How to I install A/C on my boat? How to I install A/C on my boat? Dear Boat Doctor, The blistering heat last summer has convinced me that I want to install air conditioning on my boat. I want to try to tackle this myself over my winter haul-out. I am reasonably mechanical, but could use all the tips and tricks that you can give me.Richard HoytBoston, MassachusettsDear Richard, Sailing purists will probably scoff at air conditioning, but it is very nice on a hot night. There are five things you need to worry about: getting the right sized unit, powering it, water cooling it, draining the condensate from it and managing the airflow to and from it. An air-conditioning unit needs to be the right size for the space you want to cool. If the unit is too small it will not have the capacity to cool the area and may run continuously to the point of freezing up. Conversely, if it's too big, the unit will cool the space quickly but not run long enough to pull the humidity from the air. A good rule of thumb is to specify 14 British thermal units per cubic foot of space.

An aft cabin that is 8 feet long, 12 feet wide and 6 feet tall contains about 576 cubic feet, and thus would require an air-conditioning unit of about 8,000 Btu. An air conditioner consumes a significant amount of power, so you will likely need to plan for a second shore-power cord to be able to run the unit under all conditions. A modest air conditioner of 9,000 Btu will draw approximately 8 amps when running, but will need almost 15 amps when starting (the start current is typically 1.8 times the running current). If the air-conditioning unit tries to start at the same time the water heater or other large load is running you'll likely blow the dockside breaker. Your best bet will be to install a second 30-amp shore power inlet and breaker. Marine air-conditioning units require seawater cooling. It is important for the intake to be well below the waterline and to flow "uphill" through the strainer to the water pump, which all must be below the waterline. The output of the pump will then flow through the air-conditioning unit and be discharged overboard.

The output should be between 4 and 8 inches above the waterline; lower than 4 inches and the output needs to be considered a below-the-waterline through-hull with a seacock, and higher that 8 inches would make excessive splashing noises. It is important to use a strainer on the outside of the through-hull to prevent debris from clogging the seacock or internal strainer. Finally, you'll need to route the cool air into the cabin. Air will flow about 6 to 8 feet so you'll likely need multiple outlets in a larger boat. Try to keep the runs as straight as you can, as every turn and elbow inhibits airflow. Can I use a regular computer monitor?Why are my halyards fraying?How do I track my boat's systems?How do I install an AIS antenna?Why do I need to clean new fasteners?Why does the tachometer read high?What features do I need in a PFD?How do I install a battery monitor?Avoid the dangers of poorly installed shaft sealsWhat's a quick-drying filler for gouges? What Air Conditioner Do I Need For My Walk-In Cooler?

There are 3 elements to consider: A/C Size in BTUs Unit type – window unit or mini split. Please note A/Cs must have digital controls to work with the CoolBot. This site uses cookies and similar technologies. If you not change browser settings, you agree to it.air handling unit measurement A dominating presence on both land and seawhy does a central ac unit freeze up Your Trusted Source on the waterbest air conditioner split 2012 Browse thousands of constantly-updated listings and search by location, brand, and boat type See more... Connect with our expansive community and tap into the knowledge base of the most dedicated boaters around. Browse and search for hundreds of thousands of boat parts, accessories, and supplies to suit your every need.

Posted January 8th, 2008 by An ohm meter is a poor way to check bonding connections. I use a 12 volt lamp and make a probe using a screwdriver. Hook a long enough wire to the positive terminal of the starting battery and then poke the screwdriver into each of the through hull fittings and make sure the lamp lights. An ohm meter is only testing the circuit at micro-amps. The following applies mainly to boats left in the water. Trailered boats rarely spend enough time in the water for electrolysis to be a problem.I've worked with electrolysis for 18 years including live-aboard on a steel yacht for 14. We have sold thousands of our galvanic isolators and handle numerous emails/phone calls daily on electrolysis situations. Although your copper straps look impressive they are totally unnecessary. The wire at the most only carries a few milliamps and there is no concern for voltage drop so the copper only needs to be heavy enough to resist deterioration from oxidation. A 10 gauge copper wire is more than adequate.

I use non stranded 10 gauge bare copper wire for my installations, being careful to secure it so it is not subject to flexing from boat motion. Non stranded wire has much less surface area and avoids the cavities between the strands where moisture and corrosion/oxidation can progress. Electrolysis only happens when two dissimilar metals are immersed in an electrolyte and connected together. The dissimilar metals have different electrolysis voltages so if you connect them together current flows through the connecting wire one direction and through the water the other. As the current leaves one metal to travel to the other, it causes metal to come off one surface and be deposited on the other like battery plates so the higher voltage metal suffers electrolysis. Electrolysis can also occur when an adjacent structure or boat is injecting DC current into the water and that current goes in one end of your boat and out the other on its way to the destination. This can cause electrolysis even though your boat is not an offender.

There are basically 2 ways to reduce electrolysis. The PREFERABLE one is to DISCONNECT the electrical circuit. If this can't be done, the second method is to provide a sacrificial anode (Zinc) so it deteriorates rather than your expensive equipment.a) DISCONNECTING Electrolysis cannot occur on an isolated piece of metal in salt water. It is all at the same voltage but if it is isolated no current can flow so there is no electrolysis. When it is connected to another piece of metal, ESPECIALLY if the other piece is a different metal, you just created a shorted battery and electrolysis will start. By following the wrong advise and bonding everything in the boat you are creating batteries where it is unnecessary and making electrolysis problems worse.Only bond underwater items that are showing symptoms of electrolysis. If it ain't broke, DON'T fix it. Once you bond it unnecessarily you have CREATED the circuit rather than DISCONNECTING it. You are now stuck with providing Zincs since you have removed the first line of protection.

Although some through hulls appear to be isolated due to sitting in fiberglass and using non-metallic tubing, they quite often are not and WILL need bonding. For example the raw water cooling inlet for an inboard engine is in fact connected to the engine block by the salt water in the tubing and may need bonding so the current flows though copper rather than the water and in/out of the through hull.b) SACRIFICIAL ZINC There are situations where different metals cannot be disconnected and you are stuck with putting zincs on them to provided a target for the electrolysis. Zincs have a higher electrolytic voltage than marine metals so it is the first to deteriorate. Keep in mind that the zinc will CREATE electrolysis (favorable electrolysis since the zinc is being eaten up). Putting zincs where they were not needed will still cause the zincs to erode away since they create the battery situation where none may have existed. The range of protection a zinc can supply to other metals bonded to it is limited by the conductivity of the water.

In salt water you get coverage for a radius of about 4 to 6 feet. A zinc on the stern of a 14 ft boat where everything is bonded is only protecting half the boat. This range gets even less in fresh water and may reduce to only inches. Often magnesium is substituted for zinc in fresh water to provide an even higher voltage to push through the fresh water. Over 90% of our customers electrolysis problems are created by the shore power connection. You could theoretically disconnect the ground connection in the shore power and avoid electrolysis (and in some cases this is a solution) but ABYC regulations require the AC ground be connected to the DC ground so an electrical fault on the boat won't electrocute swimmers in the vicinity. When you connect your underwater metal to the shore power ground you have "bonded" with every other boat on the docks who have the same connection. Now electrolysis currents are free to flow anywhere in the marina and it only takes one boat with a 12 volt DC leakage to eat up every boat within a wide radius even though the offender has zero electrolysis evidence.