A Solar-Powered Boat Hartmut Ginnow-Merkert copyright 1991 Hartmut Ginnow-Merkert In 1989 I had to decide what to do during my one-year sabbatical, a much-needed break from my teaching duties at the Minneapolis College of Art and Design. My desire to make a meaningful contribution to an environmental issue combined with my interest in boating and solar energy resulted in the decision to develop a solar- powered boat. Background My background in mechanical and electronic engineering and industrial design provided the foundation, and a week of volunteering at the second American Tour de Sol provided me with additional wisdom concerning solar energy systems and components. At the Tour de Sol I also noticed what I considered a basic problem in the area of solar-powered products: People need to identify with a product in order to accept it. It is not good enough to make the product work; it also has to motivate, stimulate, trigger peopleÕs curiosity, attract them, make them want to own and operate such a product. They need to see and understand the benefits of using a product. Many of todayÕs solar-powered consumer products fail this test, because they donÕt relate to the consumers' physical and psychological needs. I decided to test this idea in the design of my own solar-powered boat. I had not built a boat before, and work with fiberglass was out of the question, so I decided to purchase a used hull and build the superstructure out of plywood. It seemed to be logical at that time that a catamaran (twin hull) design would be a good start. Catamarans are fast and provide plenty of area for solar modules. A used Prindle 16 was purchased, and I had to make the painful decision to disassemble it to a point where it could never be used as a sailboat again. Together we enjoyed one more beautiful day of sailing on a lake nearby, a good breeze propelling the boat at hull speed. Sailing is an environmentally sound way to enjoy our natural resources, but wind is also a form of energy which fights you every inch of the way. It throws you into the water, surprises you by randomly choosing directions, abandons you just when you need to go home. Masts needs to be stepped, get entangled in power lines. Miles of ropes snatch at your feet, booms try to break your skull, heavy keels make your life miserable. Some people like the challenge, those who donÕt drive power boatsÑand pollute. I donÕt think of solar boats in terms of competition, however. Solar boats provide an alternative for those who want to enjoy a lake or river, who are too lazy to paddle or sail, and who want to keep the environment there for our children. Solar boats are great for wildlife observation, cruising, reflecting, relaxing. Construction The Prindle was dismantled, the hulls were switched and mounted to the original aluminum extrusions with wedges that would hold them perpendicular to the water surface (they normally point slightly outward). My design was to defeat comparison with existing types of vessels: it was not to be a sailboat without mast, or a power boat without power. I wanted the boat to look different, something people hadnÕt seen before. Connotations of other high-tech products wouldnÕt hurt, and as speed was not an issue, I was not interested in a speed-boat look. A box would be just fine. I decided not to use a rudder, instead I would use two electric motors, one on on either side of the boat. This would reduce the component count and increase the reliability. By running the motors at different speeds and varying their direction, the boat would become highly maneuverable. The controller could be a joystick, or better a knob whose movement the boat would duplicate: forward, reverse, rotation left or right. There had to be a roof for the solar modules, so what could I put under the roof? I decided to turn this part of the boat into a sleeping cabin, for extended camping trips. The front portion would be the cockpit, to be designed more like the interior of a van than that of a conventional boat. There just had to be two gull-wing doors. I consider the roof a desirable feature, because it protects from ultraviolet radiation and rain. It also prevents fishing. I donÕt fish. Solar boats have yet to be defined. Many exist, mainly in Europe and Japan, and there are many different layouts. A solar boat has a ÒpersonalityÓ defined by the relative size of each of its main components: 1. Solar generator (solar modules), 2. Battery storage capacity, 3. Motor(s). The size of each of these components depends on the type of use the boat is intended for. The two corner stones are: (a.) a boat which is used once a week for a few hours. This boat needs lots of battery storage capacity and very little solar generator area, because the boat has six days to recharge. And (b.) a boat thatÕs used for racing purposes and needs to go for hours or even days at peak power. This type of solar boat will need a huge solar generator and very little battery storage. There is an infinite number of combinations, each with a special purpose or type of use. The configuration I chose uses four M75 Siemens Solar modules (with room for two more), two 100 Ampere-hour deep-cycle, maintenance-free lead-acid batteries, and two electric trolling motors operating at 24 V. and 30 A. The electronic ÒglueÓ consists of a SCI battery charger (Photocomm) and two Curtis PMC 1203A motor controllers. Additional electronics had to be developed. The two motors are mounted on pods which extend from the battery boxes sideways. These pods are driven by two Warner Electric electromechanical linear actuators with potentiometer feedback. A rotary switch in the control panel sets one of 4 programmable positions (maintenance, shallow water, deep water, trailer). An electronic circuit compares these settings with the actual motor pod positions, and power is fed to the linear actuators until they reach the desired position. A future extension of this concept includes the possibility of interfacing this circuit with the depth finder, so that motor position adjustments are automatic. The human interface uses a tandem Penny+Giles T-bar potentiometer with a tandem rotary potentiometer on top. These pots were used, because they are hermetically sealed and very reliable. They are also very expensive. More electronic devices were used to make the boat more exciting and to distract onlookers from asking questions about the top speed (5 mph). These devices include a mobile phone which allows me to conduct my business from the boat, a Loran C/Depth Finder unit, and a compact disk player. The boat was built during Spring and Summer of 1990 and test- launched 10 August 1990. It took another few months to finish, test, and rebuild some of the electronic components, and the boat finally became operational in May of 1991. It has been on the water and operated flawlessly for over 100 hours. Experience The boat was named ÒNeah BayÓ after a Makah Indian Reservation on the Northwestern corner of WashingtonÕs Olympic Peninsula. It generated some interest among the local media (two video clips on the local TV news, a radio interview, two newspaper stories). Many individuals commented about the boat, and I was invited to speak at several schools. A local high school is exploring possibilities to start a solar boat design competition. It was my intention to hold the first American Solar Boat Regatta in Minnesota, June 91. This attempt failed, because many of the prospective participants couldnÕt get the funding at a time when the Gulf War and the recession made many corporations reluctant to sponsor this event. Solar boat regattas have been conducted in Europe and Japan for several years. Solar boats are now commercially available in Germany. So far I have not been able to attract investors to start a solar boat business here. Obviously it is easier to see the need for solar boats in Europe where environmental pollution and public pressure have turned many lakes off-limits to gas-powered boats. Those among us watching the development of environmental issues in this country should be able to see the advent of similar restrictions on the horizon, restrictions which may severely hurt a boating industry unprepared for change. I will continue to pursue this project. Stage 2 will see the redesign of this boat for production in fiberglass, with simplified mechanical and electronic functions. It should retail for around $8000, seat four adults, reach a top speed of six mph provide a range of three hours at full speed (no sun), and an unlimited range under sunny conditions at speeds of up to three mph. This boat would allow fishing and could be a real attraction at a lakefront resort. You want to know what IÕd really like to do? Be among the first few people to cross the Atlantic Ocean in a solar-powered boat. Hello, anybody else out there? Access Hartmut Ginnow-Merkert, 1840 Lakeview Terrace, Orono, MN 55356 ¥ 612-473-8699