Hi Tom,
I don't often visit this part of the forum at the moment, so I've only just seen your post. I did fit the louvres, and quite a bit of water comes out when sailing. I haven't succeeded in getting her sailing correctly yet. I have been having problems with the drive system. I am now using toothed belts, but one keeps slipping. I need to re-do the motor mounts. From what I can tell from my limited time on the water, you don't need rudders. I am using an Action combined ESC and mixer.
I moved house recently, so it will be a while before I can do anymore work on Lulonga - and then I need to find a club.
I do have a few more pictures from the build. If you would like them PM me your email address. I will also include a close up of the louvres on the model which inspired me to build my version. Mine are not quite like these!
Barrie