Scoop & Round Strainers

What Are Scoop & Round Strainers?

Scoop and round strainers are critical components in a boat's raw water plumbing system. Mounted at or near the hull, these fittings intercept debris — seaweed, shells, sediment, and other foreign matter — before it can enter and damage pumps, heat exchangers, engine cooling circuits, or other onboard systems that depend on a clean, steady water supply. Without a properly functioning strainer, even small obstructions can reduce water flow enough to cause engine overheating or accelerate wear on downstream components.

Scoop vs. Round: Understanding the Difference

The two primary styles serve slightly different purposes, and choosing the right one depends on your vessel's configuration and intake requirements.

• Scoop strainers are thru-hull fittings shaped to "scoop" water into the intake as the boat moves forward. Their angled profile creates a dynamic pressure that actively forces water into the system, making them especially effective at speed. Forespar scoop strainers are a popular example of this design.
• Round strainers (also called hull strainers or intake strainers) sit flush or nearly flush with the hull. They rely on suction from the pump to draw water in through a screened, circular face. Their low-profile design works well for vessels where drag or protrusion below the waterline is a concern.

Why Strainer Material Matters

In the marine environment, material selection is everything. Traditional bronze fittings are strong but susceptible to galvanic corrosion when in contact with dissimilar metals. Modern engineered polymer strainers — like those made from Forespar's proprietary Marelon® material — offer zero corrosion and eliminate the need for bonding or cathodic protection. Molded from lightweight, high-strength Marelon, these intake scoop strainers are highly resistant to corrosion, UV degradation, and abrasion. Designed for use with existing thru-hull fittings, they require no bonding or protection from electrolysis.

Key Considerations When Choosing a Strainer

• Hose size compatibility: Match the strainer's thread or port size to your existing intake hose diameter — common sizes include 3/4" and 1-1/4".
• Above or below waterline: Confirm the strainer is rated for its intended position on the hull. Some strainers can be used above- or below-the-waterline and are engineered to exceed ABYC and ISO standards.
• Flow rate requirements: High-demand systems such as engine cooling require strainers rated for adequate GPM throughput.
• Ease of cleaning: Look for designs with removable screens or clear lids that allow quick visual inspection and maintenance without tools.

Featured Brand: Forespar

Robert Foresman started Forespar Products Corporation in 1966 , and the company has since grown into one of the marine industry's most trusted names in plumbing hardware. Over the years, Forespar Products Corp. has brought forth a steady stream of truly innovative, high-quality products that have increasingly incorporated lightweight, space-age materials that will not corrode or degrade from galvanic reaction. Their Marelon® plumbing line — which includes scoop strainers, thru-hulls, seacocks, and vented loops — is particularly well regarded. Marelon plumbing is now used by custom builders such as Wally Yachts, Oyster, Swan, Baltic, and Morris, and virtually all North American production boat builders use some Marelon plumbing components in their boats.

Browse Forespar scoop & round strainers to find the right fit for your vessel's raw water intake system.