GROCO Backing Block for 1.25 and 1.5-Inch Seacocks

The GROCO Backing Block for 1.25 and 1.5-Inch Seacocks gives a stable mounting foundation for compatible GROCO seacocks installed through a boat hull. Its rigid marine-grade PVC foam construction helps distribute mounting loads while retaining enough flexibility to conform to minor hull curvature.

Threaded brass inserts are pressed into the appropriate holes to match the seacock flange pattern, creating durable attachment points without relying on the backing material to hold threads directly. The closed-cell material does not absorb water or swell in damp bilge environments.

Confirm seacock size, flange pattern, hull thickness, mounting surface, fastener length, and installation method before use. Prepare the hull surface properly, select the matching insert locations, bed and secure the assembly according to marine installation practices, and inspect the completed mounting for rigidity and leaks. There is more in our bilge and water pumps.

• The backing block helps distribute mounting loads at the hull.
• The rigid material retains limited flexibility for practical installation.
• Closed-cell PVC foam is suited to damp bilge environments.
• Brass inserts match supported seacock flange patterns.