Thanks guys

. I checked the 2 on-line fishing stores that I have used in the past & the heaviest line they carry is 100lb -- so the Sea Angling magazine will be the next port of call. I might also check the hardware store for some thinner, more camo strimmer mono. I'm quite please with the temporary spearline that I rigged last night -- but it's
rather bright and, being quite thick, it will be a tight fit through the muzzle opening when firing.
I've added some strimmer mono & whipping cord to the small repair kit I carry round. I'm trying order a second speargun currently -- want to avoid being left without a usable speargun on holiday.