| Pumps, pumps, pumps, you gotta love 'em. If you | | | | the good old bilge pump is often your first line of |
| have any boat larger than you can turn over by | | | | defense against losing a boat and sometimes |
| hand and dump out, you have to have them. But | | | | more. At the very least, in a flooding situation, |
| which pump, what size, type, and how and where | | | | good pumps can buy you time for options. |
| to install it? This article offers information and | | | | It is important to understand that advertised |
| considerations you need to know. | | | | marine pump ratings in gallons per hour (GPH) are |
| Bilge pumps. These are most important because | | | | not accurate for normal use. Pumps are tested |
| they keep the boat afloat. There are two basic | | | | and rated in laboratory conditions with short |
| types: centrifugal and diaphragm. Centrifugal | | | | outflow pipes on the horizontal. Under actual |
| pumps use impellers, and are usually electrically or | | | | conditions we have to consider "head" which |
| mechanically powered. They are dependent on an | | | | means overcoming both the friction of the |
| electrical source or direct mechanical power as | | | | outflow tubing and gravity to raise the water to |
| from the engine or generator shaft. When | | | | the thru-hull fitting. Common bilge pump tubing is a |
| installing electric pumps, the wiring connections are | | | | corrugated design which creates a great deal of |
| critical. Connections must be watertight, and | | | | friction. Smooth bore tubing is more expensive, |
| securely fastened as much out of the way as | | | | but better. |
| possible to prevent interference with the pump | | | | Also, consider friction loss as outflow is restricted |
| and/or float switch. | | | | at the smaller diameter thru-hull fitting. Now we |
| Some electric marine pumps include an internal | | | | have to lift the water from the bilge to |
| float switch which, of course, activates the pump | | | | overboard, usually through a thru-hull fitting. Holes |
| when water rises. These are usually smaller | | | | in a boat near the water line are to be avoided as |
| pumps, and the internal switch design can render | | | | much as possible. The thru-hulls for your pumps |
| them more susceptible to blockage and sticking | | | | should be at least eight inches above the |
| due to bilge debris. Most bilge pumps require a | | | | waterline. For mono hull sailors, don't forget you're |
| separate float switch allowing easy testing of the | | | | going to heel. For small boaters or commercial |
| switch and pump (manually lifting the switch arm) | | | | applications, remember that the water line will be |
| and separate installation positions for the switch | | | | higher if you heavily load the boat. You should |
| and pump. For example; wisdom holds that two | | | | always use a "safety loop" when piping overboard. |
| pumps may be better than one. | | | | That is, the piping should be looped higher than |
| Both pumps can be strategically located in the | | | | the thru-hull to prevent water coming in if the |
| bilge, but the switch for one pump can be higher | | | | thru-hull is submerged. This loop, of course, |
| than the other. This allows automatic operation of | | | | increases the head, so it must be considered |
| only one pump for regular duty, thereby reducing | | | | when choosing a pump. |
| current draw and the life of only the one pump. | | | | The following chart is only a General |
| As any long time boater knows, emergencies | | | | recommendation for boat and pump sizes. |
| happen. When water intake exceeds the | | | | Boat Length 16' - 20' No. Pumps: 2 GPH: 2500 |
| capabilities of the primary pump, the higher switch | | | | Boat Length 21' - 26' No. Pumps: 2 GPH: 3000 - |
| will activate the back-up pump. My back-up pump | | | | 3500 |
| is usually larger, because if I need it, I want to | | | | Boat Length 27' - 35' No. Pumps: 3 GPH: 3500 - |
| move a lot of water fast. | | | | 4500 |
| For smaller boats or those without power such as | | | | Boat Length 36' - 42' No. Pumps: 3 GPH: 6000 |
| sailboats, rowing boats, etc., a manual suction or | | | | Boat Length 43' - 49' No. Pumps: 3 - 4 GPH: 8000 |
| diaphragm type works well. These pumps can be | | | | Boat Length 50' - 59' No. Pumps: 4 - 5 GPH: 9000 |
| inexpensive and portable. They also have the | | | | - 10,000 |
| advantage of not being easily blocked by debris in | | | | Boat Length 60' - 60' No. Pumps:4 - 5 GPH: |
| the bilge. They are reliable and work great as long | | | | 10,000+ |
| as you can power them. The problem is, on larger | | | | Please remember that multiple pumps, often in |
| boats, how long can you man the pumps? While | | | | multiple locations, offer the most security and |
| these pumps can also be powered mechanically or | | | | peace of mind. With electric pumps, consider your |
| electrically, they are usually larger and heavier, so | | | | power sources and connections. With installed |
| centrifugal pumps are the common choice; but | | | | manual pumps, consider location and ease of |
| options are good. If applicable, consider both | | | | access. Use all the information you can acquire |
| types. | | | | with common sense. Don't be misled by "bargain" |
| This brings us to another point. When purchasing | | | | offers. In an emergency, bilge pumps can be your |
| pumps, do not skimp; as important as life jackets, | | | | best insurance. |
| rafts, ELT's and VHF's can be in an emergency, | | | | |