So, I have a boat that had been sitting up for 7years. When I was redoing the wiring, every piece of heat shrink was loose and freely sliding over the wire. I put them on myself and they were shrunk down properly.

Liquid electrical tape looked the same as the day I put it on.

Has anybody else seen this?

I’ve been in the 12v electrical industry for 34 years. I have seen it happen maybe 3 times.

Cheap shrink tubing. A quality tubing will not do that. However, either is so much better than crimping or simply using electrical tape.

That wouldn't surprise me, I probably went to either wal mart or Oreillys when I did it the first time.

Use heavy wall glue lined heat shrink like us old tower guys.

Cast, Too late, I already liquid taped everything. Unfortunately I don't have the patience to go back through and do it again, lol. I'm a big guy and boats aren't made for us to be working on wiring.

Will it say all that on package? thats type I need.

It might just say glue lined but you can tell. It won’t be folded flat like thin wall heat shrink, it will be circular or oval. It can also be buried and hold up. Works great on trucks and tractors. I recently removed some 20+ year old lights from old truck and the splice was still just like new.

You can get it at Vantex Electric in Fort Worth.

The proper term is "dual wall" tubing.
Your liquid tape is just as good, just messy.