Prop questions

The propeller on your boat has a big impact on the performance of your boat. This is the place to discuss this subject.

Prop questions

Postby charcoal1500 » Tue May 16, 2017 6:39 pm

Boating season is upon us....Looking to step up to a 4 blade prop( I think) . Boat is a little slow getting a skier up and coming on to plane with a full load.

Info:
2008 217 LS
5.0 Mercruiser Alpha 1 drive
current prop 3 blade 21 pitch stock aluminum
Pretty much operate at sea level to 2,000 only

I have started the research and now have so many questions.... I was always under the impression 4 blade ss was the way to go for pulling power, with what i have been reading just going to a different pitch in ss will do the same thing? Top speed is nice but it really is skier and tubing with a load of people and gear we are looking to do.

A few questions
1. 3 or 4 blade?
2. Stainless or composite, or something else?
3. what manufacturer and family of prop, so many to choose....

I'm just not familiar enough with props to even start to make a good decision so looking for some working advice, I also don't have the funds to keep buying props. Any pointers and advice you all have would be appreciated.

Thank you!
2008 217 LS
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Re: Prop questions

Postby youmansjason01 » Tue May 16, 2017 7:06 pm

Yes, switching from an aluminum 3 blade to a SS 3 blade will give you a noticeable improvement in pulling power and overall performance. It's going to give you better "bite" when accelerating and will stay "hooked up" to the water better when carving sharp turns. Assuming your current 21 pitch aluminum prop has your engine operating in the proper max RPM range at wide open throttle, you'd probably need to drop to a 19 pitch if you go with 3 blade SS.

Then, going to a 4 blade SS prop is going to give you serious pulling power and the ability to stay on plane at lower much RPM's. However, this performance gain comes at a cost of losing a couple of MPH at the top end. Again, if you go to 4 blade SS, you'd probably need to drop another 1-2 in pitch and go with a 17 or 18 pitch SS.

If you plan to spend a lot of time skiing, wake boarding, and/or tubing, and you want to have peak performance for those sports, you probably want to go with the 4 blade SS. Otherwise, if it's just some watersports with a lot of general cruising around you want, then you'd be good with the 3 blade SS.

As for brands, you're probably not going to see much variation in performance from one brand to the next. I like Solas and Michigan Wheel props, but there are many other good ones out there. The bigger gains will be seen when switching from aluminum to SS, and from 3 to 4 blades.

For me, I have both a 3 blade SS and 4 blade SS that I swap out occasionally depending on how much watersports vs. general cruising I plan to do.

Another big factor to consider is finding a prop that uses the Flo-Torq breakaway hub. That's what helps protects your outdrive from extensive damage if your prop hits something in the water (rocks, log, stump, etc).

Good luck! I'm sure others will chime in with their opinions too!
2007 Caravelle 237 LS
350 MAG 300HP with Bravo 1, Captain's Call Exhaust, Black wide band with matching Caravelle Trailer
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Re: Prop questions

Postby charcoal1500 » Tue May 16, 2017 8:01 pm

Thank you. It looks like I have a bit of homework to do next time on the lake to check the W.O.T info so I have a solid starting point. It sounds like a 4 blade would be the prop of choice for us most weekends on the water, lake is not too large and pretty crowded along with all the watersports fun. A nice 3 blade would be fun for the days when just a couple of us sneak out during the week.....But first I need to pick a new 4 blade it sounds like.
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Re: Prop questions

Postby AndrewT » Wed May 17, 2017 5:18 am

My 2c worth, I think a 19P 4bladed Stainless steel unit would be ideal,mine 212 still does 50MPH wot at 5000RPM with the mentioned prop and 55MPH with a 21P 3bladed stainless steel prop.
The 4 bladed pulls a lot better, I can get couple of 200lb plus gentlemen up with out any drama,the boat maintains plane at a lower speed as well.Last few years the 4B prop hasn't come off ,don't really need the 55MPH top end.
2005 Interceptor 212
Volvo 5.0 GXi 270hp
21P 14.5 3B SS prop and 19P 4B SS for wakeboarding and tubing.
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Re: Prop questions

Postby charcoal1500 » Thu May 18, 2017 12:51 am

AndrewT thanks for your 2 cents. I think you have a little more go juice with the Volvo GXI than I do with the 5.0 Merc, however I think it is a good comp to my set up. Any advise on manufacturer and model of the props you are using?
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Re: Prop questions

Postby HOT PURSUIT » Thu May 18, 2017 9:24 am

OK! I have experimented with many props on Hot Pursuit, before and after engine mods. Good rule of thumb: Switching to a 3 blade stainless will normally drop RPMs by 200 because of less flex and cupping in the blades for a "BETTER GRIP", LESS SLIP on the water. Adding a 4th blade will drop RPMs another 200. Changing pitch by "1" will normally add or subtract 200 RPMs. I also experimented with many props on my previous rig, an 18 footer with Merc 4.3L.

WOT RPMs with your current setup is an ABSOLUTE must KNOW! If your WOT RPM is where it should be, then the above applies. If not, then you will need to either go up or down in pitch ln to take advantage of the horsepower built into your engine by the manufacturer.

Based on all my trial and error experimenting my conclusions are: The BEST 4 blade on the Merc is their(Merc) "Revolution 4". Heavy, but pulls like a diesel tractor, if you go here you will lose maybe 2 or 3 MPH at top end. The Merc "ENERTIA" is the BEST 3 blade prop. Merc's claim that it increases hole shot AND top end are true. It does NOT blow out on sharp turns, holds even better then the the REV 4. I can turn my 212 Interceptor so tight at 35-40 MPH it will throw people, including the operator out of their seats (DANGEROUS).

If you or anyone else would like to understand this process better, go here to Mercury Marine's Prop Selector: https://www.mercurymarine.com/en/us/pro ... #/step-one

The 217 is just 400 pounds heavier then the 212 Interceptor. If you are serious about pulling power and hole shot being MOST important in your use I recommend the REV 4. Good luck and if you have any more questions please feel free to ask :beer:

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Re: Prop questions

Postby buyfire » Thu May 18, 2017 10:05 am

Man, we really need Rivertown to "sticky" one of these threads. HP and I, as well as others, have covered this topic a lot. There are probably 50 threads with the recommendations.




.....I must be in a bad mood from puking my guts out these last couple days. :twisted:
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Re: Prop questions

Postby HOT PURSUIT » Thu May 18, 2017 10:16 am

Aw nuts Buyfire! Flu bug eh? Get well soon my friend! Yeah, stickys would be cool! No boat yet? I know you have the urge :mrgreen:

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Re: Prop questions

Postby charcoal1500 » Thu May 18, 2017 3:45 pm

The flu....Bummer.

Yes there are lots of threads and I read through them first, I also had used the Mercury prop selector. The one thing I was not 100% clear on was the W.O.T rpm understanding. Now that I have a better grasp on that I know that is where I need to start to make sure the 21P is my starting point. I was also very confused when it came to all the different brands and models so was looking for some advice on that. There is a staggering amount of props available just look at all the different "families" at Mercury Marine.

A sticky might be useful, however I know I'm pretty new to this forum I believe the current posts will keep it relevant to any new Caravelle owners searching the internet.

Thanks everyone for getting me started hopefully this weekend I'm out and can get some Numbers and report back.

Thanks!
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Re: Prop questions

Postby HOT PURSUIT » Thu May 18, 2017 4:16 pm

That's why we try to help! There are MANY available and many some of us have tried thereby saving you the hassle :mrgreen:

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Re: Prop questions

Postby buyfire » Fri May 19, 2017 10:14 am

HOT PURSUIT wrote:Aw nuts Buyfire! Flu bug eh? Get well soon my friend! Yeah, stickys would be cool! No boat yet? I know you have the urge :mrgreen:

HP



Feeling MUCH better now, thanks. No new boat yet, but you notice that I'm still here after 3 years of not owning a boat. I think that if I did pull the trigger again I'd end up with a smallish (25-27') outboard catamaran.
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Re: Prop questions

Postby HOT PURSUIT » Fri May 19, 2017 11:30 am

Glad you're better Bud! :P What kind of Catamaran? Not familiar I think.

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Re: Prop questions

Postby buyfire » Sat May 20, 2017 10:08 am

Boatless, again.
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Re: Prop questions

Postby AndrewT » Sun May 21, 2017 3:48 am

buyfire wrote:Something similar to this.

http://www.boattrader.com/listing/2004- ... na-699325/

Very nice, twin 300HP outboards,I like as well!
2005 Interceptor 212
Volvo 5.0 GXi 270hp
21P 14.5 3B SS prop and 19P 4B SS for wakeboarding and tubing.
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Re: Prop questions

Postby charcoal1500 » Mon May 22, 2017 6:33 pm

I was able to get out on the water this weekend. First for the year!

Looking at my motor I have a sticker that say's max rpm 4400-4800. Trimmed up in a pretty decent lake chop ( lot's of tubers, skiers, wakeboarders and a slight breeze" my RPM gauge would show 4800 at WOT. The prop finder in the above link recommends all the props in 21p except for 1 in 22 pitch?

thank you
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