Future Hybrid Catamaran Cruiser

Discussion in 'Boat Design' started by Becaris, May 26, 2009.

  1. Becaris
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    Becaris Junior Member

    I'm taking a look at 'near' future technology as applied to a catamaran cruiser. What I mean by 'near' is technology that has been announced, but is not yet commercially available, and how that technology could be used to improve a hybrid sailing yacht.

    First off, there have been some recent breakthroughs in solar panels. These 'thin' panels are lighter and they claim they are cheaper to manufacture (therefore cheaper to the consumer). Right now the only issue is efficiency, but so far each year they have improved efficiency on this technology.
    Simply projecting the improvements forward it is somewhat safe to assume that we will have commercially available thin solar panels in the next few years. Once these new lighter panels are available why not use a Catamaran (with the large deck surface area) and design it to handle quite a few of these light panels? An array of 54 panels that each put out about 200 watts would get you a around an 11 kWh array.

    But thin panels isn't the only breakthrough. What about that problem of 'angle efficiency'? On a yacht creating a mechanism to angle your panels to the sun is too heavy and problematic. But, another new breakthrough in solar panels might deal with this. A technology that captures 30% more light at more angles has been announced.


    Assuming a catamaran of about 50', with two electric motors for propulsion, I wonder how fast it could motor using power right off an 11kWh array? However, that's only good during the sunlight, which brings up batteries. Right now the problems with batteries are weight and price. However, there are already some new lithium batteries out that hold three times the energy of a typical lead acid batter at the same weight. They are currently hideously expensive ($8,000 by some reports) but as we all know, technology prices drop like an anchor, so we can expect more reasonable pricing in the near future.


    Additionally, there is a LOT of competition right now in the area of efficient lighter batteries due to the push for hybrid and electric cars. There is also that breakthrough from MIT that allows lithium batteries to take on a charge MUCH faster (though this might not help a yacht situation away from a marina).

    So assuming we get cheaper, lighter batteries to go along with our new solar panels in a few years, how does that change the landscape in designing a yacht to use these emerging technologies?

    If we were to create an 11 kWh solar array, and have sufficient battery storage to run off fully charged batteries for several hours, why not then design a catamaran to only use diesel fuel in emergencies? I'm currently designing/dreaming of a biplane rigged catamaran (I like the redundancy, safety, ease of use of twin un-stayed rotating masts with In-boom furling for a shorthanded yacht). The yacht would have twin motors rather than diesel engines. While sailing the solar array can charge the battery bank, and when needed you can use the motors (in reverse while sailing) as generators to help charge the batteries. When more power is needed or during nighttime the motors can run off the battery banks. During the day when sailing isn't possible they can run off the solar array and/or batteries as needed. There will be a diesel generator for emergencies (foggy day, no wind, power depleted, got to move). However, baring that rare circumstance the yacht should be able to move via wind, solar and/or battery 99.9% of the time, requiring very little diesel consumption, or none.

    I'm planning to start building my yacht in a year or two, with a two year build time. That puts it three to four years out from now before it gets wet. I'm planning on using emerging solar and battery technologies that will hopefully be commercially available by the time I'm ready, though the yacht isn't dependent on them.

    The idea of a hybrid cat is not new, there are hybrid cats out there right now, but what IS new is using a MUCH larger solar array (due to lighter more efficient panels) and more battery storage (due to lighter batteries). This just isn't currently possible, the weight of the panels and batteries is too much. But with these new breakthroughs improving those areas, can might finally make a yacht that can dispense with regular diesel use.

    What am I missing here? What are the issues? (other than we're waiting on the commercial release and drop in price of these technologies).

    I have questions for those in the know. For a 50' cat, how much sustained power does it take to move what weight catamaran at what speed? Any estimates? What size motors would be best? Can a larger motor be used with lower current? (Example can a 20 kWh motor be run on 6kWh power from a solar array? The idea being that there would be a diesel generator that could put out much more power for emergency speed, but most of the time the motors would need to run off solar and/or batteries at lower power.)

    There is a hybrid yacht out there right now that claims 5 knots off of a six kWh array during sunlight, but this is a smaller (12m) yacht, using current heavier solar panels and less efficient Lead acid batteries. It is also has no sails (which is silly). Why ignore free wind to move and charge batteries? Here is the yacht though.


    My design will increase the size of the solar array by double (minimum) and use lighter panels and will be on a sailing cat. I'm not a yacht designer so I'll soon be hiring professionals to help bring my concept to reality. But, I do have the money, the time and the desire to create my dream. I'm confident that a hybrid system on a blue water sailing catamaran cruiser can use the new emerging breakthroughs in solar panels and batteries to make for a mean, green sailing machine.


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  2. brian eiland
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    brian eiland Senior Member

    First off I might ask why you didn't continue with your previous discussion of this same subject matter??

    Look at the trials and exponential complications this fellow is going thru to get a hybrid yacht:
    Granted this is larger than you are looking for, but take a look at some of the circular problems he runs into trying to get 'free energy'.

    Basically it sounds as though you want a solar powered vessel that can also sail. Even with the emerging technologies of solar power, I do not foresee solar panels directly capable of powering a 50 foot yacht for a large number of years, and/or unless they are the size of a football field. Hopeful energy storage technologies (batteries, etc) will move along at an accelerated pace, but that still won't let you get along with an aux diesel source (hybrid), unless you plan to move along at a snails pace.

    Keep track of those new battery technologies here, or add to the discussions.

    I'll post a reply to you smaller size vessel over on the other subject thread where I suggested an alternative
  3. Becaris
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    Becaris Junior Member

    I did not continue my previous post simply because this is a new subject and is NOT a continuation of previous subject matter. Certainly my personal project stays the same, but the discussion of this thread is supposed to be about NEW breakthroughs in technologies that are not yet commercially available. And how those new technologies could help to improve a hybrid catamaran.

    Also, why does it bother you that I start a thread about new solar and battery technology uses on a sailing cat rather than continue a specific discussion of my yacht project? Are you the forum police or something? Did this thread bother your delicate sensibilities? If so, place a cool wet rag on your forehead, lie down and... get over it.

    As to your assumption that I want a solar powered vessel that can also sail... that is a false assumption. All I'm looking at here is how lighter and more efficient solar panels and batteries could change or benefit hybrid catamaran sail boat designs.

    No one can deny that more solar panels would charge batteries faster, and/or power an electric motor(s). This is already being done in on this yacht:


    But that's not a sailing cat. What I'm attempting to discuss here is the concept of how lighter, cheaper, and more efficient solar panels and batteries could improve and change the design of a hybrid sailing cat.

    Now as to your link to the people having problems getting 'free energy', ALL sailing is about getting free energy. In one form it's called wind. There are, however occasions when the primary means of free sailing energy are not available or convenient. Like when moving around in a marina, or pulling in or out of an anchorage, etc. At those times we currently tend to rely on fossil fuel engines. Can we change that with the new technologies coming out?

    In addition to this, there is the need to run our engines a couple hours each day to charge up batteries to power water makers, electronics, air conditioners, etc. In the past it did not make sense to put a large array of solar panels on a yacht simple due to the cost and weight. But new breakthroughs are perhaps changing all that. With enough solar power could we generate and store enough power to never run the engines just to charge up the batteries?

    There are already cats that use hybrid electric propulsion in place of fossil fuel engines (Lagoon 440 for example). However there are CURRENTLY limitations to this technology (price and weight primarily). The question is simple, if the cost and weight are reduced, why not add a large array of solar panels to improve what solar panels already do currently on a smaller scale? Why not add more batteries if they are lighter and cheaper so that you can store MORE energy off that array to go further without having to turn on an engine(s)? Finally, if the array is maximized to use as much area as possible, and give you as much power as possible, how fast could the yacht motor straight off say a 11 or 12 kWh array? (Even anywhere from 1-5 knots would be useful for moving about in certain areas).

    None of this changes that we are primarily a sail boat, but as solar power is on the cusp of becoming cheaper, lighter and more efficient why not look at the uses to enhance a sailing cat?
  4. XHeeler
    Joined: Apr 2009
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    XHeeler Junior Member

    Green propulsion

    Green efficient is not cost efficient, and get used to slow

    Since we are in a period of transition where battery and solar array technology is immature, whatever you design should have the ability to change these systems to upgrade the boat easily. If I was doing it now, I would start with several Prius battery packs and electrical system, and upgrade to Chevy Volt systems when available.

    I think it would be desirable,but very complicated, to have the ability to get to your destination by any one of the three propulsion systems, wind, solar, and carbon. But how do you optimize being a solarmotorsailor? (I made a new word). Well, research all the information on motorsailing and see if you can add more solar power than battery weight to the boat.

    For instance, you only get good power from solar for 6 hours in the middle of the day, maybe a little more if you can track the panels toward the sun, but that really increases your wind resistance. Make sure your array doesn't become a sail if you get into a storm. Sails will shade the panels to lower the solar production, which is why the solar c(t)rawler doesn't have them.

    If I was going to do it now, I would start with the solar trawler and put unstayed masts in each corner with furling sails. and only use the masts where the sails don't cast shade on the solar array. One mast will always be more efficient with the wind than 2 or 4, but not in this case if you would only use 1 or 2 of the 4 masts. At least those heavy batteries will help your righting moment. Remember to wash that array frequently to get the salt buildup off for maximum efficiency.

    I would have a smaller and larger diesel genset with dual electric motors and the best variable pitch feathering props, but only run one motor most of the time.

    I would have redundant watermakers to reduce water tankage if it was energy efficient, to offset the battery weight.

    I would have minimal amenities. It's normal for green people to sweat, but just about every window would open for ventilation.

    And be prepared to never sell this boat.
  5. apex1

    apex1 Guest

    An array of 54 panels as mentioned, where do you put them on a 50´cat? Each of them has a 1m² surface! The market estimates a increase up to 14% efficiency in the next few years (from 12% today) (Solon AG).
    Assuming they are perfectly positioned and only one third of them is in the shadow of the sail, you would need 72 m² of PV panels.
    72 times 600 is 43200$ (one watt is about 3$ at present and will not come down during the next 5 or so years)

    So, what was your idea?
  6. brian eiland
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    brian eiland Senior Member

  7. Becaris
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    Becaris Junior Member

    Well, a couple things. I would not plan to motor off the array for any serious distances. For 90% of travel I would be sailing. If the sails blanket some (or even a lot) of the panels while I'm sailing, I wouldn't care. When I do lower the sails I would have a large array to help charge the batteries faster while there is sunlight. While sailing I can use the props and motors if I need to charge the batteries. While at anchor I would have a significant array for making hay while the sun shines (charging batteries).

    This whole idea is useless with today's technology and prices. From the beginning of this discussion I'm projecting forward to cheaper, lighter, more efficient solar panels and batteries. As for opinions on how much solar will cost per watt in five years, that's debatable and I can show you just as many projections for less as more. I'm not prognosticating WHEN solar will be cheaper, lighter and more efficient, only that there is a lot of 'buzz' on the net from several manufacturers, universities etc. talking about breakthroughs that address all these problems. I'm also basing this on the history of technology starting expensive and getting cheaper quickly. It's always been the trend, I see no reason to believe that will change.

    Since this discussion is based on the assumption that some (even one) of these breakthroughs will pan out, then the question is... if you COULD put say 54 panels on a cat, and have more battery storage (since they would be lighter) what could we do with that?

    You asked where I'd put 54 panels, there are 54 panels (to correct scale) on the concept cat pictures included in the first post. This is just a concept, but they are represented on that cat model.

    Now, as to redundant water makers,, yes, I would agree that would make sense. Power on a yacht using this (as of yet unavailable) technology would not be the issue, but weight is always an issue. No matter how light a battery might get, if we can save weight in one area we could add more batteries.

    Using one of the new possible breakthroughs listed by link above in my original post, you wouldn't have to be so concerned with angling solar panels anymore. They have increased the angle at which the solar panels are efficient by significant amounts.

    This yacht is not as much science fiction as you guys seem to think. There are already hybrid cats. The main difference is simply that I'm projecting more panels (because they are cheaper and lighter) with more battery storage (because they are lighter) once weight and price come down. Other than that, there is no new technology here.

    We are in complete agreement that this could not be done today, or likely in two years, after that... who knows? Your guess is as good as anyone else as bringing technological breakthroughs to market is a minefield. I'm just hopeful and looking ahead to what I might do IF it comes about in the next few years..

    One final note, I don't give a rat's *** about resell value or how much it costs to build a yacht. This is more of a discussion about what could be built with the new technology that is coming down the pipe. I wouldn't build ANY yacht were money something I was worried about spending. A boat is a big hole in the ground where you throw money... I plan to dig my hole vary large and I don't care about how much I toss in. :)
  8. peterAustralia
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    peterAustralia Senior Member

    hi Becaris

    If you are building a large catamaran, that implies you have money, I guess that is a good start. Some things, crossing an Ocean with 2.5hp, point is that modest power can do good things if modest speeds are acceptable


    nigel Irens.
    High speeds with low power, efficient hullform means less fuel is used (less energy)

    of course you can do without an engine if you need to, here is a 38ft Wharram that is currenty somewhere near the Marquesas and has no engine at all


    So maybe having less power input that is ideal, but having a stronger motor that allows for easier docking and getting in and out of inlets. May I ask what you wish to achieve, to cruise in an environmentally sustainable way? or to demonstrate new technology?

    The reason I ask is this. If it is the first, maybe is easiest to build a conventional cat with a 4 stroke outboard, and use it sparingly. With the money left over find a way of using it to help the environment.

    Can you buy carbon credits?
    Is there a way of using money to protect tropical rainforest from logging and clearing? For the money saved you may be able to do really good things by saving a patch of forest from destruction in the long term, maybe go to a small island and say, if you resist the loggers I will pay you so many hundreds to dollars per year to protect what yo have... just an idea
  9. XHeeler
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    XHeeler Junior Member

    Solar arrays are heavy

    and 50 some current highest density panels would weigh more than a ton, which would raise your center of gravity too much for a sailing vessel. I think you should look at nanosolar.com. They are making roofing materials out of solar particles which are less dense and powerful at present, but are 100 times thinner.
    consider that the whole gelcoat above the waterline would be the solar array, rather than the current silicon wafers that are so fragile that they need heavy aluminum boxes and glass panels to protect them.
  10. Guest625101138

    Guest625101138 Previous Member

    I have been working on the design of a solar/wind powered vessel. The best preliminary design I have come up with so far is a what I have termed a faux-tri. It is a very slender monohull below the water, a conventional monohull above the water but at the surface it is a trimaran.

    It is far superior in overall performance than a catamaran or slender monohull. The catamaran will require around 40% more power on the hull for the same displacement in calm conditions and will have much more windage. I doubt that it could be built to the weight target as well. The slender monohull ends up being higher drag by the time it is made wide enough to gain reasonable initial stability.

    The faux-tri is very low power, requiring less than 1kW to do 8kts. With 4kW it would get to about 14kts. Just 400W to do 6kts. These figures might seem ridiculously low but they are possible. This boat in the clip displaces 100kg and is doing 7kts with 150W:
    This is a stabilised monohull, similar hydrodynamically to the faux-tri, without the cabin.

    The current evolution of the design requires lithium batteries to keep weight down, carbon fibre construction to keep weight down and would use both solar and wind turbine for energy recovery. Again the latter keeps weight low by avoiding high strength structural elements to support sail loads. The turbine loads are an order of magnitude lower than sails.

    The advantage of the combined power collection and storage means that you can collect surplus power when collection is good and release it when collection is poor. This way the speed is kept constant rather than fluctuating as you normally do in a sailing boat unless you resort to motor sailing. Makes sense when you know power is a cubed function of speed. So the power is stored rather than doing 0.5kt faster on a windy afternoon and will boost batteries for holding speed overnight.

    The faux-tri design is discussed in more detail on this thread:

    This design would gain from advantages of scale but I am really after a single person boat for coastal hops. It is designed to be self-righting with this in mind.

    Rick W
  11. yipster
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    yipster designer

  12. XHeeler
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    XHeeler Junior Member

    Solar dinghy

    Maybe it would be more practical to place most of the solar array on a tow behind dinghy. No shade worries, less design problems for the mothership and current boat owners could get it immediately. Cut it loose in a storm and track it's beacon afterwards.

    It's small electric motor could make it a limp home tractor, if the mothership's mast or engines failed, that could finish crossing an ocean.
  13. JonathanCole
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    JonathanCole imagineer

    It would be poor design to have solar panels that are shaded by sails. I do not believe that a single response to your post has been factual. The facts are that a very efficient 50 foot by 25 foot cat hull can be driven by the electricity produced by a 15 Kw array of solar electric panels of about 20% efficiency (without sails). This has already been accomplished in the 50 foot cat that crossed the Atlantic a couple of years back. (Actually that boat had less than 15 Kw.)

    You don't need to use expensive batteries. Boats are perfectly capable of handling the weight of lead acid traction batteries. Beware of people claiming expertise that is not founded on experience or engineering.

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  14. XHeeler
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    XHeeler Junior Member

    Sailors cross the oceans at or almost at hull speed by sailing and/or motorsailing. The risk of weather prevents this from being a leisurely month sail, similar to a protected water, good weather day sail.

    The solar navigator did it at 2/3rds hull speed, and were lucky IMO to not have their array removed by a storm (it needs to be sacrificial if placed up in the air like a patio cover) or the ship to be capsized.

    There is definitely a need for better design.

  15. Guest625101138

    Guest625101138 Previous Member

    If you are going to make broad sweeping statements like this you need to offer some detailed back-up on all and every point made by others. Something you could not possibly do. It devalues what useful input you might have.

    My link provided above offers over four pages of posts. There are numerous proven facts throughout it. Please take your time to identify all the facts and tell us why they are not factual in your opinion.

    Rick W
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