Shore Power Sense

It’s obvious water and electricity don’t mix, even though electrical power is crucial to the everyday, safe operation of any vessel. However, there are a few aspects regarding your vessel’s electrical system you need to understand in order to keep your fishing and boating adventures hazard free.


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Shore power brings convenience to boats at dock, but its use comes with essential safety considerations. Photo: Steve Dougherty/

With electrocution and fire both serious hazards no boater wants to face, you need to be sure you fully understand and can properly operate your vessel’s electrical system. Before we dig any deeper we should first review basic marine electrical components and wiring procedures. While it is okay to be slightly intimidated, with just a little knowledge and preventative maintenance you shouldn’t have anything to worry about now or in the future.

Based on marine insurance data from BoatUS, 55% of fires aboard boats are caused by shore power failures or overloaded circuits.

Virtually all boats are equipped with a DC (direct current) electrical system. A DC system allows you to start your engine(s) and operate onboard lights, pumps and electronics while away from the dock. Your boat’s DC system typically operates on either 12- or 24-Volts from energy stored in the boat’s battery bank, and is replenished by the engine’s alternators as you venture from one spot to another. It is important to mention that modern outboard engines are designed to output maximum voltage at nominal speeds.

Most mid-sized vessels also have an onboard AC (alternating current) system. An AC system is powered by a shoreside pedestal hooked up to a local utility and is commonly referred to as shore power. Shore power allows you to bring electricity onboard from a land based source. You literally plug your boat into the pedestal at a marina or dock and enjoy all of the advantages of home, including but not limited to air conditioning and heating, cooking appliances, entertainment systems and much more. Shore power is also utilized to power an onboard battery charger to keep your batteries fully charged. This is obviously imperative to prevent food spoiling in your refrigerator, bait thawing in an onboard freezer, and to make certain your bilge pumps and float switches remain active.

When connecting to shore power it’s imperative you follow the correct procedure or risk serious injury and potential damage. When approaching a dock in a distant island or weathered marina this is more important than ever. Electricity is no joke, but if you are smart about it you shouldn’t have anything to worry about.

First, make sure the circuit breaker on the dockside pedestal is in the “Off” position. Connect the shore power cord to the boat first, and then to the dockside pedestal. The contacts on the male plug will only fit one way into the female receptacle, which prevents polarity problems and also provides a secure connection when the plug is twisted slightly clockwise into the locked position. This is perhaps the most important thing to take away from this entire editorial—always connect the shore power cord to the boat first! Otherwise, the power cord in your hand will be a live wire.

After the power cord has been properly secured, flip the dockside breaker to the “On” position, and then turn on the boat’s shore power breaker. At this stage, your vessel’s AC system will be powered up and you can turn on any additional breakers to power appliances and accessories. When it is time to leave, reverse the process by first turning off all of the appliance/accessory breakers, then the boat’s shore power breaker, followed by the dockside breaker. It is now safe to remove the power cord from the dockside pedestal.

It is when misguided boaters alter this protocol that things may go seriously wrong. Overheating, fires, and power cord meltdowns are actually quite common. Based on marine insurance data from BoatUS, 55% of fires aboard boats are caused by shore power failures or overloaded circuits. Boaters often suspect that they’ve caused overheating by overloading the shore power pedestal, but that is rarely the case. Overheating generally results from corrosion on the metal contacts typically introduced by exposure to saltwater. A bad connection between a receptacle and shore power cord may also be attributed to loose terminals or wires that aren’t properly secured. This sort of poor connection often results in overheating of the terminal and is often visible on the face of the device in the form of burn marks. If you see evidence of such damage, replace the connector immediately. When doing so, inspect the wire ends as well.

Whether your boat requires 30 Amp or 50 Amp power, common twist type shore power cord connecters have been the go-to choice for years and will likely never disappear, but there have been plenty of negative experiences with these plugs. One of the biggest problems with three prong twist plugs is the lack of contact area. A loose connection means there’s room for moisture intrusion and associated corrosion. SmartPlug brings an innovative solution to this age-old problem by eliminating pin misalignment with an innovative asymmetrical design. The SmartPlug power cord is easy to insert without having to align and twist and also eliminates stress on the pins. Furthermore, there’s a integrated temperature sensor that automatically cuts the power if the internal temperature reaches 200° F. Easy to install, the plug uses standard mounting screw hole patterns for an easy exchange with existing receptacles.

With a proper shore power system and procedure in place you are safeguarding against serious harm to your vessel and passengers. Electricity is no joke and not to be taken lightly. The potential risks require extreme caution and attention to detail during installation, repair, usage and inspection.