Bivi bag seams

Make your own gear? Talk about it here!

Moderators: Bearbonesnorm, Taylor, Chew

Post Reply
shutuplegs
Posts: 12
Joined: Mon May 18, 2020 9:12 am
Location: Hampshire

Bivi bag seams

Post by shutuplegs » Thu May 28, 2020 8:47 am

First post so, err, hello!

Whilst I await my order from extremtextil, I’ve been thinking about seams for my bivi bag.
I’m going for a groundsheet style base with a breathable top and simple drawstring around the head/face.
From google I’ve learnt that a felled type seam might be best for strength and waterproof-ness of the seams. However, I’m struggling to see how I can fell this seam once I’ve done the initial pass without some serious bunching up issues around the sewing machine (as the bag will be sewed inside out, all the way around)
Since I will be using an iron on seam-seal anyway, would a single regular stitch seam cut it?
I’m thinking the seams might well see a bit of stress from getting in and out and general wriggling but hoping the seam seal will provide some backup here.

Any advice greatly appreciated.

I’m a relative beginner at all this, my other MYOG items have been a bothy shelter, some dry bags and an apex quilt, inspired entirely as someone posted on here a while ago.

Thanks.
“We live and learn, and big mountains are stern teachers” - HW Tilman.

drjon
Posts: 128
Joined: Thu Aug 28, 2014 11:38 am

Re: Bivi bag seams

Post by drjon » Thu May 28, 2020 9:13 am

what material you using? can you flat fell seam (practiced it)? i find it veeeeery difficult tbh...

consider this too:

https://mountainlaureldesigns.com/how-t ... igns-tent/

that stuff is dead easy to use... i also use dots on the floor to stop the inflatable matt moving around.

also, the double sided tape for dcf with a thin dcf layer is waterproofing and can be stuck to some non dcf material....might be easier than iron on?

tbh, a bivi sack is often so wet from condensation, a simple folded corner bathtub design, with a normal seam might well cut it without any seam seal....

User avatar
sean_iow
Posts: 2484
Joined: Tue Sep 30, 2014 12:08 pm
Location: Isle of Wight

Re: Bivi bag seams

Post by sean_iow » Thu May 28, 2020 9:30 am

I just used normal seams on mine and it's been fine. The flat felled seam done in two passes is probably no stronger than a normal seam due to the way it's sewn. I assume that there is a special machine that does the folding and sews two rows of stitches all at once that the commercial text manufacturers use.

I also used a non-breathable base and breathable top and it works well. You could sew some reinforcing patches over the seam at the opening as that will be the main stress point when getting in and out.
Adventure without risk is Disneyland - Bikemonger

shutuplegs
Posts: 12
Joined: Mon May 18, 2020 9:12 am
Location: Hampshire

Re: Bivi bag seams

Post by shutuplegs » Mon Jun 01, 2020 11:34 am

Thank you both for the replies, I felled my first seam yesterday while repairing a pair of shorts that had a few, how shall I say - stressed - seams... Not sure I'd want to repeat the process on a whole bivvy bag!

Sounds like a normal seam will cut it and then sealed somehow. Dots of sealant on the floor to keep the mat in place sounds like a great tip!

Thanks.
“We live and learn, and big mountains are stern teachers” - HW Tilman.

Post Reply