11 February 2009

Repowering: Post-implementation review

The Repowering Project: one month later

Some of the little jobs mentioned in the last post are still on the To Do list, but basically the project is finished and we are delighted with the performance of the new Yanmar, coupled with the change to bigger blade on our Autostream prop, which is now well-matched to the engine.

Here, in no particular order, are the benefits of the changeover:
  • We can cruise along at 5kt doing 1800 revs, and 2000 revs gives us a cruising speed of 6kt. This extends our range when we are making short trips with deadlines at the end of them - we can start from Dover or Cygnet down the Channel and know that we can still get back to Hobart in a short day even if we have to motor into a headwind the whole way.
  • We feel we have the power to make headway even in tough conditions, although we haven't had to prove that yet.
  • The boat is much more manoeuvrable, particularly in reverse.
  • Conveniently, the changeover has reversed our prop walk, making it much easier to get out of our current berth.
  • Now that we've fixed a leak and got all the air out of the system, the engine is heating the hot water as effectively as the old engine did. We feared this might not be the case as with the Yanmar only part of the total coolant flow goes through the heat exchanger for the hot water service, and we thought we might need a header tank to avoid problems with airlocks.
  • With the new splitter installed, the alternator is delivering good charge to all batteries.
  • Fuel consumption is 2.5l per hour. Taking into account the increased cruising speed, this probably doubles our range.
  • Not a drop of oil has appeared on our newly painted engine compartment floor.
  • With the soundproofing and lower cruising revs, we can have a conversation when the engine is running without having to shout at one another.
We visited the Yanmar stand at the Wooden Boat Festival to report in as satisfied customers, and went off clutching Yanmar caps, stubby holders and a rather nice mat, which Peter is thinking of putting under the engine to see if it further reduces the noise level. Suspect the Yanmar agent was hoping that we'd put it somewhere a bit more public, so it's on deck for the time being.