POWER GENERATION
I weigh our options for off grid electricity generation. For freedom from the ties of shore . Phone in hand I research solutions, as Stargazer swings to the tide. There are three main technologies to consider.
Water powered generators have developed apace - since their adoption by the planet circling, solo sailors, of the Vendee Globe Race fleet . They use the motion of the boat through the water to drive a propeller, which in turn powers a generator.
The Watt & Sea is the current state of the art. They mount, like an outboard motor, and can be pivoted clear of the water to reduce drag. That's one downside . Their action slows the boat . Another is that they really only generate power, in useful amounts, at speeds over 5 knots. No problem on a Vendee Globe IMOCA 60 averaging 20 to 25 knots. But an issue for a 31' cruising boat, with an average cruising speed around 5 knots - like Stargazer.
When in the lowered position, the leg exerts a powerful lever, as the propeller bites. Reports have surfaced of mounting bracket failures. A heavier duty bracket is now offered. My thinking is that the stresses will now be transferred to the stern of the boat - which won't have been laid up with such loadings in mind . Structural modifications would be required for a reliable set up.
Wind powered generators are familiar technology. They operate day and night, whether the boat is at anchor or at sea. They also take up minimal deck space, an important consideration aboard Stargazer. One downside is that the best power is produced only at relatively high wind speeds.
Another is that some designs, particularly the higher output ones, create a loud thrumming roar from their rotating blades. The elegantly sculptural Air Breeze is a notorious offender. I once left an anchorage, off the otherwise idyllic island of Houat, rather than endure its siren call through the night. Almost all wind gens, which I have encountered, create some level of vibration . It is not heard on deck - but resonates below, within the sounding box confines of the hull.
The wind gen which, from my visits aboard other boats, combines the least blade roar and the lowest level of vibration is the Eclectic Energy D400. Indeed, when French builders Ovni fit them to the integral stern gantries of their admirably idiosyncratic shoal draft aluminium craft, I can vouch that the D400 is entirely rumble and roar free . However this is not universally the case with all installations . A Najad ,which I was invited to shelter aboard (when caught out by a rain squall, whilst rowing ashore, on the Kenmare River), had a robustly pole mounted D400 professionally installed . It rumbled and growled unbearably as the wind shrieked overhead and the rain danced on her immaculate teak decks. .
Solar panels, photovoltaic cells, convert the sun's rays into electricity . Even on overcast days . They are silent in operation, with no moving parts - and are therefore free of the maintenance requirements of wind or water powered generators . Their downside is that they demand significant space in order to mount the required square metre-age to supply a boat's electrical needs . Perhaps accommodating them would be too tall an order aboard Stargazer?
Or perhaps not.....There is a patch of cabin top, just forward of the windscreen and aft of the twin 'saloon skylight' hatches, which is relatively un-shaded and traffic free . Its just large enough for a 25W panel . Then there's our existing 'roving' 50W panel to be deployed, at anchor, wherever the sun falls best . On passage this stows neatly in our aft cabin . Together the two panels would get us half way to the 150W which, I estimate that, we need for self sufficiency.
Sunware (makers of our roving panel), I discover, produce a folding 75W panel. In fact it is two flexible panels mounted on a heavy duty fabric backing. It comes supplied with 'popper' fastenings, along the four sides of its perimeter, with which to clip it onto a bimini or awning. Those 'poppers' could be replaced with eyelets, to be used for rope lashings . And two diagonal pockets, for removable battens, could be added to the reverse side - to hold the panel rigid. That would produce a 75W, self supporting, roving panel which could be lashed in position at anchor; but would fold up, to stow alongside our 50W panel, when sailing. Here is our break through solution. A way to mount 150W of solar power aboard Stargazer without the structural surgery, unwanted weight gain, or aesthetic slight, of a gantry.
POWER MANAGEMENT
With a solution identified to our power generation needs, it is time to think about the deployment of that power. Since Stargazer was commissioned, ten years ago, solar controllers have come a long way. The science of Maximum Power Point Tracking (MPPT in the jargon) has been created . This maximises power extraction, from a solar panel, as light conditions and battery state vary - making the available power go further and charge harder.
I don't pretend to completely understand how this works . But its along the lines that the MPPT controller senses both the output from the solar panel and the condition of the battery bank . It then manipulates the charging voltage to optimise the charge regime many times per minute . The Victron 75 / 15 is universally praised by anyone, whom I've spoken to on the subject . The '75' refers to the highest voltage which it creates; and the '15' refers to its delivering a maximum of 15A of current . It can handle up to 200W of solar - just in case we wanted to add another panel in future .
Reduction in on board electrical consumption is the next area to attend to, in order to balance the energy equation . Stargazer's navigation lights are all LED's . They consume only 10% of the power which incandescent bulbs would . Her cabin lights, all 26 of them, however are incandescent . Even parsimonious use (say of a frugal four over the galley, followed by two in the saloon), whilst preparing and eating supper, has a profound and detrimental effect on the health of our house batteries.
The last piece of the, off grid energy freedom, jig saw puzzle is therefore to replace the G4 halogens in the deck head and reading lights with LED's . Warm white so as to maintain Stargazer's snug and homely below decks ambience.
Orders have been placed . Parts deliveries are eagerly awaited . Paul (the electrician) and Alan (the sail maker) are booked to carry out panel /controller installation, and folding panel 'enhancements' respectively .
I look back down to my phone. Exciting reports are surfacing that Dutch mainland ports will reopen to visiting yachts from the 15th of June, followed by the Waddenzee ports from the 1st of July . My heart leaps. Freedom beckons . I trawl the Dutch government website for confirmation, of what I fervently hope to be true . Sweden and the UK are excluded . A disappointment . European nautical lock down release has begun, but not yet for the UK . Freedom beckons from afar . Tantalises . France is due to review restrictions on Monday . Our next hope for good cruising news.
USEFUL LINKS
