What Is a Seawater Strainer?
A clear-cased filter fitted on the seawater intake line, screening out weed and debris before they reach the impeller and heat exchanger.
A seawater strainer is a filter fitted between the seacock and the pump, using an internal basket to catch weed, plastic bags and jellyfish. It is the first defence for the impeller and heat exchanger: a bag trapped in the basket can overheat the engine within minutes.
In weed-heavy, busy waters like Göcek, blockages during the season are common; the first point to check on an overheat alarm is always this housing.
Routine and faults
Full basket: if the discharge water has dropped, this is the first place to look; cleaning takes 5 minutes, but you must shut the valve first.
Lid gasket leak: an air leak at the strainer reduces pump suction; a hidden cause of cases where ‘the impeller is new, but the water flow is poor’.
Final step: after cleaning, open the valve, run the engine and check for discharge water; if you skip this, the impeller can end up running dry.
The routine is straightforward: before every trip, give it a glance along with the engine; if it’s dirty, close the valve, remove and wash the basket, check the gasket, open the valve again, then run the engine and confirm water at the exhaust.