Prop scenerio

[dchester]

I have just purchased a 4.5M (15') Easyrider mod-V glass hull runabout with a 1975 Mercury Blueband 1150 (115hp). It's currently in the shop being serviced before my first launching. I intend using it for fishing and perhaps a little casual recreational skiing, tube-towing, etc in the local lakes, onshore marine areas and in the close reaches of Moreton Bay around Brisbane. My question: somebody has provided me with a S/S Mercury Vengence 13 3/8" Diameter by 14" pitch, 3 blade RHS prop. Is this prop of any use to me and if so, in what scenerio? Thanks for your time folks!

 

[Ron G]

Re: Prop scenerio

Welcome aboard chester,The first, thing do you know what your max rpms are at wot?what prop and pitch is on it now?you'll get better results with these questions answered.

 

[WillyBWright]

Re: Prop scenerio

Welcome to iboats. <br /><br />14 sounds too low. I'd expect a rig like that to swing a 17 or 19, maybe a 21. But without that RPM info, it's all a guess. I know it's hard to believe, but running the motor at less than full throttle IS an option. If you have a tach, just keep RPMs below 6000. You'll have a great holeshot, but you have to mind your revs. Ski club boats are usually underpropped to allow for better holeshot.

 

[walleyehed]

Re: Prop scenerio

The prop is correct for the engine, but will the RPM be correct..??? The engine will handle 6000 ok, but my prop contacts say 5800 is best for that engine. Try the prop..see what ya get at WOT, but if it wants to go beyond about 6200, don't let it.<br />I'm with willy..I think you'll be in the 19 range..

 

[dchester]

Re: Prop scenerio

Originally posted by Ron G:<br /> Welcome aboard chester,The first, thing do you know what your max rpms are at wot?what prop and pitch is on it now?you'll get better results with these questions answered.

 

[dchester]

Re: Prop scenerio

Thanks for that...as I stated, I have not yet had the boat in the water, so I cannot give accurate WOT info. I checked on the prop select page of this site and it seems to think that my Merc 1150 should run between 4750 and 5250 RPM and use between 24 and 26 pitch props, depending upon application...seems a bit high in the pitch and low in the RPM, aye?

 

[walleyehed]

Re: Prop scenerio

The Info on max RPM is for some of the newer engines...they don't list R's recommended for older rigs. You don't want to prop for less than 5500 at any rate, and that engine runs very smooth above 5600-5700.<br />I have a customer with the same engine on an 18ft Blunt-nosed old fiberglass rig in a semi-V design, and it'll run 6100 with a 15 pitch and 2 guys in the boat..incredible hole-shot too, AND, this is at almost 4000ft elevation, so your 15ft'r should be close with the 19...borrow one if ya can when you can test it...