The Collaborative International Dictionary of English v.0.48:

Flyboat \Fly"boat`\, n. [Fly + boat: cf. D. vlieboot.]
   1. (Naut.) A large Dutch coasting vessel.
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            Captain George Weymouth made a voyage of discovery
            to the northwest with two flyboats.   --Purchas.
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   2. A kind of passenger boat formerly used on canals.
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