I remember a similar problem with our Wayfarer world. There is a bit of a labyrinth between the inner/outer hulls so persuading water out can be tricky.
With the boat on the trolley and the transom held down touching the ground most water should drain out through the bung in the transom albeit slowly. You might need to restore the boat to horizontal, leave the water to settle and then tilt it again.
If you have inspection hatches fitted then you might find it quicker to sponge the water out. Check the seals and replace if possible.
If you have not managed to get all the water out, then removing the screws and keelband will probably help – see below.
Water often gets in through the screw holes holding the keel band on.
Sealant maybe sufficient to cure that. Bit if the hole is fragile then epoxy filler first.
Another candidate is the bailers, but removing the old ones can be a destructive process. So you might prefer to eliminate other sources of water first. Once you have the bailers removed, rake out any loose filler in the hull join and replace with epoxy filler.
hope that helps