Hi,
I like multicats and am finishing my second one though I've built a few of these hulls before. Beauty of them I like is they are so easy to scale because they're just based on box shapes and not many curves. I wouldn't bother with repro companies for this, I have never re-sized any print for less than £20-30 per big sheet before but that seems different from others experiences. Your GA is a good one to work from compared to most published ones and I grabbed it also! It's almost a complete lines plan to work from. If I were you and not confident to print on multiple A4 sheets of paper, I'd either buy some A3 paper (I wouldn't even do that) stick some A4 sheets together or buy a cheap roll of wallpaper lining paper at the most (90% of it will be saved for later), and just scale-up everything manually simply using a ruler and straight-edge. If you need to draw curves then use a pair of compasses but you'll be amazed though how useful things like coins, bottle tops, anything round comes in handy if you don't have a circle template or a pair of compasses to hand. Because the hulls are box-shaped, you can just hold-up a sheet of the material against the lines and add/subcontract the thickness as required, easy-peasy.
...For that GA you have I wouldn't over think things too much as there's so little curves or much not shown in your GA. If you want to set a scale, I like 1:48/1:50 which means a commercial brass flat stanchion of 22 or 23mm high very roughly fits in nicely with the general regs. of 1,050mm to the undersisde of the top hand-rail. As I hate making stanchions I try to fit in with what I can buy so I scale accordingly around the "1,050 to 1,100mm" rule for general merchant or offshore vessels. You can pick any scale you like if you want to scratch build entirely.
I agree and disagree with Dougal. In a multicat you have almost no restriction inside for running gear, but I do agree you need to think about access. I personally just have large hatches on the deck held in-place using self-ahesive magnetic strip underneath. If it's cut neatly it is not obtrusive and if there's wooden protective planking areas you use them to advantage to cover the lines of the hatch. Some not too clever imagination is required -there's not usually much if any camber or sheer to consider on these vessels so decks are just nice easy flat sheets. The main thing with a multicat is they have such low freeboard by design, you need to keep water out if it comes on-deck, hence I use the magnetic strip which works OK so far anyway. In my designs the 20mm diameter props are set very shallow and they aerate a good bit in reverse, but I don't even have rudders and the model and it will spin on a sixpence with tank steering or a mix or using a very basic mix on my non-computer transmitter, forwards or backwards it was almost too easy to steer last time I had it out.
Hope that inspires you to have a bash,
Rich
My multicats are bit smaller but the geometries are all the same...
