When driving a boat, you must do everything possible to avoid collisions. If you’re unsure whether there’s a risk of collision, it’s better to be safe and assume there is. You should follow navigation rules, but keep in mind that sometimes, as a boat operator, you may need to break these rules to prevent a collision.
If you need to avoid a collision, you should change your direction and/or speed early, and the change should be big enough so the other boat can see what you’re doing. Small changes might not be enough to prevent a collision.