Just tried bio kleen hull cleaner on my stainless steering components and it worked exactly as advertised. My mechanical drive indicators where they're clamped along side of drives were grey and crusty inspite of my having polished them a month or so ago and only being in fresh water 3 days at a time between washing (always trailer) they got pretty ugly. I watched the youtube video where they sprayed it on, waited a minute and wiped the exhaust tips with a rag and rinsed. Well i can say it wasn't just another scam. The stuff kind foams like when you put hydrogen peroxide in a nasty cut, I went and dragged out the hose, wiped with a rag and it came really easy. The really thick spot took a second spraying but came off with a second wipe. Will buy again.

I got some at the LOTO Shootout and it does work pretty well. Pricey though.
I wouldn't want to do the entire bottom with it based on the cost.
A bottle of Sno Bowl or some muratic acid will work just about as well for a lot less $$.

Bio Kleen makes some great products. I'm a big fan of their aluminum polish. It makes polishing aluminum as easy as waxing paint. Incredible results with minimum effort.

Kurt

After 20 years of using on/off. My mailman told me works toilet cleaner works just as good. I said yea sure.
Cleaned my whole boat which sets in a slip with 1 1/4 bottles.
$1.00 at aco. Not quite as nasty as on off. Still used mask and gloves. Worked on prop and steering also.

iv been using it for ever,put it on,wait 45 seconds,rinse it off.dont let it dry on stainless ,it makes it look bluish,if it does dry,put it on again and rinse it off quickly.