Meaning of “to hear the rollers thunder” lyrics in “Privateering”by Mark Knopfler

Question

I was listening to Mark Knopfler's song "Privateering" from 2012 album under the same name and and I am intrigued by lyrics line I do not understand. The song tells about a life of a privateer, a civil sailor or a pirate authorised by a government to attack foreign vessels during wartime. The chorus goes:

To lay with pretty women

To drink Madeira wine

To hear the rollers thunder

On a shore that isn't mine

I do not understand what thundering rollers are. Is it a reference to some kind of loud harbour equipment (e.g. rollers used to move heavy loads), some type of war equipment (e.g. artillery) or am I missing the reference completely?

Answer 1

Roller seems to be a way to describe a type of wave; the thunder is the sound as they break on the shore.

An account from the Surgeon of H.M.S. Chanticleer, 1829:

One of the most interesting phenomena at Ascension are the rollers; in other words, a heavy swell producing high surf on the leeward shores of the island, occurring without any apparent cause. All is tranquil in the distance, the sea-breeze scarcely ripples the surface of water, when a high swelling wave is suddenly observed rolling towards the island. At first it appears to move slowly forward, till at length it breaks on the outer reefs. The swell then increases, wave urges on wave, until it reaches the beach, where it bursts with tremendous fury.

Manual of Meteorology, Napier Shaw, p 17.

Less poetically, from http://www.thefreedictionary.com/roller :

A long heavy sea wave as it advances towards the shore.

Answer 2

Rollers is commonly used to describe waves that break along the length of the beach. Usually it isn't used to refer to large, surfable waves, but those a bit smaller - those producing a sound that does sound a lot like thunder, especially on a long beach.