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Hydrasearch
A small fitting can serve a big job on a boat. A water intake feeds a cooling system. An outlet carries water overboard. In both cases, the connection through the hull needs the right hardware, a sound installation, and regular checks.
Thru hull fittings create these passages. Choosing one involves more than matching the size of the old part. Its material, connection, stem length, and position all affect whether it suits the boat.
Buck Algonquin by Hydrasearch offers marine hardware for commercial and recreational boats. Start with Hydrasearch’s thru hull collection to compare fitting styles, then check the details of the exact part you need.
What Is a Thru Hull Fitting?
A thru hull fitting passes through an opening in the boat’s hull. Its outer flange sits against the outside surface. The stem extends inside, where it connects to a hose, an adapter, or other hardware.
The fitting provides a passage. It does not automatically provide a way to shut off water. Some installations also need a seacock, which is a valve used to close the hull connection.
Think of the fitting as one part of a complete system. The hull support, valve, hose, clamps, and sealing materials must all suit the job.
Where Do Boats Use Thru Hull Fittings?
Before replacing a fitting, trace the connected line and identify its purpose. That simple check helps prevent ordering a part that looks right but serves the wrong job.
| Connection | Main purpose | What to check |
|---|---|---|
| Water intake | Supplies outside water to equipment | Required flow and intake location |
| Water outlet | Carries water out of the boat | Hose routing and outlet position |
| Drain connection | Provides a drainage path | Drain design and waterline position |
| Specialized pickup | Serves a specified intake arrangement | Equipment and installation requirements |
Water Intakes
An intake may supply raw water to engine cooling or other onboard equipment. A blocked or undersized passage can restrict the supply, even when the connected pump is working.
Hydrasearch lists high speed pickup thru hulls separately from standard fittings. Review a pickup’s intended use and installation requirements before selecting that style.
Water Outlets
An outlet connects a discharge line to the outside of the boat. Its position deserves attention because the waterline changes with loading and the boat’s movement.
An opening that is above the water while the boat is level may be closer to, or below, the water in other conditions. The complete system must account for that change.
Thru Hull Fitting vs. Seacock
The two parts have different jobs. A thru hull fitting forms the hull passage. A seacock provides a shutoff at that passage.
For an installation that needs a seacock, plan the fitting and valve together. The assembly needs proper support and enough room for someone to reach and operate the handle.
Browse Hydrasearch’s bronze ball type seacocks when comparing shutoff hardware. Confirm the exact model’s connections and mounting requirements before ordering.
Thread type matters too. NPS refers to straight pipe threads, while NPT refers to tapered pipe threads. Two parts with the same nominal size are not automatically compatible. Use the thread combination specified for the assembly.
Common Thru Hull Styles from Hydrasearch
Standard Thru Hulls
The standard thru hull collection is a useful starting point for comparing threaded connections. Hydrasearch lists bronze and 316 stainless steel options, with specifications such as flange diameter and stem length.
Those measurements help narrow the choice. The final selection still needs to suit the hull, connected hardware, and system requirements.
Thru Hulls with Hose Ends
A hose-end fitting provides a connection for a hose. Match the stated hose size to the hose’s inside diameter, then check the rest of the installation.
For example, the 70THH200 stainless steel thru hull with hose end lists 316 stainless steel construction, a 2-inch hose inside diameter, and a 4-inch stem length under the flange.
These details identify its fit dimensions. They do not mean it suits every boat with a 2-inch hose.
Intake Strainers
An intake strainer adds a screened opening to an intake arrangement. Its design and dimensions must suit the equipment it supplies.
Hydrasearch’s 00IS100 bronze web-base intake strainer lists bronze construction and a 1-inch NPS thread size. Review the product drawing when comparing it with an existing intake.
Five Checks Before Ordering a Replacement
A few clear measurements can save time and help you ask better questions about the part.
| Selection check | Why it matters |
|---|---|
| System purpose | Determines the fitting style and required flow |
| Connection size and type | Helps match the hose, adapter, or valve |
| Hull thickness and stem length | Affects available thread engagement |
| Material compatibility | Helps assess suitability with surrounding materials |
| Service space | Allows inspection, valve operation, and tool access |
1. Identify the Existing Part
Look for a part number and take photos of both sides of the connection. Record the system it serves. Avoid relying on appearance alone.
2. Confirm the Connection
Measure the hose inside diameter or identify the pipe connection. For threaded parts, record the thread type. Nominal pipe size may differ from the measured outside thread diameter.
3. Check the Available Length
The stem must suit the hull thickness, backing structure, and connected hardware. A short stem may leave too little engagement. A long stem may interfere with nearby equipment.
4. Review the Material
Choose a material that suits the hull, water exposure, and surrounding metals. Follow the boat builder’s requirements. Neither bronze nor stainless steel should be selected only for its appearance.
5. Leave Room for Maintenance
Check space for the valve handle, hose bend, clamps, and tools. A fitting that is difficult to reach can become difficult to inspect or close.
Installation and Maintenance Basics
Plan replacement work during haul-out. Follow the fitting and valve instructions, and have a qualified marine professional assess the assembly when needed.
Proper hull support, suitable sealing materials, and compatible connections all matter. Hoses should fit without placing sideways strain on the hardware. After launch, inspect for leaks before normal use.
During routine checks, look for:
- Moisture around fittings, valves, and hose connections.
- Loose hardware or damaged clamps.
- Cracked, worn, or strained hoses.
- Changes in the metal’s condition.
- Growth or debris at intake openings.
- A valve handle that is difficult to operate.
Keep a record of each hull opening and its part number. This makes future parts checks with Hydrasearch easier.
Find the Right Marine Hardware with Hydrasearch
Start with the fitting’s job, gather the measurements, and compare the relevant product specifications. Buck Algonquin by Hydrasearch offers categories that help make this process easier.
Contact Hydrasearch
For quotes or questions, customers can contact Hydrasearch directly or visit:
information@hydrasearch.com
410.643.8900
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