I'm building a Unionville 6' Beaver, and I got their float kit to use with it. I'll be setting it up for a "quick change" system to change between floats and wheels. Basically, the undercarriage for the floats will bolt to the landing gear mounts, and I'll install blind nuts in the fuse for the rear mounts.

I want to have water rudders, but I'm not sure of any easy way make a linkage for the water rudder that will look relatively scale, yet also be easy to connect.

I was thinking, couldn't I put a servo right in the floats to control the water rudders? That way, I all I would have is a wire running along or in one of the undercarriage struts, and just plug it into a rudder Y in the fuse.

Anybody done this?

No reason why it wouldn't work. Treat it the same as a servo in a RC boat regarding how your pushrod exits the back of the float.

It's very do-able.

Use a waterproof pushrod arrangement like this:

http://www2.towerhobbies.com/cgi-bin...&I=LXD589&P=ML

And the servo can be totally enclosed

I have been using an "in float" servo to operate the water rudder for 2 seasons in my 1/4 scale Cub, and it works perfectly. Only snag is, I'd have to cut away a section of the float to access the servo, if it needed replacing. I have fitted an extended spindle onto the servo output, which goes up through the top of the float through an O-ring seal. Servo wire is led up float strut into bottom of fuz. through another seal. Servo wire can be easily unplugged so I can remove the floats and fit wheels (normally use the Cub for aero-towing) Servo has never given any trouble so far.

You want to build a waterproof servo box in the float--otherwise any splash over the gunwales can get in and swamp you.

Also a good idea to turn the plane upside down whenver it's been in the water, or the servo may be sitting in a bathtub full of water.

It has been done.

My servos are fitted at top (inside) of float to avoid any water in the keel. Also, all my floats are fitted with a 1/8" pipe on top of the floats, front and back, extending down to just clear of the bottom inside. After a flying session, I can suck any water out (never had to, yet!) and I attach a pipe to one of the small float pipes from a small compressor, and blow warm LP. air through the floats for a couple of hours to make sure they are dry inside. Before flying, I fit rubber caps to the pipes. Simple, huh?