Special Refitting. Time for change. Ten questions in ten episodes. #8/ The energy

8.In the boat, I never have enough energy. How do I do that?

If you have found that you never have enough power on board because you spend so much time in the roadstead, it is a good idea to make all systems more efficient and to think about installing solar panels that will provide you with greater self-sufficiency. Just buy one or more marine PV panels, a charge controller, and you’re done. In this way the on-board batteries will not be in danger of being discharged, and with the proper equipment you will be able to use electricity in the middle of the sea. Truly thin and reliable solar panels have been available for a few years now: pay attention to the differences in cost and the product you are offered. To discover all the secrets of solar panels, we invite you to read all the tips on the subject from our super-expert Roberto Minoia.

And if you are a “mile-grinder,” consider installing a hydro-generator; our super expert takes the stage on this topic as well.
“If you are planning to try your hand at ocean crossings or otherwise long-distance sailing, a hydrogenerator may in many cases be sufficient on its own to provide you with energy autonomy. The hydrogenerator itself is a simple device: it consists of a propeller immersed in water, dragged by the motion of the boat, which as it turns transmits the rotation to an alternator, which in turn converts the rotating mechanical motion into electrical energy. The principle is the same as that of the engine alternator or wind generator. In fact, it is no coincidence that some hydrogenerator models can be easily converted into wind generators so that they can provide power even when the boat is stationary at anchor. Yes, because the limitation of the hydrogenerator is that it can only work when you are sailing, of course. As you may have already guessed, power production varies with the speed of the boat, just as that of the wind turbine is dependent on wind speed. But the density of water is much greater than that of air, and thus enables the hydrogenerator to produce respectable electrical power even at low sailing speeds: say starting at 4 knots, increasing exponentially as speed increases. To give you an idea, a hydrogenerator with maximum power of 300 watts can generate 100 watts at 6 knots, 200 watts at 8 knots, and 300 watts (maximum power) at 9 knots. Different pitch propellers can usually be installed in the various models depending on the speed of the boat, so as to optimize power generation.

A TEST IN THE ATLANTIC OCEAN
During the November 2015 Atlantic crossing (ARC 2015), I had the opportunity to test a Watt&Sea hydrogenerator. It was not a particularly high power model (300 watts), but I can guarantee that in terms of power production it outperformed the other electric generators we had on board (360 watts of solar panels and 400 watts of wind generator). On some days we recorded more than 300 Ah delivered by the hydrogenerator alone in 24 hours. Our boat (the Beneteau Oceanis 50 “Y2K”), super-equipped and therefore a devourer of electricity, with refrigerator, freezer, PC on for at least 12 hours a day, Chartplotter, Automatic Pilot always running 24 hours a day, SSB radio, etc. etc. consumed about 300 Ah a dayo, so on the days when our speed was quite high (over 7.5 knots on average) the hydrogenerator alone proved sufficient to supply all our energy consumption.
PERFORMANCE IS LITTLE AFFECTED
It is wrongly believed that hydrogenerators unduly penalize boat performance. We honestly did not even notice. The propeller’s “drag” should be about twenty kilograms with about 300 watts of power produced: probably traveling at 8 to 9 knots you will not experience more than a couple of tenths of a knot reduction in speed, so a completely acceptable penalty. Ultimately, the hydrogenerator is a “must-have” for all sailing longer than 3-4 days. The only flaw is the high cost: for the highest-performance models it reaches over 3000 euros.

THE SUPER-EXPERT
Roberto Minoia combined his passion for sailing and technology at www.blogdellavela.it roberto.minoia@gmail.com