Hi,

I've recently bought a steel hulled houseboat in an area I want to
move to, with the hopes of later selling it and getting one with an
aluminum hull. I got a great deal on it, but feel sure that the bottom
is in bad shape. The previous owner said it was pulled and inspected
5 years ago, and found to have no rust on it at all. But I don't believe
it was treated then. It's in a fresh water lake. How bad can I expect
it to be now, if it really did have no rust 5 years ago?

People have told me various versions of how to coat the bottom.
The simplest was to sand it down one day, coat with marine primer
the next day, add a second coat the next day, put it back on the
trailer and treat the spots that were on the blocks the next day,
put it back in the water the next day.
Another version was to sand it down, treat with marine primer,
sand that and treat again...about 3 coats. Sand final coat of primer,
and add about 3 coats of ablative paint, sanding between coatings.

One person told me that the ablative paint releases copper oxide,
which causes the paint to break down over time, but also prevents
algae from forming rust somehow. Since I won't try to coat the bottom
until next summer when we can be more certain of 50° weather
necessary for curing of coating materials, he suggested I have the
boat pulled and preasure washed for a few hundred dollars. He said
that would remove the algae that's built up over the last five years,
so the bottom would deteriorate much less in the next few months
because there would be less algae to work on it. Is that worth the
money and effort to do it? Are pulling and re-launching likely to
result in leaks?

Is algae really that harmful? Is ablative paint the best to use?
I really just want something to treat it and last for a couple of years,
since I'm hoping to sell it when I get established in a steady job in
that area. I don't want to spend money on the bottom of a boat I
don't want to keep, when it could be put into a boat that I will want
to keep. Then again, I don't want to sell someone something that's
going to sink. Right now it has no leaks, btw.

Thanks for any help or suggestions!
David