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503 rotax cage coming together

C

catfish

Well-known member
Just posted some pics of the almost finished cage in members galleries under the name catfish. It is the 503 rotax. Not to be finished until spring.
 
Your airboat is looking really awesome.

My first airboat had a 532 rotax. Not near as nice as the one you are assembling.
Good work man!!!
 
hey flying fish how did that 532 rotax perform on your airboat? could it get 2 people on plane in deep water? was it very fast on top end? Also did you have a reduction unit on it and if so what was the ratio? I am trying to get a feel for how well this boat might perform as I have never seen a rotax in action on an airboat. thanks!
 
I had that same heavy hull with a 65 HP VW engine and it was a fun boat. The 503 Rotax should be 50 HP and weigh less than the VW engine. So, you can expect it to move pretty well. I would expect it to go over 25 mph. It was fun in the snow too but it didn't have enough power to go up hill.
 
catfish":230sg6te said:
hey flying fish how did that 532 rotax perform on your airboat? could it get 2 people on plane in deep water? was it very fast on top end? Also did you have a reduction unit on it and if so what was the ratio? I am trying to get a feel for how well this boat might perform as I have never seen a rotax in action on an airboat. thanks!
Click to expand...

The 532 I had was on a 14' 48" beam I think SeaArc. Which ever one is made in Monticello Arkansas. Many years ago. Performed really well. No polymer with a ribbed bottom on the hull and ran 29MPH GPS. I had more fun with that boat than you could shake a stick at. That boat ruined me. I suffer from a real airboat addiction now.

Ran real well with 3 people. Sure enough a light hull. Probably like 180# tops.

I had a 2.58 to 1 reduction. Spun the engine to 6500 RPM.

I ran a warpdrive prop with stainless leading edges.

i sure wish I still had some pictures of that boat. I was very proud of her. Computer crashed and you know how it is.

On the first test run.
I remember thinking my whole life was a failure when I gave that engine a little gas. Plowed a lot of water. Probably like 3500RPM. I told my wife I was a completefailure. I sat there a whild listening to the rotax Idle and decided what the heck. I opened the throttle up and scared hell of out of me. Jumped up on plane just like she had a mind of her own. had to stop and grin. Lots of fun!! Ran that boat for a couple years.
Fuel consumption was like 5 GPH near as I remember.
 
The leading edge appears to basically be some type of chemical compound like polyurethane or something similar to that. Hey flying fish and des moines thanks for the info. I am a little more pumped to see this thing shred some air now. Hey fish that little rotax story of how you hit the throttle and felt something special from that little boat gave me some serious goose bumps. I hope myself and the guy I'm building it for feel the same on its maiden voyage when we crack the throttle! :twisted:
 
Hey catfish-

I ruined a brand new propellor cause I did not know she needed a metal leading edge.
400.00 hickey. Real nice warp drive.
The mist in the air sure can play havick on a leading edge. Cuts like a torch.
Gets into gas money in a hurry.

Hopefully, you wont have this trouble.
 
Hey fish thanks for the heads-up! I'll have to tell him to keep an eye on the leading edge for any suspicious wear to prevent anything worse from happening. :shock:
 
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