Page 1 Page 2 Page 3 Page 4 Page 5 Page 6 Page 7 Page 8 Page 9 Page 10 Page 11 Page 12 Page 13 Page 14 Page 15 Page 16 Page 17 Page 18 Page 19 Page 20 Page 21 Page 22 Page 23 Page 24 Page 25 Page 26 Page 27 Page 28 Page 29 Page 30 Page 31 Page 32 Page 33 Page 34 Page 35 Page 36 Page 37 Page 38 Page 39 Page 40 Page 41 Page 42 Page 43 Page 44 Page 45 Page 46 Page 47 Page 4820 JANUARY/FEBRUARY 2017 • FOGHORN “We now have five Gladding-Hearn boats. They are the 747 of our water-taxi fleet. They’re dependable, well built, and our customers really like them. The yard is also easy to work with, responsive and stands behind their product.” Tom Fox, Chief Executive Officer New York Water Taxi Gladding-Hearn all-aluminum construction, Incat-Crowther Designs, LOA 72', beam 27', 149 passengers, speed 26 knots with 12 metric tonnes of deadweight. It takes experience to integrate customer detailing and guaranteed speeds, backed by dependable customer service. All at a price you can afford. If you’re looking to build a new boat or upgrade an old one, we can offer com- plete design and construction, from security patrol boats to high-speed ferries. To learn more call Peter Duclos at 508 676-8596 or visit: www.gladding-hearn.com. The 747 of our fleet d 1 | 1/4p | 3.375” x 4.875” www.propspeed.com PROPSPEED® is effective on: Propellers | Rudders | Shafts | Struts | Trim tabs | IPS drives | Thrusters Keel coolers | Underwater lights (clear coat) | Any underwater metal surface PROPSPEED® can be used on boats of all types & sizes Both recreational and commercial, from sport-fishers, cruisers, sailboats and superyachts to work boats like ferries, trawlers, tugboats, research ships and patrol boats. Save on your boat’s running costs Having clean props and running gear lowers maintenance costs, reduces corrosion and decreases fuel burn. TECHNOLOGY the infancy of this industry, there are definitely very few standards for these systems and significant variations from manufacturers. However, this article should provide the reader with a solid understanding of the basic system functions. PROPULSION SYSTEM PROPULSION MOTOR Main propul- sion is provided by an AC motor directly coupled to each main propulsion shaft. No reduction gear is required. This provides sufficient power in a rel- atively small footprint, with far greater torque and responsiveness than an engine driven system. PROPULSION/SHIP SERVICE INVERTERS Power to each propulsion motor is provided by a variable frequency drive/inverter (typically 400-600Vac). These devices convert a direct current (DC) input to a variable frequency al- ternating current (AC) output. The vessel pilot controls the speed of the vessel with a simple digital input from his throttle to this inverter cabinet. Control features of the drive provide over-current and over-speed protec- tion for the motor; and continuously monitor the frequency (speed) and power draw of the motor. Power for ship service loads is provided by two small inverters sized such that one provides the normal load Diagram of the main propulsion and power systems for a typical battery-powered vessel.