Seriously Converting to Multiuse Only, help required

**MCBushbaby** · 03-12-2008, 03:58 PM

So first off, I finally have some time to talk after being away from the forums for a while. Welcome, welcome, yes, yes *shakes hands* *kisses babies*

Short history: After looking at my pack and all items within, I managed to get it down to a scant 10lbs including 6lb sleeping bag (it was a freebie down, how could I not take it?), 5L worth of water reservoirs/bottles, mess kit, emergency tin, health kit, and tent. Yay me! Backpack itself still weighs a horrific 5lbs but I can handle it. After reading up on some backcountry experiences locally, I realized I never did a water crossing but they say it's as easy as wrapping your pack in your tarp, tying it off, and using it as a flotation device. Now, don't knock this idea like the whole "I'm going into the Canadian bush for 3 months with just a knife" idea. This guy actually knows what he's doing. Aside from skepticism, I would really enjoy the possibility of expedient water crossing next time I come to a river or lake narrow. But because the bugs in upper Michigan are as bad as they are up in Alaska post-thaw (I blame our millions of miles of cedar swamps), I'm not switching from my bug-proof tarp tent (already only 1.5lbs) to a sheet tarp which I can use to wrap my pack.

The idea: I have a small 3x6' section of Tyvek housewrap that i use as a groundcloth every now and then. It's lightweight (about 100-150g), rip-proof (have you every tried to rip tyvek? it's bombproof!) and waterproof (so they say) so why not use it instead of a tarp? I can get a large sheet approximately 6x8' for $14 and can use it folded as a groundcloth, attach grommets to the corners for a poncho shelter (when the bugs aren't bad), and (if it is waterproof) I can use it to wrap my pack for crossing water. Not a bad idea if it works.

The problem: Is Tyvek housewrap waterproof? Waterproof is a relative term. Waterproof on a house could mean "sheds water". Waterproof while floating in a fricken lake HAS TO MEAN "water will not penetrate membrane".

**canid** · 03-12-2008, 04:08 PM

no, waterproof is not a relative term in any sense, it is totally explicit. what you're seemingly thinking of is water repellence. that said tyvek is about as close to water proof as you can get without being so. what's nice about it is that while standing water pooled in a sheet of it would hardly drip, water vapor will pass through it easily, so that humidity caused for example by human breath can pass easily out.

**MCBushbaby** · 03-12-2008, 04:12 PM

Vapor proof is not a concern. I am merely concerned whether, wrapped correctly in Tyvek, my pack will float or if I'll be dragging it along the lake bottom.

**canid** · 03-12-2008, 04:27 PM

tyvek will keep water out of your things if packed correctly for a short while. it's no immersion bag by any means, but it ought to handle a few min without any detectable leakage if not forced underwater. you know how rapidly pressures increase with immersion i hope.

i'd bet you could float a tyvek canoe for a little while. it realy is impressive stuff.

**Beo** · 03-12-2008, 04:30 PM

Should make it WATER RESISTANT, which is a better term than water proof. We use it here at the range in the shoot house which is open air with no roof, it does not leak for when it rains, from what I have learned the material is very strong; it is difficult to tear but can easily be cut with scissors or any other sharp object. Water vapor can pass through Tyvek, but not liquid water, so the material lends itself to a variety of applications: medical packaging, envelopes, car covers, air and water intrusion barriers (housewrap) under house siding, labels, wristbands, mycology, and graphics.
My thinking is it will work, try wrapping a blanket in it and dunking it in the tub and seeing if it floats. I'm pretty sure it will work though if wrapped right.

**dilligaf2u2** · 03-12-2008, 04:31 PM

I have many times crossed several rivers, lakes and ponds using milk jugs to float my pack on. It does not keep the pack dry but that is what your big plastic bag is for.

4 milk jugs will keep a 100 lbs pack floating. The plastic bag keeps it dry.

Don

**crehberg** · 03-12-2008, 04:35 PM

As long as you don't dilly-dally....Tyvek will probably do fine for you.

**trax** · 03-12-2008, 04:35 PM

I thought that if the weight/volume of water being displaced is greater than the weight/volume of object displacing it...said object will float, as long as it's water tight and said water doesn't seep in, changing the weight/volume ratio.

Now, I know that sound pretty scientific coming from me, so bear in mind that I also thought Nora Squirrel was sitting on my office windowsill this morning dictating correspondence to me, so ya just never know.....

**Alpine_Sapper** · 03-12-2008, 04:40 PM

Originally Posted by dilligaf2u2

I have many times crossed several rivers, lakes and ponds using milk jugs to float my pack on. It does not keep the pack dry but that is what your big plastic bag is for.

4 milk jugs will keep a 100 lbs pack floating. The plastic bag keeps it dry.

Don

Were you carrying the milk jugs specifically for this purpose, or were you using them for carrying water or something else as well?

**MCBushbaby** · 03-12-2008, 04:40 PM

Excellent! Thank for all the responses. With the spring thaw just around the corner, and parts of the canal opening up, I'll try throwing something wrapped in Tyvek into the lake and see what happens. I'll also test the displacement (thanks trax) because I don't know what was in that guy's pack. After all, it could've been filled with empty nalgenes and water sealed garbage bags holding his clothes.