RE: World's fastest airboat????
If I remember right, back in the early 90's there was an article in RC Boat Modeler (I think) that showed a Japanese outrigger style hull and claimed it went well over 100 MPH. I ever heard of it again, but I did take the photo and used it to calculate scale and made my own. Mine was constructed of pink foam, skinned with 1/16th ply, and it HAD TO HAVE an elevator (like a plane) tocontrol the angle of attack at high speeds.
This was before GPS, and since it was all foam/wood it never tracked on radar. It had a YS .45 with rear exhaust/pipe. The whole thing weighed only 3lbs without fueL.
After many attempts to go super fast, and find the "sweet spot" in the elevator, it finally destroyed itself. But I will say, I have never seen an airboat going as fast!
In 1987 I did built a semi-flat (very little V) boat, put a K&B .61 on it and BEAT my 18' Skiff with 65 HP Evenrude!!! Ran circles (literally!) around myself as I had a friend drive the skiff as I ran my airboat around it.
Size: 31" length 16" beam
1/16" Aircraft ply skinned. I just finished one for old time sake, this week. It will get the radio gear installed this weekend, then off we go for the maiden voyage!