Delay in revs

Bowlerhat

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2 Jul 2017
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Our previous boat had shafts. Engaging ahead instantly produced engine and shaft revolutions. Same for astern.

Our current/new boat has a B3 leg driven by a Mercury 3.0L/260HP diesel inboard. When I engage ahead, shaft revolutions immediately commence (I’ve checked with the leg trimmed out/up), but the engine revolutions (judged by the sound of the engine more than the revs on the dial, which barely change on engagement from neutral) remain audibly almost the same. After about 6 seconds, the ‘rumble‘ of the engine picks up, as I would expect. On engaging astern, the shaft revs and increased ‘rumble’ occur simultaneously.

Is this some clever computer controlling things, or is this abnormal? In terms of berthing/manoeuvring etc, I can’t say it bothers me particularly and everything else works as expected (i.e. smooth revs on further acceleration), but this is something I haven’t experienced in (much older) boats.
 
Having experienced this a lot more now, the better description is ‘delay in clutch engagement’. Only happens ahead and is quite disconcerting. I’ve trawled other threads and the potential culprits seem to be drive oil (wrong type or amount), the shift cable/assembly/lever or the cone clutch. With only 140 hours on the clock I’d be surprised (and disappointed!) if it’s the cone clutch, but we’ll see.
 
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