shanemax
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Was doing 4.2 knots motoring and just cut the revs by a third(save fuel) and am now doing 3.87 i lost just over third of a knot. Must be worth it.
Displacement hull
- Thread starter shanemax
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Chiara’s slave
Well-Known Member
How long is your waterline? We get 5.5kn at half throttle with a 8.8m waterline, and about 4kn at half that, though we’d be badly affected by the slightest adverse condition at 1/4 thottle
shanemax
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shanemax
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It's not a big boat, I have a man in the engine room and a man steering.
johnalison
Well-Known Member
That sounds fine for flat water, but a current or seaway can change things. Taking a reductio ad absurdum, if you motor at three knots against a three knot stream your fuel consumption becomes infinite. Depending on the prop perhaps, you may find that motoring slowly against wind or waves is very inefficient. I get the impression that my 2-bladed folder 'slips' more at low revs and is sometimes more economical when motoring moderately hard.
shanemax
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shanemax
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Don't know what happened there
shanemax
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If I up the revs on mine it does not double the speed but it certainly doubles the consumption.
shanemax
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shanemax
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shanemax
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No wonder I could not hear it. It sounded like a milk float.
Chiara’s slave
Well-Known Member
Ok. If I put just my headsail up today, I’d probably get 6-7kn, it being a F4. Its why we only ever motor in and out of harbour. Unless we’ve got 5kn or less wind, we’ll be faster sailing. Even then, we’d still beat the 1/4 throttle motoring with 5kn on any point of sailing apart from a dead run.
Our tender outboard sounds like those boats in Harry Potter. Silent.
shanemax
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Now pushing foul tide, head sail only 3.81 over ground.
Shaz77
Well-Known Member
I did not know large ships could be battery operated.
newtothis
Well-Known Member
There are several shortsea passenger and cargo ships already operating. Yara Birkeland is the posterboy but there are others, including a 700 teu containership working coastal services in China.
Chiara’s slave
Well-Known Member
Boats that, by design, don’t float, have been electric since almost the beginning
johnalison
Well-Known Member
I'm sure it does. All I'm saying is that other factors sometimes come into play, such as the pub closing time.
Sticky Fingers
Well-Known Member
Your boat isn't especially typical though it it, think you'd almost never need to motor on passage unless it's flat calm?
shanemax
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The ship is called Rem Energy and worth a Google. It can run on clean hydrogen, batteries or be charged by a wind farm.
Fascinating tech.
Fascinating tech.
shanemax
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Submarine Yes good old fashion diesel, no DPF or Exhaust recirculation, no oxygen sensors just a smoky diesel charging lead acid batteries.
