2010 Yamaha F60 Questions - rpm, wot etc

[ahamay]

I have a 485 runabout with an F60 and 80L tank. The fuel range is quite good for an average of around 5000rpms and 20 knots. I'm getting 180klms or around 100nms from a tank.

Questions are:

1. This engine has peak hp at 5500rpms and wot at 6000rpms. Can you run the engine at 5500rpms continuously ?

2. Can you run WOT continuously ? I'm not saying that I do this but can these modern engines handle it ?

My boat tops out fully loaded at 24kn and 6000rpms (WOT) so I think I have it propped correctly. Cruising speed is around 20-21 knots at 5000rpms and 23-24 at 5600rpms.

I usually travel 45mins at 5200-5600rpms to get to my spots when fishing. Is running these rps ok ?

I see no increase in speed above 5600rpm so 5600 technically my WOT.

Cheers

[bugman]

Gday mate,

I have a 2008 model the same as yours. Mine pushes a 5m Brooker tinny.

My WOT is around 5600 as well. I rarely run mine over 5000 unless towing the tube or the wakeboard. I find mine the most fuel effecient at around 4500 sitting on about 20knots.

It's enough and find I can't travel any faster offshore anyway.

Brett

[winston]

Ahamay, your top end seems a too little low. I have a Brooker 4.85 side console with a Yamahs 60 efi fourstroke and at 6000 rpm I am travelling at 30 knots, and at 4500 rpm I am travelling at approximately 22 knots. I changed from the standard prop to a stainless one with an inch less pitch so that I can pull 6000 with two up. This reduced top end from 32 knots but significantly improved the midrange response. I suspect that your runabout must be very heavy in comparison. I usually travel between 4000-4500 rpm with the occasional burst to w.o.t. It is my understanding that fourstrokes are not meant to be driven at the top end of their rev range unlike two strokes. The fuel ecomomy between 4000-4500 rpm is exemplary so why go faster? I think that the most significant issue is that you have your boat/motor combination propped correctly. Cheers Winston.

[Scott nthQld]

I've got an '04 model and WOT is about 57-5800 and pushing 28-9 knots, would be more but I had an incident in some shallow stuff and took a few mm off the stainless prop, used to get 29-30 at WOT, loaded with 2 up.

Mine sits on a 4.85 quintrex weighing in at 360kg, hull weight, plus 60l of fuel, esky, ice, gear, etc. All up its pushing about 750kg including engine weight, before i fill the esky.

I'm no good with propping, but with those figures I would hazard a guess at yours being underpropped?

I get the best fuel economy from 4-4500 rpm sitting on about 22 knts at 3km per litre in good conditions

my figures all come from GPS ground speeds, and the engine tacho, fuel figs came from experience working out dist travelled and fuel added after a trip (always head out with a fullt tank)

[ahamay]

Thanks to those that have replied. I must say that I did have the next pitch prop and it maxed out at 5600rpm loaded rather than being able to go to the full 6000.

I think I'm carrying more weight than those those have given examples here.

Hull is 440kg
Fibreglass Helm/Anchor well etc Guessing - 100kg
80L Fuel - 80kg
Motor + Dual Battery - 120
2 UP - 200kg
Storage - Seat Fishing Gear Eskys etc 150kg

Approx 1100kg at an estimate.

[ahamay]

Here is some Fuel Figures for you as well based on a few trips I've done.

Tank Size - 80L
Range 182km
Average Speed - 20kn
Average RPM - 5000
L Per kilometer - .439
K per Litre - 2.3

I'm happy enough with the fuel range based on these figures as the range is more than ample for what I do in it.

So basically the question is: If i'm traveling a distance for example - 1hr, is it ok to run the engine on 5000rpms the whole way ?

[Scott nthQld]

It'd be best to run it in its cruise range, that is 4-4500rpm, but I rarely take that sort of advice, if its nice and flat calm, I'll be sitting on WOT just for the fun of it. but then my fishing spots aren't 1/2 hour away let alone a full hour.

I spose if you were to run at slightly higher revs all the time, i would at least be expecting to do more regular servicing as the engine will be working harder more than a motor being used at cruise with the occasional WOT squirt.

I reckon you would be right, but servicing should be done at more regular intervals, like every 80hrs or 10 months rather than 100hrs/12 months

[megafish71]

Thanks to those that have replied. I must say that I did have the next pitch prop and it maxed out at 5600rpm loaded rather than being able to go to the full 6000.

I think I'm carrying more weight than those those have given examples here.

Hull is 440kg
Fibreglass Helm/Anchor well etc Guessing - 100kg
80L Fuel - 80kg
Motor + Dual Battery - 120
2 UP - 200kg
Storage - Seat Fishing Gear Eskys etc 150kg

Approx 1100kg at an estimate.

If that is the case, I think you should be looking at engine height and changing to a four blade prop to help carry the extra weight. Might be worth playing with as your top speed appears to be down.(to much prop slip) Try the numbers you have on a prop slip calculator, should be aiming for under 20% slip.

Ron