1. Keel rigidity:
Block with a clamp (protecting well the keel before) the keel on a table, and leaving 400mm of keel could exit.
Put a standard 2800 grams weight to flex the keel and measure the flexion distance. The lower is the distance and the better is the keel. If you use a bulb of 2800 grams instead the
standard weight control that the central bulb axe is at 400mm from the table.
If your bulb is heavier or light weight respect 2800 grams, increase or decrease the 400mm distance following this formula: Distance=1120000/your bulb weight in grams.
For example your bulb is 2850g the distance is 1120000/2850=393mm.
Reference values:
-More than 50mm, Not so good
-Between 40mm and 50mm, Normal
-Between 30mm and 40mm, Very good
-Less than 30mm, Exceptional
2. Keel thickness:
Measure the keel thickness (with a normal keel width of 80mm>90mm).
Reference values:
-More than 7mm, Not so good
-Between 6mm and 7 mm, Good.
-Between 5mm and 6 mm, Perfect.
-Less than 5mm Not so good.
3. Boat vertical mass distribution:
Use a chair as shown on the picture:
Control that the distance between the hull and the lower bulb side is 420mm and the total boat weight has to be ready to sail. Find the equilibrium vertical point. If the boat bow, or
stern, is heavy, the boat could rotate: that could be normal, let that the boat find its lateral equilibrium point. When the boat will be perfectly stationary, measure, as shown on
the image, the distance between the lower part of the bulb and the equilibrium point:
The shorter is the distance and the better the boat is.
Reference values (with a standard keel+bulb 420mm distance):
-More than 250mm, Not so good
-Between 250mm and 240mm, Normal
-Between 240mm and 230mm, Good
-Between 230mm and 220mm, Very Good
-Less than 220mm, Exceptional
4. Boat rigidity:
Put your boat on a rack as shown on the picture:
Control that the distance between the hull and the lower bulb side is 420mm, the total boat weight has to be ready to sail and that the two rack arms are perfectly flat.
The bulb has to be outside one arm of the rack.
The distance between the second rack arm and the hull has to be nearby 110mm,
as shown on this picture:
If the boat rotates laterally block the hull putting a little weight on the rudder.
Masure the distance between the floor and the mainmast head as shown on this picture:
Then measure the rack height and calculate the boat flexion:
(Rack height)-(mainmast head height).
The lower is the value and the rigid is the boat.
Reference values:
-More than 400mm, Not so good
-Between 400mm and 300mm, Normal
-Between 300mm and 200mm, Good
-Between 200mm and 100mm, Very Good
-Less than 100mm, Exceptional
