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Old 10-11-2011, 08:29   #16
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Re: Bottom Paint Question

I did the bottom of my Irwin 38 by using a good quality random orbit wax applicator and just sticking the sand paper right to the foam pad. It wasn't really that corse of sand paper either as I recall the bottom paint sands off pretty easily as compared to the gell coat. I then applied a barrier coat, and it all worked out great.
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Old 10-11-2011, 09:04   #17
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Re: Bottom Paint Question

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Originally Posted by albergsailor View Post
thank you thank you thank you, thats exactly what i needed to know. when i first got the boat i used a belt sander on the bottom because i could not find a soft pad that fit my angle grinder, i remember trying to make a softpad out of the buffer that came with a sander/polisher, boy did that piece of sandpaper go flying even after using glue. I was really pissed that i could not find a "soft pad" in any of the stores. Untill now i did not know that such an attachment existed. I just googed soft pad and found them online. Anyone know if any local stores carry these? I also cant wait to do some experimenting with my harber freight diegrinder using fiberdisc. I just got a voltage limiter for it so maybe it will come in handy. thanks again for all the advice i should have consulted the experts here about this long ago.
If you already own a Makita sander/polisher, the softpad will chuck right on to that. It's actually much lighter than a 6088, just not as torque-y. Will do the job fine, we just use the more heavy duty equipment because it lasts so much longer and we grind all day every day. Plus I think the boss likes to make us cry. You will find fiberdiscs just clog up right away, depending on which paint you are removing clogging can be an issue on regular grit discs as well. Use a wire brush to clean grit discs or just chuck em faster and use more grit.
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Old 10-11-2011, 09:33   #18
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Re: Bottom Paint Question

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I have been involved with most methods out there to strip bottom paints and have some practical opinions on options for removing your old anti fouling. I list them here from best/ easiest to most difficult:

1.) Easiest way: Hire a professional to bead blast the bottom, the last project we did was a Cape Dory 27, contractor came with a specialized box truck with all equipment in the vehicle. They completely tented off the boat and ran high volume vacing equipment hoses under the tent to suck up the old bottom paint as they blast. Equipment shoots plastic beads, gets most of the paint off, does no damage to the hull. In the end we still spent a good deal of time sanding. Somewhat environmentally friendly if high volume vacing equipment is utilized. Expensive, the Dory was over $800.00.

Since you had to sand quite a bit anyway, why wouldn't you just start out with a sander? I find it takes me about the same amount of time to strip a bottom to the gel with 36 grit as it does for most other techniques to do a final sanding, which is required for almost all of them.

2.) Soda blasting: Basically same as the above except contractor shoots baking soda in a high pressure water stream as the cutting medium. On the hull I witnessed soda blasting being performed on there was some damage to the gel coat; contractor claimed he was just opening up blisters. Soda blasting equipment usually allows the operator fine adjustment of the amount of blast medium allowed into the water stream as well as the water pressure level. This allows the operator to fine tune the gear and if experienced he should only use the amount of soda and water pressure required to remove the paint and not damage the surface being prepped. The soda blast left a much cleaner final surface than the bead blast process but in the NY metro area was much more expensive. Environmentally the process is not as clean as the bead blast method as the paint and soda runs all over the ground making cleanup more difficult in a marina environment.

This is illegal, at least in my state, unless you have a catchment system to collect the runoff and filter it out. This means the boat must be moved to the filtration pad and reblocked for blasting, and again for block spots and jackstands. Takes too much time and costs too much. We do have one but don't use it since sanding is so much easier.

3.) Chemical Stripping: For the do it yourself guy/ gal without very deep pockets I feel this represents one of the best methodologies. I have personally used a product called “Peel Away” Peel Away® Products on many occasions and can attest that the products work as advertised. Basically the stripper is painted on the hull and covered with a wax paper. After the proper dwell time a scraper is used to lift the old paint from the hull. Depending on the thickness of the old bottom paint you may have to do a couple of applications to remove as much paint as possible. You will still have to spend a fair amount of time sanding if you want a perfectly clean bottom prior to recoat, however if done correctly you can remove 80% of the old paint prior to the final sanding. This method is much cheaper than any blast process. I have even used “"Peel Away's” home version paint strippers sold in bulk at Home Depot with no discernable difference over their "Marine" more costly products. Environmentally it can be very clean allowing the stripped paint to drop onto plastic tarps then wrapped up for disposal. From an efficiency standpoint this is a much faster and cleaner method than sanding and scraping alone.

This product is one of the worst scams I've seen perpetrated in the marine industry. They sell it as being able to strip multiple layers in one application, but I've never seen it strip a bottom clean in less than three. Since it costs about 1k per application, that means they are selling three times as much product and making three times aas much money based on a marketing lie. I did a few bottoms this way because the boss wanted to try it. Never again. This product has been banned from our yard because it makes such an ungodly mess. Imagine turning all the bottom paint on your boat into a muddy paste, and then scraping it off overhead. It gets all over you and everything else. We banned it after it was repeatedly tracked all over the yard and on to other peoples boats.

4.) Sanding alone to remove bottom paint represents the stone ages in the hierarchy of bottom paint removal methods. It probably represents one of the least desirable projects you can do on your boat. It doesn’t matter what machinery is used, a belt sander, palm sander, DA sander, random orbit sander or whether it’s connected to a vacuum or not or whether your completely encapsulated in a nuclear/ biological suit with a filtered air supply and little gnomes handing you filtered spring water, sanding is painfully slow, very physically demanding and extremely dirty. The high powered larger pad sanders can cause damage to gel coat if not utilized properly. In the end this is probably the most cost effective method of paint removal. If you choose this process wear a full Tyvec suit and good quality resperator, (Not a dusk mask) goggles and gloves. Environmentally this is the dirtiest process of all and will send old dry bottom paint everywhere. If you value your relationship with your neighbors the boat should be as far away from them as possible. There is reasonable priced sanding equipment like the “Rigid” brand random orbit sanders that can be attached to a shop vac for dust control, while not perfect they go a long way to minimizing sending toxic paint into the atmosphere. Good luck with your project
The stone ages? This is how it's done by the pro's. I do multi million dollar mega yachts all the time. It is very hard work, hence all the different ways to try to get around that. IMHO, they are all for pansies. Yes, I've seen large muscular men break down and cry after a day on the job with me. I've also seen them drop all tools and walk out after an hour or two. And I've seen little wiry guys keep at it year in and year out. It's just hard work.
Damage can be caused with any technique, sand/bead blasting is easier to gouge with a moment of innattention than a sander. A scraper will ruin your gel for sure. All of these techniques require the same safety gear, tyvek and fullface. And you only think it's "painfully slow" because you are advocating using a random orbit with vac attachment, that's for amateurs. A 7" is at least 10 times as fast. And if you want to blow your relationship with your neighbors in the yard, try chemical stripping for a week straight. Sanding gets it done quick, cleaned up and out of the way. Your neighbors will thank you as long as you tent off well and clean up thoroughly.
The regional EPA office is less than a block from our yard. The local head of the EPA gets her coffee in the morning across the street. We get constant visits. They hate bead blasting with filtration, because the filtered water goes right into the sound, and although its legal and filtered, it's not "clean". They also hate chemical strippers for obvious reasons. Sanding is actually the most environmentally friendly method, as long as tenting is thorough and so is clean up. We tarp off before blocking boats, so when we are done it's spotless. No toxic bottom paint dust left anywhere. The EPA loves us and uses our yard as an example for other's in the area.
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Old 10-11-2011, 10:01   #19
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Re: Bottom Paint Question

I'll hijack this thread just for a minute. I looked at minarets pics of his boat and damn it's a nice one. Really nice. Check it out. I think he might know what he's talking about. BOB
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Old 10-11-2011, 10:04   #20
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Re: Bottom Paint Question

OMG. Palm sander, (don't shop the discount aisle) 220 grit paper (enough to change every 5-10 minutes), paint (enough for 2 coats) and masking tape. (mask before sanding for waterline, remask after sanding) Paint with a roller and a 2" brush and you'll be done in 2 tide changes.

SAND TILL SMOOTH ~ DO NOT SAND TO GELCOAT!
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Old 10-11-2011, 10:15   #21
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Re: Bottom Paint Question

P.S. Slop the paint on (It's underwater). Don't be cheap. Don't paint the zincs or transponders, wheels (props) or shafts. If you live in a high growth area add about 1 cup of ground cayenne pepper per gallon. Keep the mixture mixed while applying so as the solids don't settle to the bottom.
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Old 10-11-2011, 10:29   #22
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Re: Bottom Paint Question

I dont know of any yards that allow sandblasting without a complete tent (if that) except commercial yards. Are there any large commercial boat repair yards in your area? You might get them to blast your bottom on a floating dry dock. Sand blasting is just plain too agressive though.

You need to hire the right man with a good 8-9" disc grinder. It's an art for sure. If you're not a metal worker or dont have extensive experience, you are going to gouge your bottom all over! Either that or get suited up, use agressive grit sand paper and just remove the loose stuff until your arms fall off. No reason the bottom has to be "smooth as a spanked babies butt!" though.
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Old 11-11-2011, 21:56   #23
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Re: Bottom Paint Question

Minaret

I'll be facing the same task and I have read this post with interest.

Quote:
There is certainly a learning curve, and you can gouge up a bottom if you haven't learned to feather the trigger, but it's not that hard a technique to develop


Can you give us a hint on the technique?

also

Quote:
some preservation seal and duct tape for tenting,
How do you tent?

THanks for your help
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Old 11-11-2011, 23:20   #24
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Re: Bottom Paint Question

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Minaret

I'll be facing the same task and I have read this post with interest.



Can you give us a hint on the technique?

First, take off the side handle. It encourages you to sand off the flat. Once you are really good then you can put it back on. Sand with one hand on the trigger and the other on the back of the grinder directly behind the shaft, this will help you keep the soft pad flat on the work surface. When sanding, instead of just locking the trigger down, which is unsafe IMHO anyway, you must feather the trigger. This means you are pulling the trigger in the middle of each stroke but letting off at either end, just like a spray gun operator sprays paint. If you don't do this the tiny moment of "dwell" at the end of each stroke will cause you to create half-moon gouges. Most people catch on to this technique pretty quick once somebody shows them; I've trained lots of new guys and bottom paint removal is one of those jobs we like to work the new guys up on. Shows you their mettle or lack thereof real quick.
The really tricky part comes when you get to the turn of the bilge or any other area with too much curvature for the softpad to sit flat while sanding. Here, you must take the pad off the flat and sand with it on edge. This is where some real skill and technique come in to it. But if you do the rest of the bottom first to develop skills, and really feather that trigger, it comes pretty easy. Worst case scenario you hand-fair a couple of gouges before bottom paint. It's rare that I see someone screw it up so bad that they go through the gel, but some boats have thicker gel than others. As long as you plan on barrier coating and it comes out fair it doesn't matter though.
The 36 grit profile provides really stellar "tooth" for the 2000/ barrier coat of choice as well. You'll still be able to see it for the first coat or two, after that it'll be gone. I like to use 1/4" nap candy striper roller covers for applying the barrier coat, they give a nice even fine stipple that comes out looking very proffessional with no sanding.

also



How do you tent?


Tape heavy duty visqueen to the hull as high as you can reach ( unless you're really short, then get someone taller), leaving big pleats at bow and stern and a couple either side. Use preservation seal to tape to the hull. If it's a wood boat with enamel, don't tape to it, you must find another way. You can then build a nice 1x frame work underneath if it's going to be a big job, ie glass repairs etc. If it's just a quick bottom paint removal, you only need 6-10 1x pokes per side, depending on boat size. Wrap the upper ends of the pokes with rags and duct tape so they don't scratch the hull and insert them under the plastic, after cutting to the right length. Then roll up some 1x in the excess plastic footing, and screw them to the vertical 1x at ground level to keep the spacing even. Stick some cement blocks or whatever else heavy you can find on top of these to hold them down in high winds. 5 gallon buckets half full of cement work great. The higher your plastic and pokes on the hull side, the more room you'll have when you do the waterline. Give yourself at least 3 feet above the waterline.This kind of tent will be tight when doing the waterline, but you only need it for a week or so, and then only if you are also using it to keep the bottom dry while coating in the rain. Don't forget a tape drip dam if this is the case. It also helps to take some 8" or so scraps of 1x and screw them to the vertical pokes from outside the plastic, trapping the plastic between 2 layers of 1x. This helps to take out slack and keep the tent tight.

THanks for your help
Hope that makes sense and is helpful!
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Old 12-11-2011, 02:16   #25
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Re: Bottom Paint Question

G'Day Minaret,

As usual your advice has the ring of authenticity, and I appreciate it. I'm not faced with this job just now, but am finding the description of your technique quite interesting.

But... for us not in the trade, just what are "pokes" and "1x's" ? (Please excuse my naivety but I'm having a hard time imagining your setup).

Thanks for sharing your experience with us.

Cheers,

Jim
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Old 12-11-2011, 03:37   #26
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Re: Bottom Paint Question

Sorry, I meant cheap 1"x2"x10' lumber for pokes. Sometimes it's nice to use 1"x4"x10' instead for a stiffer better tent. And on a bigger boat you might need 1"x4"x12' to get the necessary length, but that would be for a big boat blocked high due to keel/draft.
A poke is just boatyard slang for any piece of timber you use to prop up a tent. I'll find a pic.
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Old 12-11-2011, 03:44   #27
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Re: Bottom Paint Question

Here's a quick one to give you an idea. This one could be made better with foot connectors and more weights, but you get the picture...
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Old 12-11-2011, 03:50   #28
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Re: Bottom Paint Question

Bit of an art to using a disc sander - but sure shifts stuff

Downside is that the surface left won't be perfect - but that is fixable

FWIW, have recently been using a disc sander attachment on a 18v (90 degree) cordless drill for a few jobs - the lack of weight makes control very easy.
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Old 12-11-2011, 06:41   #29
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Re: Bottom Paint Question

Having read reviews and usage instructions for most of the current "approved" bottom paint removal chemical systems, it seems to me that the old fashioned brutal, but simple sanding/grinding is the most cost and time effective procedure. The main concern in environmentally sensitive countries is the containment of bottom paint dust from the procedure.

- - Tenting with sturdy plastic sheeting both under the boat and vertically up to seal with the boat hull probably takes more time than the actual sanding. But with most jobs, proper preparation can make a big difference in the successful and quick accomplishment of the job.

- - For long duration projects tenting using "green-house" grade plastic film is worth the extra cost and trouble to find. Normal plastic film will dry out and fall apart due to the sun's UV quite quickly when compared to "green-house" grade plastic film.
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Old 12-11-2011, 09:30   #30
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Re: Bottom Paint Question

Invaluable information and advice. Thanks for the picture and for sharing this with us.
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