I have decided to go with the Fig 1 Hull. This is a L58 x W15 x H12 cm section, four required. For anyone interested the cost per section (in the UK) are:
Time for print: 133 minutes (Printing at 125mm per second)
Electricity : £0.08
PLA material: 26 metres @ £1.49

I am going to do some weight calculations as I am sure I can reduce the height of the hull by 25mm.

Just a quick update to show how the hull sections join. I have only got the bow section to print then the gluing starts 😁

Finally finished printing all of the parts. I made some modifications to the ribs which will give extra strength across the beam, and allow for support if a flat floor is put in the hull. Maybe smooth side insert/hopper. Just as a guide: It has taken a total of 24 hours of printing time. 264 metres of 1.75mm PLA filament and a small amount of electricity, about 3.8kWh. So far material cost is about £17.00 (€20.00) or ($23.00) Now the gluing starts.

I have now glued all of the sections together and the results are reasonable. As this is a protype I am not too bothered. I have made some adjustments to the CAD drawings and files so the next print will be much better. However with some filler and sanding I am sure I can get this looking good. I had to use my monitor speaker as a weight. The barge makes a good speaker stand if nothing else 🤣

After some sanding down and P38 filler I managed to get a couple of undercoats on. It didn't need a lot of work. Turned out not too bad.

I answer to Ian's question: This is a towed barge. However I have just started to do a pointy bow and a stern engine bay with appropriate super structure, wheel house etc.. The idea to have exchange ends and make it as short/long as you like.

Just finished designing and printing some extra parts. Bollards, cleats, hinged-hatches and hopper bay removable covers. Just about ready for final paint job.

In answer to WOLLE question, "what kind of scale is it". I used the dimensions from the barge (shoe box) one of the club members already had. He tows it behind, what he says is a 1/33 scale tug so I assume it is 1/33 scale. I suppose scale is relative, so it can be anything you want up to a point. Nice trailer by the way..👍

All done from my point of view. The club member who is having the barge will do the final paint work. I hope to add some pictures of it finished and floating.. I have started work on two other versions. One will be a powered barge and one will be much the same as the first, but have a 55 mm draft and 15mm free board when laden.