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Old 14-02-2008, 13:36   #1
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Ferro hull fairing

Dear All,

Have just bought a 32 hartley ferro for fitting out, and wanting to know what I should do to fair and finish the hull. The previous owner has done a very nice job on the hull, and it has been sitting for around ten years now. The below water line has nothing on it at present, but they have already impregnated the topsides with an epoxy and top coated it - not sure what the product is that was used, but am finding out. I am trying to get a fine finish to the hull as I have done with my plastic boats of the past.

What would anyone suggest to obtain this finish

Thanks again to all
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Old 14-02-2008, 14:45   #2
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Head scratching and photos....

I built a Hartley RORC 32 from scratch some years ago.

It is hard to answer your questions without more information. Some photos would be very helpful as would information on the build.

Spending a lot of time thinking and planning can save much time later.
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Old 14-02-2008, 14:55   #3
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Dear Boracay

Thanks for your reply, I will get some photos and post them, so you know what it is like, will also do when have the details of what is on the topsides at the moment

I definitely think things through to the death before starting things

If it is worth doing, it is worth doing right, and therefore starting on a good foot

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Old 14-02-2008, 20:14   #4
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I'm midway doing the same thing. Where there is nothing on the hull you will want to scrub it with muriatic or sulphuric acid and wash it a couple of times with water, and then apply a neat coat of epoxy followed by a filler mixed coat of epoxy. I used West System and you want to work a fairly small area at a time. When the neat epoxy is tacky apply the filler. I used West 207 low density. (West doesn't recommend using 210 Micro Light because of heat issues). Once that is on you need to wash it with water to remove the Amine blush before sanding. Then sand it fair and apply more filler if needed, wash with water and sand and repeat until you have the finish you want. Then after a final sanding apply 3 or 4 coats of neat epoxy (if you time it right these can be applied while still tacky without washing and sanding in between.) Then a coat or two of epoxy primer (I used Interlux 414-404), sand and apply the top or bottom coat or coats. Below the waterline some recommend a primer made specifically for below the waterline.

I started with a bad chlorinated rubber finish that I needle-scaled off. Mine is a 39 footer and it's a long ways around. It's a lot of work and an expensive finish but the results are good. I haven't figured out my bottom coat yet but a friend in England used epoxy mixed with copper powder and it has held up for four years and many Atlantic crossings.

If you go the epoxy route, there is a mixer sold by Indco (CM-KR90S) that you can chuck into a drill that makes the mixing bearable. (I used chicken salad tubs from a restaurant that fit just right.) The mixer is under $25 and has a finish that can be cleaned. Otherwise you need one person mixing and one applying.

Probably the most important things to remember are washing the cured epoxy with water and a scotchbrite pad to remove the blush before sanding and never applying fresh epoxy on cured epoxy without first sanding. West System and Interlux both have excellent free booklets on the procedure, and the West people are really good to talk to when you run into problems.

If your hull is outside, as mine is, epoxy work is made much more difficult because of temperature variation and working in the shade or sun.

And each time you mix up a new batch and head for the boat, repeat three times—boy am I having fun. Good luck

Ellis
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Old 15-02-2008, 00:47   #5
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Good information encore. But.....
Quote:
Where there is nothing on the hull you will want to scrub it with muriatic or sulphuric acid and
I suggest you use Phosporic acid. It is an excellent concrete cleaner and non-toxic and a little less harsh.

Stay away from Chlorinated rubbers. You can't make anythign stick to the stuff.

The best approach to underwater area's is simply a below waterline Epoxy undercoat. Both Altex, Ameron and International have these products. If you really want to, you can coat the hull with pure epoxy resin as a barrier, but you don't need to and it is not an easy task, as resin has no Thixotropic compunds in it. That means there is nothing to stop it from running and saging. If you put it on thin enough, it won't sag. But the paint is easier to apply and sand if you really need to. If the hull is not as fair as you would like it, then use two or three coats of the epoxy highbuild undercoat. Easier to sand. Then use the barrier coat. The anti-foul will go right overtop of the Epoxy when you are ready to launch.
If you want to do this quickly, you go hire an airless paint sprayer. Buy the undercoats
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Old 15-02-2008, 01:34   #6
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Dear Alan

I actually have an airless sprayer and have worked with epoxies for many years, and thus used to the lovely pitfalls.

The fairing of the topsides of the hull is what most concerns me to get a real glassy finish. Currently the boat is well faired but with the typical plastered look about it.

I really do enjoy reading all of your comments, and have been doing so for some time

Thankyou again for your help.

I am actually hoping to get the boat here in a couple of weeks, and the to quickly get the fairing done on the hull and the barrier coat onto it

What epoxies would you suggest to use, I have read about the west system and boat kote I think it is called. Others I have used commercially in the past am unsure of how they would like being on a hull in this situation.

What would you also suggest in fitting a rubbing strake to the side of the boat, one for looks and to help protect the hull - varnished of course with a brass strip.

thanks again
hooked
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Old 15-02-2008, 04:32   #7
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Quote:
Originally Posted by hooked on water View Post

... have worked with epoxies for many years, and thus used to the lovely pitfalls...
I am not a technical expert on epoxies but I have used a couple hundred litres of the stuff over the last 20 years. I have used WEST, International and Bote Cote (Qld made).
IMO Bote Cote is by far the best. I always thought there was not much difference between the various retail marine expoxies but that view changed when I tried Bote Cote. I have NEVER yet managed to get any amine blush what so ever with BC - even on cold wet nights. The amount time (and effort) saved by not having to remove the blush has been amazing. It also easily to mix (2:1 by vol, 100:44 by weight), very tolerant to mixing errors and even smells nice. The manufacturer claims it is far less allergy producing than the others but I have never had a reaction to any of them - so far. I have no commerical interest in Bote Cote.

BTW Hooked, whereabouts in Tassie are you. I am moving to Port Huon / Geeveston sometime in the next few years.
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Old 15-02-2008, 09:11   #8
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The advantage of using a coat of neat epoxy over the etched hull is that it tends to soak in (especially if the cement is warm or hot) and you get a better bonding for the additional coats. Bonding is a problem with some concrete hulls, especially if they are finished too smooth. The neat epoxy will help alleviate this problem.

I'd agree that West system probably produces more blush, with the exception of their special coating. To test for blush, hose it down with water and if the water beads, you've got blush, even if you can't see it. All it takes is a quick scrub with a Scotchbrite pad and water to get rid of it. Leave it on and it acts like release agent for the additional coats. Sanding without removing it only makes the problem worse—with the exception of wet sanding. (Learned the hard way in a small area.)

As far as running and sagging, I got none. West advised me to use chip brushes with half the bristles cut off. If the filler is applied while the neat coat is still tacky it won't sag either. I found about a 12 square foot area about right on days when the temp was around 85.

Chlorinated rubber for topsides and coal tar epoxy for below waterline have two things in common. They make a pretty good finish but wheels is right, the only thing you can use on top of them is more chlorinated rubber or coal tar epoxy.

If you are not sure what was used on your topsides, sand a small area and apply a test coat to be sure it is compatible. Two part epoxies could loosen what you already have and make a real mess. If you are able to and choose to use epoxy, you can end up with a glass-like finish without too much effort.

ellis
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Old 15-02-2008, 12:00   #9
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Quote:
IMO Bote Cote is by far the best.
The main difference with BoteCoat is that it remains a little more flexable than many other Epoxies names. This aids in the joints not cracking when severly stressed.
A little tip, Epoxies that have a higher ration, (4:1, 5:1) etc, tend to be stronger when cured. But they have the disatisfaction of being less tolerable to mix inaccuracies and also tend to be harder on your health. Low mix ratio's of 2:1 tend to be more tolerant of mix inaccuracies and are a lot safer to your health. Resins are mostly all the same, although they do have minor variations for each manufacturer. It is the Hardners that a "engineered" to produce the results. ie, cure speed, mix ratio, hardness of cured resin etc etc.

For trying to obtain a very fair finish, there are no tricks as such. Just a lot of work. Keep layering on fairing compunds and sanding away with long boards. The compound used to thicken the glue is the real key to sanding. You have many differing variations available. West have a brown coloured powder called microballons, that is very easy to sand. But very expensive. The Microspheres are OK, but not quite so easy. You can alos mix the two powders together to get a combination. Using a small amount of coloidial Silica or Fumed Silica(normaly used as glue powder) acts as a thixtropic compound that helps prevent sagging. Don't put too much in as it also makes the filler harder to sand.
You can get around the Amine Blush issues by ensuring the next coat of epoxy whatever, goes onto an uncured coating underneath. Usually within 24hrs is OK. The amine simply becomes part of the next coat. Epoxy continues to cure for many days but how long exactly is temperature dependant.
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Old 15-02-2008, 12:26   #10
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Wheels,
You're right on except for your allowing "within 24 hours" to recoat. It must be slightly tacky or at least dentable with a fingernail. I've found that with neat epoxy, fast or slow hardener, working in direct sun with temperatures in the upper 80s, you may only have a couple of hours to work without washing and sanding. The stuff can become sandable in 3 to 4 hours in the right (or wrong) conditions. With filler added such as the West 207 which is the brown you are talking about the process is slowed down considerably.
Ellis
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Old 15-02-2008, 16:23   #11
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It must be slightly tacky or at least dentable with a fingernail.
Agree totally but if someone knows any tip or trick about this aspect (or any aspect) of expoies, I would love to hear it.
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Old 15-02-2008, 21:32   #12
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Amine blushing is a thing of the past. Most all modern day Epoxies do not have this problem.
If you are mixing correctly, you should have no Blush at all. You should not have to wash between coats. I have never washed and never had problems with sanding cured Epoxy.
Applying additional coats of epoxy can be done without sanding for upto five days. After that, you need to give a slight ruff up to key.
When fairing, you are going to be applying thin coats. You need the epoxy to be hard to be able to sand it. Using a long board, you sand till you have knocked off all the tops. Then you apply another coat and repeate till you have no tops and no hollows and you have the shape you want.
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Old 16-02-2008, 00:14   #13
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Wheels,
You're right on except for your allowing "within 24 hours" to recoat. It must be slightly tacky or at least dentable with a fingernail. I've found that with neat epoxy, fast or slow hardener, working in direct sun with temperatures in the upper 80s, you may only have a couple of hours to work without washing and sanding.
Ellis
You should keep epoxy out of the sun. UV will degrade it. I've used over 400 litres of epoxy in the last 2 years and never had amine blush. I avoid epoxy work if the relative humidity is over 80% though.
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Old 16-02-2008, 12:44   #14
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Yes very good point 44, UV quickly degrades Epoxy in both uncured and cured form.
80% humidity must be a nightmare to work in :-(
Heat is another killer. You do want to work in direct sunlight if the temperature is extreme. Heat can also make the epoxy cure too fast, unevenly and cause sagging as the epxoy loses viscosity as it gets hotter and can actually "bleed" out of the filler to the surface, producing a harder surface to sand afterwards. Deep fills can also over heat and start to boil. This greatly reduces the strength of the epoxy and can lead to bubbles and voids underneath. Extreme heat (above 40c and no hotter than 50c) should only be applied after the epoxy has actually hardened, to produce a post curing reulting in a harder and more uniform strength. Those temperature sound high, but can actually be quite achievable in direct sunlight, especially if using dark filler powders.
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Old 16-02-2008, 15:39   #15
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UV question - apart from degrading expoxy, does anyone know if UV accelerates curing in general marine expoxy? I had heard it did and experience seems to confirm it but I can't find any definitive reference to that aspect right now.
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