Max RPM

[Moose]

Neither engine is reaching its max RPM of 2800, the port reaches 2700 and the s'board reaches 2750ish. They have allways reached 2800 before, and they did going to Cowes for the Fireworks but only reached the above figures the next day. Also the Port Engine Turbo is now about a half a second slower than the Starboard.
Could it be the heat?
I will be checking the Air and fuel filters tomorrow.

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El Alce

 

[tcm]

Aha! So you WERE belting up the channel fast! I spect the airfilters are chock full of fog.

Seriously, the heat is as likely to make your underwater hull-based garden grow more than it will affect the inlet density. Of course, you can try first on a cooler day - bound to be some along soon. The airfilters are a possible, but not really fuel filters, surely?

If these don't work I would organise for someone to get a snorkel on and use a 50p scraper to clean the props, rudders and the waterline. I wonder who will get that job? Buy a few scrapers cos they get dropped. Well, mine do anyway.

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[Moose]

But I cleaned the Hull last week!
Fine, I admit I was racing up the channel in zero vis. at 32kts/forums/images/icons/laugh.gif

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El Alce

 

[Renegade_Master]

Ian I posted recently about loss of speed / revs they would not pull above 3500 which was 21knts normally
24 at these revs. Had her lifted out to remove a rope from port prop which was causing horrendous vibration,
and at the same time pressure washed her hull and props etc. Dropped her back she went straight up to 3800
27.5 knts and 3500 now equates to 24knts again, Great Joy. Down side Cost €346 aaagggghhhh

<hr width=100% size=1><A target="_blank" HREF=http://www.suncoastmarine.co.uk>Sun Coast Sea School & Charter</A>

 

[MainlySteam]

Has anyone else noticed, while his revs might be down, Moose's footsteps on all his posts are in step?

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[tcm]

yes, i had considered that as a reason BUT I think his moose walks backwards anyway. And when he first came on, he had no moose prints at all. Perhaps removing the mooseprints would make his boat all newer again?

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[MainlySteam]

Hadn't noticed that. Will have to do some research on what way around moose feet should be. Maybe his rev's are down in reverse - blinded by the light.

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[stuartw]

I would think that if this a recent problem, then it is probably nothing more simple than the current high air temperatures. High revs mean lots of oxygen required and with the air at around 30C instead of say 23C, there is less oxygen going in because the air is already expanded, and to make matters worse, the charge air cooling cannot take the temp down to as low as normal, so not so much oxygen going into the cylinders, hence loss of power.
Conversely, in winter you can get fantastic performance.

Interestingly, I believe in the med, boats that were fitted out in UK, require finer pitch props, so that the engines do not struggle. Perhaps TCM & co could confirm this. I have a spare set of finer pitched props which I believe was for this purpose.


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[oldgit]

Had you got a proper boat with proper marine type proper outdrives you could have cocked your leg and done the business with the rope for 1P worth of button pushing while drinkin a Dorada./forums/images/icons/laugh.gif

<hr width=100% size=1>Two boats please one here n one in the Med

 

[tcm]

ooh. i thought you meant they are for my boat for a moment!

I am a bit unsure of the oft-quoted inlet density argument. The overal heat of the boat engines is stable once warmed up, always around 85 degrees, and these monster lumps of metal, occupying a lot engineroom, but still leaving a good few minutes beween air changes plus the longish inlet tubes heat the inlet air significantly. Colder air of course will be heated up more than any warmer air.

Of course, in any case the difference is not the percentage difference between 23 and 30 degrees centigrade(say) but between the kelvin equivalents of these temps, namely erm 296K and 303K - or if the temp is raised by say 10 degrees for warm air and praps 13 degrees for cold then it might be the difference between say 309K and 313k - not much at all. And our friend Moose says his speed changed overnight , from one hot hot day to the next hot hot day. Aren't those finer pitched props of yours for a loaded boat, not a med cruise? - the coarser ones for a new empty boat keen to show the maximum speed with empty tanks? I think moose has picked up a bit of rope on the props, or as before, his air filters are clogged up with fog.

But i wd be happy to be proven totally wrong when the temperature drops.

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[Moose]

"Clogged up with fog"
Err, mmm yes okaaaayyyy erm!

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El Alce