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peterd51 - n/a
16-Aug-07, 09:04 PM
Hi,



my hovercraft doesn't have skids underneath...it's a flat bottom (bit like the wife!).



I'm going to rub down hull, re-seal the joints and re-paint so I could add some skids if a few people think it's a good idea.



The hull is 10 x 6 feet at the top deck and I guess the bottom is about 8 x 3.5 feet...



does it need skids?



If so, what would be recommended...



Two or three?



How far in from the sides (with a third one down the middle?)?



What sort of width and thickness?



Hard or soft wood?



Regards

Peter

Russ Pullen - n/a
17-Aug-07, 08:01 AM
Hi Peter



What are you using the hover for? Not neccessary for racing or grassy fields, almost essential for proper crusing and gravelly/rocky slips etc.



Best to use a hard wood with an aluminium strip to protect it or it'll be gone in no time.



And don't drop it whilst traveling sideways....or its over and out. http://hovercraft.org.uk/images/icons/smiley_icons/icon_smile.gif



Russ

sixpackpert - n/a
17-Aug-07, 08:18 AM
Hi Peter



What are you using the hover for? Not neccessary for racing




Not strictly true, we have skids on ours (Moto) and they have been invaluable for protecting the hull as we have a low hover height when the splitter is down and the floor takes a real caning at times. We replaced the skids twice in one season, better than patching up the floor!!! http://hovercraft.org.uk/images/icons/smiley_icons/icon_rolleyes.gif

peterd51 - n/a
17-Aug-07, 08:48 AM
Hi,



where I use it depends on permission...



I'd prefer Cleethorpes beach but until it's running I'm not going to approach the council.



If I can't get there then it'll be a water-sports centre just outside Scunny and that's grass/water with a sandy bit between (looks like builders 'sharp' sand/aggregate mix).



I'd assumed that if I was installing them then I'd chamfer the edges a little.



How far in from the sides should they be?



For sizes I assumed about 1 - 2" wide and 3/4" thick glued and screwed...



does that sound OK?



Regards

Peter

kevinf - n/a
17-Aug-07, 08:51 AM
I've got to agree with Jon. We fit skids to our racing craft too, they have been invaluable in reducing the fibreglass repairs required to the hull to a minimum. We use 12mm WBP ply approximately 100mm wide stuck on with a polyurethane panel adhesive (Sikaflex or similar). They are located right at the edges of the bottom, next to the planing surfaces, along the full length of the craft. We then add 2 more short lengths (900 - 1000mm long) about 200mm in from these under the driver area - this stops the floor flexing and gives added support under the driver's knees. Chamfer off the outside edges and they don't grab if you land sideways. If the ply gets damaged it's fairly easy to scarf in a new bit.



The skids on Bob Beech's Scat are about 25mm deep and located 50mm from the edge. These caused a lot of grab when he first had the craft so we fitted chamfered hardwood fillets up to the edge of the planing surfaces and the problem went away.



I've seen skids made from aluminium, nylon strips, hardwood, softwood and plywood. They all do a good job.



Kevin

peterd51 - n/a
17-Aug-07, 12:23 PM
Hi,



actually it's just popped into my mind that the skirt segments are cable-tied just under the ouside edges of the bottom...



If I'm remembering this correctly then I'd be setting the skids about 50mm in from the sides.



Regards

Peter

jon_curtis - n/a
17-Aug-07, 01:08 PM
i kinda agree with everyone! my little craft had 25mm square box skids on the bottom, with stainless strips on! these help a great deal when landing on hard ground! They do however if you stop sideways wana dig in, and make the craft flip! did this once, now i dont stop sideways if i can help it!



all above is good advice, and i recon a wide flat skid, as suggested is the best option. larger surface area on skid bottom and less likely to dig in, if landing sidways. if i was doing a similar thing i would encapsulate a bit of 6mm ply to the base of the craft in glass, and then put an ally strip on the outside!

depends on the craf type i spos, and how much weight you wana add. sacrafical skids = less weight, but need replacing regularly. more substantial skids with nylon or ally or maybe even very thin stainless sheet afixed to = more weight, but less hassle!



regards position of, with only skids on the outside the floor takes a lot of load when standing in the craft, therefore perhaps a central skid would be benifitial.

Russ Pullen - n/a
17-Aug-07, 06:02 PM
Ahhhh.... all my race craft have hovered okay so i haven't needed them.... http://hovercraft.org.uk/images/icons/smiley_icons/icon_razz.gif

Paul Fitz - n/a
17-Aug-07, 06:43 PM
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skirt segments are cable-tied just under the ouside edges of the bottom...
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If I understand you correctly Peter, the lower skirt fixing is extremely low. You are likley to rip some of the skirt ties off every time the craft bottoms out, even with skids fitted.

peterd51 - n/a
17-Aug-07, 06:55 PM
Hi,



yes, they would be at that...



I'd mis-remembered and now I've just had another look they're about 4 inches up the side panels.



I had it in my mind that I'd had to chock up underneath to lift it off the base while I cut the cable ties.



So I now plan to glue a plywood skid close up to each side and another one in the centre with chamfered adges all around...



Thanks for all the advice.



Regards

Peter

kach22i - n/a
17-Aug-07, 07:14 PM
I really hate skids; they catch on land and give you lower back pains from the shocking jolts. I have not missed them one bit since I took them off my Scat-II several years ago.



However, because of major modifications including a section of the stern which has been built-out or squared out I had to install some skids. The stern skirt was being chopped in half, adding a rubber spacer and skids are part of my home brew solution.



My plan was to stagger the outer most skids so WHEN they catch the ground most unpleasantly (and they will) the stagger may provide some stabilizing roll and directional correction.



After reading this thread I want to add 45-degree canted/sloped material to the 1-inch square aluminum tubes/skids. I also want to fill-in the space between the short skids and long skids (see #1).



I am considering adding even more material between the long skids, but really don't want to go that far - kind of defeats the purpose of having skids.



What do your think?



http://i184.photobucket.com/albums/x295/kach22i/Fill-1.jpg



http://i184.photobucket.com/albums/x295/kach22i/Fill-2.jpg



NOTE: Craft such as the American "Universal Hovercraft" UH designs (square stern - sort of) but also have a 3-inch stern step which I am missing, this is why I had to add add the skids.

kach22i - n/a
21-Aug-07, 04:06 PM
My skids/rails are a little like the MAD hovercraft - I recently found out. My front skids/rails however continue all the way back and will be filled in. A center/central opening will be maintained.



http://www.mad-hovercraft.cz/20.3x1.htm (www.mad-hovercraft.cz/20.3x1.htm)

http://www.mad-hovercraft.cz/obr_male/catalog/mini-aluminum_skids.jpg

kach22i - n/a
4-Sep-07, 02:38 PM
UPDATE: 09/04/07



SKIDS:

I have to add 45 degree wood pieces to each of the the sides of the skid pads, and add fiberglass all the way around.

http://i184.photobucket.com/albums/x295/kach22i/SKID-1.jpg

Leading and trailing edges are beveled/canted 45 degrees.

kach22i - n/a
5-Sep-07, 04:00 PM
More skid pad pictures.



Gallery:

http://s184.photobucket.com/albums/x295/kach22i/ (s184.photobucket.com/albums/x295/kach22i/)

http://i184.photobucket.com/albums/x295/kach22i/Skid-Again-1.jpg

http://i184.photobucket.com/albums/x295/kach22i/Skid-Again-2.jpg

http://i184.photobucket.com/albums/x295/kach22i/Skid-Again-3.jpg

http://i184.photobucket.com/albums/x295/kach22i/Skid-Again-4.jpg



I did not like they way the 45 degree wood outside edge skid pieces were fitting, they would have been only 18" long. I decided not to fit them just yet.



Stern-Plane-1:

The round tube and rubber hot tub hose at the stern edge are to keep the sten skirt from being severed in half. I just don't trust the roughly 3 inches of total rise. The tube cuts down on rise height by about one inch, but it's worth it to me.

http://i184.photobucket.com/albums/x295/kach22i/Stern-Plane-1.jpg

profqwerty - n/a
5-Sep-07, 07:47 PM
I'm using these bits of wood but shorter and with chamfered edges/ends. It's Iroko 1"*2" - very hard wearing. It's mainly for stopping on concrete/tarmac which really wears out the fibreglass. I've screwed it in from the cockpit floor.



http://www.imagehosting.com/out.php/i1089491_miniDSC00266.JPG

kach22i - n/a
6-Sep-07, 01:42 PM
That African Teak looks nice, its a shame no one will see it. Through the hull bolts are a nice idea if you can find the right spots for them. I think someone once suggested coating them in silicone to waterproof them.



The rear corners of my craft are all busted up, this is not uncommon. I find it difficut to place the craft up on jacks without doing even more damage. In truth my skids act as excellent stern jacking points - something I need as I tinker with the hull.



IDEA: This thread got me to thinking this morning, what if someone were to drape and secure over a non-skid/railed craft a pressure sensitive contact membrane. They would then put the craft through the paces, flip it over and examine the wear patterns.



I think we would find that at least 50% of the wear was lateral. And that of that 50%, 90% occures at the stern corners. So if I've done my math right (not sure I have), 40% of all wear is sideways at the rear corners.



Does this sound right?



My first idea was to place beveled/canted round flat disks of slippery plastic at the rear corners. Hovever my corners were shot to heck already and there would of been little to secure to. If I could of just started over.