Last season was very limited but I did manage to get my newly acquired Parker 21 - Wave, on the water in Pwllheli marina for 6-weeks. I was very pleased with how the boat handled and enjoyed some great days out.
On one occasion we put into Llanbedrog bay and dropped the kedge so that we could stop for lunch. The Kedge was a Danforth anchor with some 3 meters of chain to which was attached a heavy line. The wind started to rise and became gusty the kedge held but the boat stated to shear around and would not settle, so much so that we gave up on the idea of stopping for lunch as it was uncomfortable and could have been a problem with the other boats in the area.
The problem of the boat shearing around has left me wondering how the boat will behave on a swinging mooring in Abersoch bay. I appreciate there was no weight in the line from kedge to bow to hold the boat into the wind. My swinging mooring will in comparison be very heavy and have less scope for movement but nevertheless that experience of shearing around has left me uneasy about he boats stability on a swinging mooring. I would anticipate that leaving the keel down would help the situation, the mooring is non drying and tides through mooring are a maximum of 1 knot on springs.
I would very much appreciate some feedback from other members of their experiences of mooring a Parker 21 on deep water swinging mooring.

Yes, the 21's do move around a lot when anchored or moored. Leaving the keel and rudder down helps a lot - although I lash the tiller with a stiff bungee rather than rope. When anchored, I also put a bucket over the stern.

I'm on a drying fore-and-aft mooring in Fishguard but she still moves around; I've tried dropping a sandbag over the stern on the basis that it would be ok if she landed on it, but it didn't last long!

Thanks for that. I have wondered about using a drying mooring in the harbour when I am not in the area maybe I should consider this more seriously ! Rob