Yep the ''water tank '' is a pretty good ol' school trick there mate.
But I hope that you pack them better than that for your trips. BJ... I've seen a few broken rods where guides from another one had rubbed on them in transit on rough roads for an hour or 2.
Personally I roll them up in a sleeping bag or put them inside pool noodles if only taking a couple. A bit of ''the 5 Ps'' definitely helps whether you are going on a short trip or smashing accross Arnhemland on bad corrigations for 100s of km. I'd perhaps add a small bottle of water or pvc section as a ''dummy tank'' and a secure torx screw in the cap too...
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