One of the first things I do on a used boat is change all the fluids. The second thing I do is add a sea strainer. Here’s why. A sea strainer filters the cooling water before it goes into the engine. It catches any debris large enough to clog up your cooling system, which would cause your engine to overheat. They’re an absolute must for anyone who runs in salt water, the Great Lakes, and anywhere where there’s a lot of vegetation or junk in the water. Which is pretty much everywhere, right?
I’ve bought a couple of different kinds, but I always get one with a see-through lid or housing. That way, you can spot any debris build up inside. If the strainer starts getting clogged, you just take off the lid, remove the screen, clean it, pop it back in, and you’re on your way. It’s a quick process, easy, and practical.
Strainers will not stop sand from getting into your engine. Any strainer with a filtration medium that small would clog so often you’d have to clean it every mile or so. It does prevent larger bits from entering, which can prolong the life of the raw-water pump impeller, a hopelessly fragile rubber piece that must be replaced about once every boating season as it is.
The point is, you want to replace the impeller at your convenience, not when it breaks. If it disintegrates, it sends pieces throughout the engine’s cooling systems for oil, fuel, and power steering. Then you have to remove all the hoses and find all those bits to keep them from clogging those fluid coolers.
Installation is no fun. You’ll be down in the bilge, and it seems you always need a part you don’t have, so you have to get out of the boat, clean up, drive to the marine store, drive home, and work on the boat some more until you discover you need yet more tools or more parts from the marine store. Repeat this process at three times and you have a realistic picture of what it will take to install the strainer. But it will be worth it in the long run.