Lepke, Interestingly I just looked into the cost of this.

If I went to Oceanvolt for this system it would cost me 54000 euros ex 25% sales tax for the following system.

Shaftdrive 20

40-60hp equivalent

35nm range on 26.6kwh battery bank

11h shore charging on a 2kw

charger
300W hydroregen at 6 kns

To make the boat truly all electric I would also have to add induction cooker and electric space heating plus a 5kw

inverter (mainly for the cooker). So all in we are talking nearly 80000 euro to go all electric.

Is such a system viable for

long term cruising? Lets say that when cruising you spend one day a week traveling for every 6 at

anchor. Lets also imagine that you manage to keep motoring down to 10nm on that trip and that you use your stove for about an hour a day at an average effect of 1,5kw. Add all the other systems in lets say that you daily usage on the hook is 2,5kWh. Over 6 days that is 15 kWh. Now add the 750kWh/nm x 10nm to get you into and out of that anchorage, and you have used 22,5kWh of your 26,6kWh bank. This looks good, there is enough capacity in the battery to get you into and out of the anchorage plus meet your domestic needs.

But now you need to replace all that energy. Lets say that you sail for all of the 7th day at 6kn. Through hydro regen you would replace 7,5kWh. That is enough to cover getting you into and out of the

anchorages but not enough to cover your usage in the anchorage. You are going to need to augment the hydrogenation with something else. If you do it with

solar then you will need to generate 15kWh of energy every 7 days of insolation on average. That works out as 2.2kWh per day on average. Lets be generous and say that you get effectively 5 hrs of insolation a day on average, then you are going to need about 500W of

solar panels to meet these needs given allowances for inefficiencies.

So add 600W of solar to the above system to be on the safe side and you have a workable system. On my boat that would require an arch over the aftdeck plus panels and sundries and fitting. All in we are talking another 10000-15000 euros by the time we are finished. But now you are generating more energy aboard both when stationary and on the move so you can probably get away with a slightly smaller battery pack. Lets say that you judge 20nm of range as sufficient. Then you only need about 15kWh of battery and you have reduced the cost of the system by 10000 euros.

So the all electric sailboat, that is totally independent of

shore power, gas and diesel is a practical proposition if you throw about 80000-85000 euros at the problem.

Now consider the diesel electric equivalent that uses gas for cooking.

The spec of such a boat would be:

20kW diesel generator

40-60hp equivalent electric motor

8nm range on 6kWh battery bank

6h shore charging on a 1kw charger

300W hydroregen at 6 kns

The 6kWh bank is 6000 euros and the diesel generator installed is about 18000 euros so together they come to 25000 euros. That is almost precisely the same as the 15kWh plus solar

installation of the alternative (maybe 5000 or so cheaper). So no big win here. The costs for the electric engine

installation, chargers and so on are also nearly the same. But where the win comes from is the auxiliary systems. You don't need an

inverter with this system and you certainly don't need one that is 5kw. You also don't need to replace your diesel electric

heater, your belt driven

bilge pump, your gas stove, your hot water exchanger, etc, etc. Replacing all of that is maybe 20000 euros all in.

So for me, given where I am starting from, a diesel electric repowering is going to cost about 60000 euros, whereas a full all electric repowering is going to cost at least 80000 euros. That is a big difference on a boat that is only worth maybe 200000 euros to start with.

Finally, going back to where this thread started it is also questionable whether it is worth it environmentally. The diesel electric boat will be doing most of its motoring on electric anyway, and will be generating enough under sail to cover its much lower energy needs when stationary so run time on the generator and thus diesel usage will be minimal (particularly with a couple of solar panels added). Admittedly, one would still be using hydrocarbons for cooking and heating away from harbour (in harbour one can just use portable induction hobs and electric heaters) but the pollution from this and the diesel has to be measured against the embodied emissions in the extra 9kWh of batteries in the all electric boat and the

research form Lund suggests that in that calculation the diesel electric will win even using standard fuels, and will win big using HVO and bioLPG.

In summary, the all electric boat gives you complete autonomy and is utterly clean at the point of use and is very low

maintenance. However, it is questionable whether it is actually superior to a diesel electric system over its entire life cycle in environmental terms and it is at least a third again as expensive from my starting point as an upgrade over the diesel electric alternative. That alternative also offers benefits in terms of range under power.

But to be honest all these calculations are making wonder whether I should just not bother with the

repower. Why not just avoid using the 90hp

Yanmar as much as possible, fit sufficient renewables to cover my power needs without relying on the engine, and stick with gas for cooking. Probably the embodied emissions in upgrading to diesel electric over what I have is likely not to be worth it even given the fuel savings, and I could do a really mean power and gas system upgrade for about 20000 euro.