Selecting a replacement Prop

[BornBlue82]

Ok all, I'm very new to the boating world. I just purchased an 01 bayliner 4.3 alpha 1. I'm looking into replacing the prop b/c the current one is all dinged up. I currently have Michigan Wheel Vortex XHS 992005 Aluminum Boat Propeller installed and I was looking into replacing it with with a 4 blade. What rout should I go? I plane on using it to pull tubes and skii's.

 

[BornBlue82]

Re: Selecting a replacement Prop

Bump

 

[steelespike]

Re: Selecting a replacement Prop

To do this right we need a lot more info.If you answer the Qs in the stickys at thge top of the prop forum we can be more accurate
evaluating your present setup.
On the face of it if you go to a 4 blade you would normally go to 1" less pitch.
It's important for the health of your motor and the best performance that the motor is able to operate freely within its wot rpm range.

 

[BornBlue82]

Re: Selecting a replacement Prop

To do this right we need a lot more info.If you answer the Qs in the stickys at thge top of the prop forum we can be more accurate
evaluating your present setup.
On the face of it if you go to a 4 blade you would normally go to 1" less pitch.
It's important for the health of your motor and the best performance that the motor is able to operate freely within its wot rpm range.

Ok thanks, I'll see what I can come up with.

 

[BornBlue82]

Re: Selecting a replacement Prop

Let me first start out by saying, I appologize for my lack of boating knowledge. I didn't see the questions in the sticky, all I seen where info on different props. What I do know is that I have a 01 bayliner capri with a 4.3 apha 1.
WOT RPM is 4600
42mph @ WOT
14 1/4 x 21 - 3 blade current prop
What other infor do I need.

 

[steelespike]

Re: Selecting a replacement Prop

No problem everyone has to start somewhere.
We need the horse power or the gear ratio,ratio may be on the outdrive.
Also the Capri series ranges from 18' to 24' in an I/O version.
Everyone does that with the Capri.Actually the smallest is a 16ft outboard.

 

[BornBlue82]

Re: Selecting a replacement Prop

No problem everyone has to start somewhere.
We need the horse power or the gear ratio,ratio may be on the outdrive.
Also the Capri series ranges from 18' to 24' in an I/O version.
Everyone does that with the Capri.Actually the smallest is a 16ft outboard.

Gear Ratio is 1.81
Boat Length 19.5 (actual 18.9')

 

[SkiDad]

Re: Selecting a replacement Prop

those numbers sound good to me. Is that with a full load of people or just you ?

i use this site that helps me: Propeller Calculator / Prop Calculator

Seems your prop slip is high, which makes sense... you should be about 45 mph. You could try a 20 pitch. I think most boats come with around a 19 for all around use. You just have to make sure your WOT is not over 4800 - or just watch it if you must have a lower pitch.

it's hard to tell exactly what you need b/c your old prop is banged up so you don't have a great reference point

 

[BornBlue82]

Re: Selecting a replacement Prop

those numbers sound good to me. Is that with a full load of people or just you ?

i use this site that helps me: Propeller Calculator / Prop Calculator

Seems your prop slip is high, which makes sense... you should be about 45 mph. You could try a 20 pitch. I think most boats come with around a 19 for all around use. You just have to make sure your WOT is not over 4800 - or just watch it if you must have a lower pitch.

it's hard to tell exactly what you need b/c your old prop is banged up so you don't have a great reference point

I had 3 adults to include myself and my wifes chihuahua. Thanks for the advice.

 

[blackhawk180]

Re: Selecting a replacement Prop

Pretty easy to calculate until you added that chihauhua. That throws everything off with the beast romping about the boat causing massive ballast changes.

 

[jestor68]

Re: Selecting a replacement Prop

I am assuming you have a Bayliner 185(came with a 14.25X21 prop). If it was a 195, it would call for a 19 pitch prop(3 blade).

Putting the 185 numbers through the Merc prop selector comes up with(you guessed it) a 14.25X21 in aluminum 3 blade, and suggests a 14X20 in alpha 4(aluminum 4 blade).

The capacity sticker should have the model number on it.

 

[BornBlue82]

Re: Selecting a replacement Prop

Pretty easy to calculate until you added that chihauhua. That throws everything off with the beast romping about the boat causing massive ballast changes.

Yeah I was afraid of that.:lol:

 

[BornBlue82]

Re: Selecting a replacement Prop

I am assuming you have a Bayliner 185(came with a 14.25X21 prop). If it was a 195, it would call for a 19 pitch prop(3 blade).

Putting the 185 numbers through the Merc prop selector comes up with(you guessed it) a 14.25X21 in aluminum 3 blade, and suggests a 14X20 in alpha 4(aluminum 4 blade).

The capacity sticker should have the model number on it.

I have a bayline capri 1950.

 

[SkiDad]

Re: Selecting a replacement Prop

i say go with a Michigan Match 19p 3 blade then. Michigan match are nice props I just got one last year. Of course this is just a suggestion and you have to make your own educated guess. I'm thinking that if your 21 pitch was not dinged it would be running about 4400 rpm but the dings are making it slip. So they 19 would put you about right. Alot of times people put bigger props on thinking it will improve there speed but it might only give them a little (1-2 mph) So if you are into skiing I think the lower pitch makes it much easier to get up and you should still be able to hit 40 MPH no problem.

 

[SkiDad]

Re: Selecting a replacement Prop

but please don't just buy something b/c I said it might be good. I think a 19p would work but you have to make sure you RPM doesn't go over 4800....your rpm will vary depending on brand even in the same pitch. i wonder if you can trial a prop or 2 from a local marine shop. I think the one by me will let you do that as long as you bring it back like new condition.

 

[BornBlue82]

Re: Selecting a replacement Prop

but please don't just buy something b/c I said it might be good. I think a 19p would work but you have to make sure you RPM doesn't go over 4800....your rpm will vary depending on brand even in the same pitch. i wonder if you can trial a prop or 2 from a local marine shop. I think the one by me will let you do that as long as you bring it back like new condition.

Awesome, thanks for the advice Mitzysman. I think I will try the 19. I don't believe the one I have is original, I think the po replaced it.

 

[SkiDad]

Re: Selecting a replacement Prop

one thing I didn't mention is that the prop you have now has a hub kit on it - so maybe you should look at the same brand so you can re-use the kits. The prop i mentioned just requires a thrust washer. Maybe the 20 4 blade of the same brand is the way to go. how badly dinged is the prop - pic ? and are you looking to ski on 1 ski or 2. if you are just going to do 2 skis it won't make too much difference to you. if you like the performance of the current prop maybe look at the same thing. Sorry for all the words. I just want to be sure you don't hurt your engine... the RPM must be in the range of 4400-4800. top end of it is better. If your current prop is really not that bad then running 4600 is perfect really.

 

[BornBlue82]

Re: Selecting a replacement Prop

one thing I didn't mention is that the prop you have now has a hub kit on it - so maybe you should look at the same brand so you can re-use the kits. The prop i mentioned just requires a thrust washer. Maybe the 20 4 blade of the same brand is the way to go. how badly dinged is the prop - pic ? and are you looking to ski on 1 ski or 2. if you are just going to do 2 skis it won't make too much difference to you. if you like the performance of the current prop maybe look at the same thing. Sorry for all the words. I just want to be sure you don't hurt your engine... the RPM must be in the range of 4400-4800. top end of it is better. If your current prop is really not that bad then running 4600 is perfect really.

Ok, well my wot rpm is 4600. I plan on just using a two person float for now, not so much skiis. So is it better to go 20/4 blade or 19/3 blade? Also what about aluminum vs ss?

 

[SkiDad]

Re: Selecting a replacement Prop

20 is probably a safe bet, should give you a little more power but not change the RPM much. It really doesn't take the much power to pull a tube.

i have only used aluminum props and only 3 blades - 4 blades are relatively new idea. The nice things about AL is they are easily repaired and cheaper. If you hit something the prop will just bend but your engine will be ok. My dad has had boats for 40+ years and always aluminum b/c of cost. I know we ran a 13p in our one ski boat 16' with 115 Merc outboard and I run a 15 pitch on mine - but the pitches are different things on outboards of our horse power. If your current prop was perfect condition it would be easy to answer your questions more accurately,say you were at 4400 and 21 pitch it's just math that a 19 pitch would take you to 4800, each pitch lowered raises about 200 rpm. These vortex props are cheap enough you could just get another if you don't like the one you pick and then keep the one for a spare.

 

[BornBlue82]

Re: Selecting a replacement Prop

20 is probably a safe bet, should give you a little more power but not change the RPM much. It really doesn't take the much power to pull a tube.

i have only used aluminum props and only 3 blades - 4 blades are relatively new idea. The nice things about AL is they are easily repaired and cheaper. If you hit something the prop will just bend but your engine will be ok. My dad has had boats for 40+ years and always aluminum b/c of cost. I know we ran a 13p in our one ski boat 16' with 115 Merc outboard and I run a 15 pitch on mine - but the pitches are different things on outboards of our horse power. If your current prop was perfect condition it would be easy to answer your questions more accurately,say you were at 4400 and 21 pitch it's just math that a 19 pitch would take you to 4800, each pitch lowered raises about 200 rpm. These vortex props are cheap enough you could just get another if you don't like the one you pick and then keep the one for a spare.

Awesome, thanks for the advice mitzysman. 20 it is.