Kris,
Yep, do a fair bit of CAD work for a living. One day I will have to get some pics of the CNC machine I designed a few months ago for machining on the side of amoured personnel carriers! B)
I built my tunnel over 10 years ago during school holidays once, was the fastest built boat I have ever done, 2 weeks from bits of wood to ready for paint. I just scaled the plans from the RCMB mag which had the construction article and re-drew them by hand at 1/2 scale. I doubled the thickness of most of the ply and swapped balsa for ply and it was still the lightest boat I have ever had! I mis-interpreted the drawings and didn't realise the enderside of the sponsons were stepped, so mine were not. I put a stock K&B 21 on it, and had a 6oz tank just in front of the motor. I put all the radio gear in the front and used standard size servos for steering and throttle. The battery was a four cell AA nicad pack. I made a very simple balsa cowl instead of the elaborate carved one.
The boat was only my second boat. I wasn't able to tune engines properly at that stage and never really got the boat going that well. But it needed very calm water because the CG was too far back.
I didn't get enough paint on it, and built it using PVA gule, so eventually it became waterlogged and started to fall apart. I never raced the boat and literally threw it in the bin about 5 years ago when I got out of outboards.
Ian.
