I have been collecting Xyston 1:600 ancient galleys for some time; mainly from ebay. The largest ship they produce is a heptereme. But this vessel, although large, isn't quite large enough to represent the largest vessels in a battle fleet such as those used by Antony at Actium.
This, being one of my ongoing projects, led me to cut up and convert a heptereme into a decares. Although not perfect, the vessel does stand out from the rest.
The Xyston Heptereme
The conversion to a Decares.
Side by side.
To make this conversion is easy, even if I say so myself. Outside drying times between stages the whole process only takes an hour or so.
STAGE ONE: Put the main hull vertically in a vice and cut down the middle using a hacksaw (a junior hacksaw will do if you have not got a bigger one).
STAGE TWO: Glue a piece of balsa wood sheet, 4mm thick, sandwiched between both halves.
STAGE THREE: Cut 2 pieces of 5mm balsa sheet wide enough to cover both ends of the new hull shape. Stick these to the hull ends.
STAGE FOUR: Stick the stern and bow sections of the casting to the new main hull.
STAGE FIVE: Using a scalpel, files, etc. trim the balsa connecting the main hull an bow / stern sections so that they match up. This is the hardest job but is still quite easy.
STAGE SIX: Add a 1mm sheet of balsa wood to the bottom of the hull. Trim, as described in stage five above.
STAGE SEVEN Soak all the balsa wood additions with super glue, (I use the cheapo stuff for this) and once dry, sand down with fine emery paper.
STAGE EIGHT: Assemble the rest of the model (oar sections, rudders, etc.) and paint as normal.
This is an easy conversion providing that the tools and materials are available. You could substitute the wood with modelling putty, but this, quite frankly, is more trouble than it is worth (soaking with super glue makes the balsa very rigid and it is 'even & flat' to begin with).