View Full Version : Newcomer questions

ScotsSpeed - n/a
21-Nov-07, 03:05 PM

ScotsSpeed - n/a
22-Nov-07, 11:42 AM
I will try again, this may be moved to another forum. New to the hover scene. Bought a craft in need of TLC that came with a Robin EC25PS engine. As its only 19hp I thought that this may be a little under powered. So found 2 Rotax engines, a 440 and a 503, both single carb ex skidoo. The question is out of all the engines which one to use and what type of fan would I need considering that the duct is 800mm. Also looking for advice on finger skirt material. Any pointers helpful. Cheers. Millar

jar2 - n/a
22-Nov-07, 01:11 PM

Have you any idea what make of craft it is (post a pic here if you aren't sure)? If it's a small craft (10ft or less) then any of these engines should be OK AFAIK

The fan blades commonly used are either Multiwing 5Z or Hasconwing (different hub). The blades and skirt material (neoprene coated nylon) are available from suppliers listed on this site .


Give me a call if you need any help (I'm Scottish branch chairman - number is on branches page).

Ewan might like to move this threead to the General forum - hint hint! http://hovercraft.org.uk/images/icons/smiley_icons/icon_razz.gif

ScotsSpeed - n/a
22-Nov-07, 03:29 PM
Thanks John. The craft according to the log book is a Vortex, but having spoke to Vortex it seems that its from an early mold sold to another. It was constructed in 2001 and raced with a TZR engine until 2005, since then it has been kind of abandoned. Sold on as a project and now its lying in my workshop unit. No intention of racing it, just looking for a bit of fun, but I like speed.

team black - n/a
22-Nov-07, 07:28 PM
It's my old craft (a vortex as opposed to a Vortex Storm) and as I've mentioned by telephone, I'm happy to give any info you need.

The craft ran (in race form) 5 Z5 multiwing blades at 3000rpm. The turn of the blades was right handed, meaning the flow straighteners are in the wrong direction for the Rotax engines. replacing them is simply a matter of drilling out the present ones and replacing.

I would suggest that as you want a play craft rather than a racer, you use the 503 and go to 6 5Z (or equivalent blades in a 12 blade hub, at 3000rpm (ie reduction of 2.33:1). For skirt material, go to the supplier I suggested- I'm still loking for the template.


jon_curtis - n/a
23-Nov-07, 12:39 PM
are you interested in parting with the robin engine?

i saw this craft on ebay a little while ago http://hovercraft.org.uk/images/icons/smiley_icons/icon_smile.gif

ScotsSpeed - n/a
23-Nov-07, 12:53 PM
Thanks, Its Ewan I think. Yes we spoke on the phone. Well sadly the craft looks nothing like this now. The hull is broken in several places, the Gel coat is crazed. What we have got is in need of attention. Once I get the nightshifts finished and the extension to my house wind and water tight, I will start to dedicate some time to it. Your picture says a lot, just need to get it back to its former glory. At least its under cover. All I want is to get the poor thing back onto the water and have a blast. As for the engines, the 503 you recon is the one to go for. Can I ask what the difference is between the 440 and the 503. I know that the 503 with a single carb should produce about 46hp when in good order, what about the 440?

Your photo has been saved as a reference point and is very much appreciated. Cheers

ScotsSpeed - n/a
23-Nov-07, 01:00 PM
Dangerman, thanks for your interest. Yes, the craft was on ebay. I tried to get it about 18 months ago but missed out, got it this time. The Robin EC25PS, its a bit rough, runs all the same. The inlet manifold rubber is cracked so won't tick over, its got good compression, the exhaust is there but is very rusty. I would consider letting it go but I would need to be happy in own mind that its not going to detonate within the first few hours. Cheers

profqwerty - n/a
23-Nov-07, 01:22 PM
by 440 do you mean 447 (or possibly 443). I have 447, it's about 39hp on single carb. It's a lower cc than the 503.

I am also using an EC25PS as the lift engine in my craft.

ScotsSpeed - n/a
23-Nov-07, 02:40 PM

The plate on the engine says 440. The other one says 503.Both are ex skidoo. One was resuced from Glencoe ski centre in the mid 90's the other came from a farm in the borders. My mate had them for a project which he abandoned and they were left as scrap. Will need to strip them down and check them over before firing them up.

profqwerty - n/a
23-Nov-07, 05:38 PM
oh yeah; i had no idea they existed http://hovercraft.org.uk/images/icons/smiley_icons/icon_razz.gif

It looks to be a powerful engine - first one here (www.hovercraft.com/content/index.php?main_page=buyselltrade) seems to say 60mph with one of those.

It could be an experimental excercise i guess.

Hovertrekker - n/a
24-Nov-07, 01:35 PM
That reference is to a Rotax "type 453" liquid cooled, RAVE valved (commonly known as the MXZX 440 race sled engine - dual 34mm carbs, about 92HP). He most likely has one of the fan cooled 440's that Rotax made in the 70's.

ScotsSpeed - n/a
24-Nov-07, 07:15 PM
Dave, thanks for the reply. Yes, you correct in saying that its a fan cooled engine. However its a single carb but in size its bigger than the 503. So maybe its got more power than the 503?

jon_curtis - n/a
26-Nov-07, 11:42 AM
the rotax 440 is a 436.6cc twin, fan cooled engine it puts out 42hp, so is similar to a 447!

just because its bigger dont mean its better, its a 30-40 year old engine!

profqwerty - n/a
26-Nov-07, 01:02 PM
aaahhhhh http://hovercraft.org.uk/images/icons/smiley_icons/icon_smile.gif

how come it's the same cc, more powerful, and older?? That just doesn't follow the trend http://hovercraft.org.uk/images/icons/smiley_icons/icon_rolleyes.gif

ScotsSpeed - n/a
26-Nov-07, 01:52 PM
Thanks for that. I figured that it was old. But its in better condition than the 503. I will need to rebuild the 503 motor, bearings rings, etc. I recon the 440 would fire up easier. Can I ask where you get all this info?