Mercury F60 EFI Prop Pitch

[Robert1]

Hi all!
I am running a Ribcraft 4.8 with a Mercury F60 EFI. I am on standard prop at present, but 2 up, the engine revs to 6200rpm and tops out at a rather disappointing 25-28kts. Its revs maximum is 5500-6000. I also want to waterski. Clearly, the engine is revving too high. Should i increase or decrease pitch, and what affects will this have on top speed, acceleration and power to pull a skiier.
Thanks guys
P.S. The engine has only done circa 20 hours...Does this change the way you would look at the above info? Still, adivce of effects of changing pitch would be much appreciated!

[Rogue Wave]

where are you based

[DJL]

Does the rev limiter kick in at 6200rpm?

I'm running a 13" SOLAS SS prop from Steel Developments. The engine will just pull 6000rpm at ~35kts. What pitch is your current prop? - It sounds like you need to increase the pitch by a few inches.

If you can get to RIBEX you could participate in the try a prop scheme.

edit: If your anywhere near Southampton I have got a spare 13" ally you could try.

[Robert1]

Rouge and DJL,
Thanks for the replies. I think I will, as you suggest, pop along to RIBEX and visit the nice propellor people and try some bigger pitch props. The rev limiter doesnt seem to kick in, mainly because I don't want to let the engine rev much past 6000rpm.
Thanks very much guys for your suggestions,
Robert

Edit: I am in Portsmouth
DJL: Thanks for your kind offer, but I am reluctant to try much before the engine is fully run in hence the general enquiry. I think RIBEX, as you suggest, is the best time to have a fiddle!

[rib-x450]

I have a simlar outfit a 4.5 with 60 merc with similar problems.........


Wondered waht prop ypu settled on...........

Mine is a 2 stroke though..............

[Turbodiesel]

Go up a pitch and try a four blade prop if you want to pull a skier!!

[matt h]

who is running the try a prop thing at ribex?? any contact numbers would be great

[DJL]

Originally Posted by matt h

who is running the try a prop thing at ribex?? any contact numbers would be great

Steel Developments did 4 years ago. Don't think they did it again.(?)

[kergoat]

hello

put à 14 " mercury vengeance SS on a merc 60 efi, got 35 knt @ 6000 tr/Mn

try 14" mercury black max alloy got 33-34 knt @ 6200 tr/mn

try 13 " mercury black max got 32/33 knt with overange cut @ 6250 tr/mn

[Turbodiesel]

I would come stay at the same pitch but try a 4 blade stainless prop. The 60 EFI makes 60hp at 6000rpm, so you need it at 6000rpm. The four blade will give you better hole shot etc but they rev about 200rpm less than a three blade, hence staying at the same pitch.

I have spent 3 weeks proping a warroir boat with a 60EFI and trying a massive amount of different props.
Also check the engine height? is it sitting in the right place, we dropped one hole and got 3 more knts top end because you could trim the boat much more. Also are you running a bigfoot gearbox or standard?

[yorfuoj]

On my Tomcat/Stingray 4.5m catamaran, I am running a SS Powertech SRG3 on a Merc 60-EFI, small foot (not the big foot), it is a 12.50 diameter, and the blade area is very close to that of big foot props.

The other standard props (diameter 10" approx.) aluminium, SS or composite like the 4 blades Comprop do not work well (they don't push, and they cavitate ...) on this hull because of not enough blade area and/or length/diameter.
The problem is for sure the diameter, because the Comprop has more overall blades area than SRG3.

I think there is no other prop of this size for 13-splines 50/60Hp matching its performance, and I have a spare one in 13"

[tinker]

I have a Michigan Rapture thats 11 3/4 inches x pitch of 15" and it fits my small gearbox 13 spline 60hp 2 stroke. Performance was limited by the max 4800 rpm achieved. I have also run a 17" pitch quicksilver. Settled on a 13" pitch quicksilver, which I started with . It runs to around 5300-5600 rpm and gets about 33 knots, quick hole shot with a full tank and 5 adults, 27 knots.
The gearbox ratio on this engine is quite high, 1:2.1. I think. The prop spins faster than most outboards hence the lower than expected pitch.