My son having achieved getting the dingy and outboard stolen whilst on shore in Ibiza, I am extremely sensitive to the issue. Not to say the cost.
Small petrol outboards have a standard
safety cord anyone can buy for a few €. No
security at all.
What I have done is to buy a Torqeedo
electric outboard. Not only for
security, but it has a major security advantage. When I leave the dingy ashore I now:
a. take the control handle. It is very light and fits into a rucksack. Without out it the unit is useless to anyone
b. take the handle of each of the aluminium oars. Which also fit into the rucksack.
No deterrent is absolute but I am hoping that is enough to put off most thieves.
Oh, and on the boat I was always taught to never rely on a
single line. I use a clove hitch on each and then tie a bowline with the bitter end. So in practice four points of contact with the pushpit.