No. 17*15 was fitted to many boats of around 40' and the 50hp engine. First check the prop you have - the size will be stamped on the boss but often difficult to find under years of crud. second a way to check that the size is correct is to do a run at maximum with a clean bottom and flat water. You should be able to get within 200rpm of the quoted maximum rpm for the engine.
Note that the size is only for the fixed 3 blade. Folding and feathering props are often a different size and best to check with the maker of the prop for the recommended size.