While I mostly agree with
@Julian I do believe a bit of risk prevention can go a long ways in not making you the easier target and dealing with all of the headaches involved. Do you have a home security system and lock your doors? Do you have a safe in the house? Do you keep a PDW by the bedside? Same type of thinking but it can all be taken too far as a professional thief will find a way and some of those options come with their own risks. With a boat the first rule of thumb is to cover it. Most boats are very easy to hotwire for anyone that knows what they are doing. Installing a hidden DPDT switch on the hatch clean outs or the lanyard will do the job for starter disable.
Before doing a starter disable I would do a very simple car alarm with only the hood pin switch ground trigger which would be a lot more than most folks have. Just don't enable traditional shock/motion sensing or it will be going off all the time when it the water or on a lift. Ground triggers can be disguised as a fake shore power plug, loops of aircraft cable, working shore power plug also powering a relay (power outage will cause false alarm with this one), wire to a solar panel (solar panel doing nothing but rewired just to create a closed circuit when plugged in on the dock), or even a PIR sensor under the cover. If not on a lift with some sort of lock then a starter disable would be secondary to the above techniques IMO. The best is something that runs through the cover and hooks up to something on the dock. This forces a thief to unplug something whether they are trying to steal something out of your boat or the whole boat itself. A loud car alarm going off and flashing the anchor light on a boat will certainly surprise/confuse a thief and attract attention. Most certainly will scare off teens up to no good late at night. If a two way alarm and you are in range you can also be notified.
My boat is at a marina and it may employ one or more of the above risk prevention techniques on top of being up on a lift operated by a code hoping rf remote control system. I am not aware of any boats being stolen in the last 3 years from this dock but I know boats left uncovered have had fishing gear, water sports gear, and other stuff turn up missing. High end fenders and lines even when in use have been known to go missing. I find that those who spend a few extra minutes securing everything at their slip properly, and don't make it obvious if they leave items of value on the boat have never had an issue. Those who rush to save time and don't bother with a cover, openly stash away items of value in the boat, or don't bother to air down inflatables well I am sure you can guess. Again this can be taken too far but if simple 12v DC electronics are in your wheelhouse a basic car alarm using the hood pin switch trigger is cheap, easy (power, ground, and trigger) , and unexpected on a boat. The chirp chirp when you arm the system also make it known to those in ear shot that you are not an easy target. Just make sure you don't have a dead battery the next time you go to use the boat and do the other simple out of sight out of mind steps first.
I bet it does not work abroad very well.
