Painting Steel Motorboat
Painting a steel motorboat
Pretreatment of your steel motorboat
To get the most out of your painting job. Is pretreatment still the most important. Not so much the brand of paint.
If there is a lot of rust in your old paint system, it is best to have the boat blasted. Blasting gives a surface roughness of Sa 2.5-3, ideal for building a new system. However, blasting is not something you can do yourself, and often too expensive due to the strict environmental requirements in the Netherlands. Therefore, below is some advice.
Degreasing – sanding – degreasing
Because…the cleaner the surface, the better the adhesion. First, any thick layers of rust must be chipped off. Next, the substrate should be thoroughly degreased to remove oil, grease and dirt.
You can then remove the paint system by hand; by using paint scraper and a hair dryer. Or by doing it mechanically, such as a grinder with a bowl steel brush or flap disc, or an air ratchet. If there is little paint on the surface, you can also use a sanding machine with a coarse grit (P20-60).
Note that when using chisels, wire brush or air ratchet, sanding should always be done afterwards!
Is your paint system still intact? Then thorough sanding will suffice, in which you build up the sanding system from medium grit to fine grit. For example: start P 180,2nd time P220, last time P 320.
Tips:
- First degrease with a mild degreaser, such as St Marc or Rinser.
- After sanding, degrease again possibly with corresponding thinner.
- Clean welds very carefully!
- Apply the primer immediately after degreasing.
- Sand after machine cleaning, with coarse grit.
Always remember your safety! Safety glasses, everywhere , work boots and gloves!
Painting your steel motorboat.
When you have had to bare the airframe. Need a paint system in return. Ask the specialist (or call us!) for a consultation. Some paint brands include: Sikkens, Epifanes, IJssel, International and Sigma.
On the bare steel, apply 6-7 coats of primer, from any of the above brands. This primer protects the steel from rust and weathering. Lacquer is purely cosmetic, and depending on the color, you need to apply 3-5 coats. Choose a high gloss paint for the hull and superstructure and a non-skid paint for the gunwales.
Once you have stripped the underwater ship bare, choose a primer suitable for underwater use. The same layer structure is needed as above water. With a 2-component system, you need 3 different primers. As a final coat you need an antifouling, it has no effect cosmetically, but repels algae growth.
If you underwater system is still intact, and only the antifouling needs to be reapplied (note antifouling never works for more than 2-3 years). In that case, mild degreasing, sanding (coarse grit) and degreasing again is sufficient. Next, you can paint.
Tips:
- Some paint brands include: Sikkens, Epifanes, IJssel, International and Sigma.
- There are different types of primers for different applications.
- Protect yourself and nature, through sanding with dust collection and a rug under the boat when painting.
- Empty paint cans (with residue) and cured brushes and rollers are chemical waste.
- Varnishing is done by rolling or ironing the paint from bottom to top. For lacquer, use a fine foam roller with rounded sides or a round/oval brush. For primers, you can use a coat roller. This provides a coarse texture, but also a good layer thickness.
The best conditions for painting are in a conditioned room. However, a climate-controlled shed is not feasible for most do-it-yourselfers. If you want the “like new” result with a 2 component system, we recommend hiring a proffesional. Prices vary between €800 – €1,200 per linear meter, for normal repainting without blast cleaning etc.
When you get started yourself, and so the end resultat does not have to be like new, you should pay attention to the following things:
- Work dust-free, that is, not under a tree! And dust the surface with a tack cloth before painting.
- Work dry! Paint, in particular, turns dull in a humid environment. Actually, you can only paint from 15 degrees. Check by means of a blotter that the hull is not condensed. If it sticks, then the surface is damp. There are special products on the market for painting from -5, but you won’t find these in the watersports store and they are also a lot more expensive than the well-known agents.
- Be well informed about the products at your local watersports store, not your neighbor’s.
- Purchase a good sander, some brands are Festo (my favorite), Rupens, Hitatchi, and a Bosch will do as well. But please no Black and Dekker, Einhell or other Aldi stuff. It vibrates harder than it sands, and you take three times as long to get the desired result. Good stuff is expensive!
For more advice, please contact us at look at our advice page.