Tunnel tent/double poling question

[Moondog55]

My winter tent is set-up to allow double poling to increase strength.
I have a spare long pole here that I was thinking of adding in, just in case of really bad Alpine weather.
The second pole is a DAC Featherlite green tho and smaller in section than the supplied poles.
The spare pole is 8.05mm but the supplied poles are bigger at 9.3mm.
It's a partly academic query as I'll be selling the tent soon but I'd like to be able to inform the new owner about the strength increase over the use of the single pole.
I'd like to think that adding the slightly smaller extra pole would increase by 50% but I could be wrong, it may be less or more.
I need to shorten the smaller pole to the same length; am I right in assuming it's better to cut a little from each end that 100mm from one?

[Franco]

Not sure either but I would think that a 50% icrease would be a conservative estimate.
Yes, cutting 50mm at both ends would be better.
I discussed this with Henry Shires at Tarptent when I was making shorter section custom poles for bike riders.
Can't remember the minimum suggested for the 8.6mm poles but there was definatelly a safe minimum.

[EGM]

This is of no relevance to me personally but what is the reasoning behind shortening the poles at both ends? Is it to ensure the weak points are at the same point on both sides?

[CraigVIC]

This is of no relevance to me personally but what is the reasoning behind shortening the poles at both ends? Is it to ensure the weak points are at the same point on both sides?

Ends up with two shorter sections rather than one very short section.

[Moondog55]

I've sold the tent but I am hoping the new owner comes back to update this thread when he finishes the secondary pole modification.
If it does give a 50% increase in strength this would be an incredible strong tent for white country use here. as I had no problems at all with the standard pole set.

[Franco]

This is of no relevance to me personally but what is the reasoning behind shortening the poles at both ends? Is it to ensure the weak points are at the same point on both sides?

Ends up with two shorter sections rather than one very short section.

Sorry, I forgot about this thread.
yes the shorter the pole section the more stress it puts on the ferrule increasing the chance of failure at that point.
I remember doing shorter pole sections on the TT Rainbow and Moment for cyclists , down to 12". That was a bit shorter than Henry Shires was comfortable in doing with those poles.

[icefest]

yes the shorter the pole section the more stress it puts on the ferrule increasing the chance of failure at that point.

How does that work?
Wouldn't the short pole have a smaller lever arm and thus be less likely to fail?
I'd love to know!

[Moondog55]

I've always known that longer sections were stronger, perhaps it is that with very short sections there is no flex in the tubing to absorb shock and stresses.

[headwerkn]

Any Hilleberg et. al. owners here ever actually needed - or felt like they needed - to double pole in Australian alpine conditions?
If you're doing an Arctic/Antarctic traverse across exposed ice shelfs then I can see the need (and redundancy would be worth the weight). But given how strong the 10mm Black Label poles are already, it's always struck me as 'quite overkill'
Maybe for increased snow loading if you're staying put for an extended period, though that wouldn't work with a Nammatj or other tunnel tent designs.

[Moondog55]

Not Hilleberg but with my Helsport last winter I'd have done it if I'd had the extra pole with me, the 10mm poles aren't all that strong really when you get a huge wet snowfall.
But the Helsport poles are only 9mm and bigger is almost always better in white season.