Looks like I am going to do the bottom this year and my question is how many layers of barrier coating is necessary?
Barrier coating; How many is enough?
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Interlux 2000
I'd use Interlux 2000 and short nap rollers and follow the manufacturer's recomendations. However, depending on the size of your boat you maybe able to mix paint and starting at one side at the stern, continue forward say on the port side, to the bow, continue back on the starboard side from bow to stern and start over again at the stern moving forward with the second coat in a continuous process. I'd mix a gallon at a time and see how far that takes you. When you do stop, if you wait overnight, you may need to scratch sand with 80 grit before starting the next coat. Figure out ahead of time how you expect to handle moving Jack stands or work it out with the yard how they suggest handling lifting it off the cradle to finish the cradle patches, if that's your situation. Jack stands are easiest for a do-it-yourselfer to work with. I think I did four coats in two sessions on one warm weekend on a 28.5 many years ago. Keep your eye on the air temperature and the temperature of the hull and keel (in the spring I'd assume).
I'd use Interlux 2000 and short nap rollers and follow the manufacturer's recomendations. However, depending on the size of your boat you maybe able to mix paint and starting at one side at the stern, continue forward say on the port side, to the bow, continue back on the starboard side from bow to stern and start over again at the stern moving forward with the second coat in a continuous process. I'd mix a gallon at a time and see how far that takes you. When you do stop, if you wait overnight, you may need to scratch sand with 80 grit before starting the next coat. Figure out ahead of time how you expect to handle moving Jack stands or work it out with the yard how they suggest handling lifting it off the cradle to finish the cradle patches, if that's your situation. Jack stands are easiest for a do-it-yourselfer to work with. I think I did four coats in two sessions on one warm weekend on a 28.5 many years ago. Keep your eye on the air temperature and the temperature of the hull and keel (in the spring I'd assume).
interlux 2000
when i did mine the boat yard repairmen told me figure each coat to give you 2mm of coating and you want 10mm in the end. thats with interlux 2000, remember to alternate colors so you can see where you have gotten from coat to coat if you use this.
when i did mine the boat yard repairmen told me figure each coat to give you 2mm of coating and you want 10mm in the end. thats with interlux 2000, remember to alternate colors so you can see where you have gotten from coat to coat if you use this.
Interlux 2000
John- Are you putting on a barrier coat because you have or are going to repair blisters? Or just as a preventive measure? As one very smart guy who posts on the board here says, "If you read the instructions on the back of the box/can it will have the manufacturers recommendations". They are truly the experts on their product. I dont want to come off as a a$#hole, but you will have too many varing opinions about the necessary amount. If I had blisters I would put five coats on. If I had no blisters I wouldnt put any on. As for making sure that you properly get even full coats. Interlux 2000 comes in two colors, white and gray. Alternate colors between coats. On the instructions they will give you the coverage area/gallon. To figure your square feet out L x W x .75 = SQ FT The best rollers that I have ever used for appling the BC are West System 7" yellow foamies
John- Are you putting on a barrier coat because you have or are going to repair blisters? Or just as a preventive measure? As one very smart guy who posts on the board here says, "If you read the instructions on the back of the box/can it will have the manufacturers recommendations". They are truly the experts on their product. I dont want to come off as a a$#hole, but you will have too many varing opinions about the necessary amount. If I had blisters I would put five coats on. If I had no blisters I wouldnt put any on. As for making sure that you properly get even full coats. Interlux 2000 comes in two colors, white and gray. Alternate colors between coats. On the instructions they will give you the coverage area/gallon. To figure your square feet out L x W x .75 = SQ FT The best rollers that I have ever used for appling the BC are West System 7" yellow foamies
More importantly...
More importantly before you apply a barrier coat the hull MUST be dry!!! This is a mistake many, many people make and they essentially just trap moisture in the hull causing more problems later. Before you apply any barrier coat the hull should have a moisture reading done and be confirmed dry enough for a barrier coat application!! It does not matter how many coats you put on if your hull still has a high moisture content reading when you apply it!!!!!! In MI you can strip the hull in the early fall and then let is sit over the winter and apply it in the spring before launch. It helps to install a "drip edge" or "drip skirt" of UV resistant duct tape at the water line so as rain runs down the sides of the hull it does not track down onto the below water line area and instead drips off the edge of the duct tape directly onto the ground...
More importantly before you apply a barrier coat the hull MUST be dry!!! This is a mistake many, many people make and they essentially just trap moisture in the hull causing more problems later. Before you apply any barrier coat the hull should have a moisture reading done and be confirmed dry enough for a barrier coat application!! It does not matter how many coats you put on if your hull still has a high moisture content reading when you apply it!!!!!! In MI you can strip the hull in the early fall and then let is sit over the winter and apply it in the spring before launch. It helps to install a "drip edge" or "drip skirt" of UV resistant duct tape at the water line so as rain runs down the sides of the hull it does not track down onto the below water line area and instead drips off the edge of the duct tape directly onto the ground...
A lot depends on how your use
your boat. I'm a cruiser so I use and love ablative copolymer bottom paint. It really minimizes preparation efforts each spring. I normally just powerwash or scotch brite the bottom, and repaint annually. When applying new bottom paint (I use WM CPP and really like it), I ignore the label and just apply one thin coat each year. I also use a short nap roller, not the 3/8" roller recommended. I find that one coat lasts nicely thru one full season and that is just what I want.
your boat. I'm a cruiser so I use and love ablative copolymer bottom paint. It really minimizes preparation efforts each spring. I normally just powerwash or scotch brite the bottom, and repaint annually. When applying new bottom paint (I use WM CPP and really like it), I ignore the label and just apply one thin coat each year. I also use a short nap roller, not the 3/8" roller recommended. I find that one coat lasts nicely thru one full season and that is just what I want.
I do the same as Warren:
WM's CPP ablative is great and cheap...it usually goes on "clearance" in the early Spring. I paid $63 for a gallon in April of '07 and still have enough left for this year. I also use the shortest nap roller I can get.
WM's CPP ablative is great and cheap...it usually goes on "clearance" in the early Spring. I paid $63 for a gallon in April of '07 and still have enough left for this year. I also use the shortest nap roller I can get.
Helpful hint to get a SMOOTH hull when
barrier coating. Applying barrier coat with a roller will lead to a very rough surface if you use 'just a roller' to apply barrier coat. Anyone who likes to race, or sail in 'very light' winds or just plain sail fast can benefit from the following: Apply the first one or two coats of barrier with a roller, paying attention only to the heights of the peaks ('stipple') caused by the roller - only getting the heights of the 'peaks' to the mil thickness that I want, then just before the first rolled two coats begin to harden and fully cure, with a roller and a 'large polyethylene trowel' (the approx. 12" long kind used for 'fairing') apply a 'stripe' of fresh barrier at approx. 45 degrees with the roller and immediately knock it FLAT with the poly trowel, the peaks in a semicured state will allow the trowel to fill-in only the unfilled space 'lower' than the level of the peaks. Just use 'light pressure' when 'scree-ing' off with the trowel and always work towards a 'dry edge', never going back into the 'wet'. Leave a few inches of dry space between and start another 'stripe', etc. and continue until you reach all the way around the hull until done (stripes and dry spaces inbetween). When this 'scree-ed' zone of stripes begins to fully cure, fill in between all the 'stripes' and work your way all around the boat. Clean the trowel as often as necessary to prevent 'lumps'. Most of the filling between the peaks wont happen the first one or two set of stripes and most times it will take several 'sets' of stripes (all going at different angles) to get a smooth 'fill'. Then let the next to last 'fill' almost fully cure (to the recommended time limit .... but NOT all the way to fully cured) and scree on the final leveling coat. By this time the barrer should be quite uniform in thickness and quite smooth. The downside is that a large hull may take more than 24 hours .... so I 'cat-nap' between the cures or have friends carry on as I cat-nap. If youve ever sailed single handed on a long passage you'll know how reasonable cat-napping can be. I usually wait until the last barrier coating is 'just about' fully cured (still able to deform it when strongly pushed with a thumbnail) and then immediately apply the bottom paint (called 'hot coating' - for better adhesion) in the Exact same manner as I apply the barrier coat. When applying bottom paint I do wait about 8 hours between 'screed' coats when 'filling and leveling' so that the trowel doesnt 'tear' into the softer already applied new bottom paint. I use Interlux Micron etc. for my bottom paint and I can get a bottom coat as baby-assed smooth ..... almost as smooth as if I sprayed on the paint, etc. AND the bottom paint seems to last MUCH longer than if I simply used a 'roller'. This all depends on a developed 'technique' so for the first time you try it ... just attempt a 'small area' and see how it 'works-out' for yourself. It does take much more time this way but the smoothness you can get is outstanding. I started doing my barrier coats this way instead of 'just applying with a roller', letting it fully cure ..... and then sanding down the peaks and 'errors' (with arm/shoulder excruciating pain) long fairing-boards with sandpaper attached. (Only 'fanatics' use long fairing boards.)
barrier coating. Applying barrier coat with a roller will lead to a very rough surface if you use 'just a roller' to apply barrier coat. Anyone who likes to race, or sail in 'very light' winds or just plain sail fast can benefit from the following: Apply the first one or two coats of barrier with a roller, paying attention only to the heights of the peaks ('stipple') caused by the roller - only getting the heights of the 'peaks' to the mil thickness that I want, then just before the first rolled two coats begin to harden and fully cure, with a roller and a 'large polyethylene trowel' (the approx. 12" long kind used for 'fairing') apply a 'stripe' of fresh barrier at approx. 45 degrees with the roller and immediately knock it FLAT with the poly trowel, the peaks in a semicured state will allow the trowel to fill-in only the unfilled space 'lower' than the level of the peaks. Just use 'light pressure' when 'scree-ing' off with the trowel and always work towards a 'dry edge', never going back into the 'wet'. Leave a few inches of dry space between and start another 'stripe', etc. and continue until you reach all the way around the hull until done (stripes and dry spaces inbetween). When this 'scree-ed' zone of stripes begins to fully cure, fill in between all the 'stripes' and work your way all around the boat. Clean the trowel as often as necessary to prevent 'lumps'. Most of the filling between the peaks wont happen the first one or two set of stripes and most times it will take several 'sets' of stripes (all going at different angles) to get a smooth 'fill'. Then let the next to last 'fill' almost fully cure (to the recommended time limit .... but NOT all the way to fully cured) and scree on the final leveling coat. By this time the barrer should be quite uniform in thickness and quite smooth. The downside is that a large hull may take more than 24 hours .... so I 'cat-nap' between the cures or have friends carry on as I cat-nap. If youve ever sailed single handed on a long passage you'll know how reasonable cat-napping can be. I usually wait until the last barrier coating is 'just about' fully cured (still able to deform it when strongly pushed with a thumbnail) and then immediately apply the bottom paint (called 'hot coating' - for better adhesion) in the Exact same manner as I apply the barrier coat. When applying bottom paint I do wait about 8 hours between 'screed' coats when 'filling and leveling' so that the trowel doesnt 'tear' into the softer already applied new bottom paint. I use Interlux Micron etc. for my bottom paint and I can get a bottom coat as baby-assed smooth ..... almost as smooth as if I sprayed on the paint, etc. AND the bottom paint seems to last MUCH longer than if I simply used a 'roller'. This all depends on a developed 'technique' so for the first time you try it ... just attempt a 'small area' and see how it 'works-out' for yourself. It does take much more time this way but the smoothness you can get is outstanding. I started doing my barrier coats this way instead of 'just applying with a roller', letting it fully cure ..... and then sanding down the peaks and 'errors' (with arm/shoulder excruciating pain) long fairing-boards with sandpaper attached. (Only 'fanatics' use long fairing boards.)
barrier coats
The original post was a question about barrier coating, which is a completely different product and application than bottom paint. Barrier coating is used on new hulls and after blister repair jobs. Bottom paint is what goes on over the barrier coat. You must remove all the bottom paint on a hull to apply barrier coating. Follow the instructions on Interlux website or on their pamphlet available at marine stores.
The original post was a question about barrier coating, which is a completely different product and application than bottom paint. Barrier coating is used on new hulls and after blister repair jobs. Bottom paint is what goes on over the barrier coat. You must remove all the bottom paint on a hull to apply barrier coating. Follow the instructions on Interlux website or on their pamphlet available at marine stores.
Barier coat correction
Not to be picky ajsail, it was probably just an over site, but your not looking for 10mm (milimeters, in metric)which would be close to 7/16". Instead the correct measurement is 10 mils, which is ten thousands of an inch. Using a thickness gauge on the wet surface will give you the wet film thickness which typically will dry to about half the wet film reading. (6 mils wet = 3mils dry). Simply apply material, check an area, then roll out the gauge marks. As the instructions state it doesn't so much matter how many coats as long as you end up with the correct dry thickness. Stay within the drying schedule times to keep applying wet on wet with no sanding between coats, especially when it comes to applying the first coat of bottom paint. Sanding the barrier coat opens it up and a new coat must be applied to seal it. Good luck John.
Not to be picky ajsail, it was probably just an over site, but your not looking for 10mm (milimeters, in metric)which would be close to 7/16". Instead the correct measurement is 10 mils, which is ten thousands of an inch. Using a thickness gauge on the wet surface will give you the wet film thickness which typically will dry to about half the wet film reading. (6 mils wet = 3mils dry). Simply apply material, check an area, then roll out the gauge marks. As the instructions state it doesn't so much matter how many coats as long as you end up with the correct dry thickness. Stay within the drying schedule times to keep applying wet on wet with no sanding between coats, especially when it comes to applying the first coat of bottom paint. Sanding the barrier coat opens it up and a new coat must be applied to seal it. Good luck John.
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