A Green Puffin
A new boat construction project provides an opportunity to revisit the possibilities for reducing dependence on fossil fuels and attaining energy autonomy, and Puffin is no different. While the holy grail of 100% renewable energy supply is unfortunately still not realistic, we can get closer to it with a light, efficient sailing boat that isn’t weighed down with the appliances we’ve come to depend on when living ashore.
The 4X doesn’t have the load carrying ability of the larger 5X, so we have to pay closer attention to what we bring aboard and also what systems we install. Robin and I have evolved as cruisers over the years, to a point where some of the equipment we felt we couldn’t live without on our Catana, now seems completely unnecessary. Our Catana had air conditioning, a clothes washer, AC powered watermaker, a dive compressor and a diesel generator to power it all. On our 5X we went further down the path of simple, light and fast and passed on all of the above except air conditioning. On Puffin we will have none of these items, and we’re not worried about it at all.
The air conditioning on Wildling was never needed when away from the dock, and while it was certainly nice to have in a marina, we spend very little time on our boat in a marina, so it’s not something we used much anyway.
Our clothes washer on the Catana was never used. It always felt that if we had enough clothes to wash in a machine, we had too many to fit in the tiny marine clothes washer on board. These days we hand wash the clothes we wear on passage, and when we arrive at a port we go to a laundromat or use a laundry service.
The new DC powered Dessalator watermakers are very efficient and run off our solar panels and lithium batteries. (I will do a future post on why I prefer the Dessalator over the Spectra watermaker we had on the Catana.)
The dive compressor was nice, but we find these days we go diving with local dive operators and use their tanks, and freedive the rest of the time.
The generator on our Catana was a constant source of maintenance and headaches and I am glad to be rid of it. We didn’t have a generator on Wildling and never missed it.
It would be great to have enough solar capacity that we could install electric engines instead of diesel, and power all of our onboard equipment as well, but the reality is the amount of solar required is too great to be viable, and the weight penalty of the extra batteries needed to give a reasonable range when motoring, exceeds the weight saved with electric motors. The practical alternative is to add a diesel generator to make up the difference, which puts us right back where we started with a diesel power source, only now we have a single point of failure for all our energy systems and propulsion. Perhaps one day the technology will evolve to a point where electric motors are a viable option, but for now, I can’t make the math work, so we are staying with our two 30 hp Volvo diesels. Because our boat is light, we don’t need big thirsty engines, and we can sail more in lighter winds, so we don’t need to carry as much fuel. That’s good, but we still need to power our autopilot, instruments, electric winches, refrigeration, watermaker, pumps, lights and computers, without relying on the alternators on our diesel engines to charge the batteries, and for that we need renewable energy charging systems.
Our main source of renewable energy comes from 4 x 150 Watt solar panels mounted on the davits. These are charging two 180 Ah lithium batteries. I know from experience that 600 Watts isn’t enough and we will need to run the engines to top up the batteries using the alternators. My ideal capacity for our needs is around 1000 Watts of solar, so we needed to find another 400 watts, and for that we turned once again to our friends at Gunboat!
Gunboat uses an array of flexible solar panels on the salon roof to provide their renewable energy needs with good results. In the past Outremer has advised against flexible panels as they had high failure rates on boats that used them, and they lost a substantial amount of their capacity in the heat. The new panels that Gunboat are using are much better in both regards, so Outremer is willing to consider them on their cruising boats.
I worked with Matthieu at Outremer on a design that added three flexible panels to Puffin’s cockpit roof. Since this had never been done before on a 4X, The engineering team at Outremer needed to work out the mounting system and cable routing. The result is an extra 354 Watts, giving us a total peak capacity of 954 Watts. The real output will be less, because the cockpit roof has some shading from the boom, and the flexible panels will still have a reduced output in hot weather, but it’s still a meaningful increase over the davit panels alone. The other benefits of the flexible panels are that you can walk on them, and they are very light weight.
One technical detail to be aware of when adding panels, is that each group of panels needs to have a separate charge controller. This is because shading on any one of the panels will reduce the output of the entire group, so each area needs to be independent. This allows you to get maximum available power from the system.
Solar is great when the sun is shining, but when on passage at night a lot of energy is needed to drive the autopilot, winches, radar, chart plotter and instruments. For this we have a Watt & Sea hydro-generator. This will be the racing version, the same as we had on Wildling. It produces 600 Watts peak output and in most cases will handle all our energy needs when on passage.
There is a lot of debate around the real-world reliability and benefits of these hydro-generators. We used ours frequently on Wildling, and it worked very well, easily providing all the power we needed during night passages. On long voyages, some owners have experienced broken propellers. There are two causes for this. Something hitting the prop, which can’t be avoided, and propeller over-speed. The over-speed issue only occurs on the cruising version which has fixed pitch blades that get destroyed if they spin too fast for extended periods. The racing version uses a micro-processor controlled hydraulic pump to reduce the pitch of the blades as the speed increases.
There’s no way to protect against hitting something on passage though, so we carry spare blades. Replacing blades on these units is not difficult, but you have to keep a close watch over the hydro-gen to make sure you can quickly find and fix any issues.
For times when we are at anchor and there’s no sun for several days we can resort to the diesel engine alternators to keep our batteries charged. Since we have two engines, there is some redundancy so even if one engine or alternator fails we can use the other. On a boat where we depend on power to produce drinking water, this level of safety factor is very important. And as a final stage backup, in case of an emergency, we have a hand operated watermaker!
Meanwhile, at the Factory
Lots of progress being made on construction. Here are some photos from this week: