Do-It-Yourself Generator Install

For many, many, many years, our trusty Honda 2000 portable generator supplied us with 120-volt electricity when we needed it at anchor. On our sailboat, we used an inverter most of the time and our solar panels and wind generator kept the battery banks topped off. We made the decision early on to install a permanent generator on Beach House for our upcoming cruise to the Bahamas and the Great Loop. We likely won't have the wind conditions needed for a wind generator like we had in the Caribbean, and solar panels are not practical for us right now. We want to be able to run the air conditioner in the Bahamas and the heat in the Great Lakes when we need it, and an inverter would just not do. Generator options for boats are plentiful, and deciding which one would best suit our needs took a lot of research.

Once the house battery bank had been relocated, the shelf where the generator would be located needed some reinforcement and rebuilding. It was strengthened with a layer of 1/2-inch plywood and sealed with West System.

A layer of fiberglass cloth was laid over the plywood using epoxy to further strengthen and seal off the wood from any coolant or oil that might be spilled during maintenance. All of this was placed over the existing shelf.

Everything got a couple of coats of fresh paint and all we needed was for the generator to arrive. Our choice was the Next Generation 3.5 generator in a sound shield. We wanted a small footprint that would fit in the space we had in the engine compartment. We needed it to be able to handle our 16,000 BTU air conditioner/heating system. It also needed to be capable of running all of the rest of our appliances, battery chargers, water heater, power tools and whatever else we wanted to run on board. Weight was also an important factor since the unit would be sitting against the hull on the port side of the boat and weight distribution had to be a consideration. The generator also had to have a good reputation in the cruising community for reliability, sound construction and ease of maintenance and repairs. The Next Generation scored high in every category.

The generator arrived one afternoon in a 40-foot semi and it was fun just watching him maneuver through the marina. We got the truck in front of the boat and the first order of business was to get it uncrated to make it easier to get off the truck, not to mention on the boat. Three of us and the driver unpacked it, slid it on to the lift gate and lowered it to the ground. I had rented a refrigerator hand truck with straps that made it easier to get it from the parking lot, down the ramp and dock, to the boat. Once we were on the finger pier, we made a sling out of lines and nylon straps. Next, we muscled it through the side door and down into the open hatch to the engine compartment. The whole process went easier than I expected, and by removing the sound shield, it helped lighten the load.

The sound shield was put back in place, and the unit positioned so that access around it was decent and there was room to work. Once we were satisfied with the position, the unit was bolted in place. This is where it would live.

All fittings and connection to the generator are easily made either to or through the sound shield. The fuel lines, water lines and exhaust have connections extended to outside the sound shield. The wiring has plastic pass-throughs to keep everything neat. Even the mounting brackets, which are bolted to the motor mounts, are on the outside of the shield. This make the unit almost plug and play.

The fuel tank had an unused pick-up tube and fitting for the fuel return making the fuel connections pretty easy. A cut-off valve for the fuel pick-up and a couple of elbows and hose barbs and we were in business. The fuel lines did need to be run from the generator to the top of the fuel tank, but that was all pretty easy. The fuel lines are 5/16 and the return line is 1/4.

A Racor R125 fuel filter came with the unit and was plumbed in just before the generator. Since the fuel lines needed to be mounted along the top of the engine compartment, the filter was placed high to give easy access for changing.

The exhaust system required a waterlock because the generator is below the waterline. Next Generation also supplied the Centek 1 1/2-inch waterlock with a side entry and top discharge. A small shelf was needed to mount the waterlock at the appropriate height and to keep it level in the slanted bilge.

With the shelf completed and another section of the engine compartment painted, all of the exhaust hoses were connected in place and double clamped. The exhaust was all secured so it wouldn't move around and chafe when the genny is running or when the boat is underway.

An 1 1/2-inch exhaust thru-hull was installed just above the waterline. We decided on one with a flapper cover to keep out water intrusion while we were underway and the flapper directs the exhaust water straight down. The plus is that it also reduces the exhaust noise when the generator is running.

The wiring to the generator is pretty simple, and with the provided wiring harness, it took a very short period of time to connect everything up and mount the remote starting panel. Our unit came with a standard 10-foot harness, but longer ones are available.

This was all really the easy part. The difficult part comes in wiring the generator to the boat's electrical systems. This is something I would never recommend to anyone that does not have experience with boat wiring and I don't mean casual experience. Our boat was a bit complicated but no more than most. We have 2 separate independent panels fed by two separate shore power connections. One is the main panel and the other is a smaller panel with only the air conditioning system and the outlets on the flybridge. We also have an inverter that is connected to the main electrical panel that needed to be wired into the circuit. Each electrical panel required a transfer switch to allow us to select between shore power, the generator and the inverter on the main panel without ever having two sources connected to a panel at the same time. For the main panel, we used a Blue Seas 3-way switch that lets us switch between the shore power, generator or inverter.

The smaller panel is primarily for the air conditioner and only needed a two-way switch to connect the shore power or generator. This panel is not connected to the inverter since it won't ever run the AC unit.

Because the unit is below the waterline, an anti-siphon valve is required in the raw water intake line to keep water from backing up in the engine. The sound shield also needs a way to remove the hot air that will build up inside the shield. An exhaust fan is installed and attached to an outlet on the top of the box. We attached the discharge for the fan to one of the engine room air intakes. There are four of them in the engine compartment. It's wired to the generator so the fan comes on automatically when the unit is started.

The attached exhaust fan also helps keep the heat down in the compartment when the generator is running.

Just before the initial start up, the fuel system is pushed into the engine by using a jumper on the electric fuel pump. The pump is allowed to run for a few minutes until it is pushing fuel back through the fuel return line. A quick check of the oil and coolant levels and everything was ready. It took the unit about 2 seconds to fire up, and we were very surprised and just how quiet it was. In the main cabin we can just hear a low hum and a bit of vibration, but really less that we had with our portable sitting on deck. It was an incredible relief to have this major project completed and it also meant that our cruising was about to begin for real. A quick trip north to visit the kids, grandkids, family and friends for Thanksgiving, and we returned ready to cast off the dock lines for our next big adventure. Let the cruising begin!


  1. Hi Guys!
    Sounds like all your preps made the installation a breeze! Don't you love it when a plan comes together!
    I looked online at the specs for your genset. Looks like it just sips a little fuel...great!
    Great postings. Keep all of us (your readers) informed on all your preparations for your next you know .... you are not alone when you cruise. We are there with ya (we just don't chip in on the fuel)
    George and Donna
    36' 1972 Gulfstar Trawler "Blind Faith"

  2. Thanks guys. We're currently sitting on the hook in Boot Key Harbor, Marathon with the genset running and most of the appliances, etc. on the boat in use. Ain't life grand. We had a great trip down from Marco Island and are looking forward to exploring the Keys once again. We will probably start posting on the cruise tomorrow and still have a few smaller projects that will make the blog. Hope you follow along and if you want, send some money for fuel. Just kidding. Chuck

  3. Just a quick assumption (and you know what they say about those). Where does the generator pull air from for combustion? It seems the enclosure would never get hot while running do to air exchange. If you connected the top to an exhaust fan, I assume there is another air intake preventing negative pressure in the sound enclosure. Forgive my ignorance, my gen. does not have any enclosures.

    Capt. Scott

  4. Capt. Scott, There are air intake louvers in the sound shield to draw outside air in and the exhaust fan removes the hot air. Chuck

  5. Chuck, I noticed that you have an a/c panel for shore 1 and one for shore 2. Shore 2 has a selection switch for shore 2 or generator 2. Could you explain? Is that for a future generator plus the one you just installed? Thanks. Rob Taormina

    1. Rob, Each of the two electrical panels have their own power feeds, including shore power and generator. So each needs a separate transfer switch. The smaller of the two panels run only the air conditioners. The larger panel is set up to run from either shore power, the generator OR the inverter. The air conditioner panel can never be run off the inverter. The label for the generator is just the way the label was made up and just differentiates the separate panel. Hope this answers your question. Chuck

    2. Can the generator feed both panels at the same time or have to switch between them?

    3. Rob, With a single power cord it would have to be switched back and forth in our case. Ours is set up for two power cords. However, a Y adapter could be used to connect both panels. But you need to take care not to overload the generator using both panels. We have always only connected to one with the generator. Chuck


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