Holiday progress day 9: Electric Motor reliability

Well not much progress today because we nipped home last night as our old Diesel engine was being collected today. The forecast had also helped make the decision with another storm coming through.

So rain nearly all day for the time we were in Manchester, rain for the journey back to Beaumaris and rain most of the evening.

The key progress is emotional, with the sense of freedom from having an engine sitting in our trailer, waiting to be sold. As we were driving back we were remembering all the expensive work we would have had to do in order to get what was a good engine working.

  • The survey required the raw water seacock to be changed. That was bonded in so thoroughly it needed cutting out with a hole saw. Possible with the engine in (although the two cockpit drains would have been much more difficult).
  • the survey warned that the cutlass bearing was worn and that the stuffing box needed to be repacked. We found that the propeller side of the coupling to the gearbox needed to be cut off (and so would have needed a replacement). We also found that the propeller shaft is too long to slide out because of the skeg, so we would have had to lift the engine for the propeller shaft to come out under it, that would have meant cutting off the rusty original engine mounts and replacing them.
  • the survey warned of a leaking fuel filter, would we then have found that several of the valves in the various fuel lines were seized and would we have felt we needed to add inspection hatches to the fuel tanks, replaced all the fuel lines and thoroughly cleaned all the system and all the fuel? As we did that we might have noticed and been concerned about the very rusty fuel vent fittings and the condition of the fuel filler hoses.
  • In this process would we have noticed and dealt with the rusty paraffin fuel tank for the boat heater (that failed and spilt paraffin everywhere just as I arrived at the recycling centre).
  • When would we have taken out the hot water calorifier (heated by the engine or by a mains system condemned in the survey) that was buried behind the paraffin tank, under the rusty fridge compressor and under the unreliable water pump? Because when we did take it out, we found it rusty and leaking out of sight.

In short, because everything around the engine wasn’t replaced with the new engine, we would have had large costs to get afloat with this engine and far more over time to get it to a point where it would be reliable with the many problems with the setup diesel supply (particularly water in the fuel and no way to get it out, modern problems diesel bug growing due to the use of bio-diesel and no way to get it out, old sludge in the tanks causing blockages in the pipes before the filters).

We are more and more glad that we took the plunge and decided to go fossil fuel free from the beginning rather than first fixing what we had. So we have not spent any money on fixing the diesel but all on preparing for where we believe all yachts need to be going – fossil fuel free.

Again we have been watching more YouTube videos and seeing more people having problems with diesel fuel, the old idea that diesel engines are this magical safety device because they are always reliable just isn’t the case for lots of people. Also the amount of nasty, cramped, smelly maintenance and the impact that has on sea sickness and morale needs to be acknowledged more openly in the sailing community.

Obviously, at the moment we have very little to be sure of in terms of the reliability of our electric motor system, how dependable will it be. However, from all we have studied so far we are quite confident. We will have a good installation of a brushless motor, that will be in as dry a place as possible, with potential backup batteries and tools/spares for making cables.

We have come to realise that the Rival 38 centre cockpit has a number of really good features for a reliable electric motor installation.

  • the bilge is really deep and large. So even if we get a lot of water on board it is going to be a long way from the motor or the batteries, we have made this so it is visible for checking as well as making it possible to access the pumps and hoses (initially we are fitting both an automatic large capacity electric pump and updating the original manual pump)
  • the motor compartment is not accessible from the companionway steps (but instead from the corridor to the aft cabin). Very often these steps lift up for access but that also means there is potential for water to get into the motor compartment whether it be from spray or people climbing in with wet clothing etc
  • the motor compartment is large enough so that our batteries, motor and controller can be right next to each other, so short cables that we cann easily inspect that don’t go through bulkheads where they can get damaged or through bilges where they can get wet.

We are also implementing a few things they we hope are best practice to help with the reliability

  • The motor is brushless for no maintenance and high efficiency. It is air cooled to keep our moisture (we will need to monitor temperature and might need exhaust fans)
  • All our battery banks are going to be in boxes that are watertight from below with a top that means any drips from above will not make it in. Build from epoxy coated plywood with a strong timber frame that does not allow battery movement but does allow air circulation for cooling.
  • The motor frame will have a watertight undertray and a lid that directs any drips clear of the motor.
  • Our batteries that are connected in series will have automatic battery balancers to ensure they are evenly charged. Those in parallel will have huge busbars and identical cables for equal loading.
  • We are over specifying all our battery cables and have a full size professional crimping tool to make the best possible connections.
  • Most of the batteries (5 out out of 8) have a bluetooth BMS and I will be monitoring this automatically from our Raspberry Pi system
  • All our solar chargers, battery balancers, battery monitors are from Victron with bluetooth capability so we can monitor them from their app and from the Raspberry Pi system
  • The SignalK system on the RaspberryPi will allow us to add a number of sensors to monitor temperature, humidity etc of everything, so we should know if there is a problem in any battery, bearing, motor, motor controller etc
  • We are installing a dripless seal for the sterntube. This should minimise maintenance and the chance of any salt water coming into the engine compartment.
  • We are installing an Aquadrive. This absorbs all the thrust from the propeller which means the engine and the bearings are free from these loads. It also means that the alignment of the motor is not critical. Both these mean that the motor will be on very flexible mountings so there should be much less vibration in the motor frame as well as in the boat. That should help avoid things shaking loose.
  • We plan to install an automatic dehumidifier for the motor compartment so keep the air in and around the motor plus electronics as dry as possible.
  • The cockpit floor is removable for lifting diesel engines in and out. All our electric stuff is small and light (heaviest individual items under 40kg). Even the motor in it’s frame is under 70kg and we can put it in the frame in the corridor next to where it will go. So we will use a more secure sealant on the cockpit floor, it would be possible to get it up but not as easy as it has been.
  • We will have a much more sealed bulkhead between the motor compartment and cockpit locker. So when you put wet ropes, fenders, sails in there it will drain into the bilge directly and not splash through lots of holes.
  • We are re-routing the vent for the main water tank so it doesn’t go through the motor compartment (reduce chances of water ingress)
  • The boat does not have a working electrical earth at present, we will make sure it is implemented and tested to protect the systems from galvanic corrosion.
  • All new composite cockpit drains and seacocks should reduce condensation and with much higher quality hoses should be more watertight.
  • We are not in a rush and so we can take the time to build it up slowly, carefully and with clear layouts and documentation
  • As we are doing all the work ourselves we know how it is installed and how to maintain it

Despite all that there are still some risks:

  • The biggest is the motor controller, the wiring is complex (for us, fortunately we can bring in our son who is an electrician). Also they are programmable and we don’t have the tools to reprogram it (particularly for regen but potentially also for things like throttle response and max revs)
  • We don’t manage to generate enough electricity to charge the batteries enough (separate updated blog post on generation to come)
  • We do something stupid with one of the expensive components so we need to spend a lot of money replacing it (eg shorting a battery, wiring something wrong).
  • Something we have not thought of

Compared to our lack of understanding of diesel engines this feels like a comfortable place to be 🙂 We think that overall we should be more reliable than diesel, better to live with and because of these be both more convenient and safer than a diesel engine while obviously being incredibly better for the planet.

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