Mixing props on a dual-prop drive?

[Bigbore500r]

I see guys with Bravo III drives mixing props, running a 4 blade and a 3 blade, and doing other wierd stuff. I have also ready about guys with Volvo Penta DP drives running an F3 front / F5 rear and getting better hole shot without much loss on the top end.

Volvo says not to mix props, they are sold for use as matched sets - but the props companies offer for Bravo III drives, and what people are successfully doing says otherwise.

I guess what im getting at is - I want to try running an F8 / F7 combo on my friends deck boat, will this cause stress on the drive as one prop shaft is trying to push more resistance than the other ?

What say ye

 

[mash on it]

I think the resident prop guy did this a while back?

That might have been a dozen boats or so ago?

Steeeeeeve.....2FF, where are you?

Dan'l

 

[NicPaus]

I have been reading up on it as I just bought my first boat with B3. I would call Hill propeller and ask. I took my B3 props to Wilmington yesterday was seeing if 25pitch was possible as they are 26. Not worth it $440 minimum charge to touch them and he said could not change pitch but could cut them down to get more RPM. Boat wants 23-25 mph as is to stay on plane with a load a tube was hoping to get down to 20-22 mph. From what I read a 24p by hill with 1 4 blade and 1 3 blade would be best for wakeboarding. I have the 26 3 blades which is best for top end. Looking for a set of 24 B3 to buy or try.

 

[outboardrick]

I have a B3 on a pontoon and have tried a lot of different combos. I run a 22 pitch in front and 24 in the rear and have for 10 years with no issues. The stock 24s were just too tall, especially if I had a few people on board, and the 22s just gave more RPM and less speed. The combo works great. Merc now sells 4 blade front props and I think they come standard on new drives. The also made/sell a 4 blade rear prop, as does Hill. Merc does not put any cup in their B3 props, something about a patent that Volvo has, so adding cup to a B3 prop can really help if your situation warrants it.

 

[HavaToon]

I think the resident prop guy did this a while back?

That might have been a dozen boats or so ago?

Steeeeeeve.....2FF, where are you?

Dan'l

Helping you out @2FORCEFULL


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[outboardrick]

I have been reading up on it as I just bought my first boat with B3. I would call Hill propeller and ask. I took my B3 props to Wilmington yesterday was seeing if 25pitch was possible as they are 26. Not worth it $440 minimum charge to touch them and he said could not change pitch but could cut them down to get more RPM. Boat wants 23-25 mph as is to stay on plane with a load a tube was hoping to get down to 20-22 mph. From what I read a 24p by hill with 1 4 blade and 1 3 blade would be best for wakeboarding. I have the 26 3 blades which is best for top end. Looking for a set of 24 B3 to buy or try.

24s are pretty common so you can probably find some. Also try a combo to see if it works for you. Your props may be too tall anyway but you may try having them cupped, which would make them feel even taller, but they will bite harder and that may help your low speed handling. I could loan you a 24 if you'd like to try it.

 

[Bigbore500r]

Thanks for the input guys.
And for the record...Im literally trying a different prop

 

[RodnJen]

I run standard 26’s on Essex and they work great all around. The only time I felt it needed more low end pull is when getting my old ass up on a ski. I bought a bigger ski, problem solved.

I have been interested in the 4 blade Hill props for a while, just seems like an expensive experiment for something that isn’t really broken.

 

[outboardrick]

I run standard 26’s on Essex and they work great all around. The only time I felt it needed more low end pull is when getting my old ass up on a ski. I bought a bigger ski, problem solved.

I have been interested in the 4 blade Hill props for a while, just seems like an expensive experiment for something that isn’t really broken.

I'm the same way, would love to try some but don't want to be the $1500 Guinea Pig.

 

[bradscott48]

I run a hill marine FFIV 4 blade and the factory F5 3 blade Volvo penta on my 24’ chaparral. It costs me 3 mph on the top end but the ride is way better and fuel economy seams better. When I ran both 4 blades I couldn’t get over 45 mph. 4/3 I can get 52 mph.


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[Bigbore500r]

I run a hill marine FFIV 4 blade and the factory F5 3 blade Volvo penta on my 24’ chaparral. It costs me 3 mph on the top end but the ride is way better and fuel economy seams better. When I ran both 4 blades I couldn’t get over 45 mph. 4/3 I can get 52 mph.


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Does this effectively create a different "pitch" between the 2 props?

 

[bradscott48]

Does this effectively create a different "pitch" between the 2 props?

I have no clue



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[92562]

The west coast Merc Marine rep told me they recommend it all the time. On my brother's Chaparral he runs a 26 in front and a 28 in back. It goes within 1 mph of running both 28s but has a hole shot like the 26s.

 

[Bigbore500r]

The west coast Merc Marine rep told me they recommend it all the time. On my brother's Chaparral he runs a 26 in front and a 28 in back. It goes within 1 mph of running both 28s but has a hole shot like the 26s.

The only thing I was worrying about was loading one shaft harder than the other, given that the boat is running a set speed and one shaft is swinging a higher pitched prop. They're both hooked to the same upper unit efficively, maybe i'm over thinking it. May give it a shot this weekend and see how it does

 

[outboardrick]

The only thing I was worrying about was loading one shaft harder than the other, given that the boat is running a set speed and one shaft is swinging a higher pitched prop. They're both hooked to the same upper unit efficively, maybe i'm over thinking it. May give it a shot this weekend and see how it does

Yes, I think you may be worrying too much about the load. Remember, the props are a different diameter to begin with so they will naturally load differently. I worried about this too but figured once the shafts are under load the prop difference really wouldn't matter much.