[SeaStar58]

What weight anchor would be suitable for a Contessa 26-staying put in heavy conditions using only one anchor
I have a 25Kg CQR at the moment and 30m of 8mm chain. But that seems very heavy.
Retrieval is by hand over hand!

A 55 lb CQR is for a 40 to 60 foot boat that has much more tonnage and a larger wind profile then your 5,400 lb Contessa 26.

As others said you could easily cut that down to 35 lbs with 6 to 10 feet of 1/4" chain and rope for the rode and still have more anchor than you will need and then have capacity to carry a few spare emergency anchors just in case.