Engine over revving

oGaryo said:
Hi, during the sea trial of the new boat, I noticed the RPM at WOT was between 5200 and 5400 on the gauge.. on checking the spec it should sit between 4600 and 5000.
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Just a thought, if max rpm on that engine is 4800, how come the rev limiter wasn't stopping you hitting 5400? I wouldn't expect it to let you get 200rpm over the max, which is 5000rpm.
 
duncan said:
this would be my interpretation as well

sea trial is one of the situations when a boat is probably as clean, empty of **** in lockers, low levels of water in tank, with probably not a full fuel tank either!

I would expect it to be right at the top end of a rev range - and I wouldn't be concerned if it was 2-300 over it; unless all the tanks were full etc of course
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really good point, a few things in lockers but the tanks were nearly empty and that statement covers both fuel and water.. you know you get that feeling when the boat's just right, I did on this one so I think I might simply be trying to find things to consider unecessarily.. she ran fine, oil pressure and temperature remained bang in the middle of the gauges and she spun on a sixpence at the end of a run through the ski area.. the handling was really impressive compared to the Fletcher, nimble and true would be a good way to describe it... time to go out and buy the bottle of champers ready to rename her I reckon:cool:
 
lovezoo said:
Just a thought, if max rpm on that engine is 4800, how come the rev limiter wasn't stopping you hitting 5400? I wouldn't expect it to let you get 200rpm over the max, which is 5000rpm.
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I think it's 5000rpm WOT and if I'm honest I can't recall if the gauge hit 5200 or 5400 but I will check it out.
 
MapisM said:
Yup, most navman plotters are SmartCraft compatible, so he might have bought the SC/Navman gateway, plus a SC cable, connecting the plotter to the SC plug on the engine. I did something similar on my boat, though I only fitted the small LCD screen 'cause she doesn't have (nor need, for the lake) a plotter. A couple of hundred bucks well worth spending.
If that's what he did, actually you have much more than just a fuel flow interface, because it allows you to see on the Navman screen all the engine data in real time (RPM included), thus giving a chance to cross check the accuracy of ALL other gauges, not just the tacho. No need for any additional revmeter.
You can find more details about all that on this user manual if you're interested.

But back to the engine log: you should also be able to check the TOTAL engine hours reported by the ECU through the SC interface, but unfortunately I'm sure (well, almost) that you need the Mercury scanner or a portable PC with the proper software and SC interface to check the hours logged at each RPM range, which in your case is the most interesting data I'd be interested in.
Any Mercury mechanic MUST have such equipment, and with it the reading is a 5 minutes job.
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There is a new smartcraft 'Eco' gauge that looks the goods M.
Very comprehensive info on a nice neat small digital guage.
 
Yes I know, but not worth the higher cost imho, if you compare the functions in detail with their simpler display (the smaller one, square shaped).
What's really in a different league is the Vesselview Race edition, but aside from being the most expensive among SC displays, it takes a lot of space on the dashboard. I couldn't have fitted it in mine, for instance.
 
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