View Full Version : Hovercraft Advice

dtfcarline - n/a
7-Aug-06, 11:58 AM
Hi Everyone, this is my first post!

Myself and some friends have just bought a Vortex 1-man hovercraft hull which we intend to get up and running. There are a number of things that need to be done, and just getting started with these things, it would be great if anyone could offer relevant advice in what we are trying to achieve. At the moment, our goal is to get the craft working, we are not intending, at least short term, to race it. With the engine we have got, it is not an option anyway (see below...)

Here are the things we need to do:

1. The hull has a number of cracks and dents in it, and seems to be held together with pop-rivets. One of the first things we would like to do is repair the cracks and holes, and strenghten it in certain places. Does anyone have any suggestions for material to use to achieve this?

2. We have a Robin EC25PS engine which we intend to use. I am happy tinkering with the engine, but does anyone have any manuals or tech info. for these engines? Has anyone used these and can offer advice?

3. We need a fan, where do people buy these from? how many blades work best, or is this a bit of a pandora's box?

4. The skirt needs reparing in places, does anyone know what types of material works best and where do you get this material from? This might be a silly question, but can the skirt be sewn together using a sewing machine? i.e. by my mum?

Any advice would be greatfully received. I will post some pics online at some point too, so you can see what we've let ourselves in for...

Best Wishes,


Nickinoue - n/a
7-Aug-06, 01:12 PM
Hi Dylan,

1. If the hull is fibreglass which is what im guessing it is or wood, chop strand matt (CSM) and polyester resin would be the way to go, theres alot of info on the internet about it and im sure any yauht repair store would be more than happy to help you and give you advice, or you can ask people on this forum.

3. The fans most people use are the multiwing 5z or 4z, they can be purchased from k and m products:


They are rather pricy and if you are starting from scratch it might be worth using hasconwing insted of multiwing, they are basically identical but hasconwing are alot cheaper and can be purchased from conair sports:


4. The material most commonly used for both segmented and one piece bag skirts is neoprene coted nylon, it can be again purchased from k and m products, kan who is the propiotor is a very helpful chap and will give you sound advice if you need it. The skirt is best done using a sewing machine there was a recent topic on it on this forum; a summary would include saying a normal sewing machine would be up for the job, use denim needles as they are alot stronger and wont break while sewing, also some form of non-rot and stron thread must be used again k&M will supply.

Good luck,

some pics would be good


Don83000 - n/a
7-Aug-06, 01:32 PM
For info on Vortex and skirt material try the guy that designed your craft and still produces them you will find him very helpful


or telephone 0779 3807073

For a engine manual follow this link


srn4 - n/a
7-Aug-06, 04:04 PM
The hull sounds like my first craft.....Held together with pop rivets, patched up with cancerous lump type blobs of fibreglass and resin and badly cracked around the top where the airfeed holes are like a stamp being torn out of a stamp book.

What I did with that hull was to grind off all of the old running repairs and patches and take it back right to the origional hull...In places some really large holes opened up....

I then used appropriate techniques to fill in the holes, strengthen it all up, put a new bottom on the hull and then painted it...at this point I had a "new" hull and proceeded to bolt the other bits onto it...

There are a couple of pics on the past projects page on my website...www.tegwin.demon.co.uk

I got all my parts from www.kmproducts.co.uk Ken is friendly enough but doesnt use credit cards which means things are not amazingly fast.

Regarding the fan, no doubt someone will be able to help you do the math for that.

For the skirt, If you have an old segment, undo the stiches and draw around it on a piece of hardboard. Cut out the hardboard and drill holes in the hardboard where fold/stich limes are going to be, you can then use the hardboard to make as many identical semgnets as you like...Making the skirt is a boring job, but keep at it http://hovercraft.org.uk/images/icons/smiley_icons/icon_smile.gif

Good luck, should be a fun project.


Iceman - n/a
7-Aug-06, 07:08 PM
Hi, some of the best help is usually found by finding members in your local area, so let us know where you are and perhaps there is someone not so far from you who you can contact for lots of help and advice!

Jamie Lewendon - n/a
8-Aug-06, 11:55 AM
If it is a vortex, it has probably passed through my hands at some stage. Does it have a number on it or what colour is it, and can you post some pics of it. As David (Iceman) says the best advice will come from an experienced person in your area who can actually see it. Does it have any running gear in it, or is it a bare hull. As far as the engine goes, the ec25ps should give you about 20Hp depending on how knackered it is. I have some parts for that engine depending on what it needs. The boss (Keith Smallwood at vortex) is away at the moment, so you won't get an answer from him at the mo.

The bag skirt is PVC coated nylon, not neoprene as above. Depending on its vintage, it will have diolen it it, so structually it shouldn't have any major holes.

Jamie (Storm Hovercraft)

dtfcarline - n/a
8-Aug-06, 12:12 PM
Hi Guys, thanks for all the info so far.

/Jamie - I have uploaded a photo of the hull we bought. The engine seems pretty much complete, but I am unsure whether the exhaust is the original one or not. I looks like it has been mended a time or two (I guess cracks in these things are common). Once I've had chance to turn the engine over and check its running, I'll let you know if we are in any need of replacement parts, cheers.

/Dunc - Yes, this is what I was hoping I could do re: the skirt, or, more precisely, what I was hoping my mum could do http://hovercraft.org.uk/images/icons/smiley_icons/icon_smile.gif

We live in Ulverston, south Cumbria. If there is anyone in the area who would be available to give a bit of advice or even come have a look at it, that would be fantastic! The beaches here are awesome, I can't wait to get out there!

One of my colleagues mentioned something about a hovercraft race meeting in september in (southport?) Do you guys know anything about this? It would be good to go and sneak a few ideas...

Cheers to all,


Sean Atterbury - n/a
8-Aug-06, 01:17 PM
I think I'v seen that craft before, maybe someone else can remember it, and if so then it has been raced, so the exhaust is most probebly not original but I type under correction. http://hovercraft.org.uk/images/icons/smiley_icons/icon_smile.gif

Jamie Lewendon - n/a
8-Aug-06, 05:32 PM

You need to speak to ewan black for new mouldings for that. I think it needs a new front planing surface, I think the last time I saw it, the front was inside out, havig just been fished out of the lake. Ewan checks in every couple of days, so I'm sure he'll be in touch. 20HP will be abit marginal. First thing you will need to do if using the ec25ps is reverse all the flow straigtners in the duct. The craft previously had a TZR250, which rotates the other way.

Women in Black - n/a
8-Aug-06, 08:07 PM
Yes I know that craft! I have fallen out of it a few times!!!!! We came 3rd in F3 in 2002 season (Team Black). Ricky Goosey raced it in juniors last season.

Ewan does know all about it but he is not back in the land of the living (with internet access) till friday.

hovercad - n/a
8-Aug-06, 10:49 PM

I can confirm the flow straighteners.

The hull i aquired was set up for a tzr250.

I fitted a robin ec44.

Fan rotates the opposite direction.

Removed the straighteners for now.

Once happy with the set up as is.

Will look at adding them the correct way.

Some people say yes to them other say it doesnt matter.

Welcome to the world of contradiction.

Hope to see you at a race sometime.


dtfcarline - n/a
9-Aug-06, 12:01 PM
Hi Guys,

Thanks again for all the replies. It certainly sounds like this hull has been around a bit! http://hovercraft.org.uk/images/icons/smiley_icons/icon_smile.gif

/Jamie - from what you say, it would make sense that the hull had sustained some significant damage, based on the amount of pop-rivets and such holding it all together. When was it that you saw this hull in such a bad way? Would it have been more recently than Ricky Goosey racing it last season? If it was before this, I guess it must have already been repaired to some degree for him to race it.

If I take some photos of the underside tonight, could you guys tell me what you think of it's condition? How much roughly am I looking at for a replacement front planing surface?

Thanks also to you guys for the information on fitting our engine. I'll have a look at the flow straighteners tonight.


nickyd - n/a
9-Aug-06, 12:47 PM

Just a bit of advice on flow straightners. I changed the engine in my craft which meant the blades rotated the other way. I was running out of time to change the straightners so I took it for a spin to see if it would be ok. No word of a lie it took over the length of a rugby pitch for it to turn left!

So your best bet is to either get some that go the other way or sling some plywood ones in to get you going. You really need something in there to keep the duct stiff.



dtfcarline - n/a
9-Aug-06, 01:25 PM
So does this mean that I need to acquire replacement flow-straighteners that go the other way, or can the ones I currently have be 'reversed'? If I need new ones, I presume I can get them from K&M?


nickyd - n/a
9-Aug-06, 03:13 PM

It depends on what type of straightners they are. If they are just a single profile all the way along, with no twist in the section, then you may be able to just turn them round. If not then K&M do various types that should sort you out.


dtfcarline - n/a
9-Aug-06, 03:28 PM
Ok Nick thanks a lot for the info. I suppose we are not really tied to this engine, and seeing as though the general consensus is that it will be marginal in terms of power, it might be worthwhile looking at another engine.

Do you have any ideas of the type of engine to look at? I dont want to go for a too expensive option to begin with, so what would be available? You mentioned the TZR250? I also know that people use the Yamaha RD250E? Would that be worth looking into? Something simple to get started would be good. i.e. air-cooled 2-stroke that can drive the fan directly without a gearbox on...

Look at me already planning more powerful engines http://hovercraft.org.uk/images/icons/smiley_icons/icon_smile.gif


Jamie Lewendon - n/a
9-Aug-06, 09:16 PM
It was after fawley last year, when it was heavily damaged. If you can take a picture of the front underside, we can see whether it is repairable or could do with a new front planing surface.

I'm pretty sure you will be able to get away with just turning those flow straighteners around if using the EC25.

TZR250 would be a sensible way forward, that craft has always had a tzr in it, and depending on how much in the way of metalwork is left in it, a tzr would be easy to fit.


dtfcarline - n/a
10-Aug-06, 08:25 AM
Hi everyone,

Once again, thanks for all this good advice. Lat night we got the EC25PS running on the bench, it seems to have been mouted a different way round in a previous incarnation (microlite, i believe), so we rotated the carb. round and it was basically fine.

I will get some photos of the underside of the hull posted in the next few days-

Has anyone had any experience using the Yamaha RD250 engines? What are these like for power/reliability? Presumably, they will be more powerful than the engine I currently have? Would I need to reverse my flow straighteners for use with this engine?


Nickinoue - n/a
10-Aug-06, 11:00 AM
I am currently using the RD250<font size="4">LC[/COLOR] which i think is the better model than the RD250 E this is because it has more BHP and also i dont trust air cooled engines unless they are forced air cooled. Plus when i came to look at an rd250E that was up for sale all the fins were mutilated and bent and this is much less lightly to happen in the rd250LC as i is just a solid case. The engine does turn anticlockwise if you are looking back at the duct and therefore the flow straigteners would need reversing. The reliability of the RD depends, ive seen some RD craft that work at after 1 good pull on the start and others taking hours to start, apparently the rd's have a poor reliability but i havent seen it so far, is this a problem im gunna be faced with http://hovercraft.org.uk/images/icons/smiley_icons/icon_eek.gif ....hope not lol.

The rd would have more power than your current craft but it probably with the rd wouldnt be such a competative craft but it would give a good feel of how to handle and drive crafts.

I personally would say for any school to use the RDLC as they are very easy to work with and illustrates the workings of a 2 stroke without too much complex parts. If i was going to build my craft again i would probably sway to the TZR but thats just because i want a more competitave craft. As ive said before the TZR requires more electronics that are notorious for failing.

Good luck

Hope that helps


Jamie Lewendon - n/a
10-Aug-06, 11:40 AM
If the RD rotates anticlockwise looking at the front of the fan,(i.e. same as a TZR) then you will <u>NOT</u>need to change your flow straighteners.

Be very careful running a 2 stroke on a bench with no load on it, you can easily over rev it with the minimum amount of throttle, you will then be after new crank parts which will be difficult to come by.. The only thing regulating the speed of the engine is the load on the crank, no load = no regulation.

Going back to your original post regards fans. A fan has to be matched to the engine you put in it. The reduction ratio must be correct, and the correct choice of blades and hub is critical. You need to decide what engine you are going to use before you start buying stuff, as the correct fan setup for the EC25 will not be correct for the RD/TZR.(apart from the obvious fact that you would need diifferent direction blades). Once you know what engine you wish to use, ring conrad and ask him to calculate the optimum fan/ratio. He will normally make a small charge for this, unless you also buy a fan, then its normally free.


Sean Atterbury - n/a
11-Aug-06, 05:32 AM
Y would running on the beach risk over rev.? http://hovercraft.org.uk/images/icons/smiley_icons/icon_confused.gif

If the craft is setup in the garage with the blades set to prevent the engine reving over an amount surlly it would not make a difference if on the beach or on a field on on water.?

Am I wrong? http://hovercraft.org.uk/images/icons/smiley_icons/icon_smile.gif

Nickinoue - n/a
11-Aug-06, 06:41 AM
Atters http://hovercraft.org.uk/images/icons/smiley_icons/icon_lol.gif

I think he meant BENCH not BEACH.

I hope im not wrong http://hovercraft.org.uk/images/icons/smiley_icons/icon_confused.gif


dtfcarline - n/a
11-Aug-06, 08:17 AM
lol, Yes we got the engine running on the (bench!), I was aware of the risk of over-revving it so I only let it run for a fraction of a second before stalling it.

As regards the fans, I hear what you are saying about the type of engine we will use. I will talk to the other guys and make a proper decision over whether we keep this engine or find something else before sorting out the fan. In the grand scheme of things, I guess the fan can be left until after we have decided on the engine and got all the hull and skirt repaired.

I'll upload some photos of the underside on Monday morning. Have a great weekend all, and cheers for the continuing advice.


Sean Atterbury - n/a
11-Aug-06, 09:43 AM
http://hovercraft.org.uk/images/icons/smiley_icons/icon_lol.gif http://hovercraft.org.uk/images/icons/smiley_icons/icon_lol.gif http://hovercraft.org.uk/images/icons/smiley_icons/icon_lol.gif http://hovercraft.org.uk/images/icons/smiley_icons/icon_lol.gif http://hovercraft.org.uk/images/icons/smiley_icons/icon_lol.gif http://hovercraft.org.uk/images/icons/smiley_icons/icon_lol.gif http://hovercraft.org.uk/images/icons/smiley_icons/icon_lol.gif http://hovercraft.org.uk/images/icons/smiley_icons/icon_lol.gif http://hovercraft.org.uk/images/icons/smiley_icons/icon_lol.gif

team black - n/a
11-Aug-06, 07:53 PM
Hi there. The hull is a Vortex EvoII/attack which tok third in Formula 3 in 2003. The flow straighteners are intended for a yamaha, which rotates anticlockwise when looking back at the duct. The upper front moulding has been replaced, but a new one could be made if the existing is stuffed. The planing surface can like wise be replaced. I own all the moulds so can produce any part you need.

With regards to power, the craft was set up for the TZR (45 BHp), so the splitter plate will need to be raised if you are running less power. Again the amount to be raised can be easily calculated. I've attached a photo of what it SHOULD look like

racingsnake - n/a
17-Aug-06, 08:52 PM
Thanks Team Black.

We will let you know about the parts, haven't had chance to inspect the hull closely yet.

Oh just incase you are wondering I am one of Dylans co conspirators in Project Hovercraft.

I am currently looking at engines.

The craft is set up for a 250 TZR. We are building the craft as a cruiser, we have no real intention of racing.

My thoughts were to go for a 4 stroke engine for a more relaxed, quieter craft, but I have just found out that most 4 stroke bike engines have integral oil systems for engine and gearbox. Does anyone have any experience of this?

Sean Atterbury - n/a
18-Aug-06, 05:38 AM
Stop pondering and just get yourself a Rotax. http://hovercraft.org.uk/images/icons/smiley_icons/icon_eek.gif

2 or 4 stroke, they all good. http://hovercraft.org.uk/images/icons/smiley_icons/icon_biggrin.gif

Don83000 - n/a
18-Aug-06, 06:29 AM
He says he wants a nice quiet reliable engine for cruising so why mess around with a environmentally unfriendly smelly and noisy 2 stroke that will cut down the amount of places he will be welcome at and plus the fact they drink expensive fuel / oil mixture like its going out of fashion. For a cruiser you can't beat a 4 stroke and it will cost half as much to run if not less. 4 strokes will rule its only a matter of time.