It might be worth describing my experiences with a model based on these big gun monitors. This was the free-lance model HMS Vulcan which was published in the Feb 2014 issue of Model Boats.
I too was inspired by Ian Buxton's excellent book "Big Gun Monitors" (ISBN 978-1-84832-124-3) and it gave me the chance to build a rotating and elevating gun turret. The early vessels were rather stark and perfect for their times but, at least in my eyes, failed to inspire me.
The last two built during WW2, Roberts and Abercrombie, looked more tempting. After reading a comment in this book that it was sometimes wished that they had their own aircraft embarked for spotting duties, I opted to design a couple of hangers and aircraft handling facilities into my model.
Using a notional scale around 1/144 produced a model some 30 inches (76 cm) long with a surprising large displacement of 10 pounds (4.5 kg) and powered by two RE385 motors. No rudder was fitted as the model would be steered using mixed motor control. This proved to be a mistake, at low speeds and at a reasonably close distance the model handled safely but at higher speeds it was hopeless. Once the model entered a turn it wasn't going to stop turning no matter what you did with the controls. The only way to regain control was to let the model drift to a halt and then slowly reapply power. I also found that water would flow over the bulges and despite the generous coaming around the hull access opening, get inside the model.
This lead to two changes, firstly the removal of some 3 pounds (1.4 kg) of ballast which stopped water entering the hull and made it easier to launch/recover the damn thing! Secondly, with no way to add a rudder, at least without major hull surgery, a large fixed skeg was added to the stern. This reduced the models wayward tendencies but it was never a model to take your eyes off when sailing, just like the real things!
Using a 6 Volt battery, gave the model a top speed of about 2 ft/sec (0.6 m/s) which was a shade over the dynamic scale speed. An interesting model to build, demanding to sail but good fun to bring it in close to the shoreline around the lake, rotate the turret and elevate the guns to "threaten" spectators!
Glynn Guest