UKH

I have a Montane Cobra rucksack which has a lovely hip pocket that my compass often lives in when walking.

I have recently become paranoid about the compass deciding to leave the pocket if I inadvertently left the pocket unzipped.

My thinking is I could add a key clip to the pocket to act as a compass retainer. 

Has anyone got any tips for how best to do this? I'm not much of a sew-er (sewer? Sounds wrong!) And don't really know exactly where to start?

Any help appreciated, BB.

A simple, flexible alternative is to have the compass on a cord around one's neck. Then it can be left outside the clothes, or parked inside between layers or next to the body. In recent years I have dispensed with all of that, and just keep the small, circular body of an old compass in my hip pocket, where it is very unlikely to fall out (it's half wedged in). I find I can pull that compass out and use it in a few split seconds. 

For any other ancillary equipment (e.g. chalk bag, water bottles etc) dangling from my clothing, or sack, or climbing harness, I still use old carabiners - because I like to use equipment that is strong enough to be multi-purpose. (Things like key rings just don't hack it, and can break easily.) Carabiners like these are ones that are still safe enough to use for climbing or for bailing from routes (abseiling etc), but old enough not to be much of a loss. They make good "swag" for those who are good enough to pick them up! (see other thread)

Accessory cord is probably your best bet. I attach my compass to my jacket using the cord the compass came with, but my map print-outs go in a map case that I attach to my rucksack using accessory cord tied at the map case end, and a mini-krab at the other end that then clips onto my rucksack. You could do the same with your compass and with thin cord you can still keep it in the hip pocket.

Tie a boot lace in a loop. Larks foot the lace to the hole in the hip pocket zip and the other end to the cord on the compass. You can still zip up the hip belt pocket and you’ve always got a spare boot lace just in case. Works for a phone too.

My compass lives in the right hip pocket of my rucksack and is secured by simply larksfooting it's cord round the rucksacks arm loop. Can't be forgotten or misplaced in a coat pocket and is immediately to hand when needed, but also no risk of being dropped/lost whilst you're being sucked into a peat bog.

Only downside is that having it tied to the rucksack can make taking a bearing off the map awkward, but it's easy enough to detach/reatach.

As others have said some thin cord works well. You can then larks foot the cord to whatever you decide to attach the compass to for the day. For example a jacket zipper if the jacket is being worn all day, a rucksack strap or loop or around the neck if required. Just make sure the cord is long enough so you can access easily and take bearings without untying it.

I have my compass on a length of 3mm accessory cord with one of these mini clips on the end:

https://www.amazon.co.uk/gp/aw/d/B01LZK0RAA?psc=1&ref=ppx_pop_mob_b_asi...
 

I then clip that to the zip puller on my pack’s waist belt pocket, so I know it’s not going anywhere if I do drop it. 

When I was a field geologist, working for three months at a time in Greenland, I had everything important attached me by lines. Compass, Thommen altimeter and field note-book all attached by lines to my trousers and parked in my front and back trouser pockets; light meter and two Leica cameras on straps around my neck; map-case on strap over shoulder; water bottle, food, geological hammer, spare clothing, first aid kit, flares, heliograph mirror, etc, and rock samples in the pack on my back. Many of these items were critical for the job at hand. The Thommen altimeter was quite delicate and could be broken if dropped onto rock - I did bust one.

Thanks all! Some really useful input here.

Sounds like I'm over thinking it and attachment to the zip pull maybe the simplest solution. 

I will look into mini clips and some accessory cord. 

John - I'm not planning on anything quite that adventurous. That sounds like an amazing experience. 

Thanks again,

BB

I do that too. Compass lanyard girth-hitched round the zip puller for the big pocket on my front, easy to get out and use but impossible to lose.

you may find accessory cord is a bit bulky.  Nylon cord used as pull cords for light switches is plenty strong enough, thinner and easy to come by.