Why Boats Sink
Many years ago, Queensland trawlers began sinking in record numbers. Some attributed this to the downturn in the prawning industry, and others to coincidence, but the official investigation set the record straight. After diligent detective work, they came up with the indisputable finding that all the boats sank due to the ingress of seawater.
This is an age-old problem with boats and one exacerbated by putting holes in them. The average 21st century production boat has at least half a dozen holes in its underwater surfaces. So why don’t they all sink? Quality skin fittings, some way to close them, and well-attached hoses generally make sure the worst does not happen. Skin fittings mostly last a very long time. There is not much we can do with them except keep an eye on them and replace as necessary. Double clamping hoses minimises the chances of them coming off, but they can become brittle and split. This is when it’s handy to be able to close off the skin fitting. But will the seacocks or ball valves work when you need them?
The most common failure of ball valves is the handle breaking off, which is not uncommon if the valve is never lubricated. If your boat has gate valves, consider replacing them. They are not marine equipment, especially on through hulls that are left open. In the open position, the gate seal can become clogged with growth, making it impossible to close. So let’s assume your boat has proper seacocks. To ensure they work smoothly they need lubrication, which is of course most convenient when the boat is out of the water. Most inconveniently, to do a proper job you will need to remove the attached hose, and apply waterproof grease to both sides of the ball. Operate the valve a few times to ensure it’s working well, and then make sure to exercise all the valves every few months.
While ball valves are the most common type of seacock on recreational boats in Australia, occasionally you might find a boat fitted with tapered plug seacocks. These require disassembly for servicing, but can be fitted with grease cups for regular lubrication. Remember to check the hose clamps too. They usually rust from the hose side out, so if there is staining around them, be wary. Check their integrity by tapping with a hammer, or, if difficult to reach, place the blade of a screwdriver against the worm drive and give the screwdriver handle a good hit.
The last resort (before running the boat ashore) if a seacock, hose or skin fitting has failed, is to whack a tapered bung in it. These are required equipment on racing yachts, but not so universal elsewhere. For less than a round of drinks, they can literally be a lifesaver.
Seacocks are easy to forget about, so their upkeep is worth adding not only to your haulout list, but your general maintenance routine – the boring stuff you do that actually makes a big difference to the safety of your boat and all who sail in her.
- by Petrea McCarthy