Not P but Moby-Dick (32)

[Mike Jing]

>From Chapter 48:

Meantime, Ahab, out of hearing of his officers, having sided the furthest
to windward, was still ranging ahead of the other boats; a circumstance
bespeaking how potent a crew was pulling him. Those tiger yellow creatures
of his seemed all steel and whalebone; like five trip-hammers they rose and
fell with regular strokes of strength, which periodically started the boat
along the water like a horizontal burst boiler out of a Mississippi
steamer.

What is a "horizontal burst boiler"? Does it mean that it works in bursts,
or is it something else?