There is one piece of bilge pumping equipment that is often overlooked: your engine. In a pinch, the pump that cools your power plant can provide substantial dewatering help to your regular bilge pump system – if your boat is setup to take advantage of it.
BiotechnodesignThe top panel shows a common engine cooling system. The bottom panels shows a system configured to pump water from the boat. Click to see how it works.This configuration comes standard on many larger power boats, such as Mainship's new 43-foot trawler, which has the ability to use both of its engines as pumps. It can be retrofit on many other vessels, so long as the installation is carried out properly.
Standing calf deep in water in the middle of the night is not the time to jury rig such a system. You need to be fully prepared to switch the cooling water intake line from the thru-hull, where it pulls in sea water, to a hose placed inside the bilge. A quick change of valves will allow you to pump water from the bilge out the engine cooling water discharge, with the engines in neutral and the flow rate controlled by the throttle. When the bilge is empty, the valve settings are changed back, restoring the normal raw water flow.
The ability to switch between the bilge and the normal intake is critical. The impeller pumps often used in engine cooling applications do not like to run dry, and you'll need to switch back to the normal input when the bilge is clear of water.
PROPER INSTALLATION
The system also has to be safe and robust. Marine-grade ball valves are required, as well as proper non-collapsible hose and a bronze strainer. Components need to be properly fastened down and plumbed to marine standards.
The hose to the bilge should be placed so that water is run through the boats raw water strainer, to prevent and large debris in bilge from being sucked into the engine. Great care must also be taken to maintain the valves, and make sure they are secure. If the raw water seacock and the bilge valve are open at the same time, sea water intended for the engine will be diverted to the bilge. If the engine is running, this can reduce the flow of cooling water. If it is not, the boat itself will fill with water.
Paul EsterleDone properly, however, the system may add a measure of safety in the form of a powerful bilge pump, for relatively little money. Plan the installation right, and this setup can also be used for more mundane tasks like back-flushing the engine with fresh water or running antifreeze through for winterization.
On the commercial side, Marine Technologies Group LLC has developed their Quick Flush system for use with diesel and gas inboards as well as I/Os. These systems are easy to install and have the necessary ball valves to switch the source of cooling water quickly. The system uses a quick disconnect fitting so that a standard garden hose can be connected to the engine for fresh water flushing. That same fitting allows a suction hose and strainer to be attached and placed in the bilge, which becomes the cooling intake in an emergency.
GLEN JUSTICEThis is a custom installation on a single-engine trawler. The blue handle controls the raw water intake. The red handle (at left) switches the intake inside the boat. Note that both run cooling water through the strainer.
