The Sailing Safety Secret That Could Save Your Boat from Sinking

Captain John from explains the importance and how to on maintaining your seacocks.

Did you realize that your sailboat could have between 8-12 holes drilled below the waterline to allow sea water into the boat, or to drain water from the boat? These “thru-hulls” are used for heads, shower drains, sink drains, cockpit scupper drains, instrument transducers (knot logs or depth sounders), engine intake, and other uses.

Most thru-hulls are covered by a valve–called seacocks–with a handle that can be opened to allow sea water into the boat or shut to keep sea water out. Seacocks are the most important components beneath the waterline and need attention and care to prevent flooding.

Check every handle on every seacock on every through-hull. Surveyors report time and again that they find frozen sea-cock handles on most every boat they inspect. You must be able to close any seacock with minimum effort.

Move the handle from open position (parallel to the hose) to closed position (perpendicular to the hose) and back to open. This exercises the seacock handle to keep corrosion at bay, and the handle lubricated. Open frozen seacock handles with a light tap from a hammer or mallet.

Examine the hoses at the top of each seacock. Replace hardened or cracked hoses right away. They are the number one cause of through-hull failure. Inspect the stainless clamps on each seacock hose. Replace rusted or corroded clamps.

Insure that a tapered wooden plug gets lashed to the base of the seacock with easy-to-break twine. If a seacock hose fails, you can drive the plug into the seacock hole with a hammer or mallet as a temporary repair.

Inspect, clean, and lubricate every seacock when you haul your boat. This gives you the perfect opportunity to find and fix problems. That way, you will have peace-of-mind that all of your thru-hulls are in great shape for another sailing season.

Make a Simple Seacock Diagram

Make a simple seacock diagram. Plot and label the location of each thru-hull aboard your boat.

Follow these steps to make an easy-to-read, easy-to-use seacock diagram for you and your sailing crew or partner. Create a simple diagram similar to the illustration. Divide the boat into thirds, with a light “center-line” as shown.

1. Start in the forward third of your boat (forward of the main cabin). Remove lockers, lids, or access covers to locate each seacock.

2. Plot small circles onto the diagram to indicate each seacock. Label each circle (i.e. head, shower, washdown hose) Note the dotted line down the centerline of the diagram (illustration). Seacocks should be plotted to the left, right, or along the centerline for faster access.

3. Include bilge cover plates. These can be difficult to locate in trying conditions because fine joinery work can make seams almost invisible.

4. Move to the midships section (main cabin); then to the aft section (cockpit and stern). Repeat the process described earlier to find each seacock and thru-hull.

5. Transfer your rough sketch onto the new insert so that it’s neat and legible. Post it where all hands can see it day or night.


Use these easy sailing tips to keep your boat’s “gates to the sea” working to perfection. Inspect and maintain your sea-cocks, thru-hulls, and fittings to gain the peace-of-mind you need for worry free sailing—wherever in the world you choose to cruise!

This entry was posted in Boat Rat's Tip of the Week and tagged . Bookmark the permalink.

Leave a Reply

Your email address will not be published. Required fields are marked *


You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>