Swimming Rucksack?

[Erbswurst]

I currently think about rucksack packing options and as I tend to work with absolutely waterproof dry bags anyway, I think about creating a swimming rucksack.

Would anybody tell me please which maximum total weight a 100 litres rucksack may have if I want to avoid that it sinks?

Let's say I line a 100 litres rucksack with a 100 litres dry bag and fill the space with a winter sleeping bag, padded clothing and other bulky stuff.
When I close the drybag it contains really 100 litres air and equipment.

 

[forrestdweller]

iirc correctly one litre of water weights one kg -- so theoretically less than hundred kg in a 100l backpack should keep it afloat providing its airtight... it might be a good idea to test it first in a swimming pool or goldfish pond to see if it works before going for a 30km swim with the german navy combat frogmen

 

[Erbswurst]

Thank you!

That's approximately what I did assume. But because the lake behind the woods here is already pretty fresh I prefered to ask instead of trying it out.

So, that means that every rucksack that's lined with an Ortlieb bag in the right size will swim if it's packed with a usual trekking equipment, isn't it? And every larger one will even serve as flotation device?

Edit: I see that Calais -- Dover is just 28 km. Surely worth a thought.

 

[TLM]

Almost all normally packed packs will float with an air filled dry bag. #1 son tested that in practice while serving, said military loads sometimes caused problems but not normal ones. Be careful with what you pack against the dry bag though.

 

[forrestdweller]

Edit: I see that Calais -- Dover is just 28 km. Surely worth a thought.

given the fact that the last amphibious landing happened during the napoleonic wars (and the last battle fought on british soil during WW2) i'd say they might be not fully alerted and your chances to invade Britain (successfully) should be rather high...

 

[Erbswurst]

OK, I'll come next summer with a few other friends from EU countries and liberate Britain!

I don't expect any resistance and assume that the Queen will marry me afterwards in order to legalise the act.

I will change nothing in the British order apart from annulling the tobacco tax and I will of course pass a law that Britain adopts Swedish Allemansrätten as it stands and the German laws about knives and axes, what means that everybody will have the right to wear always and everywhere a fix blade knife up to 12 cm at the belt and an axe over the shoulder.

 

[Madriverrob]

Thank you!

That's approximately what I did assume. But because the lake behind the woods here is already pretty fresh I prefered to ask instead of trying it out.

So, that means that every rucksack that's lined with an Ortlieb bag in the right size will swim if it's packed with a usual trekking equipment, isn't it? And every larger one will even serve as flotation device?

Edit: I see that Calais -- Dover is just 28 km. Surely worth a thought.

You might get pushed back by a Border Force patrol boat ....

 

[Broch]

OK, I'll come next summer with a few other friends from EU countries and liberate Britain!

I don't expect any resistance and assume that the Queen will marry me afterwards in order to legalise the act.

I will change nothing in the British order apart from annulling the tobacco tax and I will of course pass a law that Britain adopts Swedish Allemansrätten as it stands and the German laws about knives and axes, what means that everybody will have the right to wear always and everywhere a fix blade knife up to 12 cm at the belt and an axe over the shoulder.

We have a habit of being quite 'resistive' to invaders from the East so, maybe, you should stop at the Welsh and Scottish borders

 

[Oliver G]

A loaded bergan with a waterproof bag will float if there's a bit of air in the top. Consider that the density of water is 1kg per litre and that to float the density of the bergen needs to be less. If you have a 100 litre bergan that weight 20kg you'll be more than fine, plus you can use it as a floatation device (up to 80kg of buoyancy)

I recommend getting a couple of meters of floating rope and clipping that to your bag while crossing a river, that way if you let go of it you have a chance of grabbing the rope and retrieving it, just don't tie yourself to you bag, that's how people end up drowning with snagged bags.

 

[forrestdweller]

OK, I'll come next summer with a few other friends from EU countries and liberate Britain!

I don't expect any resistance and assume that the Queen will marry me afterwards in order to legalise the act.

I will change nothing in the British order apart from annulling the tobacco tax and I will of course pass a law that Britain adopts Swedish Allemansrätten as it stands and the German laws about knives and axes, what means that everybody will have the right to wear always and everywhere a fix blade knife up to 12 cm at the belt and an axe over the shoulder.

somewhere i read that one english town still rewards artists with a lifelong holiday trip to the land Down Under for decorating the town's bridges with graffiti and that in some places it's still legal to shoot Welshmen on sundays from the town walls with bow and arrow... i trust you won't change this fine law about the bridges?!

 

[Jared]

If the average density of the pack is less than the density of the water, then the pack floats.

 

[Broch]

Yep, but we have to take into account the 'density' of the person trying to swim the channel

 

[Jared]

Had a dense moment once. Trying to throw a pack with weeks worth of camping gear & food over a swift stream. Found out a pack even without a dry bag can float, and move swiftly downstream.

 

[dean4442]

I swam across one of the harbours in Gibraltar using my army bergan as a float, most people were putting theirs in a bivvy bag and tying the neck but I didn't bother. Mine was fully waterproofed with dry bags in the main compartment and also the side pockets, I didn't drown although it was close due to my poor skills rather than being dragged down.
The down side was trying to get out the other side as any non waterproofed space was full of water and so incredibly heavy!

 

[marcoruhland]

i used very oft waterproof bags or dry bags so if you search for an underwater drybag you need a higher norm than ip68

and the other problem ist that bags has no resistance against cutting

friend and i use both the very expensive arcteryx drypack 70 useing an old fish cutter for the trip 20 min after starting his pack was cut of by an old spliced cable on deck so one grand - fubar!

same with all my ortlieb bags after a time of general useing all corners are grazed and also with cameras etc. don't use ewa-marine take a massive underwater case

min. is a pelicase (only ip67/8) better a professional underwater case with 10atm

mr

 

[The Lord Poncho]

Swimming whilst floating a rucksack in front is very very slow. Ok for the width of a river, but not particularly feasible for e.g. a welsh reservoir only a few degrees above freezing. ahem. I second the comment above - dragging the flooded rucksack out of the waters edge - despite the drybags keeping its consents dry - is a deeply unpleasant task. Made easier by having large drainage holes at the bottom of every bergen, side pocket, lid pocket etc, and similarly having drainage holes at the base of every jacket and trouser pocket (or those pocket bases being made of mesh).

 

[SaraR]

We have a habit of being quite 'resistive' to invaders from the East so, maybe, you should stop at the Welsh and Scottish borders

Yes, be especially wary of pitchfork-wielding Welsh women.

Jemima and the last invasion of Britain

 

[Robbi]

When I saw the title I had a vision of rucksacks with little arms and legs swimming like a fabric frog.

 

[Erbswurst]

@marcoruhland

Ortlieb offers a sensible priced repair service. Unsure if that's an option for other people, but for Germans it is for sure, especially if we talk about bicycle side bags.
Field repairs should be done from outside because Ortlieb repairs from inside.

 

[Erbswurst]

@Robbi

I already realised that I made a translation fault.



In Germany the cork swims like the man.

We don't have an equivalent for "floating" in daily language. (Scientific we have it of course.)