It does sound like a connection problem. Also it sounds if you might be pulling excess amerage. Try taking the prop off and checking for line or something of that nature dragging on the prop causing more amp draw.

if neither of those work check the battery. E over I R. if E (voltage) drops amperage goes up. Amperage goes up breakers kick. This is rare but I have seen it. Especially on older batteries and breakers.

hope this helps
Bill Wagner