Third Eye gadget you already own.

One great tool I forgot to mention in my recent piece about boat maintenance gadgets. A digital camera. An absolute boon when you can't see what you are doing because you can't get your head or body into a space. Just set the camera on macro, point it at what you want to see, and you can get a picture instantly. Much better than those little mirrors on a stick.

For example the awkward connection to the oil pressure overflow return. I spent ages trying to feel what was there when I was trying to refit it because I couldn't see it properly, then I used the camera and it all became clear.

The other thing where a camera helps is making a record of something before you pull it to bits, eg. the alternator wiring before you fit a new one.

However it did let me down the other day when I was trying to take a picture of the main water tank stop cock.

See that square opening bottom right. That's where I put my hand through to turn off the tap. I stuck the camera in there and had several unsuccessful attempts to get a picture of it.

What would be really good I suppose would be a little webcam attached to a laptop, then you could see what you were doing in real time. Hmm, must add one to my christmas list.