Right chaps, firstly many thanks for your suggestions. I won't be doing LiPos, because the charging is too complicated for me. I can't read the instructions of my fancy charger so it remains in its box. I forgot that I can get NiMhs in sealed packs, so that'll be something I get hold of, although the shop had more out of stock than in!
Secretary, I liked the look of that servo you linked me to and will be getting one.
Norman, I have today picked up my Spektrum DX5e from my daughter's place where it was in store. I found it whilst looking for something else as always! I already have the Orange Rx and can now try binding it, when I have some batteries for both items. I also have 27meg gear, three different lots and WILL be using it in my classic
speedboat
models. I waste as little as possible!
I have now settled on a continuous loop for the sail control, which doesn't need spring tension, though haven't decided a good way to attach the sheets to the loop or how to tell when the loop has gone as far as it dare before getting a bit mixed up. But I have sorted out the plank system by making one section trap a second, both of which can be removed separately. I found a gear and shaft out of an old printer which I chucked in the lathe and turned a groove in for the loop line. Then I found a use finally for that 6mm ball race I've had in my drill drawer for years! it was an interference fit on the shaft. I had some PTFE plate for another task and in some spare I made a hole that the ball race pushes into a treat, below it an identical plate supports the other end of the shaft, PTFE being very low friction. All this levels the return "pulley" with the servo drum. I only have a limited length of run for the loop line, but it should be enough. it's all I got anyway. About 10" between pulley and drum centres. if I attach the sheet part way down the boom instead of the end I should have enough movement. So, progress. My son-in-law supplied some bike gear cable for the rudder actuation as the rudder stock is at an extreme, typically cutter, angle. A hunt through the supplies (Pringles tins) gave up enough aluminium tube to guide the cable. Alas, I installed with lots of epoxy the rudder tube and it turns out to be 4.5mm bore! Gawd knows where that came from. The tube built into the back of the rudder itself is 4 mm. So that'll be some lathe work ahead.
All good fun between the gardening chores.
Cheers,
Martin