There is no such thing as an all-purpose hose on a boat. No single hose type can withstand engine exhaust, bring freshwater to the galley, safely transport gasoline to the carburetor, drain the cockpit, and flush the head. Using the wrong hose can cause problems that range from an inconvenient mess to a burning boat. This handy run-down will help you identify one type of hose from another and assist in choosing the right hose for the job at hand. We'll start with a visual guide to common marine hoses, then go into more detail about each type. (See photo above).
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1. Exhaust hose. Able to withstand temperatures to around 250 F, an exhaust hose is often reinforced with wire, which may be stainless, or other special reinforcement. Other, more expensive silicone hoses are capable of sustaining much higher temperatures.
2. Hot and cold PEX potable water pipe. Many modern boats use PEX tubing for hot and cold plumbing. PEX is available in three distinct grades: A, B, and C. Although all are perfectly acceptable for potable water, Grade A is the most flexible and easiest to run in the tight confines of a boat. Fittings are easy to connect to the pipe, although you may need special tools. PEX is not the only option for potable water, however (see 6).
3. Sanitation hose. Often white, with a smooth bore to prevent trapping waste that could lead to odors, sanitation hose has an expected lifespan of approximately 10 years.
4. Corrugated bilge pump hose. This cheap hose is often supplied with bilge pumps. While easy to run, cut, and bend, its ridged internal structure restricts flow, making it a poor choice.
5. Smooth-bore bilge pump hose. Although four times the price of corrugated types, smooth-bore bilge pump hose offers up to 30 percent greater efficiency.
6. Potable water hose. Potable water hose comes in both reinforced and non-reinforced types. They're easy to tell apart as the reinforced hose will have strong synthetic cord strands visible. This one is clear but opaque is generally a better choice for potable water because there is less chance of algae growing inside.
7. Fuel hose. Fuel hose must be marked as such and will be stamped A1, A2, B1, or B2. Older hoses are incompatible with fuel containing ethanol, so if yours is older than about 10 years, it's most likely due for replacement anyway.
8. Thru-hull hose. For any connections to thru-hulls, reinforced hose is the only way to go. A cheap hose may fail and sink your boat.
Properties: Chemical resistance and low permeability
By Tom Burden, Last updated: 11/22/
Virtually all boats end up with unwanted water in the bilge, which must be removed. Water gets in from a propeller shaft packing gland, a leaky portlight, leaky seams in a wood boat, melting ice from the icebox and a multitude of other sources.
Leaving large amounts of water in the bilge can have several undesirable effects on your boat, including destabilizing it, lifting spilled fuel and distributing it throughout the bilge (where it can attack, among other things, the insulation on electrical wiring) and promoting the development of osmotic blisters in fiberglass hulls. And did we mention having the boat sink? Getting this water (we call it nuisance water) out of your boat is the primary function of a bilge pump.
In some cases, the leak may be of a catastrophic nature caused by a hole in the hull from a collision or a wave taken on board in a storm. These situations call for very large pumping capacity. For the most part, the largest pumps will only buy you a little time to effect repairs to the leak, limp back to shore or make preparations to abandon ship. For emergency situations like this, it is advisable to have multiple electric pumps and at least one high-capacity manual diaphragm pump.
Therefore, we&#;d like to reinforce the following words of wisdom regarding bilge pumps so you&#;re not disappointed in the future:
With these things in mind, it's time to find the right pump for your boat. We'll walk you through what you need to consider to make the right choice.
Planing runabouts and ski boats use one submersible pump located aft. Small boats with large cockpits or low freeboard need bigger pumps.
A small racing keelboat that sees lots of rough water action will need a better pump system than a large powerboat that is mainly operated on a calm lake. Here are some suggestions:
Electric bilge pumps are rated by their capacity, which is measured in gallons per hour, or gallons per minute, under open flow conditions with no restrictions to the discharge. The rule of thumb is to get the largest model that is practical for the boat. Your selection will depend on size constraints and power limitations, but choose a 1,000gph model or larger, if possible. Submersible pumps generally have great open flow capacity, which rapidly decreases depending on how high the water is lifted.
Remember that small boats need good-sized pumps because:
Medium and large sailboats use multiple manual and automatic pumps.
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Match existing hose sizes and wire capacity, unless you want to upgrade the wiring and the thru-hull size too. Buy the largest capacity pump that uses the same hose diameters. For a few dollars more you can increase pump capacity significantly and still keep the same hose diameter. For a new installation, use the largest practical pump size.
High-capacity centrifugal pumps are relatively inexpensive and the easiest pumps to install, but they are rendered ineffective if your boat&#;s electrical system fails, and this is a likely occurrence if your boat takes on a lot of water. For this reason, we recommend that, in addition to any electric pumps, you have at least one high-capacity manual diaphragm pump.
Manual pumps can move substantial amounts of water (up to 30 gallons per minute or so). With the exception of the higher-end pumps, most are very tiring to use, so be careful in your selection. Each gallon of water weighs over 8lb. and pumping it 15 feet or so is a challenging task for both the pump and the pumper. This is especially true if the pump&#;s location requires you to be on all fours or in some awkward position while pumping. An appropriate installation location and an effective pump is critical. When selecting a manual pump, it is most important to consider the gallons per stroke and the ergonomics of the pump.
If you want automatic operation, you need to install a bilge pump with a built-in or external float- or electronic-water-sensing bilge pump switch. Automatic pumps are great for removing small amounts of water but do not allow your automatic pump to lull you into a false sense of security. "Things happen." For example, in the face of an unknown leak, such as a thru-hull valve that is failing due to electrolysis, your boat will be fine&#;as long as the rate of water ingress does not exceed the capacity of the pump. But when it does, a potential sinking awaits.
The moral here is trust but verify. You can do this in several ways. First, you can make frequent physical checks of your boat. Second, you can install a cycle counter to record how often your pump turns on and off, and log this information over time. Another option is to install a light or buzzer that turns on when your pump is operating.
Beyond cycle counters, lights and buzzers you also have a high-tech option, which is to keep tabs on your boat's bilge with a remote monitoring system, such as Siren Marine's Connected Boat System. This system relieves worries about leaving your boat unattended. Using available sensors and an iPhone connection, it not only gives you the ability to connect to a bilge pump and or a high-water alarm, but also to monitor and control other systems, such as your boat's GPS, battery, engine metrics, shore power and more.
Boats that have segmented bilges need modifications to the pump system since a single intake point may not get all the water. For a diaphragm pump, use either a flexible intake hose that can be manually relocated to different parts of the boat, or an intake hose manifold with several hoses connecting at a common point upstream of the pump. Another option would be to use several centrifugal pumps.
Larger powerboats use one or more pumps.
Integral automatic switches: Many pumps are available with a float switch pre-wired to the side of the pump. This makes it simpler to install, especially in tight vertical bilges. Another way to accomplish this is with the Rule Automatic Bilge Pumps, which spin their motors every few minutes and use the current draw from the motor to detect whether there is water present. This has the minor disadvantage of running the motor whether there&#;s water present or not.
Separate float switches: A popular method of converting a non-automatic bilge pump to automatic operation is to connect the pump to a separate float switch. These switches consist of a hinged float that completes a circuit to energize the pump when the bilge water rises. Formerly, many of these switches relied upon liquid mercury to complete the circuit, but due to environmental concerns, they have been eliminated. Environmentally safe switches have taken their place.
Electronic water-sensing switches use a pair of Mirus&#; detector cells that sense the presence of water through the plastic housing using a low-impedance electrical field. Switches like the Johnson Ultima Electronic Switch have no moving parts to wear out and do not sense petroleum products, so you won&#;t accidentally pump fuel overboard if it is spilled in the bilge.
Centrifugal pumps are submersible and non-self-priming, so they must be sitting in the water in order to pump it, and can usually remove all but the last inch of water. They work best when the bilge has a small sump where water collects. Centrifugal pumps use whirling vanes to draw fluid into the center of the pump and then push it outward from the center through an outlet port. They have a built-in strainer in their base that can be removed quickly for cleaning, which is important because the small impeller can get clogged with debris.
Diaphragm pumps are self-priming, which means they can lift water up an intake hose and expel it outside the hull. They use a membrane to increase and decrease the volume of a pumping chamber, drawing fluid in and pushing fluid out through a set of one-way check valves. Diaphragm pumps require an external strainer at the end of the intake hose since a small amount of hair or bilge debris can cause the valves to clog.
Flow restrictions: Diaphragm pumps try to move the same volume continuously. If something restricts the flow, they work harder and harder until they stop pumping, at which point something usually fails. Centrifugal pumps respond to increased head pressure by moving less and less fluid until they stop pumping. The motor will not burn up, but the pump will stop moving any fluid.
Siphoning: The effect of siphoning occurs when a hose is led to a body of water above the starting point. If this water ever starts to flow backward it produces suction that draws water into the boat. This is one reason why bilge pump discharges frequently exit high on the hull well above the waterline. A vented loop can also be used to prevent back-siphoning.
Plugged Intakes: Bilge pumps with a remote water intake should have a strainer or strum box at the intake end of the hose, to prevent debris from clogging the pump or hose. Bilges are full of junk more often than not, so bilge pumps must be easy to clear and clean. The valves in some diaphragm bilge pumps are designed to pass objects as big as a marble, but hair and fiberglass strands are very difficult to defend against. Centrifugal pumps such as many we sell by Rule, Attwood and others normally snap into a base that also serves as an intake strainer. Keep it clean!
Faulty wiring or a dead battery: Corrosive saltwater and contaminants from fuel, cleaning chemicals and oil from engines can wreak havoc on wiring. So along with keeping your bilge clean, make sure to use tinned marine-grade wire and seal your connections with waterproof heat shrink butt connectors and terminals. Keep your battery charged and monitor its status frequently.
3,500gph (or larger) emergency pump located above sump, and connected to manual switch. 400gph (or smaller) pump with integral float switch, connected directly to battery.
The complete installation will consist of several components:
The sizing of wire depends on amp draw and pump capacity. Use the following chart as a guide. It assumes a wire run of about 10 feet. Longer runs need larger wire sizes.
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Pump Capacity Wire Size < 800gph 16 ga 800&#;gph 14 ga &#;gph 12 ga gph 10 ga