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.

Energy Independence

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.

Solar Power

600 Watts of solar on the davits is offered as an option on the Outremer 4X and 45

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!

Flexible, lightweight solar panels on the Gunboat 68

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.

Puffin under construction, 3 flexible solar panels will be mounted on the center cockpit roof.

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.

Hydro Generator

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.

The racing version of the Watt&Sea hydo-gen is needed on Puffin to handle the high cruising speeds

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.

Fossil Backup

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:

Forward port cabin with our extra single bunk bed option.

25 Comments on “A Green Puffin

  1. Hi Doug,

    I am typically reluctant to post on the internet but felt compelled to thank you for taking the time to share your experiences (first Wildling and now Puffin). I arrived at the party a little late, so am now enjoying binge-reading (is that an expression?) the back catalogue. Your posts are thoughtful, unbiased, and beautifully written.

    So, on behalf of the silent majority, thank you, and please keep the stories coming.

    Fair winds,


  2. Will you use propane for the stove or electric? Thanks so much for your time and effort with the blog. You do an amazing job.


  3. Hi Russell, excellent question! I would love to not have propane on the boat. Heavy bottles, hard to find refills in remote places, bottle fittings are incompatible in different countries and safety make this a problem I would like to be rid of. I’m just not sure of our electrical energy balance yet, so I decided to go with the standard propane stove for now and will revisit this when I can determine if we have enough solar capacity to support an induction system. I’ll post on this when I know more.


    • Hi Doug, Any updates on eliminating propane by moving to a fully electric (induction, etc) galley ?

      Thanks for your blog !


      • Hi Rob,
        I am going to explore an electric galley now that we have increased our solar to 1.4kW with the new hardtop. Robin does not like our propane stove, and carrying the gas bottle and trying to fill in remote locations is a pain!


  4. Hi Doug,
    Congrats on your new site. As good as Wildling !
    2 ideas you may consider:
    – Check “the sailing family” pics on Instagram: Their Outremer 51 sports 4 x 100W light flexible panels, loosely tied together, that they unfold and tie to the net when at anchor. Panels are connected to a dedicated Victron MPPT. On passage, the panels are stored under a mattress. Seems a great idea !
    – Some cooking tables in France (see darty.com for example) have 2 induction burners + 2 propane burners. This could be a nice compromise with added redundancy. I noted my propane bottles are lasting a lot longer since I started using an electric kettle whenever battery level, sunshine, etc, made it appropriate, eg most of the time, but not always !


  5. Hi Doug,
    glad to see you are getting another boat! have you seen the ita cat? They use the OCEANVOLT system where the batteries run the propellors and when sailing, the propellors are used to charge the batteries. It looks like a great system although I imagine it will be expensive until more companies produce competition. Check them out, I`d love to hear your thoughts,
    Fair winds and safe travels mate


    • Hi Bert,
      The Ita cats are using the hybrid system I mentioned in my post. They have two electric engines, a lithium battery bank and a 15 kW diesel generator. Although there is some regen produced by the props when sailing, it’s not enough to forego the diesel generator. The single point of failure, diesel power source of this design rules it out as a viable option for me.


  6. Hi. Doug
    Great to see your new boat coming along so nicely. Its wonderful to see your evolution with regards to what’s important and what is needed. All I need to do is read your blog to stay abreast of new worthwhile technology. Happy sailing


    • Hi Allan,
      I’m almost certain there is room, but won’t know for sure until I see the finished installation. I’ll post some pics.


      • Doug, have you thought about getting rid of the 2 70Ah start batteries and start from the house bank, you’ll save 40kgs. As backup get 1 (or 2) Li car jump start battery packs.


  7. I had not thought of this, it’s a very good idea! There’s already a cross connect to the house bank, so it’s easy to do. I will run some tests, the weight savings is well worth it I think!


  8. Quick update on this. Mastervolt advises to not use the lithium house batteries to start the engines on a regular basis as it will reduce the life of the batteries. I discussed with Outremer and they are trying to get a lithium solution for the engine start batteries. They need to get approval from Volvo Penta, so it might be a while.


    • Didn’t think a 1.1l diesel would draw that much, the 12/2500 rated at 10C and all that. Going to a small Li on the start, would be an acceptable compromise.

      However, curious as to what Mastervolt states the actual reduction in life is, from 3500 cycles to 2500, to 1500, to 1000? Would I be willing to live with 1000 cycles? Maybe, for 40kgs over 3 years assuming daily cycling. 350 cycles, maybe not. I’m disappointed though, over 40kgs and reduction in charging complexity, is a lot to not lose.

      Would be really keen to know what VP says about a Li start battery, I know it’s been done on older Yanmars. The existing cross connect to the house bank implies that it should be ok?

      Anyway, going into not so low hanging fruit territory, Flexofold offers composite props (actually composite hubs), you’ll save 2.5kgs each, and no electrolysis.


  9. I loved the NaviWatt system on the new TS3 Marsaudon Composites. All electric off grid is perfect. If its enough to get in and out of a port, then fine by me. Although trying to scale this up for a liveaboard cat will mean more power consumption.

    Like you I want to cut down to the basics. Ok not quite to the degree of The Sailing Frenchman on YT, but well away from a floating apartment. So zero AC, washing machine, oven, water maker. I newbie ideas so far were to maybe collect rain water and refill at dock as required. Plus keep an emergency osmosis pump. Although what are the options for keeping warm heated water for a power shower? Thats I can’t give up!

    I wonder what the largest catamaran I could get is while keeping it all electric? No diesel engines ideally. Perhaps a Dazcat 1095 or TS42? The Torqeedo idea is amazing if it will work on a larger scale?

    Thanks for any help! Your approach is so in line with my aspirations.


  10. Hi Doug, thanks for the great information in your blog. Curious what type of flexible panels you went with. Heat disapation is a big problem with most of those causing early failure, right?


    • Hi Frank,
      Yes, heat dissipation is a major cause of failure of flexible panels. Outremer stopped installing them after many owners experienced failures. The new generation of panels have improved their heat tolerance, so Outremer is offering them again as an option. Our panels are made by Solbian, they have worked perfectly so far, but I’ll report back if we experience any issues with them.


  11. Hi Doug, thanks for all the great info. Is the water heater too much of a draw for you to run through your inverter?


    • Hi Will,
      Yes, running the water heater through the inverter would be a lot of drain in the batteries. Instead I run the engine for about 30 minutes every couple of days to keep our water tank heated.


  12. Hi Doug,

    Thanks for your talk today at RQ was great to meet you and Seth. Your blog is awesome too.

    We are taking delivery of a new 12.8m Stealth Catamaran September next year and currently going through the build planning process.

    I’d love to get your thoughts and feedback on a couple of points.

    1. What flexible solar panel brand and system would you recommend

    2. Raymarine vs B&G is it worth it going for B&G in your view for coastal cruising and racing? ( Note we will have a carbon rotating rig which means we need the full wack H5000 B&G system. How technical is it to manage and maintain?



    • Hi Dave,

      Outremer has only recently been willing to install flexible solar panels at the factory, this is due to many reliability issues of earlier generation panels. They have done a lot of testing with the Solbian SP Series flexible panels and provide this model as standard on Gunboat and as an option on Outremer boats. I am using 6 x Solbian SP130 panels on the new roof on Puffin.

      Puffin is our 3rd boat with B&G instruments. I really like the B&G products, especially their H5000 autopilot. I don’t have enough experience with Raymarine to give you a comparison, but B&G works well on rotating masts, and can handle spreader mounted radar domes on rotating rigs. I find B&G easy to use and also easy to configure and troubleshoot when something goes wrong.

      My preference would be to go with B&G on performance sailing boats as that is their target market. Raymarine is more targeted at power boats, so I would be concerned about their ability to handle some of the performance features we need when sailing.


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