motor was the 5.7L 2brl, 210HP at prop. If I recall correctly, it touched on 51mph. I added vortec heads, dual plane, 4brl. GM/Merc roller cam, etc. I figured it was equivelent to the 5.7L EFI Gen+. Sold it last year and replaced it with a pontoon boat. 1st grand child was born. Now my top speed is 30mph.

Sounds like you’ve slowed your pace of life ! Happens to us all .
Yeah. She would have went well, I’m sure. Think an efi 5.7 was about 260hp. 4 barrel carb from around then was about the same. A later version of the mpi gen2 would be the one with 300hp and I higher rpm rating I’d say.

 

[QBhoy]

What is the drive ratio? I think with a boat that light will need a 1.47 drive and probably a 21" pitch or maybe a tad more pitch.

As outlined you want to find a prop shop like Hills or I think Prop MD does pitch exchange. Just need to find someone who will work with you to try before you buy...

Think it must be less than 1.47, given the reported. And just from what I know about my own boat’s performance and numbers.
Should it help with anything, my numbers and known quantities below (but please be aware it’s likely not a apples to apples comparison…given the performance oriented attributes my hull has)
Campion Chase 550 Performance edition
18ft
3500 lbs with full tank, gear and me onboard. (Roughly)
Stepped apex du-pont kevlar laid hull with pad
Mercruiser v8 mpi with cam (not always ideally suited, given the standard fuelling map) and full corsa marine performance exhaust
Around or just over 300hp as an estimate
1.47 ratio
With a 21” laser 2 she has previously managed a few 67-68 mph runs on a good day..but terrible at accelerating and lacking down low performance. Forget it completely if I have passengers or fuel aboard really…terrible
20” enertia she will run a fairly happy 64/65 mph gps around the rpm limiter
19” laser 2 runs easily to the limiter at early 60’s from memory
19” tempest plus is about the same but much better on fuel cruising with lower rpm…even as low as higher pitch props. Very happy with this prop as an all round
Did run a 19” and a 21” ballistic for a while..very good top end performance from both…but poor elsewhere in the rpms and not a nice attitude cruising I thought.
Generally the enertia 20” is a good mix, but can take a bit of effort to turn down low. Not had a chance to fully test this out well, with clean hull and running light. All day and any day…the tempest plus 19” is a great prop for everything really. Although it will hit the limiter at 5150 rpm if I allow it.

 

[Scott06]

Think it must be less than 1.47, given the reported. And just from what I know about my own boat’s performance and numbers.
Should it help with anything, my numbers and known quantities below (but please be aware it’s likely not a apples to apples comparison…given the performance oriented attributes my hull has)
Campion Chase 550 Performance edition
18ft
3500 lbs with full tank, gear and me onboard. (Roughly)
Stepped apex du-pont kevlar laid hull with pad
Mercruiser v8 mpi with cam (not always ideally suited, given the standard fuelling map) and full corsa marine performance exhaust
Around or just over 300hp as an estimate
1.47 ratio
With a 21” laser 2 she has previously managed a few 67-68 mph runs on a good day..but terrible at accelerating and lacking down low performance. Forget it completely if I have passengers or fuel aboard really…terrible
20” enertia she will run a fairly happy 64/65 mph gps around the rpm limiter
19” laser 2 runs easily to the limiter at early 60’s from memory
19” tempest plus is about the same but much better on fuel cruising with lower rpm…even as low as higher pitch props. Very happy with this prop as an all round
Did run a 19” and a 21” ballistic for a while..very good top end performance from both…but poor elsewhere in the rpms and not a nice attitude cruising I thought.
Generally the enertia 20” is a good mix, but can take a bit of effort to turn down low. Not had a chance to fully test this out well, with clean hull and running light. All day and any day…the tempest plus 19” is a great prop for everything really. Although it will hit the limiter at 5150 rpm if I allow it.

Agreed he has to have more gear reduction.

Have you tried a Rev 4 vs the enertia? The "effort to turn down low" is almost too much for my 5.0/1.81 drive. The grip on these props (incl enertia is insane)

 

[QBhoy]

Agreed he has to have more gear reduction.

Have you tried a Rev 4 vs the enertia? The "effort to turn down low" is almost too much for my 5.0/1.81 drive. The grip on these props (incl enertia is insane)

I haven’t Scott. Previously my thoughts were that I’d rather a 3 blade over a 4 blade…but lately I’ve become very aware and impressed with just a couple of these 4 blades..and mostly their ability to tame the behaviour of a light hull with a big v6 2 stroke on the transom. The rev 4 is one that can perhaps do that…and the bravo 4 blade is certainly astonishing (witnessed personally) at allowing the top end to be pushed out considerably further without chine walking…on the typical narrow deep v fast boats around here.
More relevant to the v8 boat I’ve discussed above, I’ve probably never given it a thought much, with the thinking that it doesn’t ever even show the first sign of bad behaviour at top end. It’s very very planted at anything in the 60’s. Literally, I could take my hands off the wheel at full throttle. Also my worry might be that I’d be at risk of straining the wee alpha a little, trying to turn such a grippy prop low down. One of the reasons I usually just run an easy pitch most of the time. Try and avoid a sort of hard acceleration from low speeds and I’d say I’ve only ever opened her up once or twice from near a standstill. Anyway…I’m definitely tempted to try a hood 4 blade on the wee Glastron cvx 16. With her laser 2 3 blade…she is nothing short of frightening at around 58-63ish mph. Settles a little if you push through that…but it’s a rare occasion that conditions or my bravery allow that. Not a cheap experiment however !

 

[John_S]

Sounds like you’ve slowed your pace of life ! Happens to us all .
Yeah. She would have went well, I’m sure. Think an efi 5.7 was about 260hp. 4 barrel carb from around then was about the same. A later version of the mpi gen2 would be the one with 300hp and I higher rpm rating I’d say.

This is JohnSz. I finally remembered my old user name and password.

Before I went to Vortec heads, I put on the cast iron highrise dual plane, from the 350 Mag, along with a Q-jet. That was about 250HP @ prop. I think my top speed was around 55mph. A few years latter, went to the vortec heads.

FWIW: We are on a smallish lake, so going 60mph, while fun, decided hard acceleration felt better. Went to 4 blade and dropped down a little in pitch.

At one point, even considered going to 383, but that would require me to "baby" the accelerations or change the drive. It was all fun at the time. I got to relive my youth of working on the 350 that was in my 1970 Nova SS.