I had read a couple other posts where this was done.
There's lots of misguided preferences and lots of old wives tales on the net..
1. Previous paint (5 or 6 layers) was completely flaking off in areas due to poor adhesion. Don't want that to ever happen again (guess that goes without saying).
Sadly after you finish all your HARD work, and apply a hard epoxy paint, you will eventually experience the same exact thing. Epoxy paint is NOT epoxy like West Systems or Interprotect 2000 are. It is a paint with a particular epoxy ingredient that is it. Many paints are epoxy based like Easy Poxy but it does not make them anything like epoxy resins. As such these epoxy paints are not water proof. The barrier coat is significantly more waterproof than an epoxy paint and when water gets between the two it will eventually begin to lift it. In my 35+ years of boating I have never not seen a hard paint eventually begin to peel..
2. I had planned to use only hard paint. I want to be able to clean the bottom and I'm concerned about cleaning through the ablative.
Many thousands of boats who use ablatives also clean their bottoms for racing. We wash Cordelia, the Ericson I race on, twice per year only to get a slight slime off it. If you apply the suggested coats in the suggested manner you will not likely be washing through it, we never have.
A hard first coat will ensure there is always paint on the bottom.
Yes but only until it peels or becomes ineffective. Most hard paints are ineffective after a haul out, even Interlux Ultra (this is a hard paint) can not be hauled and re-launched. No matter how much you want them to work they are toast. If the paint becomes ineffective due to time in water or a haul out you have to ask yourself, "what is the point of having a hard paint under an ablative". It will be as effective as the barrier coat after the first season meaning it will repel next to nothing. It is a total waste of time & your hard earned money if you are thinking it will offer any protection if your ablative layers wash away. If you have sailed it more than a season or you have dry stored it for any period of time Bottomkote is dead.
If I end up not liking ablative, I can always revert back to hard since it's ok to apply ablative over hard but not the other way around.
This is the only benefit, with a big caveat. In order to get back to the layer of hard paint you'll need to fully sand off the ablative you are moving away from. This is much easier said than done and might as well be another full strip. Unfortunately, I have yet to meet anyone who has actually done a bottom job, switched to an ablative, and wanted to go back to a hard paint unless they were a very competitive racer and could not burnish the ablative to their liking. Perhaps they are out there but I have yet to meet one.
3. Bottomkote epoxy is half the price of Micron Extra.
Yesand but its also half the paint. I would hope you ordered Bottomkote Classic as Bottomkote is a soft sloughing paint. Both Bottomkote Classic (hard) and Bottomkote (sloughing) are SINGLE season paints. This means they are rendered useless after haul and re-launch. USELESS !!! Wear away your ablative paint after a stint of winter storage and your Bottomkote is as useless as the barrier coat or gel coat is so why have it at all? The gray or white barrier coat also makes a great but equally as useless tracer coat...
Multi-season copolymers like Micron CSC or Extra or Ultima SR or West marine PCA are true multi-season paints. You DO NOT need to repaint copolymer ablatives until you hit your tracer color. If it takes three seasons before you hit your tracer color you just saved a TON of money over Bottomkote Classic!! If the tracer color is a copolymer ablative it will also be an efficacious layer, when you get there, not rendered useless by time or exposure to oxygen.
I paint my boat roughly every two years so that actually makes Micron Extra LESS money than a yearly paint that has become ineffective yet still stuck to your hull as a useless dead layer of added weight..
Please DO NOT get hung up on the price. Multi-season copolymers are CHEAPER, much cheaper, in the long run. If our current boat had not been painted first with a useless hard paint and was done with ablatives the last time she was stripped I would be saving 5k+ right now on a bottom job (the PO did this not me)!!
4. I like the idea of epoxy paint on top of epoxy barrier coat.
Again they are NOT the same thing!! The only thing they share is the word epoxy. Go buy some appliance epoxy spray paint at you local hardware store and compare it to West Systems resin or Interprotect 2000E. Appliance paint has about as much in common with epoxy resins as does Bottomkote Classic..
It already shipped and returning it will be very hard. So I'll go ahead as planned. I did check with my Interlux rep. on going this route and to get a recoat time (micron over bottomkote). He didn't seem to have a problem.
I am trying to help you SAVE money in the long haul. Using this method will only serve to have you back here in a few years saying "I should have listened to you guys"..
I will say this again.. There is no benefit to applying a hard paint over a new barrier coat! I know this because I have "been there, done that" and learned my lesson.
Personally I'd return the Bottomkote.. West PCA is basically the same paint as Ultima SR, its made by Petitt, and it goes on sale every spring for about $159.00 per gallon. Interlux ACT is also another excellent ablative for sailboats as it sloughs at slower speeds than does the Micron line. For Micron you really need about 7-8 knots for sloughing. ACT will leave less build up and can be hauled and relaunched. Unfortunately it wears away or ablades faster so need a new coat every season.
Hamilton Marine Pricing:
Bottomkote Classic = $129.99 X 2 Seasons = $259.98
Extra = $229.00 X 2 seasons = $229.00
Interlux ACT = $157.99 it wears away faster so you'll likely need it every season
West Marine PCA = $159.99 (sale) X 2 Seasons = $159.00
Extra & PCA are cheaper but you need to look at the whole cost equation to realize it..