If you're going to dive anyway, take a decent pair of garden gloves and use contact adhesive to stick the abrasive pads to them. Safe over barnacles and you never lose them or have the scotchbrite pad slip away from between your hand and a barnacle when you least want it to.
We have also used a bent aluminium pool cleaning brush handle (3 metres long) with a 10 litre plastic bottle (empty
) fastened to it to press it up agains the hull when we don't want to be in the water.
Be alarmed when the whole slip around your boat changes colour. This is ablative paint coming off in a rush!!