Solar panels or wind generator? There’s little doubt that for Stateside cruising, especially down South where the amount of sunshine outstrips the strength of the wind for much of the year, solar is top of the list for liveaboard and long-term cruisers. Having seen what even a small 50W panel can do in a Northeastern summer, I had been planning to bump up the solar capacity on our Pearson 39-2 project boat to 250 watts but wondered if this alone would be enough.
I hadn’t seriously considered a wind generator until I cruised the Grenadines on a charter boat a couple of winters ago. In every anchorage, it seemed most of the serious cruising boats boasted not only an arsenal of solar panels, but also a wind generator whirring merrily away in the brisk tradewinds. Since future cruising plans include lengthy periods off the grid in tradewind areas, I came home and started my research.
Every such project should start with an assessment of the boat’s power needs. Once you’ve determined the amount of current your fridge, stereo, laptop, lights et al consume over 24 hours, you’ll have a fair idea of not only the size of battery bank you’ll require but how many amps your charging devices will need to deliver. There is an excellent worksheet on the West Marine website that can help you with this.
The idea, of course, is to minimize (and if possible eliminate) the need to run your engine to keep your batteries in a decent state of charge. I don’t think I’ll achieve the latter state of Nirvana, but going three days or so without the need for additional charging beyond what wind and sun can provide seems a workable objective.
Even though the boat’s needs are modest, the only requirements being the ability to run the fridge 24/7, power a stereo and laptop at anchor and allow unlimited use of navigation electronics and autopilot underway, it became apparent that the 200W of solar panels I’d planned to add would fall short. Perhaps the obvious answer would be to install more panels, but without installing an arch there would be no room to do so—and I wanted to minimize cockpit clutter.
My wind generator shortlist was indeed short: the turbine had to be functional at medium to high wind-speeds—none of them generate much power below 8 knots or so—it had to be tough and reliable, and it had to be quiet. I’ve shared anchorages with boats whose wind generators sounded like approaching helicopters. The decision to install a German-made Superwind 350 took all of those factors into account. It’s a heavy unit, built to commercial specifications, and with its auto-feathering blades it is able to be left unattended even in strong winds. Although it would not start delivering serious amps until wind speeds were in the low teens, it would start at least trickle-charging as soon as the blades started spinning at 8 knots or so, and internet research indicated excellent reliability. (For more on wind generator tech, click here.
Location, location, location…
Once I’d settled on the equipment, there arose the gnarly question of where to mount it. This would not be much of an issue on a broad-sterned modern boat, but the comparatively svelte derrière of a 1980s Pearson did not provide me with many options. Nor had I ruled out adding an arch in the future, in which case the mounting point would likely be changed, so I did not want to mar the transom with a protruding mount, and nor did I want to spend a fortune on a heavy stainless steel pole that I might have to ditch in the future. I settled on what I thought was the least imperfect location, on the taffrail just inside the pushpit, with braces to stabilize the pole. I bought a 9ft 6in long, 2in ID polished Schedule 40 aluminum pole for $60 from a local metal fabricator, and sourced the mounting plate and support brackets from Garhauer Marine.
Then there was the issue of installing the electrics that came with the unit—the controller that regulates the power supply from the turbine, the dump load resistor that absorbs excess current once the batteries are full, and the inline stop switch that can be used to turn off the generator when desired. I had no bulkhead space in the cockpit locker for these, so I laminated a plywood plate onto the inside of the hull to hold the controller and resistor, while the stop switch is accessible from the head compartment.
Superwind’s wiring diagram was straightforward, calling for 40A fuses or breakers in the positive cables from the stop switch to the controller and from the controller to the batteries. Although I could have just about have gotten away with 10AWG cable, I opted to spend a little more on 8AWG cable to eliminate voltage drop.
Final assembly of the turbine did not take long; all fasteners were supplied and the instructions were explicit. Waiting for a windless day, we connected the turbine assembly to the pole, bolted on the blades and raised the pole into position. After double-checking all the power connections and tightening all the mountings one last time, I flicked on the circuit breakers to find—nothing. It would be another 48 hours before there was enough wind to even turn the blades. Not much happens below 10 knots, but I’ve seen as much as 7 amps with wind speeds in the high teens. At the time of writing the unit had only been in service a little over a week, so a more detailed evaluation will have to wait. I can say, however, that the Superwind is indeed wonderfully quiet and vibration-free and has been keeping up with the demands of the fridge.
All in all, this was a satisfying project, easily within the scope of anyone who is reasonably handy (and not afraid to drill holes in their boat). My next step is to install a 100W solar panel on each of the lifelines aft and see how that wind/solar combination works over the remainder of the summer.
Photos by Peter Nielsen