andlauer
New member
Bonjour
I would rise the problem of the weight and balance of the boats.
The wave effect are dynamics and forces the oscillation of the boat.
The inertia of the boat is very sensible to weight and even more to the position of the weight. (M*L*L where M is the weight of the object and L is the distance of the object centre of gravity to the boat centre of gravity).
The inertia of the boat create a pendulum effect with its own period. (remember a mooring at Alderney).
While crossing on a small boat the temptation could be to think loading in a car spirit in terms of volume. I think it would be more wise to think loading in an air-plane spirit in terms of weight and balance.
The maximal "useful" weight of a JC boat is in the magnitude of 500kg. Probably less for some of us. The temptation to move the stuff at stern or bow to keep living area is great.
The balance should favour the most heavy stuff (man, anchor, water food...) next to the centre of gravity.
If the boat is overcharged or un-properly balanced the inertia of the boat will be great. In some conditions (different periods of the pendulum and the waves) the pendulum effect of the boat may be in opposition to the wave forced oscillation. The movement for the hull in the wave is then opposing the boat inertia. It will create, on a very short time, huge accelerations and efforts, specially in the mast (L is great). the efforts have to be supported by the rigging and the structure.
If you re-enforce the rigging the weak point is moved to the structure (chain-plate, keel or hull)
With a limited centred weight the boat is more free to follow the waves and the efforts on the structures are then limited.
Eric /forums/images/graemlins/wink.gif
I would rise the problem of the weight and balance of the boats.
The wave effect are dynamics and forces the oscillation of the boat.
The inertia of the boat is very sensible to weight and even more to the position of the weight. (M*L*L where M is the weight of the object and L is the distance of the object centre of gravity to the boat centre of gravity).
The inertia of the boat create a pendulum effect with its own period. (remember a mooring at Alderney).
While crossing on a small boat the temptation could be to think loading in a car spirit in terms of volume. I think it would be more wise to think loading in an air-plane spirit in terms of weight and balance.
The maximal "useful" weight of a JC boat is in the magnitude of 500kg. Probably less for some of us. The temptation to move the stuff at stern or bow to keep living area is great.
The balance should favour the most heavy stuff (man, anchor, water food...) next to the centre of gravity.
If the boat is overcharged or un-properly balanced the inertia of the boat will be great. In some conditions (different periods of the pendulum and the waves) the pendulum effect of the boat may be in opposition to the wave forced oscillation. The movement for the hull in the wave is then opposing the boat inertia. It will create, on a very short time, huge accelerations and efforts, specially in the mast (L is great). the efforts have to be supported by the rigging and the structure.
If you re-enforce the rigging the weak point is moved to the structure (chain-plate, keel or hull)
With a limited centred weight the boat is more free to follow the waves and the efforts on the structures are then limited.
Eric /forums/images/graemlins/wink.gif