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Old 07 October 2012, 14:02   #1
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Props on RIBs

I've messed around with props before on Medium V fiberglass Centre consoles before, and ended up learning just how difficult good prop selection is, but I have ZERO experience on RIBs.

I'm guessing that given the lift provided by the tubes, lighter overall weight when compared to a similar size all GRP boat, perhaps when it comes to prop selection there are differences as well.

I've got a Merc 115EFI 4S on a 6m RIB that is currently running a 3 Blade Blackmax 17 and getting around 6300rpm trimmed out with a typical load (2 adults, 1 teen, 50% fuel) and I would say the previous owner has probably left this prop because he likes to run heavier loads with lots of people. (WOT is 5,800 to 6,400) so at circa 6,300 I can probably afford to run some more pitch.

A buddy has a Blackmax 19P, so that would be an easy swap but it likely to put me at 5,900 or there abouts which may be an issue if we run 6 adults and a couple of kids.....

But it's a Stainless Steel Prop that i am really after and it seems that from Merc it's the Laser II or Trophy Plus 4 blade as options (Vengeance is too bog std). I'm drawn a bit to the Trophy as the 4 blades should give me a good hole shot and mid range and I can prop move the engine up a bit.

Any experiences with the 115EFI and props that run well on a similar sized RIB?
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Old 11 October 2012, 17:27   #2
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Anyone running a MW Ballistic prop on their boat?
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Old 12 October 2012, 11:51   #3
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Quote:
Originally Posted by npm108 View Post
I've messed around with props before on Medium V fiberglass Centre consoles before, and ended up learning just how difficult good prop selection is, but I have ZERO experience on RIBs.
Prop selection is just as difficult on RIB's as hard boats. Mostly a matter of trial and error, in my experience.

jky
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Old 13 October 2012, 00:43   #4
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Thanks jky.

I was trying to get some pointers on prop models/brands that perhaps guys with a similar sized engine/boat were using given the characteristics of various props like bow lifting, stern lifting etc.

I'm getting around 8% prop slip which I understand is very good and hard to improve upon but will be trying a Blackmax 19P to see how the numbers turn out and re-checking the figures on the 17.
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Old 13 October 2012, 08:21   #5
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Quote:
Originally Posted by npm108 View Post
I've messed around with props before on Medium V fiberglass Centre consoles before, and ended up learning just how difficult good prop selection is, but I have ZERO experience on RIBs.

I'm guessing that given the lift provided by the tubes, lighter overall weight when compared to a similar size all GRP boat, perhaps when it comes to prop selection there are differences as well.

I've got a Merc 115EFI 4S on a 6m RIB that is currently running a 3 Blade Blackmax 17 and getting around 6300rpm trimmed out with a typical load (2 adults, 1 teen, 50% fuel) and I would say the previous owner has probably left this prop because he likes to run heavier loads with lots of people. (WOT is 5,800 to 6,400) so at circa 6,300 I can probably afford to run some more pitch.

A buddy has a Blackmax 19P, so that would be an easy swap but it likely to put me at 5,900 or there abouts which may be an issue if we run 6 adults and a couple of kids.....

But it's a Stainless Steel Prop that i am really after and it seems that from Merc it's the Laser II or Trophy Plus 4 blade as options (Vengeance is too bog std). I'm drawn a bit to the Trophy as the 4 blades should give me a good hole shot and mid range and I can prop move the engine up a bit.

Any experiences with the 115EFI and props that run well on a similar sized RIB?
Have a look at the Rev4 props, I'm guessing a 17p would be about right. you drop about 200rpm going from 3 to 4 blades, but you gain a similar amount by going from ally to stainless. The Rev4 can run higher & has terrific grip & holeshot.
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Old 13 October 2012, 09:20   #6
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Hi Dave,

Thanks for the advice. Would love a Rev4 but looks like they only make them for 135hp and above as the Prop diameter is 14.x

I've been advised to look at a PowerTech Red3 which is close the Blackmax but in S/S and from Merc trying to see if anyone is running a Trophy Plus 4
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