flushing your boat engine

Most seagoing motorboats pump saltwater through the circulation system to keep the engine cooled for optimum performance. Because of the corrosive nature of saltwater, it’s necessary to flush your boat engine regularly. Since all boats use garden hoses when flushing there boat engine, it is important to know that their flow rates vary.

Flushing your engine and flow rates

A simple definition of flow rate is the amount of water that passes through a conduit per minute or GPM. Several factors affect garden hose GPM. These include the diameter of the hose, the water pressure, and the length of the hose. The water flow rate through different size hoses can vary between 6 and 72 gallons per minute. The most common garden hose diameters for flushing your boat engine are 1/2, 5/8, and 3/4 inches. In short, it is important to know that a smaller-diameter hose or a hose with greater length will deliver fewer GPM. likewise, a larger diameter hose or one of shorter length will have more GPM.

Using the correct size hose

What is the correct size hose for flushing boat engine? This really depends on the hose size and GPM of your water pump. for example, if you flush your boat’s engine with a 5/8-inch hose that is 50-foot-long using standard city water pressure of 40 psi, the hose will deliver 22 gallons per minute. If you increase the diameter of the hose to 3/4-inch and decrease the length of the hose to 25 feet it will increase this amount of water flow to 72 gallons per minute. With this in mind, this is too much water considering that most raw water pumps have a flow rate of less than 22 GPM at idle. Too much water is only a concern when using a shut-off valve due to overpressurization. Hence, the amount of water that a garden hose provides depends on its size. Generally speaking, most hoses will work. although, too much water using shut-off valves can cause over pressuization to the pump. On the other hand, too little water can cause cavitation. The garden hose flow rate chart below shows that most hose sizes will work. [email protected]

flow rates chart for garden hoses