Police arrested the man in the back garden of a cottage on Waterside, where he was seen making his way down to the river shortly after 9pm on Tuesday July 4.
Officers called to reports of suspicious circumstances located and arrested the man, who currently remains in police custody.
North Yorkshire Police said a 30-year-old man from Harrogate was arrested on suspicion of aggravated burglary, theft of a boat, possession of a weapon and possession of a class B drug.
Anyone who was in the area at the time who witnessed anything, or has any information which could assist the investigation is asked to contact 101, select option 1 and speak to the Force Control Room.
Quote reference 12170117122. Crimestoppers can be contacted on 0800 555 111.