How to Strip a Boat before Painting it

Every time you decide to paint you boat, you will face the laborious task of stripping the hull before you start with the paint. This can turn into the ultimate nightmare – or the most expensive part of your little painting endeavor. Therefore, it is well worth reading a bit into the possibilities and different techniques to strip your boat efficiently. That’s what I wrote this article for.

What excites a real sailor more than a decent strip? Sorry, chauvinist joke of the article, from now on decently…and actually, stripping can be a real pain or – if you decide to outsource it, very expensive causing as much as 75 percent of the final cost of re-painting or varnishing a boat. In brief: Stripping is not only laborious, it is also dull and everybody involved with boat repair dislikes it. Or at least I do.

Why stripping at all? These days there are plenty of modern, highly-adhesive paints available, and so some of you might wonder if it is necessary at all to strip a yacht before re-painting it. The answer is simple: Many smaller boats, especially modern ones of fiberglass, actually do not require frequent stripping. Once every couple of years you will probably need to fix minor damages in the paint, but generally speaking, painting efforts are decreasing for years now with better materials being on the market.

However, essentially every boat needs to be stripped at some point to keep the paint thoroughly on attached to the surface of the hull; at latest once there are several layers of paint on the boat. A common estimate when this is the case are 20 years, assuming that small or medium-sized patches get partly stripped and then painted over about once every five years. This is more or less educated guessing and it really depends mostly on where your boat lives, how heavily you use it and what the quality of the finishing and painting work is.

If you need to fix only small patches, a bit of dry scraping should do the job – get rid of every bit of paint that doesn’t adhere perfectly and paint over the open wood, fiberglass or metal. This is the easy bit and you will probably have to do that once every couple of years (for example in the South or in California) or even annually (Great Lakes, New England). But this bit of work is bearable and shouldn’t worry us any longer.

Back to the point: You realize some day that your yacht looks bad and that paint is peeling off on several ends. A drastic re-paining of the boat is required and before you do that, you need to strip the hull off several layers that tell the exciting past life not only of you boat, but also of you life as a proud sailor.

Techniques for Stripping a Yacht

What can you do? There are several different techniques that you can use to strip a boat. In the following paragraphs, I will briefly outline what the most common means are:

1.) Burners and Flame Guns: This ancient technique does not only offer exciting toys, it is also very efficient in terms of time and cost. Burners work by lightly melting the paint and then peeling it off manually. This can be achieved by flame guns, electric heaters or hand-held burners.

The disadvantage of this method is the heat – it can damage the hull itself or the interiors of the boat; it is therefore limited to solid timber boats. Otherwise, many yacht owners prefer this quick method, as it also works as an anti-fouling agent and kills barnacles and other unwanted visitors.

If you decide to strip a boat with burning techniques, take great care not to get injured. Keep some buckets of water at reach; use a fire-proof screen to protect yourself against the wind; and work from left to right if you are right-handed (burning-device in the right hand, scraper in the left).

2.) Stripping by chemical means: Much more state-of-the-art, but not necessarily superior, this method is commonly used in industrial applications. Less popular with private boat-owners, chemical stripping normally involved soda solutions or acidic gels that dissolve paint. These chemicals are generally not restricted to timber boats, although many are material-specific.

The disadvantage of chemical stripping are mostly based on the toxic effects of the substances: they can harm you; they can harm the environment; and they can harm parts of the boat that are not supposed to be stripped.

With many chemical stripping agents, you will have to apply solutions several times. Most manufacturers give guidelines on how many layers of paint a single application will remove; this is moderately reliable. The best thing is to ask people with experience on how they do it, since the effectiveness of chemical solvents depends on the type of paint you have used.

After applying the stripping agent, make sure to get rid of all the chemicals by applying the recommended neutralizer. If the procedure requires a final rinse with water, make sure that the hull is dry before you start painting it again.

If you apply chemical stripping agents, make sure to have sufficient amounts of neutralizer handy – this equals the buckets of water with the burning technique. Mask all parts of the boat that are exposed, not supposed to get stripped and potentially sensitive to corrosion. Work in a well-ventilated environment and wear a breathing-mask if necessary.

3.) Coarse sanding: The 21st-century answer to burning, coarse sanding is the favored technique to strip large vessels these days. Sanding works quickly, efficiently and helps to generate a roughened surface with good adhesive properties.

The disadvantage is that is requires heavy tools and a workshop, since sanding generates a lot of dust. This technique is only moderately suitable for private boat-owners. You will need a suitable disc and paper that won’t scratch the underlying surface. There are too many sanders available these days to give even an outline; the best thing is probably to ask for advice in a specialist store and in you local yacht club or marina.

The most suitable tool will also have to match with the paint that you have used before and with the structure and material of you boat. Generally speaking, sanders generate dust of paint, antifouling remains, varnish and other healthy bits – wear a mask when sanding; gloves and an overall work suit also help to decrease the health risk.

After stripping: No matter which technique you decide to apply to your boat – there are a couple of things that you should keep in mind. Always work in a suitable environment such as a workshop; get a first-aid-kit and read the instructions of your tools or chemical agents; and make use of experienced sailors around you.

Once you boat is stripped and exposed in all its natural beauty, take good care of optimal adhesion before you paint the boat. Keep the surface perfectly dry and free of dust. Remove all rust, first manually by scraping it off, then chemically – for example with acids. The adhesive properties of fiberglass, resins and other modern materials can be improved with special chemicals based on hydrochloric acid.

4.) Dry scraping: The ultimate nightmare. Not only a great way of damaging your boat, but also exhausting, slow and painful. I generally recommend this technique only for small dinghies and people with a lot of time and too much energy. The advantage of this technique is that it requires neither fancy equipment, nor anything seriously dangerous or unhealthy.

If you are masochistic enough to strip your boat by dry scraping it, make sure that you are using quality tools. There are several scrapers available specially made for boat-stripping applications and you shouldn’t even think about dry-scraping unless you have proper tools. Most sailors use dry-scraping is a somewhat supplemental technique in combination with one of the others – mostly for narrow parts that you could hardly access with burners or sanding tools.


Further Reading

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General Boat Maintenance: Hull, Deck and Interiors

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