Blue View – Choosing the Right Options for a Cruising Boat

This week I'll share my thoughts about some of the other options that are important on a cruising boat – fresh water systems, stove options, heating and cooling, generators vs solar and wind power.

Freshwater Systems and Tanks. When we bought Nine of Cups, she had four 60 gallon stainless freshwater tanks. When she was built, watermakers weren't a reasonable option, so she needed enough tankage for extended cruising. Now that we have a desalinator, we don't need that much tankage, so we converted two of the tanks into storage for canned goods and spares. The two remaining tanks seem about right for us. When on a passage, we use about 4-5 gallons a day, and at anchor it's more like 7-8 gallons. We try hard to conserve every drop, but in all honesty, we use more now than in our early days.

Whether or not the boat has a watermaker, it is still important to have two tanks. On more than one occasion, our freshwater pressure system sprung a leak, and most if not all the water in the tank being used was pumped out into the bilge before we noticed. We like tanks made of stainless as it doesn't 'flavor' the water after it's been sitting in the tank for awhile.

We have a pressure operated electric pump that provides pressurized water to the sinks in the two heads, the cockpit shower and the galley sink. We also have a foot pump and faucet at the galley sink that allows us to pump water directly from the tank. It does a better job of conserving water than the pressurized system does when washing hands or brushing our teeth as only the water needed is pumped out. It is also a backup system if the freshwater pressure system is down.

We've added a filter to the pressurized system that helps with the taste of some of the water available in various parts of the world. The water from the desalinator tastes great, but unless we're at sea, we can't always turn it on – such as in some of the polluted harbors we've been in or if the water is too muddy or silty.

Stove. There are several options for the type of stove.

  • Propane. Far and away, the most common type of stove is a propane stove. Propane is available everywhere in the world, is usually inexpensive, and is clean and efficient. The biggest downside on a boat is that it is heavier than air, so any leaks will cause the gas to collect in the bilge. If enough collects down there and any spark is introduced, the results are catastrophic. We have friends whose boat was sunk and the wife suffered serious burns as a result of an onboard propane explosion. If used, the tanks must be stored outside, preferably in a vented locker. The tank should have an electric solenoid on it that will shut the flow of gas off and which can be operated in the galley. Once done cooking, we shut the solenoid off, let the flame continue to burn until the gas in the line has been consumed, then shut the stove knob off. The propane line should be inspected periodically ( we check it as part of our annual maintenance), and have vapor tight connections where the hose passes through bulkheads into the boat.

  • Natural gas. Natural gas is a more efficient fuel than propane and is lighter than air, so it doesn't present as big a safety issue as propane. It is, however, not as easy to come by – either domestically or overseas. In some parts of the world where propane is the universal fuel, it is not available at all.

  • Alcohol. Alcohol fuel is easy to come by, is usually inexpensive, and is easy to transport. The downsides are that it doesn't produce as hot a flame as gas, takes a little understanding to get it to burn properly, and can cause a major fire if spilled. We've seen a few smaller coastal cruisers that use alcohol stoves, but very few offshore boats.

  • Diesel. Diesel makes sense for a stove since it is relatively safe, is already aboard on most boats, and burns very efficiently. In the warmer climes – where most of us like to cruise – it produces a lot more heat in the galley, however, and requires preheating to get the flame going.

  • Electric. Power boats often have electric ranges, but except for some very large mega-yachts, we rarely see electric ranges aboard cruising sailboats. Due to the amount of power required, the boat must be running its generator or be connected to shore power.

  • Microwaves. Just like in a house, most cruising boats have a microwave in addition to the stove. We have one, but unless it's a sunny, windy day (generating a lot of solar and wind power), we are running the engine or are connected to shore power, we rarely have the excess power needed to run it.

  • Any of the options above can come with or without an oven. We bake a lot, so an oven is important to us, although we know several cruisers who have opted to plunk a microwave into the space normally used for the oven.

The stove should be gimbaled so that the pans don't go flying when the boat rolls. Cups came with a Force 10 propane stove, and when it came time to replace it a few months ago, after surveying the available products, we ended up buying the latest version of the same stove. Given all the options, even with all the precautions necessary to safely use it, propane is still our fuel of choice.


Heat. We've spent a lot of time in the high latitudes, and we always vow we'll add a heater to Cups before we go back. Then we sail back to the tropics and worry more about keeping the refrigerator going than adding heat. We have, however, looked at most of the options:

  • Diesel powered forced air. Several manufacturers make diesel heaters that heat the air, which is then blown through ducts to the living spaces. The heater is usually mounted in the engine room or a cockpit lazarette where it can be vented to the outside. These are reasonably inexpensive and, other than the ducting, easy to install. They do require power, which is always an issue aboard a cruising sailboat.

  • Diesel powered hot water heat. Similar to the one above, except water is heated by the diesel heater and is pumped to radiators located throughout the boat. These are more expensive and require more power than the forced air versions, but the heat produced is more even and pleasant than forced air. Usually, it is easier to route a couple of heater hoses to different parts of the boat than it is to install the 3”-4” ducting required by the forced air versions.

  • Bus type heaters. This type heater passes the engine coolant through a heat exchanger. Air is blown through the pipes in the heat exchanger and into ducts that are routed to the living quarters. It works great while motoring, but is quite useless while sailing or at anchor.

  • Standalone stoves. Think of an old potbellied stove that was reduced in size to fit a boat. They are often quite attractive, produce a nice warm glow in the area, use very little or no power and are quite pleasant. They come in various models that can burn diesel, propane or solid fuels like wood, coal, or pellets. As with potbellied stoves, they heat the surrounding area quite effectively, but the further away from the stove, the less heating it does. They also have to be manually started – at least I don't know of any that are thermostatically or timer controlled.


BVRightBoat Heater.jpg

Our first choice was to add a standalone diesel stove, but could not come up with a plan that didn't involve doing major reconstruction to our salon area. Our second choice was to add a diesel heated forced air system, which we may yet do if we ever head for the high latitudes again.


Cooling. When we bought Cups, she had two air conditioning systems aboard – one for the forward cabin and part of the saloon, and one for the aft cabin and the rest of the saloon. It was great while we were in a marina in Kemah, TX, prepping Cups for her departure. Once we left, however, we were rarely in a marina, and since we didn't have a generator, we rarely used it. I'll bet in our first five years of cruising, we ran it less than a week total. Eventually, I removed the aft one to make room for something we needed more – a step-down transformer to convert from the 220 VAC prevalent in most of the world to the 110 VAC needed for most of the electrical things on board. It's been so long since it was last used that I doubt the other A/C unit still works.

Whether or not your cruising boat should have air conditioning depends on the type of cruising you'll be doing. If you're heading for the high latitudes or the the Caribbean trade winds, you'll probably never miss it. If you plan to spend a lot of time at marinas in Florida, you might want it.

Instead of A/C, we use lots of fans. Whether I'm sitting at the saloon table, at the Nav station, or reading in bed, there is always a low power fan that can be turned on and aimed directly at me. It's amazing how effective a well directed fan can be. We did just fine in steamy Colombia and up the rivers of Panama using our fans. It looks like we will be ensconced in Virginia this summer, however, and we might want to rethink that, but so far we've managed quite well without A/C.

Charging systems. No matter how big the house battery bank is, it has to be routinely recharged. Most cruising boats have some combination of the following charging systems:

  • Engine driven alternator. If the boat has an engine other than a small outboard, it most likely has an alternator that can at least recharge the starter battery. Most cruising boats also use the alternator to recharge the house batteries. If this is the primary method of recharging the house batteries, the alternator should be a high output type – preferably 120-200 amps, so that the time required to recharge the batteries is minimized.

  • Battery charger. A battery charger uses AC power to charge the batteries and can only be used when on shore power or when the generator is running. To properly maintain expensive marine batteries, the charger should be a three stage type. They range in output from 5 amp trickle chargers to 200 amp mega-chargers. If most of the time is spent in a marina or there are alternative methods of charging the batteries, a 20-30 amp charger may be adequate. If this is the primary method of charging for extended periods away from shore power, a larger output charger would be better. Many boats use inexpensive, small, portable gas generators to power their battery chargers, while other have large, elaborate, expensive water cooled diesel generators.

  • DC generator. There are AC generators and DC generators. AC generators typically produce 120-240 volt AC power that in turn powers a battery charger. DC generators are usually diesel powered and use an alternator to produce 12 or 24 volts DC to charge the batteries directly. The alternator output is controlled by a voltage regulator. As with a battery charger, this should be a smart three stage regulator to properly charge marine batteries.

  • Solar. There's nothing better than using free energy from the sun to keep the batteries charged. The initial cost is high, but once installed, they are efficient and can last decades. They must be mounted, of course, with maximum exposure to the sun and in a place where they won't be damaged by lines or flogging sails, which often limits the number and size of panels that can be effectively used on a sailboat. While they produce a lot of amperage on bright sunny days, the output is greatly reduced on overcast days, and they produce nothing at night.

  • Wind generators. Wind generators have come a long way in the past decade. The newer wind generators are quiet, reliable and generate a lot of amps. The upfront cost is fairly high for a good one, but if properly maintained, will last at least a decade or more. They are great in the tradewinds, especially when anchoring each night. They typically start producing power at 7-10 knots of wind. They are less effective when sailing downwind since the apparent wind is reduced by the boat speed.

  • Water powered generators. These come in several varieties. Some are towed behind the vessel and some are rotated down into the water. Both use the forward movement of the boat as it sails along to turn a propeller, which in turn rotates the shaft of an alternator or generator. Another variation is to connect the alternator or generator directly to the prop shaft of the boat and allow the prop to free-wheel as the boat moves through the water. These generate a steady output, 24 hours a day, as long as the boat is moving. Typically, the boat speed has to be greater than 4-5 knots to generate any significant power.


        Prop Shaft Generator

        Prop Shaft Generator

When we bought Nine of Cups, her only means of charging the house batteries were a 20 amp battery charger and an 80 amp alternator mounted on the engine. We had enough in the budget to add either a generator or solar panels and wind generators. We decided to do the latter, and mounted three 80 watt solar panels on the top of our dinghy davits and added two wind generators. Between the wind and solar devices, we could keep up with our power needs on sunny, windy days at anchor – which describes most of the days in the tradewinds. In other places where the wind wasn't as consistent or the days were overcast, we still had to run the engine an hour every day or two. Likewise, when on passages, our electrical needs were higher and the wind gens less effective, so we usually had to motor an hour or so each day. To make running the engine as efficient as possible, we upgraded the alternator on the engine to a 180 amp model. A couple years ago we also connected an alternator to the prop shaft, and we now generate enough power from our three alternative energy sources while sailing to completely eliminate the need to start the engine while on passages.

Blue View - Choosing the Right Boat Electrical System