4.50 Metre Rib-x 60hp Mercury What prop?

rib-x450 · 10 April 2008, 21:02

Can anyone recomend a prop for my outfit?

Often runnig with two to three adults in it.

I have a 4.5 meter centre console rib, it has a 2 stroke 3 cylinder mercury outboard with currently a 14 pitch prop.

It seem to rev too high to 6500 rpm???........... Mercury quote 5500 rpm max.

Current prop is 73138A4OP14 (14 Pitch)

Does anyone have a recomendation for a prop?

Does anyone have a spare prop for sale?

Many thanks

Chris

ashbypower · 10 April 2008, 21:11

As a general rule of thumb a 2" change in pitch will have a 200 RPM change. i.e up in pitch down in RPM.
Hope thatb helps

By the way Welcome to the Forum

Nos4r2 · 10 April 2008, 23:22

Odd question but are you sure your revcounter is reading right?

Red Fox · 12 April 2008, 17:58

http://sites.mercurymarine.com/porta..._schema=PORTAL

reinier · 12 April 2008, 22:48

Quote:

Originally Posted by ashbypower

As a general rule of thumb a 2" change in pitch will have a 200 RPM change. i.e up in pitch down in RPM.
Hope thatb helps

By the way Welcome to the Forum

To be honest, I don't think that's correct, the rule of thumb: 1" higher pitch = 200 RPM less. So 2" pitch higher will result in a loss of 400 RPM. I think it's reasonable to test a 19" pitch prop on the 60hp merc.

rib-x450 · 14 April 2008, 19:52

Thansk for the advice everyone...........

The highest pitch mercury make for my engine is a 19 pitch, if we base 1 pitch on 200 rpm will it be enought to bring the revs down to a safe limit? 1000 rpm to high ?

Has anyone else got a 4.5 meter with a 60hp on it?

Many thanks for the advice........

Quote:

Originally Posted by reinier

To be honest, I don't think that's correct, the rule of thumb: 1" higher pitch = 200 RPM less. So 2" pitch higher will result in a loss of 400 RPM. I think it's reasonable to test a 19" pitch prop on the 60hp merc.

reinier · 14 April 2008, 22:43

Yeah, from 14" to 19" pitch = 5" pitch increase, mutiplied by 200rpm = 1000rpm decrease... If you use a stainless steel prop your rpm's will fall another 100 or maybe 200rpm. If you use a fourblade prop it will decrease the rpm's also with 100 or 200rpm.

If the 6500rpm is with a 14" aluminium prop, I suggest testing a 3 blade S/S 19" pitch prop.

Red Fox · 15 April 2008, 17:28

Your prop number 73138A40P14 is the standard Black Max prop that is put on a 60hp Mercury so are you sure the rev counter is accurate. Get a dealer to rig your engine to his laptop with the diagnostic program running and he will be able to tell you the exact revs the engine has been doing.

rib-x450 · 16 April 2008, 19:55

Thanks for your advice, I took out the rev counter today and found it to be sqithed in the wrong position, eg for the wrong number of cylinders........ Havent been able to retest it yet. Then will need to check the prop again. A rule to never trust somelse to do things right.........The guy I bought it from installed the rev counter!!!

Will it be reading double?

Quote:

Originally Posted by Red Fox

Your prop number 73138A40P14 is the standard Black Max prop that is put on a 60hp Mercury so are you sure the rev counter is accurate. Get a dealer to rig your engine to his laptop with the diagnostic program running and he will be able to tell you the exact revs the engine has been doing.

davej · 17 April 2008, 20:44

I have a Tornado 5mtr with a 60hp 2 str that I run with a 13p and a 14p Alu Merc prop on. Usually I run with the 13p as I take up to 4 divers on it. However when I am running with the family and just pottering about I use the 14p, I would have thought that the 14p is probably about right for general use and then perhaps a 15p for light use. I use Alu as I have heard the odd horror story about SS props damaging the gear box if you hit the bottom.

jakemarsden · 20 February 2022, 18:08

Hi all, hoping I get a response as I have the same 4.5m rib and Merc 60hp combo. Just hoping that I can find out what results the owner had after the fact. I haven't had my boat on the water yet but I'm sure the 14 inch pitch will be too shallow. The boat is very light and I believe the 60hp is actually closer to 70hp by today's standards. Was thinking about finding a 19in pitch prop somewhere but I'd like to be sure before buying a hard to find prop!!

Thanks!!

Pikey Dave · 20 February 2022, 19:01

Quote:

Originally Posted by jakemarsden

Hi all, hoping I get a response as I have the same 4.5m rib and Merc 60hp combo. Just hoping that I can find out what results the owner had after the fact. I haven't had my boat on the water yet but I'm sure the 14 inch pitch will be too shallow. The boat is very light and I believe the 60hp is actually closer to 70hp by today's standards. Was thinking about finding a 19in pitch prop somewhere but I'd like to be sure before buying a hard to find prop!!

Thanks!!

Until you’ve had it on the water & got some WOT figures, it’s all hypothetical & pretty pointless tbh.

jakemarsden · 20 February 2022, 19:05

Quote:

Originally Posted by Pikey Dave

Until you’ve had it on the water & got some WOT figures, it’s all hypothetical & pretty pointless tbh.

Yes of course! Just wondering what other people's experiences have been for the time being. I imagine it'll be quite a fast rib, secretly hpoing for 40kts

Limecc · 20 February 2022, 21:47

By coincidence this was recently discussed.
2005 Mariner 60hp 2 stroke