A sheet of 6mm ply was placed on top of the supports and all openings and edges traced onto the sheet from underneath. The outline was cut out and the two hatches carefully cut from the anchor well area. I carefully painted the "non glue" areas with epoxy and polyurethane paint before applying epoxy glue to all supports and screwing down the prepared foredeck. I quickly cleaned up the glue squeezed out around the openings and along the chines. The hatches worked well!
 
Note that a small triangle of 6mm ply was required at the bow of eachhull to finish the foredeck.
 
Next I moved onto the cabin.  

The support beams were then glued across the top of the anchor wells. Note the infill pieces on the centre line at the front of the anchor wells. These were from some scrap coachwood that I had and were to provide a solid mounting for the bow roller. The inside of the anchor wells were painted with epoxy filler and then a couple of coats of "Aquacote" polyurethane. As I was still having problems with the application of this paint the inside of the bow lockers (in the hulls) and the storage areas at the forward end of the bunk were painted with yacht enamel. Be careful not to paint the top edges as the foredeck needs to be glued down to all the supports.

The dividers between the anchor well and the interior were cut to suit and holes cut for round hatches to be inserted. Stiffening of 20mm square cedar was epoxied to the edges and all corners filletted with epoxy filler.
 
The floors of the anchor wells were given a layer of fibreglass mat

The width of the floor was measured at about 300mm intervals and then marked onto 6mm ply and cut out. The floor fits on top of the bottom stringers and if you try to not make it  too snug a fit it is easy to lift up (and I guess it is easy for water to drain into the bilge).

At the same time I was filleting the stringers, chines and keel in the hulls. I found the best tool to provide a "nice" semi rounded fillet was a plastic measuring spoon (used backwards). These come in sets of about five sizes and are cheap. By producing fairly consistent smooth fillets I hoped to minimise any sanding later on. ( seemed to work as mostly a fairly quick sand with a coarse sandpaper was all that was required to get the fillets to painting stage.

The hulls were levelled on the trailer and the trailer placed on timber blocks to stop any rocking. The straightness and level were checked regularly during the next construction phase which will "lock in" the shape of the catamaran.
Once all set up the fllets around the inner stringers in the anchor well were formed. The space between the stringers and the hull sides at the forward end of the anchor well was filled with resin /filler mix.