Is Your Boat Proving ‘Almost' Watertight?

Water can sneak into your boat undetected for years. Øyvind Bordal explains where leaks develop, and how to find them in time

- Øyvind Bordal

There’s no such thing as ‘almost waterproof’. Still, that’s how most boat owners would describe their boat, if they were being totally honest.

Somehow, somewhere, a tiny bit of water always seems to find its way through the outer shell. Most often the problem is above the waterline, so the boat won’t sink. But it can create serious damage over time.

If you think about it, leaks are natural.

Windows and hatches will often develop leaks over time. This sort of repair is not a permanent fix…

When a vessel is underway, rigging places huge loads on chainplates and blocks. Rain and waves are splashing over everything and there are hundreds of entry points through deck gear, stanchions, steering systems, etc. And, as we all know, the sealant doesn’t last forever. In spite of this, it is possible to keep your boat waterproof, but you will need to keep an eye on things, track down the source of the problems and know what to do about it.

Two types of leak

There are two types of leaks: the ones you know about, and the ones you don’t. The first ones will most often be fixed with a minimum of effort and cost. The latter are the ones you should worry about. Most boats have wooden interiors, and bulkheads are often built from plywood. Some boats have chainplates attached to wooden bulkheads. Behind inner liners tiny, unseen streams of water can trickle down for years and end up where rot can develop undetected.