Understanding Boat Generators: Powering Your Voyage

Boat generators are a great way to power your vessel when away from shore. They are engines that convert energy from gasoline or diesel fuel into electrical energy, providing a constant feed of power for your boat. When choosing a generator, it's important to consider your vessel's power needs, available space, and safety precautions. Portable generators are an option, but they may not be as efficient or safe as built-in marine generators. Built-in generators are easier to use, quieter, safer, and more efficient, but they are also more expensive and require regular maintenance. Ultimately, the decision to install a generator depends on your specific needs and preferences as a boater.

How to determine your vessel's power needs

Before installing a generator on your boat, it's important to calculate your vessel's power needs. This will help you choose the right generator and ensure you have sufficient power for your on-board systems and appliances. Here are some steps to help you determine your vessel's power needs:

Identify Your Vessel's Systems and Appliances:

Make a list of all the electrical systems and appliances on your boat that will require power. This includes items such as air conditioning, lighting, refrigeration, electronics, and any other equipment you plan to use. Consider both the number of systems and their sizes; a larger boat will typically have more and larger systems, requiring more power.

Calculate the Power Requirements:

For each system and appliance, determine its power consumption, typically measured in watts or amps. You can usually find this information in the product specifications or user manual. If the power draw is given in watts, divide it by 12 to get the 12V amps. If it's given for a standard house power supply (e.g., 110V), multiply the amps by 10 to get the 12V draw.

Estimate Usage:

For each item, estimate how many hours per day you expect to use it. Multiply this by the power draw in amps to get the amp-hours required for each device. For example, if a device draws 1 amp and you use it for 5 hours per day, it consumes 5 amp-hours.

Total Power Consumption:

Sum up the amp-hour requirements for all the devices to get the total power consumption for your vessel. This will give you an idea of the minimum power generation capacity you need.

Battery Capacity:

Check your boat's battery capacity, which is typically measured in amp-hours. Determine how much of this capacity you can use (e.g., 50% for lead-acid batteries, 80% for lithium batteries). Compare this usable capacity with your total power consumption to see if your batteries can meet your needs.

Power Generation:

Consider your power generation options, such as solar panels, wind generators, engine alternators, or a dedicated generator. Evaluate how much power each source can provide and how quickly they can recharge your batteries. A generator is particularly useful if you need a significant amount of power, especially for high-wattage appliances like air conditioners or if you plan to be away from dock for extended periods.

Balance Power Supply and Demand:

Finally, compare your total power consumption with the available power generation and battery capacity. If you have sufficient power available, you can proceed with your chosen setup. If not, you may need to adjust your power requirements, consider alternative low-power options, or increase your power generation capacity by adding a generator or additional batteries.

Remember, it's crucial to ensure your vessel has enough power to support your on-board systems and appliances safely and efficiently. Taking the time to calculate your power needs will help you make informed decisions about your vessel's electrical system and generator requirements.

How to determine your boat's available real estate

To determine your boat's available real estate, you need to consider the engine room space. Generators are often squeezed in, so it's crucial to ensure you have enough room for installation and maintenance. Measure the dimensions of the generator and compare them to the available space in your engine room. Make sure to allow for sufficient clearance around the generator for ventilation and access.

Additionally, consider the weight of the generator and choose a sturdy mounting surface. Through-bolts or hefty brackets are recommended for secure mounting. If your boat originally offered a generator as optional equipment, check with the manufacturer to see if pre-tapped mounting plates were laminated into the stringers, providing an ideal mounting point.

Don't forget to account for the space needed for cables and hoses. You'll need room for the cooling water feed, exhaust run, fuel lines, and any other necessary connections. Ensure that the generator can be accessed easily for maintenance and that it fits through the hatch or entry point.

By carefully considering these factors, you can determine whether your boat has sufficient real estate for a generator and make an informed decision about your power options.

How to mount a boat generator

Mounting a boat generator is a complex process and is usually best left to professionals. However, if you are considering installing one yourself, here is a step-by-step guide to help you with the process:

• Generators are heavy, so you will need to find a solid, level mounting surface. Use through-bolts or brackets to securely mount the generator, similar to mounting an engine.
• If your boat originally offered a generator as optional equipment, check with the manufacturer to see if pre-tapped mounting plates were laminated into the stringers.
• Choose a generator offered with a soundshield to minimise noise levels.
• Install a cooling water feed via a through-hull with a seacock, and an exhaust run. Ensure that intake lines have a sea strainer between the seacock and the generator, and do not depend on a scoop-style through-hull.
• Exhaust lines should have an anti-siphon loop installed at the manufacturer's recommended minimum height above the waterline.
• Get fuel to the generator by tapping into the vessel's existing supply or installing a separate tank with fill and vent lines. Don't forget to plumb in a fuel filter between the tank and the generator.
• Follow the manufacturer's specifications for wiring, ensuring all wiring is supported and protected from stress and chafing.
• Ground and bond the generator in accordance with USCG regulations.

How to plumb a boat generator

Plumbing a boat generator is a complex task and is best left to professionals. However, if you are confident in your abilities, here is a detailed, step-by-step guide on how to plumb a boat generator:

Firstly, you will need to determine the optimal location for your generator, taking into account space and accessibility. The location should provide easy access for simple servicing, such as oil changes, and allow for the removal of the sound shield. It is also important to consider the routing of utilities like cooling water, fuel supply, and air intake, as well as the installation of the exhaust.

Next, you will need to install a cooling water feed via a through-hull with a seacock. The intake lines should include a sea strainer between the seacock and the generator, and a scoop-style through-hull should be avoided to prevent water from being forced into the generator when it is not in operation. Additionally, an anti-siphon loop must be installed in the exhaust lines at the manufacturer's recommended minimum height above the waterline.

Now, let's talk about fuel. It is recommended to choose a generator that burns the same fuel as your vessel's powerplants to minimize the hazard of mixing fuels. If you choose a different fuel type, you will need to install a separate fuel tank, fill, and vent lines. Don't forget to install a fuel filter between the tank and the generator to ensure clean fuel and prevent injector clogging.

Finally, for the seawater system, use a separate seawater supply seacock and strainer, which should be cleaned regularly to prevent high temperatures. Avoid using a scoop-type inlet, as it can pressurize the water and cause issues with the water pump.

Remember to always refer to the manufacturer's manual and specifications for both the boat and the generator during the installation process.

How to wire a boat generator

Wiring a boat generator is a complex task and is best left to professionals. However, here is a step-by-step guide on how to do it:

The Electrical Source: A Battery

Firstly, you need to understand the electrical source of your boat, which is usually one or more batteries. These batteries are charged by your boat's engine alternator or an auxiliary battery charger. They can store a large amount of energy and are capable of pushing hundreds, or even a thousand amps, so proper circuit protection is crucial.

Main Battery Switch

Your boat wiring system should have a marine-grade main battery disconnect switch, which allows you to turn off everything at once in an emergency. There are different types of battery switches, such as the 1-2-BOTH type, which lets you select which battery to use or parallel both. Remember to turn your battery switch to the "house circuit" when your engine is off, so you only draw power from your deep cycle house battery.

Battery Switch Bypass Loads (Bilge Pump, etc.)

It is common to bypass the main battery switch for the boat's bilge pump float switch. This means that even if your battery switch is off, if your boat starts filling with water, the pump will still activate. You can also bypass a stereo memory line.

Get the Source to the Boat's Helm

Now, you need to get power from the house battery up to the switch panel. Two conductors, a positive from the battery switch (with a fuse) and a negative from the ganged battery negatives, should be run to the central switch panel. Marine-grade primary wire is recommended for this. The length of this wiring run depends on your boat's layout, and these conductors will carry the combined current of all electrical loads, so they need to be sufficiently thick cables.

Install Terminal Block as a Breakout Point

At this stage, you'll have a wiring harness coming off your switch panel, which should land on a terminal block. This provides a handy breakout point for troubleshooting and adding items in the future. The positives from the switch outputs will go to the terminal block, and you'll need to crimp ring terminals on the positive load wiring that runs around your boat to various loads.

Run Load Wiring to the Terminal Block and Bus Bar

Finally, connect your boat's existing wiring infrastructure to the terminal block and bus bar. The positives go to the correct gang on the terminal block, and the negatives can go anywhere on the bus bar as they are just returning to the negative post on the battery.

Additional Considerations

• Ensure all wiring is supported and protected from stress and chafing.
• Follow the manufacturer's specifications for both the boat and the generator.
• Generators must be grounded and bonded according to USCG regulations.
• Consider using a generator with a soundshield or adding acoustic insulation to reduce noise levels.
• If your generator is in line with the inboard engine, utilize the stringers for solid mounting points.
• For plumbing, you'll need a cooling water feed, an exhaust run, a sea strainer, and an anti-siphon loop installed above the waterline.
• Choose a generator that burns the same fuel as your vessel's power plants to minimize hazards and increase efficiency.

Remember, this is a complex process, and it is recommended to seek professional help or refer to detailed guides and manuals for a more comprehensive understanding of how to wire a boat generator.

Frequently asked questions