Boat kits tend to be fairly "round number" scales. If metric, 1:10, 1:50, 1:100 etc. If imperial, usually something convenient for reading off a ruler, like 1:12 (inch to the foot), 1:48 (1/4 inch to the foot) and similar, or a binary scale, like 1:16 or 1:32. But occasionally, a model is designed to be a certain size to fit either the drawing board it was designed on or the box that the kit is going to ship in. This does result in strange and unlikely numbers.
Figures can be got from other hobbies that have other ideas about suitable scale, but it has to be remembered that while people are all the same scale, they are not the same size. Answer is to look for figures the right height, or near enough. A bit smaller usually fits more easily. Boats are very much a minority hobby, and this is reflected in the supply of the extra bits. Very specific scales require the right tooling, which is a big outlay for a small market. 3D printing is one way forward, but such figures, if they are scaled for one single application, will take expensive time to produce.
Fittings in the model boat world tend to go by size. Things like cleats and bollards tend to keep the same broad design whatever the size – bigger ships/boats get bigger fittings, but they look the same.
Careful measuring on a 1:33 model might show that it is really 1:32 or 1:35 anyway.