Gary’s Q&A

Listener question & Gary’s response · Transcript passage

Bairbre N’Cinneide from the Facebook group asks, My father took a barge off the bottom of a lake in Ireland (many years ago) He was sure it would float because rust needed moisture and oxygen. How long would a metal boat survive underwater? Have there been cases of boats being salvaged years after the sinking? The lake in question was in Ireland.

For starters, there is dissolved oxygen in water, so things can absolutely rust at the bottom of a lake.

There are some lakes that are an anoxic environment, but they tend to be rare.

How long a metal boat could last after sinking would depend on the metal used in the boat and the type of water it was in.

The deep ocean has less dissolved oxygen than the surface. The further down you go, the more difficult it is for water to be replenished. Small organic particles will sink to the bottom and oxidize, removing dissolved oxygen from the water.

For the average lake, it isn’t deep enough to have anoxic conditions at the bottom. Some bodies of water, like the Black Sea, are very anoxic and are able to preserve shipwrecks for thousands of years.

Likewise, if it is an aluminum boat, it is going to be more resistant to corrosion than if it is made of iron or steel.

So, without knowing the boat or the lake, it would be impossible to say.