Blue Water Navy used to market separate accessory packs, including a 26ft motor whale boat and a 40ft personnel boat in 1:350 scale. These where white metal with PE interior details. I haven't seen the set since Yankee Modelworks took over from BWN.
The Tamiya Fletcher will have a pair of 26 ft MWB
Other sources might be some of the boats provided in the Iron Shipwright kits. I think they come with & without the hard-top canopy
If you come up completely blank post back - I'm sure I have some ISW boats in the parts bin