Fromwhale +‎boat.

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whaleboat (pluralwhaleboats)

1. A long narrowrowing boat, formerly used inwhaling, which is pointed at both ends so that it can move either forwards or backwards equally well.
   • 1886 October –1887 January,H[enry] Rider Haggard,She: A History of Adventure, London:Longmans, Green, and Co., published1887,→OCLC:

     Before we had gone fifty yards we perceived that all hopes of getting further up the stream in thewhale-boat were at an end, for not two hundred yards above where we had stopped were a succession of shallows and mudbanks, with not six inches of water over them.

2. A boat resembling this and carried on awarship or othership.