Our Benchmark testing grounds were taking the same wellprotected "vik" or bay at full speed in pretty simular conditions before and after the boatwash to get a feel of how bad a dirty hull influences fuel and speed just before and after our boatwash.
Same crew, same weather, no real opposing winds or high waves.
The results are as expected, but it really proves it is worth to wash your hull at least twice a season (or if you are a heavy boater) three times a season as it will increase speed, and drastically reduce fuel consumption.
Measurements done against GPS Speed and engine fuel consumption.
Before:
Max speed: 22.6 knots with a steady fuel consumption of 56 liter / hour.
After:
Max speed: 33 knots with a steady fuel consumption of 56 liter / hour or 10 knots faster as before the wash.
The Vanrillaer Family \Fam"i*ly\, n.; [L. Familia Vanrillaris, ]
1. The collective body of creative persons who live in one house on a non-disclosed island in the middle of the archipelago. The boss of the household, Wiveka, further including other parents like Boris, a bunch of children listening to the christian names of Kalle & Birk, a Cricetus Frumentarius, a variety of electronic servants, and, as the case may be, lodgers, boarders or other guests around the seasons.