Author Topic: Hydro static head and Elan bivi bag and Alpkit  (Read 256 times)

Hydro static head and Elan bivi bag and Alpkit
« on: July 10, 2020, 07:43:40 am »
I understand the Wikipedia explanation of hydrostatic head even though it involves the idea that a 5 metre column of water will be withstood by the weave of a material with a 5,000mm hydrostatic head.
Under that circumstance I'd have thought that being crushed would be a bigger concern than being wet.

In terms of bivi bags is 10,000mm hydrostatic head better than 5,000mm and how does this tie in with breathability, if at all?

I ask because this bag: https://www.amazon.co.uk/dp/B005BN4RY6?slotNum=17&linkCode=gs2&imprToken=qNCL.qGni2DB1ciS8mkQIQ&creativeASIN=B005BN4RY6&tag=theadvejunk-21
has a 5,000mm head but the Alpkit Elan: https://alpkit.com/collections/bivvy-bags/products/elan
Has a 10,000mm head.
Does this make the one better than the other as a side entry bivi bag?

I have had a misfortune with Alpkit.
In early June I decided to pe-order the Elan. I thought I had and when I received an email on 2nd July saying it is on the way I ordered bunting, balloons and cake, as anyone would.
It hadn't arrived by the 6th so I queried it and it seems it was all a mistake and I hadn't pre- ordered.
But why did you think I pre-ordered, I asked and that question prompted another email, not answering the question, saying it was definitely on its way but the RM is taking up to 10 days. So, I put the bunting and balloons back up and reordered a second cake having used the first to assuage my disappointment.
Finally, I hope, an email yesterday confirms it is all a mistake but I can be put on a special list for those who would like an email to be told when it is time to pre-order for the batch coming in late August which the RM will, no doubt, deliver mid September.
That email prompted me to remember that I was on that list in June and six weeks later I have another nine weeks to wait if I take up their kind, thoughtful and generous offer.

I cannot find any record of a recent payment to Alpkit and I have registered some disgust with the working of their 'support' system that is glacially slow and maliciously raises one's hopes, dashes them down and then repeats. It is the Alpkit Groundhog Day Support system where you can only email but questions in emails remain unanswered.
I still have no idea why they thought I had pre-ordered but money-wise I am ok, bivi-wise I am bereft!
Never knowingly under caffeinated

Re: Hydro static head and Elan bivi bag and Alpkit
« Reply #1 on: July 10, 2020, 08:21:50 am »
To my knowledge, Alpkit hold very limited stock. They are well known for running out. Keeps overheads down, I guess, and enables them to introduce new models cheaply.

Hydrostatic head will give an indication of the bag's ability to resist penetration by raindrops - think how fast and hard rain falls.

I'm not sure that there is necessarily any relationship between hydrostatic head and breathability.
<i>Marmite slave</i>

Re: Hydro static head and Elan bivi bag and Alpkit
« Reply #2 on: July 10, 2020, 09:48:54 am »
Thank you

I like your signature. It's good days for Marmite fans with Marmite Cheddar and Marmite Peanut butter being available  :)
Never knowingly under caffeinated

Re: Hydro static head and Elan bivi bag and Alpkit
« Reply #3 on: July 10, 2020, 06:04:18 pm »
Today Alpkit tell me that they are trying to discover why I am in their system as having ordered but no payment has been taken.
A substantial discount has been offered if I would like  to pre-order again.
Never knowingly under caffeinated