Hull shell

 

The shell is build from a conventional carbon foam sandwich construction. I chose to use 200 gms cloth on the outside and 160gms on the inside. This should save approximatly 250gms.  The inside layer is orientated at +/-45 degrees, while the outer skin is at 0/90 degrees. This allows the laminate to carry loads in all directions. The +/- is applied to the inside so joins are not visible in the cloth. Photo 3 shows the inner skin on the mold with the peal ply applied.

  

Next the foam is applied. 70Kg/m^3 Corecell foam from SP systems is used. Flat sheets are used for the bottom and sides and in this Mk1 Geko cross cut foam was used for the corners. The rounded corners required much fairing of the foam to produce a fair shape. Again, I would advise any would be builder to use sharp chines. Photos 4 & 5 show the foam being applied.

  
Four strips of foam glued together are used for the bow. If you wish you could include a block of wood where the forestay fittings attach. Photo 6 shows the bow construction.

  
Once the foam has been faired, the outer carbon skin is added and vacuum bagged. Once this has cured the shell is removed from the mold. There are several methods to help pry it of. First is to bang a wedge in under the transom. I eventually drilled a 5 mm hold in the middle of the mould from underneath and put a high pressure air line to it. This popped the shell of nicely!

Once its been removed replace the shell back onto the mold and construct an enclosure around the shell. I used the carboard that the foam came in. The shell now needs to be post cured for 12 hours to cure the epoxy further. Try to get the shell hot so you cant touch it.

At this stage i decided to cut the hull down as described in the hull design section. At the time i had access to a laser level that helped me get the gunwales perfectly level.