Marine Technical Training Academy

 Air Conditioner Sizing When an A/C unit works more than 30 minutes per hour is an indication that the unit is undersized. Take into consideration the following factors to size an A/C unit in your boat. Room Volume and Material  Source of Power AC or DC Average people in the room Unit location Ducts route Wire gauge Seacock, Sea strainer, and Raw water pump location Thermostat location and Harness length Air conditioner size is rated using the number of BTU's or British Thermal Units of heat that it can remove per hour.  1 BTU is the amount of energy to raise the temperature of one pound of water by one degree Fahrenheit. You may also hear A/C size referred to in "tons" which is the equivalent of  12,000 BTU’s = 1 Ton. Conversion for heat and power units. 1 kwh is equivalent to 0.7457 horsepower.  1 Kwh  is equivalent to   3,413 BTU/hr 1 Hp = 746 Watts To Calculate Main Breaker Capacity:   P(Kw) = Volt X I(Amp) 1 ton is equivalent 12,000...

  Raw Water-Cooling Systems Raw water-cooling systems draw water from outside the boat (seawater or lake water). Water is pumped from the source to the engine block then the engine circulation pump forces the raw water thru the engine block and the water is expelled thru the exhaust. On larger engines and inboard engines, the raw water pump is located inside the boat and is driven by a v-belt or directly off of the crankshaft. There are hidden dangers that can accumulate over time causing you to spend big Dollars on repairs. The danger is using salt water as a coolant in your engine. Salt water can be highly corrosive. Get here the Marine Diesel Engines Book where you can find all the information on this and many other topics. Get the book Raw Water Pumps This pump sucks water from the sea. It typically goes through a strainer as it is sucked towards the pump. Saltwater Pump and Impeller Kit: A flexible impeller pump provides an efficient solution to most raw water pumping needs. T...

  DC Circuit A Direct Current (DC) circuit is a circuit that Electric Current flows through in one direction.  DC is commonly found in many low-voltage applications, especially where these are powered by Battery.    Short Circuits A low-resistance connection established by accident or intention between two points in an electric circuit. The current tends to flow through the area of low resistance, bypassing the rest of the circuit. Series Circuit A series circuit is a circuit in which resistors are arranged in a chain, so the current has only one path to take. Solving Series Circuits Get here the Marine Electricity Handbook where you can find all the information on this and many other topics.                                                                Get the book Parallel Circuit A parallel circuit is a ci...

  Battery Storage Capacity The Amp-hour (Ah) Capacity of a battery tries to quantify the amount of usable energy it can store at a nominal voltage. Storage capacity is additive when batteries are wired in parallel but not if they are wired in series. When two 6V, 100Ah batteries are wired in Series, the voltage is doubled but the amp-hour capacity remains 100Ah (Total Power = 1200 Watt-hours). You may decide to wire batteries in series because a single 12V battery with the right storage capacity is simply too heavy, unwieldy, or awkward to lift into place. Batteries consisting of fewer cells (and hence lower voltage) in series can provide the same storage capacity yet be portable.  Two 6V, 100Ah batteries wired in Parallel will have a total storage capacity of 200Ah at 6V (or 1200 Watt-hours) Battery banks wired in Series-Parallel are even more complicated. Here, four 6V cells are wired in two "strings" of 12VDC that were then wired in parallel. Using 6V, 100Ah batteries, thi...