A narrowboat propeller sometimes gets tangled in weed or rope as you are moving along. You may find your boat loses power if something gets caught, or you may see the wash come from the back unevenly. In the autumn, fallen leaves are a real problem as they clog up the propeller and slow you down considerably.
In this little one minute video, Aaran demonstrates how to free things up using reverse gear without having to venture down the weedhatch.