When doing an annual refit and painting a new antifouling, you will need to know the right quantity to buy. To do this, you need to know the surface area of the hull and refer to the manufacturer's recommendations to apply the optimum quantity.
An over-thickness leads to unnecessary pollution and increases the cost of the work. On the other hand, a lack of thickness can cause the premature appearance of "dirt", and a dryness in the middle of the season.
However, from one year to the next, we often forget how many pots were consumed during the preparation of the launch.
How to define the right amount of antifoulingeuros?
We suggest you use the following 3-step method to determine, with relative precision, the volume of antifouling paint you will need.
1 - Determine the surface to be painted
We will use a formula that takes into account the type of boat. Thus you can know the approximate surface of your hull. These formulas do not include the keel or the rudder(s). You will have to add to the result the calculation of the surface area of the appendages which are generally easy to measure (L x W) x 2.
S = Surface of the hull (in square meters)
L = Length at waterline in meters
l = Width at the beam in meters
TE = Draft or hull depth in meters
For modern sailboats
S = 0.5 x L x (l+TE)
For motorboats
S = L x (l+TE)
For traditional sailboats (long keel)
S = 0.75 x L x (B+T)
2 - Determine the number of liters for a layer
To determine the number of liters of product per coat, divide the surface area by the hiding power of the paint you have chosen. The hiding power is written on the back of the antifouling cans. In general, for a roller application, the coverage is between 7 and 9 m 2 per liter.
The covering power of a paint depends on :
- The application method (spray, airless, roller)
- Of each formulation (hard or erodible matrix)
- From each manufacturer
3- One last calculation before going to the dealer
To get the total amount of paint to buy, you will multiply the result calculated above by the number of coats you want to apply.
Manufacturers generally recommend two coats per year.
Tips for better protection
Feel free to apply an extra coat of paint to the appendages, especially along the leading edges. Do the same along the waterline.
Indeed, the friction of the water due to the turbulence to which these zones are subjected causes the early degradation of the antifouling.
