sounds like it may have already started to turn - as others have noted washed up kelp types are likely to be a bit damaged and may have already started to go off.
I've only had oarweed crips once but the taste you're describing doesn't sound like what i tasted at all.
||I might have to try and find some fresh oar weed or sugar kelp as they both seem to be considered edible kelps and I used to buy kombu to add to bean dishes, soups and stews; and that's another kelp. Just need to find some growing rather than washing up on the beach.|
||Abottsham cliffs at really low tide. There are scars jutting out into the sea and the kelps can be seen growing in the inlets between them.|
much like fish if it is floating avoid it
my fav seaweeds include ,sea lettice ,dulse ,laver ,sugarwrack ,the green grassy one that grows on limpets
kelp needs a good boil,most improve for drying and rehydrating during food prep
||what dpack said. you should always cut fresh and healthy weed from plants attached to the rocks, leaving the holdfast intact. Also some weeds have all their reproductive parts at the top of the fronds, so you need to cut vertical sections to ensure that it can reproduce. there's a book by Prannie Rhatigan called Irish Seaweed Kitchen which is worth a look.|