Where are the seacocks on a Hallberg-Rassy 36, and how should I service them?

On a Hallberg-Rassy 36, look beneath the galley sink, in the heads plumbing lockers and low in the engine compartment, tracing each seawater or discharge hose to its hull connection. Positions and numbers vary between Mk I, Mk II and modified boats; operate accessible valves gently, inspect the whole assembly and leave dismantling or replacement until the boat is ashore.

Find and label hull connections

Start with the boat's plumbing drawing, preferably matched to its hull number. The HR 36 Standard drawing provides a starting point, but optional equipment and later alterations can change the installation. Not every outlet shown necessarily has a seacock.

• Galley: look below the sink and behind removable locker panels for the drain valve. Trace any seawater tap supply separately.
• Heads: follow the toilet inlet, toilet or holding-tank discharge, and washbasin drain. Valves may be below the visible plumbing, behind access panels or beneath adjacent sole boards.
• Engine: trace the raw-water hose back from the seawater strainer to its inlet valve. The strainer itself is not the shut-off.
• Additional equipment: trace watermaker, refrigeration and deckwash supplies if fitted, plus any separate shower discharge.

At haul-out, walk round the hull and match every opening to an internal fitting. Include cockpit drains and outlets above the static waterline, recording which have valves. Photograph each location and label each valve's function where you can read it quickly.

Inspect before applying force

A seacock assembly comprises the through-hull fitting, valve and hose tail. Inspect all three. A valve that looks sound tells you nothing about the condition of the threaded fitting beneath it.

Before disturbing a below-waterline connection afloat, have a correctly sized softwood bung within reach. Leave dismantling until the boat is ashore.

1. Dry the assembly and check for fresh weeping, salt deposits, cracks and movement at the hull.
2. Inspect metal bodies and hose tails for pink areas, crumbling surfaces or deep pitting. Pink, porous brass suggests dezincification and warrants replacement.
3. Move the handle gently through its full travel while watching the body. Stop if the fitting twists or needs substantial force.
4. Check hoses for splits, hardening and chafe. Inspect clamps for corrosion, particularly underneath.

On a conventional quarter-turn ball valve, the handle normally lies parallel to the flow when open and across it when closed. Confirm this on your installation: a loose handle or damaged spindle can mislead you. Never use a pipe extension to free a seized valve.

Service each valve type correctly

Operate sound valves regularly during the season and inspect them at every haul-out. Ashore, check the outside openings for shells, growth and excessive antifouling, then inspect the bore with a torch. A handle that moves does not prove the valve seals.