20 October 2018 – Measuring speed under power

Start position
The Elephant Boatyard
Start time
10:20
Start engine hours
855.2
Towards
The Elephant Boatyard
ETA
Distance travelled
11
Finish position
The Elephant Boatyard
Finish time
12:40
Finish engine hours
857.6
Skipper
Richard
Crew
Weather
  • Calm, Variable 1
  • Sunshine
Tide
  • HW Portsmouth 09:40
New faults
  • Slight condensation on P70
Np->Sp %
25

Checked stern gland, which is not dripping measurably, when cold.
Inserted paddlewheel log and calibrated it on the way out, before tide got going.
Motored around off Bald Head measuring boat speed against engine speed at various settings. Perfect conditions for this, with almost no wind. The goal is to collect data to understand better why we don’t reach full engine speed under load.

  • Engine speed Boat speed
  • 1200 rpm: 3.5 kts
  • 1400 rpm: 4.1 kts
  • 1600 rpm: 4.7 kts
  • 1800 rpm: 5.2 kts
  • 2000 rpm: 5.6 kts
  • 2200 rpm: 6.1 kts
  • 2400 rpm: 6.6 kts
  • 2500 rpm: 6.7 kts (throttle wide open)

Engine revs to 3200 rpm out of gear.

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