What I am imagining, but my brain can't quite grasp, is if you can wire up your standard house bank of 12v batteries to ALSO supply a 24V supply for a windlass.
House bank = 2x 12V group 27 batteries wired in series to supply 12v to the house.
Can these 2 batteries also be used with parallel wiring to supply the 24v windlass?
First you mixed the two
Series is to increase the Voltage, Parallel to increase the Ah
Do you have any 24V installations already?
What is the reason for this question
install a new anchor windlass?
The benefit of installing a 24V windlass is that you can use thinner cables for the same wattage, assuming two similar windlass'es of 1000W
But as have been already explained (in other replays), you cant have the batteries wired both ways at the same time.
If you have 12 volt charging this would turn the charging off while you use the windlass.
assuming that you currently have 12V only, I would say that you should stick to that.
There are other ways to feed a hungry windlass
-Install correct sized cables
-But a dedicated battery close to the windlass and charge this through thinner cables
If you already have a mixed 12/24 Volt installation you have other options.