…is not going to happen. I’ve thought about it a lot during the past two weeks, I’ve been studying a lot and I know pretty much what I’d want but unfortunately the total costs would add up to more than I was prepared to spend, as well as work hours. That said the project is definitely on the horizon and will most likely happen in the future. The setup I am envisioning (the main parts) would be:
• 5 kW brushless 48V DC motor
• Direct drive with gear reduction – wouldn’t want to connect to the existing transmission even though it would be easier/quicker/cheaper (short term), due to the losses in efficiency, meaning it would end up more expensive
• 48V 100 Ah LiFePo4 batteries – would consider as low as 60 Ah or as high as 200 Ah depending on finances (lead acid / AGM makes zero sense for this application*)
• 2-400W of solar panels – this is probably the area I’ve thought about the least (might want to combine solar with wind)
• DC-DC converter – to get 12V for instruments/domestics
*) You can run lead acid down to 50% charge and AGM even lower but their main drawback is their inefficiency while drawing high loads like with an electric motor
Range with an electric motor
Range is the main (only?) downside of electric motors vs diesel so let me explain my thought process and requirements. This above setup would give around an hour at full speed (~5.5-6 knots) or ~10h at 2-2.5 knots (20-25 mile range). Plenty enough for our use case, which mainly consists of getting in and out of tight marinas (and sometimes anchorages) and having maneuverability when becalmed in shipping lanes. Hence I would consider a 60 Ah bank as well, as you essentially only need to be able to maneuver away from a ship’s path, no need to be able to cross the whole shipping lane. And while charging from solar panels we could motor indefinitely at 1 knots (if completely becalmed for longer periods of time like in the doldrums).
But why not?
There are just so many various bits and pieces required for this setup (missing from the above bullet points), like motor controller, BMS (battery monitoring system), battery chargers (from solar and potentially shore power), inverter etc. Not to mention that the 12V charging equipment (solar panels and wind generator) we currently have would become useless. Simply too much time and money required at this point. Let’s see if/when we’re wintering somewhere in some nice place with ample time where it’s easy to get parts shipped (definitely not Canary Islands).
But why electric in the first place..?
Some people view electric motors in sailboats as a replacement for a diesel engine but it’s not. It’s simply auxiliary propulsion, a replacement for a sculling oar or a small outboard. You could of course couple the system with a diesel generator to get “unlimited” range, but then you’d still have a diesel engine which would defeat the purpose.
Something at least came out of this
One thing these two weeks of studies have resulted in though is that we will be switching the existing batteries to lithium (LiFePo4). It just makes a ton of sense to have less weight and more capacity per rated amp hour, plus not having to worry about maintaining a particular level of charge. All in all LiPoFe4 only has advantages (aside from cost) vs traditional batteries. And it’s not that much more expensive if you employ a bit of DIY, like installing your own BMS to monitor the cells instead of buying ready assembled batteries (with internal electronics). Or you can, at least in the US, find used Tesla battery packs for very little money (in terms of watt/money). And used LiPoFe4 batteries (80% of the original capacity) is an option as well.
Because of not going electric (at this point) and needing improved access to the engine, we will be flush decking the cockpit and adding some sort of access hatch (like on Taleisin pictured above) to be able to more easily do maintenance on the engine and to use the newly gained space below for added storage. Let’s get rid of that space waster and pooping hazard enhancer! Some shelves will be added to the outside of the cockpit coaming to be able to sit there more comfortably.
At this point the SJR (split junk rig) makes the most sense if we want to try to keep the existing accommodation. In any case the conversion will happen in any case as the current sails/wardrobe would need to be upgraded in any case. I’ve sourced canvas and will be making an order soon, whatever the final rig choice will be.
Topsail for junk rig
I’ve also recently started thinking about the idea of trying to incorporate a topsail (like on a gaff rig) for use in light airs. Since I’m not convinced on the merits of high angle yards on JR’s it would make sense to have the option to rig a topsail to extend a couple of meters above the mast and gain some 15% more sail area, and to have a more well-optimized sail area when the wind picks up. This would require storing a long (4 meter?) spar on deck but would definitely help a lot when sailing in light conditions. Acceptable tradeoff in my opinion. If I manage to engineer it properly, we’ll see.
Thoughts? Shoot a comment below.
Torqueedo have pretty good systems BUT very expensive. I cringe at their cost.
After sales service is reported to be good and being German the quality is expected to be good
Yeah there are a large number of commercial alternatives nowadays but they’re all very expensive compared to buying and assembling everything yourself. And even though DIY requires more work and study, you will in the end have a good understanding of all parts of your system, which is something I highly appreciate.
Ahoy! Are you a member of the Junk Rig Association? Lots of knowledge in there 😆
Yes ma’am, since 2012. 🙂
Great news, Oscar! I personally prefer a deep cockpit one could spend time and feel safe, but everyone has its own and it’s great to see you moving forward!
I’ve been thinking of replacing my batteries (3x70Ah + starter one) to LiPoFe4 and would be happy to collaborate if possible…