Cop-R-Bote Coverage and Quantity Estimation.
You can plan on 10 to 12 square metres per litre per coat, with a recommendation of 3 thin coats. Thus you can expect to use about 250ml per square metre.
The question of how much area my boat has underwater is a bit harder. We have doen measurements on a number of boats and have come up with an approximate underwater surface area table. This table gives an ESTIMATE of how much will be required for typical boat hulls.
LWL | Beam | Approx under
water area |
Estimated
Cop-R-Bote required |
6m | 2.2m | 18m^{2} | 3.6L |
7m | 2.6m | 18m^{2} | 5L |
8m | 3m | 32m^{2} | 6L |
9m | 3.3m | 41m^{2} | 8L |
10m | 3.7m | 50m^{2} | 10L |
11m | 4m | 61m^{2} | 12L |
12m | 4.4m | 72m^{2} | 14L |
14m | 5.2m | 98m^{2} | 20L |
16m | 6m | 128m^{2} | 26L |
18m | 6.7m | 162m^{2} | 32L |
20m | 7.4m | 200m^{2} | 40L |
This table is a useful estimate for motor cruisers, trailer sailers, conventional keeled yachts and (interestingly) catamarans. It estimates the amount of Cop-R-Bote required to apply two coats at 10 sq metres per litre.
If the boat's beam is 20% greater, increase the amount of Cop-R-Bote by 10%.
If the boat's beam is 20% less, decrease the amount of Cop-R-Bote by 10%.
Formulae. (Dimensions metres and square metres).
This table. Underwater Area = 0.5 * LWL * LWL
Previous Boatcraft formula. Area is between 0.5* LWL* (Beam + Draught) and Area = LWL * (Beam + Draught )
Another formula. Area = 0.85 * LWL * BEAM
Of course you can set about calculating your boats underwater area more accurately, but when it is all said and done, what is needed is an area which is close ( within 10% or thereabouts) of the actual area, which will allow you to buy enough to do the job, but not leave much over, so great accuracy is not really needed.