Hi Paul,
Yes, I used Photoshop Elements to extend the body plan depth by half an inch but kept the width the same as that would have complicated things a bit. I needed some extra ballast and there wasn't much free space inside so I ended up sticking motor cycle balance weights to the bottom of the hull and covering them with epoxy resin. Bath trials suggest it has done the trick but pond trials have been delayed due to the constant bad weather.
At the moment the boat uses Glynn Guest design fixed float paddle wheels as featured on his Eccleshall tug model and they appear to give plenty of thrust. The geared motors don't make much noise really, they are 11:1 reduction on a low drain 385 motor with a maximum shaft output speed of around 630 RPM with a final belt drive reduction down to 315 RPM although normal sailing will be at a lower speed.
Colin