I have a tough prop question for you guys

[kd6msd]

I have a 2006 32' Renegade open fish with Tripple Suzuki DF250's, I bought the boat from a government auction and it has 14 1/2 X 27 pitch 3 blade Mirage props (The boat was propped to carry 30 people). I redline at 3/4 throttle and 63 MPH, I called Renegade to find out the correct props to put on it and to try to use the lifetime hull warranty but they were not willing to help unless i brought them the boat and paid them to do the work. I really dont need the extra speed but i have hit the rev limiters several times and have to shut the motors down to reset them not to mention i dont want to damage the motors. I would appreciate any advice on the correct props i should use as far as 14 1/2 vs 16" diameter, 3 or 4 blade and pitch. I have taken the props to get cupped but i didnt notice a difference the shop that did the work could not give me an answer on the correct size to use.

 

[jimmbo]

Re: I have a tough prop question for you guys

Welcome to iboats

What is the recommended WOT rpm range for that engine? what rpm is the rev limiter activating?

 

[Fun Times]

Re: I have a tough prop question for you guys

Hi there, welcome to iboats!

Sounds like you may need some specialized propellers to make your boat preform correctly. If found to be true then one of your best bets to do for additional advice would be to try contacting Brett Anderson owner/operator of BBLADES Professional Propellers. Brett has a vast history of working with many high performance boat manufacturers making extreme boats run better, faster, safer, efficient, etc. etc.... Boat Propellers - Lab Finishing, Mercury, Hering Propellers and More!

He is also an avid poster on offshoreonly Prop Talk. If Brett can't help you he'll probably know who can.
Good luck.

 

[Sea Rider]

Re: I have a tough prop question for you guys

If you are over revving lightly loaded, then the combo must have beeen near or max wot rpm propped stated for those engines to carry 30 passengers. If so, will need to re prop engines to be within safe min, max wot rpm factory stated for those 250 engines to match your particular boating/passeenger needs.

Happy Boating

 

[kd6msd]

Re: I have a tough prop question for you guys

Welcome to iboats

What is the recommended WOT rpm range for that engine? what rpm is the rev limiter activating?

5800 rpm is the max, but if i push the boat to 5500 then i will usually get an over rev alarm on one of the motors within a minute or so.

 

[Tail_Gunner]

Re: I have a tough prop question for you guys

That is a lot of boat you have going on there and the prop's will cost a pretty penny....So give this guy a call Boat Propellers - Lab Finishing, Mercury, Hering Propellers and More!

He will get you where you want to be in the least costly manner..just dont let him talk you into labbing the prop's....:laugh:

 

[funk6294]

Re: I have a tough prop question for you guys

You need to get with a good prop shop (I believe bblades was mentioned and I have heard good things) that will let you demo some props. As an FYI according to mercs prop page the mirage plus series goes up to a 29 pitch, but if you step into the bravo series they go well into the upper 30's. So you should be able to find some props for it.

 

[SkiDad]

Re: I have a tough prop question for you guys

If you are not going to carry that kind of weight, maybe you should just take off one engine and keep for spare or sell ? Or would it help to lower the engines a few holes and drop some rpm ?

 

[kd6msd]

Re: I have a tough prop question for you guys

That is a lot of boat you have going on there and the prop's will cost a pretty penny....So give this guy a call Boat Propellers - Lab Finishing, Mercury, Hering Propellers and More!

He will get you where you want to be in the least costly manner..just dont let him talk you into labbing the prop's....:laugh:

everyone is recommending BBLADES so ill give them a call and keep you guys posted on the final numbers.

Thank you everyone for taking the time to help me out.

 

[jestor68]

Re: I have a tough prop question for you guys

The Suzuki 250's WOT rpm range is 5500-6100 rpm. Which means the rev limiter should not activate until about 6300-6400 rpm.

He says it's activating around 5500 rpm. Sounds like the affected motor(s) need to be checked to see why you're getting a premature over rev alarm.

Maybe a call to a Suzuki dealer/tech is in order before you go off buying props.

 

[jestor68]

Re: I have a tough prop question for you guys

5800 rpm is the max, but if i push the boat to 5500 then i will usually get an over rev alarm on one of the motors within a minute or so.

5800 rpm is the rated hp rpm; not the max rpm. If you're getting over rev alarm(s) at around 5500 rpm, you have motor problem(s); not prop issues.

Your 2.29 gear ratio, 27 pitch, and assuming a 9% slip factor indicates the motors should be turning about 6180 rpm at your stated actual 63 mph.

 

[dan02gt]

Re: I have a tough prop question for you guys

Have you verified the tach (s) is correct? Are the other motors turning 5500 RPMs @ 63MPH? Something is off here. Based in some of Jestor's numbers you would have to be running somewhere in the 1% slip range (not possible with your hull) to run 63 MPH @ 5500 RPMs.

 

[jestor68]

Re: I have a tough prop question for you guys

Whenever you buy a boat like this at a "Govt" auction, it was was abused by the Seals or drug runners. In either case, they don't give a crap, cause they can afford (either has millions of $ to waste) to replace it every couple of years.

The first thing(step one) to do is take it to an authorized dealer(for whatever motors are on it) and have the motors/instruments diagnosed for proper operation.

Once they have tuned up the motor(s) and fixed any non functioning sensors, you are ready(step two) to verify the props are correct for the application.

Incidentally, a nice set of Bravo 1 ( 4 blade) 15.25 X 28 might be a good place to start once you have the motors diagnosed and are sure they are running correctly and showing correct rpm readings.