Finally I was able to make a clip for my Motorboat.
The hull I used appeared to be not very stable and I had lots of problems with balance.
Effectively I had to use a kind of float to keep the boat leveled - Lego pontoon wrapped with duct tape to close all the gaps not to allow water to get in)
It does not look very well, but works :)
Steering is solved by changing a position of the propeller which is being moved with linear actuator.
I was afraid for IR receivers in case if the boat will go down :) so I covered them with plastic bag closed with rubber band (fortunately I didn't have a chance to check if this solution works).
I used two receivers - one for steering with 8885 remote and one for propeller control with 8879 remote. Initially I wanted to use 8879 remote only, but steering with that was a little bit complicated. Also using only 8885 remote cased the boat was very hard to control as it reacts for every change of propeller speed and position very fast.
Actually I was very surprised how tight turns it can carry out. It turned nearly in place.
It is a little shaky but I hope you like it...
Doing the tests appears to be more complicated than expected. I was trying to play with the boat on the lake but the waves were to big and nearly sank the boat. I have no pond anywhere near me that I can do a test drive as the water have to be quite calm for it as the hull is not very stable even with float made of Lego pontoon. What is the most interesting, adding additional keel ballast at the bottom of the hull doesn't help to stabilize the boat - I think it is because of quite heavy battery box and engines situated pretty high as for the ship. I do not want to put the boat on the river or big lake (again) as I do not like the idea of loosing all the parts involved if something goes wrong ;P. Probably I will have to take it to the swimming pool, but I do not know if I will be allowed to shoot the photos or movie there... Well... will see...