Removing bottom paint

bgary

bgary

Advanced Beginner
Blogs Author
Fork from another thread.

I need to put a bottom on Makana, and want to put it on the most solid base I can. Surveyor suggested stripping the existing bottom paint off and putting new primer/base-coat directly on the barrier rather than layering on top of existing paint.

What's the best way to do that? I'd like to try to satisfy three conflicting goals

-- not compromise the existing barrier coat
-- not spend a fortune
-- not run afoul of environmental regs (not sure what is allowed here in Washington)

From the other thread, the choices are blast, sand or strip. The surveyor mentioned that there are some chemical strippers that he felt would do a good job without damaging the barrier coat, and without creating a mound of sanding dust, but didn't provide any specifics.

Anyone have hints, experiences or best practices?

Thanks!
 
E

e38 owner

Member III
fwiw

bgary said:
Fork from another thread.

I need to put a bottom on Makana, and want to put it on the most solid base I can. Surveyor suggested stripping the existing bottom paint off and putting new primer/base-coat directly on the barrier rather than layering on top of existing paint.

What's the best way to do that? I'd like to try to satisfy three conflicting goals

-- not compromise the existing barrier coat
-- not spend a fortune
-- not run afoul of environmental regs (not sure what is allowed here in Washington)

From the other thread, the choices are blast, sand or strip. The surveyor mentioned that there are some chemical strippers that he felt would do a good job without damaging the barrier coat, and without creating a mound of sanding dust, but didn't provide any specifics.

Anyone have hints, experiences or best practices?

Thanks!
Click to expand...

I have done way to many bottoms and each time state this is the last.
Removal of old paint I find sanding the best. For budgeting time it not too many coats on the boat plan on a little over an hour per foot, If lots of old paint I have tried a stripper but that does not eliminate the sanding just reduces it. You may want to get a bid for Soda Blasting or dry ice blasting before you begin. My suggestions are as follows.

1. Try to determine what paint is on the existing bottom and if you want to stay with it.
2. If staying with same paint and it is pretty good shape full removal might not be needed only a heavy sand
3. If going to a softer paint or ablative and old bottom is in decent shape full removal may not be needed. only a heavy sand
4. If barrier is bad or old paint not adhearing then removal is suggested.
5. A good orbital sander with a vacuum attachment is suggested. I prefer the 6 inch model. There are two thoughts, a friend of mine bought a home depot sander and went through three of them on one bottom. Kept taking it back. I own a good one and it has done many a bottoms and still keeps ticking. From time to time I borrow a friends Fein, What a tool
http://feintools-online.com/7220781...636-1-6-in-dust-free-random-orbit-sander.html
http://www.cpoworkshop.com/porter-c...ult,pd.html?start=7&cgid=porter-cable-sanders
6. Make sure the you get the sand paper with holes for your sander.
7.Sand with 80 grit
8.Plan on adding two coats of barrier when done as a primer . Interlux interprotect or pettit 4700
9. Get the good mask and overalls http://www.amazon.com/Safety-Works-..._UL160_SR160,160_&refRID=0M8WAVDBXAE2VK1AS6Q1
10. Soda blasting also works well. Need to find a professional and get a bid in your area. Can create a mess and needs a big compressor.
11 Tape the boat at the waterline before you start. I try to keep the cover with my Winter cover. If you wax the waterline before you start cleanup is easier. Try not to get excess wax below.
 
Last edited:
Alan Gomes

Alan Gomes

Sustaining Partner
e38 owner said:
I have done way to many bottoms and each time state this is the last.
Removal of old paint I find sanding the best. For budgeting time it not too many coats on the boat plan on a little over an hour per foot, If lots of old paint I have tried a stripper but that does not eliminate the sanding just reduces it. You may want to get a bid for Soda Blasting or dry ice blasting before you begin. My suggestions are as follows.

1. Try to determine what paint is on the existing bottom and if you want to stay with it.
2. If staying with same paint and it is pretty good shape full removal might not be needed only a heavy sand
3. If going to a softer paint or ablative and old bottom is in decent shape full removal may not be needed. only a heavy sand
4. If barrier is bad or old paint not adhearing then removal is suggested.
5. A good orbital sander with a vacuum attachment is suggested. I prefer the 6 inch model. There are two thoughts, a friend of mine bought a home depot sander and went through three of them on one bottom. Kept taking it back. I own a good one and it has done many a bottoms and still keeps ticking. From time to time I borrow a friends Fein, What a tool
http://feintools-online.com/7220781...636-1-6-in-dust-free-random-orbit-sander.html
http://www.cpoworkshop.com/porter-c...ult,pd.html?start=7&cgid=porter-cable-sanders
6. Make sure the you get the sand paper with holes for your sander.
7.Sand with 80 grit
8.Plan on adding two coats of barrier when done as a primer . Interlux interprotect or pettit 4700
9. Get the good mask and overalls http://www.amazon.com/Safety-Works-..._UL160_SR160,160_&refRID=0M8WAVDBXAE2VK1AS6Q1
10. Soda blasting also works well. Need to find a professional and get a bid in your area. Can create a mess and needs a big compressor.
11 Tape the boat at the waterline before you start. I try to keep the cover with my Winter cover. If you wax the waterline before you start cleanup is easier. Try not to get excess wax below.
Click to expand...
This fall I am planning to remove all of the past years of bottom paint that have accumulated on my boat, though I have no plans to barrier coat it. My method for attacking this problem is a bit different from yours, though it is admittedly somewhat Southern California-centric:

1. Load boat with significant quantities of bovine flesh, beer, pipe tobacco and cigars.
2. Load two good sailing buddies and assorted gear on to the boat.
3. Harbor-hop down to Ensenada (via Dana Point and then Mission Bay), consuming the aforementioned items in point #1.
4. Pay highly desirable labor rates at Baja Naval for them to sand off the old paint and apply new.
5. Have the Baja Naval yard staff buff and wax the boat, change out cutless bearing, and perform any other misc. stuff.
6. While points #4 and #5 are in process, consume roasted chickens, inspect the "Tres Cabezas" for signs of wear and tear since our last trip, and check on the proper functioning of the "La Bufador" blowhole. Also, stock up on Cuban cigars and replenish the by-then dwindling supply of cervezas.
7. Smile while I write Baja Naval a check for about half of what this would have cost me to have done in So. Calif.
8. Head back to the barn.
 
C

Ccaptain

Ccaptain
I have removed bottom paint from three different boats I have owned over the years. The first one (a Trident 27)was taken down to the gel coat using a scraper and sanding. The Ericson 34 had damage that extended to the fiberglass which left little doubt as to sanding the remaining paint from the hull. The last one I did was this last fall (an O"Day 31). In about three hours and $570.00 the job was done by a contractor at the marina using a sand blaster. Sounds expensive until you realize that the sanding technique would cost that much in beer consumed. All of these boats were covered with 10-12 mil of West barrier coat and the ablative applied over the lightly sanded barrier coat. I was once told when removing the paint from the bottom of a boat to look back at what has been accomplished and only then look ahead at what remains. Good luck.

Ccaptain
 

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frick

frick

Member III
DeWalt 5 inch Random Orbital Sander

This last year I did the big sanding job.

I picked up a new DeWalt 5 inch Random Orbital Sander that also can hook up to a shop vac. I bought a 4 inch pack of 80 grit sand paper with the velco like stick on backs. Change your disks often, your time is more important the a few extra disks that you will use.

It took me two good afternoons to finish the job, but I had almost 5 pounds of dust in the Shop Vac when I was done.

I helps to have a multi lever step stool so you can rest an elbow on a knee when sanding.

My issue... The old Epoxy bottom paint was starting to chick and flake off. I always use a Co=polymer Ablative paint so it does not build up to much.

This was the second time in 14 years I did some sanding of the bottom, but the first time and I to do all the way to the old former owner epoxy bottom paint.

Rick
 
bgary

bgary

Advanced Beginner
Blogs Author
For those that sand or scrape... are there ways to do it without damaging the barrier coat, or is that damage just the price of getting the old paint off?
 
markvone

markvone

Sustaining Member
Take a look at the pictures in post #35 of the thread below:

http://www.ericsonyachts.org/infoex...-1983-Discovery-Port-leaks-Bottom-Paint/page3

My paint was well attached to my barrier layer (grey) in most areas, except for a few spots where the barrier and paint were missing down to gelcoat. I lightly sanded with a 5 inch random orbital and 60 grit to get any loose paint off. I experimented with sanding more paint and barrier off near the waterline and down to the barrier on the rudder as shown in the pictures. I plan to re-do the barrier and some other repairs in a full winter-long haul out when I need to paint again.

It will take more time and technique to get most of the paint off and not damage the barrier coat. You can see two white spots on my rudder where I went through the grey barrier, although I was not really trying to save the barrier. If you are comfortable that your barrier layer is intact and working and it doesn't need repairs. you only need to get most of the bottom paint off - like my rudder. The paint remaining is really well attached and due to the texture/level differences, you will start taking off the highest layer of barrier in order to get down to the lowest layer of paint. If you look closely at the picture of my waterline sanding you can see I've got pockets of red paint very near where I've cut into the barrier and even down to the gelcoat. If you need to remove ALL the bottom paint to repair the barrier or due to a paint incompatibility issue, I would not waste time trying to sand and would just blast it all off and plan to reapply the barrier.

I would ask around at your local soda/sand bottom blasters to see if they feel they can blast (most of the) bottom paint without damaging the barrier coat and what they feel the risk of barrier compromise is. Blasting has a lot of variables. I've heard of sand, soda, wet glass, plastic beads and walnut shells as media. The operators skill and technique as well as experience are also a big factor. Tenting and tarping the bottom area to contain and collect the media during the blasting has to be done so that the operator who is inside the tent in the dust cloud can actually see what he is doing and not over/under do it.

Mark
 
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