How much paint do I need?
Applying the right thickness of the paint is very important. For instance, to prevent osmosis the coating system acts as barrier against the penetration of water vapour. If not thick enough, chances on osmosis are higher. Applying the right thickness is therefore important to achieve good protection.
The same accounts for antifoulings. The whole panel was coated with two layers of antifouling exept the horizontal band in the middle that only received one coat of paint. It is clear that after the same immersion time, the first coat of antifouling has been consumed already and slime starts to grow. all other parts with two layers of antifouling are clean. For this reason it is always advised to apply two layers of antifouling.
In Transocean product information you always find the spreading rate in square meter per litre for the recommended dry film thickness. In order to calculate the litres op paint required you need to know the surface area of your boat and how many layers you have to apply. From our vast experience in practice applications, Transocean has compiled a table that helps you to get a fair estimation of the surface area of your type of boat.
1. Formula surface ares of underwater hull
Surface area in m² = Hull coefficient x length (at waterline) x (width + draught)
The hull coefficient, determined by the shape of the hull, is given in the table below.
| Type of boat | Hull coefficient |
| Underwater hull of motor boats | 1 |
| Sailing boats with planning hull | 0.75 |
| Sailing boats with keel | 0.5 |
2. Formula surface area freeboard (topside)
Surface area in m² = 2 x length (overall) x width x height (waterline to deck)
3. Formula surface area decks
Surface ares im m² = 0,75 x length (overall) x width - surface area cabin.
Notes:
- Once the areas have been calculated, the required paint volume can be calculated with details (volume solids) from the product datasheet and specified thickness. Our paint calculators for use on your own computer can be downloaded on our documents page.
- Remember that rough or porous substrate require more paint. Also by using thinners, spreading rates can change too. Therefore, above formulas are not absolute figures, but using them enables you to get a good result.
