What to check on a Boot Topping Coating.
The boot top band sees a different exposure than either the submerged hull below it or the topsides above it: it is wetted and dried repeatedly as the ship rolls, changes draught with loading, or simply sits at anchor with a shifting waterline. That cycling, combined with direct sunlight exposure that the permanently submerged hull never gets, breaks down antifouling biocide release and topside gloss coatings faster than either was designed for. Boot topping is therefore its own coating system, chosen for abrasion and cycling resistance rather than for antifouling…
What Sets This Type Apart
The boot top band sees a different exposure than either the submerged hull below it or the topsides above it: it is wetted and dried repeatedly as the ship rolls, changes draught with loading, or simply sits at anchor with a shifting waterline. That cycling, combined with direct sunlight exposure that the permanently submerged hull never gets, breaks down antifouling biocide release and topside gloss coatings faster than either was designed for. Boot topping is therefore its own coating system, chosen for abrasion and cycling resistance rather than for antifouling performance or gloss retention alone.
Main Components
Surface preparation
Abrasive blasting to the specified cleanliness and profile is the foundation; boot top failures trace back to inadequate surface preparation more often than to the coating product itself, because this band takes more mechanical abuse from fendering, ice and floating debris than the rest of the hull.
Primer / anticorrosive coat
Typically an epoxy anticorrosive, matched to the same system used on the adjoining hull and topside areas so the boot top does not become a compatibility weak point at its overlap seams.
Intermediate / tie coat
Where the primer and finish coat chemistries differ, a tie coat is used to secure adhesion between them, particularly important given the flexing and abrasion this band experiences.
Finish coat
A high-build, abrasion- and chemical-resistant finish, often in a contrasting colour from the hull and antifouling for visual demarcation of the waterline and easy inspection of draught marks.
Selection / Practical Notes
Because this is a simpler, single-purpose product rather than a complex assembly, selection comes down to a short set of criteria.
- Compatibility with the antifouling below and the topside system above, checked against the manufacturer's system compatibility chart, not assumed.
- Colour, chosen for waterline visibility and to make draught mark reading easier for the crew and surveyors.
- Abrasion resistance rating, since fendering contact and ice concentrate here more than on any other hull area.
- Dry film thickness specified per coat, checked with a wet-film gauge during application and confirmed with a dry-film gauge after cure.
Typical Faults
| Fault | Cause | Consequence |
|---|---|---|
| Blistering | Moisture trapped under the film from inadequate surface drying before coating, or osmotic pressure through the film over time | Local coating loss and exposed steel, accelerating corrosion at the waterline |
| Early chalking / gloss loss | Finish coat not rated for the UV and cycling exposure specific to the boot top band | Faster repaint cycle than budgeted, cosmetic degradation ahead of the rest of the hull |
| Mechanical wear at fender contact points | Coating abrasion resistance too low for the vessel's typical berthing and fendering pattern | Localised bare steel and pitting corrosion at contact zones |
| Delamination at draught mark stripes | Poor adhesion where draught numerals were re-touched without proper preparation | Peeling paint immediately adjacent to marks surveyors rely on for readability |
What to Look for in a Supplier
- A published system compatibility chart tying the boot topping product to specific antifouling and topside lines.
- Documented abrasion and impact resistance data, not only antifouling efficacy figures which do not apply to this product.
- Clear recoat interval and overcoating window guidance, since boot topping is repainted more frequently than the rest of the hull.
- Technical support for surface preparation standards specific to a high-wear, cyclically wetted band.
Inspect the boot top at every drydocking even when the rest of the hull coating looks sound; this band ages faster than the hull below it and the topsides above it, and it is usually the first place bare steel shows.