Article by Capt. Steve Katz
What floats your boat?
The bilge pump is one of those pesky items on a boat that always seem to need attention. It’s no wonder why, since the pump and associated float switch are placed down low in the boat, often in or under water.
Often the pump, float and wiring are exposed to chemicals, fuel, oil, fresh water and salt water. The pump is often stepped on and kicked, the wires pulled, pushed or corroded. After all of that, we expect the pump to always stand guard, 24/7 to be ready to pump accumulated water or save us from a sudden leak.
Unfortunately, when needed the most, it seems that bilge pumps fail. There are numerous reasons a bilge pump fails and is a popular service call for many marine service companies. One of the most difficult parts of installing and servicing a bilge pump is often determining the location to place it.
To be effective, they are often mounted low in the bilge, which can prevent access for most people unless you are a yoga expert. It also seems that many boat builders connect these pumps with the shortest amount of wire, not allowing a replacement pump to reach the boats wiring.
Here are a few tips that can help you when it comes time to fix or replace your bilge pump and or automatic float switch.
If you need to replace the bilge pump, its best to replace it with the same size (in capacity) as was installed by the manufacturer. Smaller pumps may not have the correct capacity to meet the requirements of the boat and larger pumps may not be effective with the existing discharge plumbing. The physical size of the unit is also critical since often times the same size and model pump is the only one that can easily fit in the location of the existing pump. When it comes to mounting, if the existing mount is in good condition, it can be reused, saving time and difficulty of the replacement mount. Be careful if you need to replace the mount, since you are working on the inside of the hull bottom where any screws used could potentially go through the bottom of the boat, causing a much larger problem. Some boats have a pump mounting pad in the bilge which is advisable to use.
The automatic switch or float switch is critical to the operation of the bilge pump. This automatic switch is designed to turn on the bilge pump if the bilge water rises above a certain level. The most common automatic switch is the float switch. The float switch is a hinged paddle that is buoyant and when it floats upward with the rising bilge water, it completes an electrical circuit, allowing the bilge pump to run until the water level decreases and the float settles back down to its resting position. While this seems simple enough, the proper operation can be a problem for many boaters. These automatic switches should be checked regularly for proper operation, both to assure the pump will turn on and off when needed.
It is common for a float switch to get stuck in the up or down position, often due to debris or oil in the bilge. Additionally, degradation by chemicals or water intrusion into the sealed float can cause failure of the float switch.
There are a few improvements in the traditional paddle float switch that many boaters find useful. The simplest upgrade is an enclosed paddle switch that allows water into the float area but blocks debris from restricting the movement of the float switch. Another popular switch is the cylindrical float switch contained in a round chamber. This also blocks debris and since the float is not connected by wires, it can easily float up and down on the center shaft, allowing for long term operation without wear and tear. These cylindrical float switches also have a tell-tale LED light on the top of the switch, allowing you to easily confirm power is going to the switch.
The newest automatic switches do not have a float. They use tiny electrical sensors to determine when water is present and appropriately turn the bilge pump on and off as needed, with no moving parts.
There are all-in-one solutions that contain an automatic switch inside of the bilge pump. This allows for an easy installation, especially in confined spaces. Some of these units use a conventional float switch and some use electronics to determine if there is water in the bilge. The electronic units cycle every few minutes to sense if there is water in the bilge, and if so, it continues to run the pump until it senses the water has dissipated. If no water is sensed, the pump turns off. While the design and installation is a benefit, especially for confined locations, these pumps use electricity to sense for water and at some point could discharge the battery if unattended for a long period.
Where each boat and pumping system may have different wiring methods, most are powered by two power sources, an “always on” source, unusually from the battery, fused and connected to the float switch for automatic operation and a manual fused feed from a switch at the helm.
Learning where and what type of bilge pumps and switches you have allows you to maintain your systems and know there is a small problem before it turns into a big problem.
Captain Steve Katz is the owner of Steve’s Marine Service and holds NMEA, AMEI and NMEA2000 certificates along with ABYC Master Technician certification and factory training from many manufacturers. To reach Steve, call (631) 264-1600.