Slamming loads on a small high speed craft

[nikezz]

Hi all,
From experience, does anyone know of the slamming loads if you travelled on a small HS craft?

At
25 knots
Sea State 3

The craft would be about
12m length
5 tonne displacement

Edit: 5 tonne

[Mr Efficiency]

The biggest slam would come at the fuel pump, directly to your pocket ! Any 50 tonne, 12 metre length vessel would need to be jet propelled to reach 25 knots.

[rxcomposite]

That is not a HS craft. That is a displacement boat at 12 meter, 50 ton displacement. Is it an oil rig?

[PAR]

Without considerably more data about what you want, the vessel and the context, you're not going to get much more the glib replies from the board members.

[nikezz]

I apologise. That was a typo. It was meant to be 5 tonnes.

[PAR]

You can't possibly think that you've provided enough information to warrant a reasonable reply do you?

The answer is . . . yes.

[Mr Efficiency]

This thread is making excellent progress, isn't it ? Keep up the good work, I say !

[rxcomposite]

Probably because it is too easy.

"The hydrodynamic load on the panel is
calculated by dividing the panel into several
strips. The flow over each strip and the
corresponding pressure distribution is
derived by a Wagner-type approach as
described in [13]. The actual response of the
panel is calculated by a modal approach.
The generalised hydrodynamic forces are
derived by integrating the pressure over
each strip. The response and, in particular,
the instantaneous velocities on each point of
panel surface, are then obtained and
summed to the overall rigid-body velocity to
calculate the panel immersion and the
hydrodynamic loads for the following time
step. With a constant or decaying impact
velocity, the maximum amplitude of
response is attained during the first cycle of
oscillation of the panel; hence the iteration is
normally stopped after the first response
peak is observed."

An alternative approach to the design of structures exposed to
slamming loads.
P.F.Manganelli, M.A.Hobbs, SP Technologies, UK

[PAR]

The Wagner impact theorem has a low angle deviation that's unacceptable to most. Are you recording peak pressures during transitional impact or maximum strains on impact or averaging pressures at impact?

[Mr Efficiency]

As a rule of thumb, with slamming loads, the people break before the boats.

[nikezz]

I see. Quite different from what I've heard. Strangely, another someone told med "Most importantly, we need to know the boat speed, length and displacement and also a little bit about the shape of the boat." to estimate the g's.

May I know how you guys do it instead and what information you require?