You also seem a little unsure of your boat''s bottom condition. While some light growth is unlikely to be very noticeable on a breezy day and a "non performance" boat, your symptoms could be explained by growth on the prop blades.
Last year, while my bottom cleaner was slowly putting himself out of business, there was a period where the job wasn''t getting done, and I didn''t know about it. While the hull had fairly fresh paint
and didn''t get too ugly, the metal bits were crusted over to extreme. The prop blades looked like two baseball bats, instead of blades. Under power, the engine lugged, and top speed was 4 knots under power, and fuel
efficiency was terrible. Under sail, there was practically no effect from the crusty prop on the boat''s performance.