Prop size on a F60 Yamaha - 4.55 Quintrex Coastrunner

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garrynt
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Prop size on a F60 Yamaha - 4.55 Quintrex Coastrunner

Post by garrynt »

20210503_121936.jpg
Have done a bit of research of late & there never seems to be a resolution with Prop Sizes / speed/ etc

My usual prop is a 11 5/8 X 11G Alloy (standard 60 Yam)
WOT 5400rpm 41kmh on almost 4 trim (if I go to 5 it sucks air)

Spare prop is 11 5/8 X12G Alloy
WOT 6000rmp 43kmh on 4 trim
will cruise on 33kms at 4400rpm

Logic tells me that swapping to higher pitch 12, should of made WOT less than 5400 (ie should of been harder to get there), but it got better to about max 6000 - 6100 rpms. I only gained 2kms per hr more & it spins faster. Pickup is way better to get on a plane.

Boat 2000 Quintrex Coast runner 4.55 with full windscreen. Alloy prop cause I ding them.
I raised my motor up years ago and cannot recall what increase I got at that time, but it was better.
My top plate on yamaha is out of water by an inch. Cavitation plate still under water.
But maybe I need to drop it back?

Mate has a Stacer 4.55 side console with yam f60 & same 11 5/8 X 11 pitch prop & he gets 52kmh WOT

I know Its holden & fords all over again

* So therefore Should I go back to the 11pitch & cruise at just under my WOT which is way under the 6000 max rpms at 5400 to get better speed & economy.

What other prop options do others have, I'd like to try smaller / bigger props to find the happy medium for my boat, so are looking for what you have on similar size boats / motors to narrow my many choices.

Pic is motor at 4 trim angle, best speed before it sucks air.
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Matt Flynn
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Re: Prop size on a F60 Yamaha - 4.55 Quintrex Coastrunner

Post by Matt Flynn »

Can speak from experience as I did several prop changes and engine height adjustments trying to get a new but under-performing 90hp engine to go.

Having a setup that produces lower revs than within spec at WOT is not good for an outboard, it makes them work harder. Best to have it running in spec and probably slightly at the upper end within the range in my opinion, because in the hot tropics you don't want an outboard working hard on long runs up and down rivers and along the coast. Outboard motors like to rev, although this probably applies more to 2-strokes.

Would be good to hear a marine mechanic's opinion.
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joesgotone
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Re: Prop size on a F60 Yamaha - 4.55 Quintrex Coastrunner

Post by joesgotone »

I would try a SS if you can find one to try. I have a 50 pushing 5.5 and now 5.3. Hull swap. Ising a 11 inch SS and getting 5600 revs. With a solas 10inch can get 6100. The SS seem to push better. Originally had ally 12 inch but struggled to get 5400. Dont get too much speed on the big hull but floats in bugger all water.
how many is enough lures, rods and reels. Is there a magic number, considering you usually only catch 1 fish on a single lure on the one rod and reel your casting with.
garrynt
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Re: Prop size on a F60 Yamaha - 4.55 Quintrex Coastrunner

Post by garrynt »

I Have dropped the motor another notch (from 3rd hole to 2nd hole from top).

2 props tested for this session
11 3/8 X 12G 6000 WOT 44kmh , 4400rpm 30kmh (this is a 11 3/8 not the 5/8 I first imagined)
11 5/8 X 11G 5700 WOT 47kmh, 4400rmm 35kmh (original prop)

My official specs for my motor F60CET is WOT 5000-6000 (which seems very varied) So everything fits the 11G props outputs.

The clear winner is the original 11G prop with a lower motor & current weight
Testing was done in Katherine River over a 300 hundred metre stretch that was deep enough at 1.8 -3 metres without the logs. Further trimming can be done at another time when there are kms of free space. Had about 60kgs less weight than previous tests when a notch higher.

I've ordered an 11 1/8 X 13 prop for the hell of it. Who knows it may be the right one for those long haul weighty trips. All my props are dented & chipped & filed back, so will stay with more malleable metal.

Hope these results help others one day
garrynt
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Re: Prop size on a F60 Yamaha - 4.55 Quintrex Coastrunner

Post by garrynt »

OK so I know you been waiting for more, I got a 11 1/8 smaller prop with 13 pitch to test. Cruising speed was better, but WOT was down (bit still in 5-6k specs)

11 1/8 X 13G 5200 WOT 47kmh , 4400rpm 37kmh
***
11 3/8 X 12G 6000 WOT 44kmh , 4400rpm 30kmh (this is a 11 3/8 not the 5/8 I first imagined)
11 5/8 X 11G 5700 WOT 47kmh, 4400rmm 35kmh (original prop)

Swapped back to to 11 5/8 11G original but like to 2kmhs faster for cruising speed.
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