Here's some pictures of some Kep's .21 ´09 riggers I built last winter. I built some extra boats and later on sold them like they're shown in the pictures to some new boaters in Eksjö. The boats below are exactly the same as the boats me and Mikael Sundgren have raced this season (but he didnt test his '09 until end of the season though).
I built them (last winter) with a rear ski/ramp set-up and I raced my own boat like that for the most part of this years season but for the last race of the season I took it off and mounted some old sponsons and it was way better. So just because you see the pics with the ski-ramp on it doesnt mean I recommend thats set up (on a Kep's rigger).
See THIS blog about my race experiences with the Kep's .21 ´09.
These "stealth" look sponsons are cool but they're a bitch to build... ;) There is no differences in how they work vs the other design you can see if you scroll down a bit...
Mikael Sundgren's rigger with these type of "stealth" sponsons.
Notice the small "hook" I've glued to the bulkhead. They're used as strap mounts to hold down the receiver. We dont use any lid cover for the radio compartment - only adhesive "tape" (it comes on a 2 feet wide roll and is used for covering books etc). So its nice to know the parts are hold down securely.
Here's the hook system for holding the RX battery pack (5xAAA NiMH cells). The hooks are made of K&S brass stips that are 0.8 mm thick (1/4" wide) and equally thick plywood.
Pre-drilled holes for S9650 servos for channel 2 & 3 and for S9551 on the steering. The short rear servo mount is made out of scrap pieces of the same 6 mm thick okumé/gaboon plywood as we use for the tub sides and bulkheads. If you look closely the top part is at 90 deg so the screws doesnt split the wood... ;) The other servo mount rails are normal 8x8 or 8x10 mm spruce.
This is the sponson design I have raced all season with. No chine angles what so ever and it works great. The need of chine-angles are way over rated. The rigger wont trip on these - I promise. :)
My race boat with these sponsons.