Bilge pump: what is it and how to use it?

April 7,2021.

The function of the bilge pump is to discharge the water accumulated in the bottom of the ship. In most cases, there are several reasons for the accumulation of water at the bottom of the ship:


It may be rain water, or it may be sea water on the deck of the ship;

When cleaning the yacht, the flushing water infiltrated;

The water in the engine room cooling system leaks to the bottom of the bilge.


Generally, on large yachts, the cooling water will be discharged outboard through a complete drainage system, but on small-sized boats, this water can generally only be discharged to the bilge; water may also flow into the bilge through some tiny pipe gaps. , Such as water leakage in the shaft seal of a direct-shaft engine.


Especially when the ship's hull has cracks and water ingress due to impact, or the water pipe ruptures due to the high temperature of the engine, a suitable and large flow bilge pump can accelerate the drainage speed so that it will not sink quickly, so as to buy time for repairs or wait. Rescue.



Where should the bilge pump be located on the ship?


Install at least one bilge pump at the lowest part of the bottom of the ship. Larger ships should be equipped with one in each closed compartment, and the drain must be at least about 20 cm above the waterline.


All bilge pumps should be located in a position that is convenient for the staff to operate, so that it is convenient to check the condition of the pump and its float switch, and to remove the debris sucked around the pump. If the bilge pump is located in an inaccessible or hard-to-reach place, such as under the stern engine, please consider changing the location of the bilge pump in this case.


How and when should the bilge pump be activated?


Bilge pump switches usually have "automatic" and "manual" configurations. When water accumulates in the bilge and reaches the set water level, the bilge pump float switch automatically opens, and when it drops to the set water level, the float switch automatically stops ; Generally, small boats only have manual pumps, as shown in the figure below, the manual pump button on the bridge.


It is very important to regularly check the area around the pump for debris that may block the pump opening. Especially new yachts need to pay more attention, because all kinds of construction debris-wood chips, fiberglass dust, foam fragments, epoxy fragments, and even screws-can enter the bilge.


Check the function of the float switch regularly, it may freeze or corrode over time.


The distribution of bilge pump drain pipes should be concentrated on the top to keep them away from the wet bilge.


If the bilge pump is not frequently turned on, a small amount of water can be injected into the bilge water to check its function. This can not only confirm the performance of the automatic switch of the bilge pump, but also observe its drainage route.


Choose the right bilge pump for your ship


The rated power of a bilge pump is determined by its pumping capacity, and the unit is GPH per hour. However, the power is relative, because the length, height and type of the pumping pipe will affect the pumping rate of the bilge pump. An empirical standard in the industry is that if the bilge pump can pump out 60% of the approved power flow, it is qualified.

If the drain hose is tortuous, replacing it with a straight hose can increase the pumping capacity by up to 30%. "A small ship with a small flow pump is enough." This sounds logical, but the fact is just the opposite: when the boat has a hole in the hull or other more serious marine accidents, the impact of sea water on the boat It is much faster than the impact on big ships.


In this regard, experienced shipowners will use a dual-pump strategy, especially when they are on a long voyage: a smaller flow (400-500 GPH) automatic bilge pump is installed in the lower part of the bilge to cope with rainwater seepage. For daily situations such as leakage, a high-flow pump (3,500 GPH) is installed at a higher place to deal with more serious situations.

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