Since this is a work boat teak and other more exotic woods are not appropriate. For example Nevins' rule for wooden yachts specifies cypress as decking material. Yellow pine is strong, very durable and straight-grained. Usually it's used for stringers, clamps and for planking not on decks.
White pine is more common on decks.
What ever wood you end up using try to get rift sawn lumber. Shrinkage of rift sawn lumber tends more toward reducing thickness than width, producing boards with greater dimensional stability than flat grain ones.