i leave my cat on the beach all the time and am able to keep; sails, daggers and main sheet and block in a lockup just over the road with wetsuit and pdf

not relevant where i am but if i was worried about joyriding if i was pulled up at another beach, and away from the boat at a restaurant or something, i would think just taking the main sheet and block would be enough.
small enough to put in a back pack, boat can't be sailed without it being as it's the smallest most expensive thing probably the most attractive to a walk by thief