Bladder Gas Tanks

[Curious]

Has anyone heard of inserting a bladder tank into the old aluminum tank as opposed to a complete tank replacement?  A friend was telling me about this today and he says he read  about it as an option on a boating forum somewhere.  Doesn't sound right to me for any one of a number of reasons.

[Mcdiver]

I have used a product before that is applied to the inside of a tank and acts like a bladder.  My local radiator does the application and backs it with a guarantee. I have tried to apply it before with no luck.  When its done professionally, it seems to work.

[CaptGuy]

I would really be interested in the tank "insert". I've replaced my small tank and planned to replace the main (100 gal) this year. Cost will determine which way I go.