Looking at an older steel hull by drifter. survey done in 04 and all repairs performed. has anyone heard of spraying such a hull with a truck bedliner polymer after sanding and primer? it seems to be very durable once adhesion/bonding takes place.

I wouldn't use any products that weren't made for marine use specifically. Why not use the tar-type coatings. They last through scrapes and scratches, are relatively inexpensive and last a long time.

I have heard incredible stories about the durability of bed-liner type products.  I used it to seal the top of my houseboat and would use it on the bottom of a steel boat also, probably the rolls on products to save money.  The best results would probably come from using a rust preventative primer then the polyurethane.  I used Durabak, they have application recommendations on their website.

thanx for the replies. outside of the saltwater impacts I can only imagine the liner would hold up just as well on a boat as it does the truck bed, and a clean install of the liner should seal out the slatwater concerns as well. It would seem the liner may also help substantially with the electrolosis problems many people report with steel hulls...any thoughts or experiences on this? The sacramento river leads to the delta then the vellejo bay and then off to San Fran bay (for the most part these are "protected waters" if ya watch the reports) so salt water is going to be encountered on a fairly consistent basis, yet the last leg home is about 25 miles of fresh water (sac river) as we head up current to sacramento, thus providing a "washout" if ya will, of the hull and engine cooling system

I would definately do this if I didn't sell my steel hull boat, and if I was planning on keeping it for a while. After this is done, then I wouldn't hesitate a bit to beach the boat frequently.

I got some feedback from a Line-X dealer regarding my request for Spraying the Hull, this is what he said:

"We have experience with this kind of project...We have had what I would
consider above average results.
The cost would be in the $5000 - $6000 range. I would only spray one color
and it would require a special primer application. Yes the boat could be
beached but not rammed nor would it be warranted against running into under
water obstruction. Not sure of the weight until sprayed but I would estimate
in the 200 -250 range."

I do think I would stick with the coal Tar as you could do it yourself for $500 You can really put a lot of money in an old boat and never get it out.