A long hidden bolt or machine screw can be used to pin a companionway hatch
in place and keep it from sliding open.
Stainless steel plates can be installed to reinforce the companionway washboard track.
The hinge pin on a hasp for a lock can’t be driven out if it’s fixed near the edge of the hatch.
An immediate show of strength might persuade a thief to try another boat.
A solid aluminum plate makes a very secure washboard.
A set of bars will keep a boat cool and secure in the tropics. Installing pipe over the bars makes them harder to cut with a hacksaw, because the pipe rolls with the saw blade.
The bars can be used in lieu of washboards or can go in front of them, in a separate metal track, as extra protection.
Some thieves use cordless power tools to break through hatches on deck. A steel strip bolted across a hatch window might thwart this.
If you add a couple of long angled brackets to either side of the hatch, a bar or bars (with rollers) can be locked across the opening. The hatch can then be safely left open in hot weather. The brackets can also be used to set up a wind scoop and mosquito grill. You might want to cover the brackets with bits of rubber to save bumping your head.
Use lock nuts or split pins on the end of exposed bolts to protect expensive deck gear.
If the bolt heads could conceivably be cut off, tap the fitting and add a threaded stud.
L Peen over the end of your anchor shackle bolt.
M You can rig a simple alarm by setting a foghorn in a box like this. When opened, the hatch pulls on the string, the wedge pops out, and a bungee cord pulls the lid down on the horn’s button.
N Inaudible ultrasonic alarms now on the market will deter insects and rodents.
O If cut, special locking wire straps will sound an alarm signal.
P Given the price of fuel these days, you might want to install a locking filler cap.
Q Mounting your liferaft in a pulpit cage makes it easier to launch and secure against theft. A big tag on the lock will remind you to remove it at sea. Scratch your boat’s name into the raft canister, then paint it over to make it harder to remove. You should also put some kind of ID inside the canister.