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Potter On Performance: No Strain, Big Pain

People often ask me if their boats need sea strainers. They usually follow up with “My boat was not equipped with one from the manufacturer.” One of the first things I ask is: Do you boat in waters that have seaweed or turtle grass? If the answer is yes, than I strongly recommend adding a sea strainer.

Most high-performance powerboat manufacturers today install sea strainers. This is very important on boats with hull-mounted water pickups as they scoop surface water. The vast majority of debris picked up is usually on the surface. That is not to say that only boats with hull-mounted pickups are prone to picking up contamination—any boat can be subjected to water starvation as a result of debris entering the seawater system.


Sea strainers are a must for high-performance powerboats, especially in areas where seaweed and seagrass are abundant. Photo courtesy/copyright Pete Boden/Shoot 2 Thrill Pix.

The majority of family-oriented pleasure boats don’t have strainers. Most of these vessels have a production drive where the water pickup is in the sides of the gear case. The drive is deep in the water, and the water inlet is well below the surface. This helps in reducing the chance of catching floating debris.

The two most common complaints associated with a restricted water supply due to contamination are high engine temperatures (i.e. “running hot”) and overheating. This is usually due to seagrass that has passed through the sea pump and is clogging a cooler. Most of the time this can be corrected by removing the hoses from the cooler and back flushing with a garden hose. Sometimes it is necessary to replace the sea pump impeller as well.

If the restriction is severe and left unattended, it can lead to major engine damage. Always keep an eye on your water temperature and pressure. A shallow boat ramp or low tide when launching can also be a source for trouble. I can’t tell you how many times I have put a boat in for a sea trial and had to clean the strainers before even getting on plane.

Another strainer used in the protection of an engine is a sand filter. A sand filter is a very fine, screen mesh filter used to protect the intercooler, which in turn is used to reduce air inlet temperatures on a supercharged or forced-induction engine. Intercoolers have cores similar to those found in car radiators. Intercooler cores have small channels that can become restricted or plugged with the slightest bit of debris. A sand filter installed before an intercooler can prevent debris from entering the core. Sand filters have a removable element, which can be cleaned and reused.

Space allowing, all boats should have sea strainers. There are many brands, styles and price points available. We like the Stainless Marine sea strainers and Hardin Marine sand filters.

Without question, you should aave a qualified marine mechanic perform the installation as he will know the correct method for installation. A seawater shut-off valve must be installed before the strainer, and only marine-rated hoses and clamps should be used on the installation. If your boat is not equipped with a water pressure gauge, I strongly recommend having one installed. This is an important gauge and can help you to monitor your systems operation. It can also give you an indication of a potential sea pump impeller failure.

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