GROCO builds the bronze seacocks, valves, and fittings that control water below the waterline. Match the material, size, and thread to your through-hull and do it to ABYC standards. Anything that lets water in or out below the waterline has to be done right, and GROCO has built marine seacocks, valves, and through-hull fittings to that standard for generations. This collection covers flanged seacocks, ball valves, thru-hull fittings, flange adapters, check valves, and the bronze and stainless plumbing parts a safe install needs. The keys are material, correct sizing and thread, and a seacock you can actually reach and operate. Use a real seacock below the waterline A seacock is a valve bolted to the hull that you can shut...
1-1/2" Bronze In-Line Check ValveFeatures: C83600 cast bronze construction NPT threaded ports 1/2" - 2" sizes Suitable for use with diesel fuel or gasoline Groco 1-1 / 2...
3/4" Bronze In-Line Check ValveFeatures: C83600 cast bronze construction NPT threaded ports 1/2" - 2" sizes Suitable for use with diesel fuel or gasoline Groco 3/4 bronze online...
Perforated Hull Strainer with Access Door 3" Max Thru-HullFeatures: Access door design allows easy access to Thru Hulls C84400 bronze body and door Cast filter slots Pressure relief...
1-1/2" Inlet Hydromatic Self-Cleaning Strainer - 12VFeatures: 30-second cleaning cycle is automatically performed at user-selected intervals Optional interface with SSA system ( initiates cleaning cycle when flow is...
2" Bronze Tri-Flanged Ball Valve/SeacockFeatures: 1-1/4" sizes and larger include one grease zerk fitting for lubrication (use only with the valve in the open position), and one drain...
1-1/2" Bronze Tri-Flanged Ball Valve/SeacockFeatures: 1-1/4" sizes and larger include one grease zerk fitting for lubrication (use only with the valve in the open position), and one drain...
1-1/4" NPT x 1-1/8" ID Bronze 90 Degree Pipe to Hose Fitting Standard Flow ElbowFeatures: 90 degree Male NPT x Hose connection C83600 Bronze Sizes from 1/2" to 5"...
1-1/2"" NPT x 1-1/2" ID Stainless Steel Pipe to Hose Straight Fitting Features: Male NPT x Hose connection #316 Stainless Steel Sizes from 1/2" to 3" Standard Flow NSF-61...
1-1/4"" NPT x 1-1/4" ID Stainless Steel Pipe to Hose Straight Fitting Features: Male NPT x Hose connection #316 Stainless Steel Sizes from 1/2" to 3" Standard Flow NSF-61...
3/4" NPT x 3/4" ID Stainless Steel Pipe to Hose Straight Fitting Features: Male NPT x Hose connection #316 Stainless Steel Sizes from 1/2" to 3" Standard Flow NSF-61...
1-1/2" NPT x 1-1/2" ID Bronze Pipe to Hose Straight FittingFeatures: Male NPT x Hose connection C83600 Bronze Sizes from 1/2" to 5" Standard Flow UL Listed 647B Note-...
1/2" NPT x 1/2" ID Bronze Pipe to Hose Straight FittingFeatures: Male NPT x Hose connection C83600 Bronze Sizes from 1/2" to 5" Standard Flow UL Listed 647B Note-...
1-1/4" Bronze Pipe Nipple Check ValveFeatures: C83600 cast bronze construction NPT threads 1/2" - 2" sizes Not suitable for use with diesel fuel or gasoline Maximum recommended temperature...
1-1/2" NPT #316 Stainless Steel In-Line Ball ValveFeatures: 1-1/4" sizes and larger include a grease zerk fitting for lubrication (use only with the valve in the open position)...
1/2" NPT Bronze In-Line Ball ValveFeatures: Female NPT Threads 1-1/4" sizes and larger include a grease zerk fitting for lubrication (use only with the valve in the open...
Backing Block for 2" & 2-1/2" SeacocksFeatures: Each size fits multiple seacock sizes Press threaded brass inserts into the hull side of the backing block into the holes...
1-1/4" NPT x 1-1/2" Bronze Full Flow Pipe to Hose Straight FittingFeatures: Full Flow Male NPT x Hose connection C83600 Bronze Sizes from 1/2" to 3" UL Listed 647B...
1" NPT x 1-1/8" Bronze Full Flow Pipe to Hose Straight FittingFeatures: Full Flow Male NPT x Hose connection C83600 Bronze Sizes from 1/2" to 3" UL Listed 647B...
1-1/4" Bronze Flanged Full Flow SeacockFeatures: 1-1/4" sizes and larger include one grease zerk fitting for lubrication (use only with the valve in the open position), and one...
Bronze Slotted Hull Scoop Strainer with Access Door for Up to 1-1/4" Thru HullFeatures: Access door design allows easy access to Thru Hulls C84400 bronze body and door...
Deck Scupper 90 Degree 1-1/2" Hose ConnectionFeatures: 90 Degree Barb Scuppers are installed flush with the deck and have a removable drain. #316 Stainless Steel Thru Deck Drain...
1-1/4" Hose Barb Stainless 90 Degree Deck Drain Features: 90 Degree Barb Scuppers are installed flush with the deck and have a removable drain. #316 Stainless Steel Thru Deck...
1-1/4" Hose Barb Stainless Straight Deck Drain Features: Scuppers are installed flush with the deck and have a removable drain. #316 Stainless Steel Thru Deck Drain with Bronze Hose...
3/4" NPT Bronze 3-Way Valve Features: 3-way valve operates logically - The handle points to the direction of flow Center position is "off" Handle rotates a full 180°. Mount...
GROCO builds the bronze seacocks, valves, and fittings that control water below the waterline. Match the material, size, and thread to your through-hull and do it to ABYC standards.
Anything that lets water in or out below the waterline has to be done right, and GROCO has built marine seacocks, valves, and through-hull fittings to that standard for generations. This collection covers flanged seacocks, ball valves, thru-hull fittings, flange adapters, check valves, and the bronze and stainless plumbing parts a safe install needs. The keys are material, correct sizing and thread, and a seacock you can actually reach and operate.
A seacock is a valve bolted to the hull that you can shut to stop the flow through a through-hull, and it is what stands between your boat and a sinking if a hose fails. GROCO flanged seacocks mount to a backing and take the load off the through-hull itself. Do not substitute a cheap gate valve or a bare ball valve threaded onto a through-hull for a below-waterline application.
GROCO bronze is the traditional choice below the waterline, strong and proven, and it must be bonded to the boat's system to control corrosion. Stainless is common for above-waterline and adapter fittings but is not ideal for a submerged valve body. Match the material to the location and keep dissimilar metals in mind to avoid galvanic trouble.
Fittings are sized by pipe thread, and marine plumbing mixes NPS straight and NPT tapered threads. GROCO offers flange adapters to mate NPS through-hulls to NPT valves correctly, which is exactly where people get into trouble forcing mismatched threads. Match the size and thread type, and use the right adapter rather than overtightening a bad fit.
Check valves keep water flowing one way, which protects pumps and prevents back-siphoning. Raw-water strainers on the intake keep debris out of your engine cooling and pumps. Size these to the hose and flow so they do not choke the system.
A seacock you cannot reach is a seacock you will not close in an emergency. Mount valves where you can operate them by hand, and exercise them regularly so they do not seize. Replace any valve that is stiff, corroded, or weeping.
Not sure which GROCO parts your plumbing needs? Tell our techs the through-hull size, location, and thread, and we will match the seacock, valve, adapters, and strainer so the system is safe and seals tight. Always confirm thread types before ordering to prevent leaks at the hull. Regular inspection of all below-waterline fittings helps catch corrosion early and keeps your boat safe on the water.
A seacock is a valve designed and mounted to take the load off the through-hull and let you shut the flow if a hose fails. Below the waterline, that is what stands between your boat and sinking. Do not substitute a gate valve or a bare ball valve threaded onto a through-hull.
Bronze is the traditional and proven choice for submerged valve bodies and must be bonded to control corrosion. Stainless suits above-waterline and adapter fittings but is not ideal for a submerged valve. Match the material to the location.
NPS is straight thread and NPT is tapered. Marine plumbing mixes both, and forcing them together leaks or cracks. GROCO flange adapters mate NPS through-hulls to NPT valves correctly, so use the right adapter instead of overtightening a mismatch.
A strainer on the intake keeps debris out of your engine cooling and pumps, which prevents clogs and overheating. Size it to the hose and flow so it does not choke the system, and clean it regularly.
Mount them where you can reach and operate them by hand, exercise them regularly so they do not seize, and replace any valve that is stiff, corroded, or weeping. A seacock you cannot close in an emergency is a real hazard.
