Cooking

Drivetrain progress

Dave Warnock

Dave Warnock

— 3 min read

Today we took the big step of drilling a hole through our new thrust bulkhead for the propeller shaft.

Thrust bearing in the foreground, behind it you can see the end of the stern tube.

Eventually, this hole will be significantly larger as the propeller shaft comes through it and ends inside the Aquadrive flexible coupling which gets bolted onto the forward side. At the moment the hole is going to support the propeller shaft and hold it in exact alignment through the stern tube to the outside where the propeller will be.

First, we need to get a new propeller shaft, the old one is in poor condition and is too short for where we have positioned the thrust bulkhead. We are switching from the old fixed 3-blade propeller to a Bruntons Autoprop Eco*Star which has an amazing combination of properties.

  • Due to the blades being able to feather it results in 85% less drag when sailing, which should increase speed by about 1 knot (given we expect to sail up to a maximum of just over 7 knots this is a huge gain)
  • The automatic pitch adjustment matches the torque of the motor so power is delivered more efficiently so more power with less energy
  • The blades are more efficient in reverse than fixed propellers.
  • The blades are more efficient when used for energy regeneration (using the water to turn propeller and charge the batteries from the motor when sailing.

The new propeller shaft will come with the right taper and key for the Autoprop Eco*Star to fit straight on.

We also need a new cutlass bearing. This is what fits inside the stern tube and has a rubber-bearing surface that the propeller shaft turns inside.

The stern tube that the cutlass bearing goes into. Not sure yet if we will need to get grub screws to go through the threaded holes to hold the cutlass bearing in place (it looks like locktite might be enough).

We won't finalise the alignment and fit the Aquadrive flexible coupling until we have the new cutlass bearing and the new propeller shaft. But we can still progress with the electric motor positioning and sort out the motor mounts. We can also fit the cap to the top of the thrust bulkhead and add the braces that will stop it moving when we reverse (when the propeller will try to pull it backwards and tear it off the engine bearers).

We are very much looking forward to getting the motor out of the main cabin where it had been blocking the port seating area for a long time. It means we don't have a lot of living space at the moment.

The saloon, its a lot colder this weekend so we have had the fan heater on for a while as well as the infrared panel heater. The table swings out so there is room for one of us on each side of the table leg. We are now very sophisticated with only one area with no floorboard.
Our galley which works pretty well. We made a cabbage stir fry this evening. The sink drains into a bucket, we use a variety of metal water bottles from about 1/2 litre to 2 litres in size. We have a simple cooler box "fridge", induction hob and combination oven.
And one of our favourite things about our boat. The corridor to the aft cabin with the comfy double bed (complete with electric blanket). Hidden to the right just before the bed is the ensuite composting toilet.

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