Beaching a cat is not rocket science.
Check the sea bottom is even to avoid twisting of the hulls when grounded. Choose a calm day.
If the beach angle is more than say 5 degrees, assess the final resting angle of the cat and make appropriate arrangements to cope with it. This includes use of the galley
when the inevietable mealtime comes around and the use of the heads afterwards.
Approach the beach VERY slowly and gently ground the bows. (I would never approach while going astern as there a high probability of damaging rudders or props). Stop the engines.
Unless there is significant wave action or a cross current
, the cat should rest there quietly without any help from engines or anchor
and a 47 ft cat has enough weight to weather
When the time comes to float off, you will feel the boat come unstuck and must have engines ready to pull you off. Take care that if a swell has built up, you do not bounce the props off the bottom.
Hope this helps.