Positioning of guying points

[Mark F]

I am slowly refining my tent design and am now thinking about where to place additional guying points. Should they be on the roof seams or centred on the panels? Any other comments also welcome.

Tent design

[icefest]

The answer, like many things, depends.

For increased stability: guy from the solid seams near the poles.
For increased living space guy from the centre of panels.

Guy lines parallel to the direction of wind increase wind resistance.

EDIT: Rereading this, I'm pretty sure you already knew this, sorry for the non-help.

Last edited by icefest on Sun 03 Nov, 2013 4:44 pm, edited 1 time in total.

[GPSGuided]

Surely that'd be a question that's ideally solved by finite element analysis! Anything less is just not good enough.

[Mark F]

I expect my finite element analysis will be to stick some in the centre of the panels and see what happens.

[Nuts]

Yeah, centre of the panel surely? Perhaps you don't need one, I had one in the centre of the bulk of the panel but yours isn't a huge?
How did you make those diagrams Mark?

[Gusto]

I have a few thoughts.

A) Because your poles are straight, your tent walls tapers towards the top at a constant rate to a point. What I mean is there is a far greater surface area down low than up high.
Therefor half way up does represent the position that is in the centre of the panel. I would think that you would be better to attach at about one third of the way up. (If you use some math you could find the exact point)

B) my other thought is that you could have several attachment points. You could attach some cord between them and then tie the guy rope to this. This has the benefit of spreading the stress across more of the seam and pole.
I wondered if this is also benficial for the pole given it is a rigid pole.

C) my third thought is that walking poles are very tough. So it wouldn't matter where you placed the guy as long as it's in the top three quarters of the panel.

D) you may wish to add a peg point at the base of the walking pole was it won't have the same outward spring to it that normal poles have. On.

E) On Aarn tent the guy ropes attach to both the base of the walking pole and another position up higher.

F) How is your tent attached to your walking poles? It may be easier to just guy rope directly to the pole. Avoids extra sewing. The stress will ne spread along all the current points where the pole is attached to the fabric.

G) Wind speed increase as vertical height increases too. So that may be worth considering. But I think this will be of very minimal affect in this case.

H) My final thought is a more unusual. You could consider adding attachments on the inside of the tent that connect to the centre of the ridge pole and then to the walking poles. Then in extra high wind you'd have the option of adding internal guy ropes.

[Mark F]

Nuts - I use Draw which is part of Open Office. I have had a couple of tries with SketchUp but haven't come to grips with it sufficiently to achieve what I want.

Thanks for your comments gusto. I have just received a parcel of tent poles, corners and other bits from Quest and can now start to tighten up the design. It seems easier to make some compromises with the design and be able to use standard parts. I bought some sil-nylon to make a trial version but the first job is to get the pole structure right.

A. I think the 1/2 way point is about right. Wind strength is much stronger as you go higher on the panel, but I note that on my Hexamid the panel tieouts are positioned quite low, possibly below the 1/3 point.

C. Part of my design thoughts were to use the walking poles as a full structural member rather than just a vertical prop. I have Ruta Locura poles and I can get a perfect join with Easton .433" 125 deg arch into the handle of the pole. There will be a strap between the pole tips so I can flex the structure a little. Playing with it, it seems to be very solid and gives that outward spring. I will make provision for a pegging point but expect hat it will not get much use.

F. I will attach the main pole structure to the cuben with velcro wrap around tabs. I may put a sleeve on the horizontal roof section.

H. I like the idea of the internal guying hat you see in some tunnel tents, but I think it will be overkill for this project given the strength of the walking poles.There is the possibility of triangulating by putting internal guys from about 400 down the side poles across the the opposite corner but the corner connectors are .433" tube not the common .340". I could rejig the connectors to use .340" angles and save 12 grams - good thought!

This is the way the poles are shaping up. Both poles will be vertical rather than raked. This will provide an inner 600 wide at either end and about 900 wide at the main pole. The vestibule will be 450 at the main pole tapering to about 100 at the ends. The weight of the small pole is 65g and the spreader 60g.

[Gusto]

Vertical poles would be just as good.

Will you cantenary the fabric?

What are those walking poles? And how are you connecting it to the spreader bar.

I feel I would snap walking pole that look as skinny as those.

The spreader bar on my My Aarn tent requires the walking poles to be upside down. The bar is also very tough.

[Strider]

They don't appear to be walking poles, just poles with walking pole tips?

[Mark F]

They are walking poles from Ruta Locura - carbon fibre adjustable 2 piece 110g per pole and I have at least 1,000 km on them. The only incident with them was a possum deciding it liked the salty foam grips. At 2am it ripped the pole out from supporting my tarp and ran off with it into dense undergrowth. I recovered it the morning but the grip had been well chewed. Ruta Locura sent me a replacement no charge. Now I much prefer to keep the grip at the top.

The simplicity of the poles allows their use point down. I have removed the plug in the top and the 125 degree arch fits perfectly into the tube. I could change the top bar to Easton 0.433" tube but the tube is mainly under compression so I expect the much lighter Easton CF pole section will be adequate. The cf pole ferules also mate perfectly into the arch ferules. With the point down it is also much easier to connect the bottom of the fabric to the pole.

When I make the sil-nylon version I will catenary cut it but not as severely as the Aarn tents. I feel with them you are losing a vast amount of volume. I would be interested to find out what the height is at the ends. With the final cuben version I may put a very small catenary into the main seams.

[Gusto]

Head height at the ends of the Aarn tent is quite low. I wouldn't know how high without looking pitching it. The Aarn tents are rather long.

But what most people are unaware of is that the inner tent is Asymetrical. The inner goes up to the pole on one end, but not all the way on the other end. So one end of the inner tent is taller than the other. Also, the lower end is narrower. They are indeed cosy. But rock solid in high winds.

I presumse the Aarn 1 is asymetical too, I haven't seen inside one before.



With respect to Guy Height. If a tent was a pyramid then I would expect the Guy to be at about One third up on the fabric. Which would be lower than One third up in height.
But given that in the real world wind speed increases with height then my previously suggested height may be too low.