dom
Well-Known Member
Quick background point from one of the French teams this morning -- perhaps interesting to some:
These vessels have all been designed by 'expert' design teams, but expert in this sense means the use of theoretical frameworks calibrated in imperfect empirical data. Pure theoretical models are not possible to fully constrain as there are simply too many variables.
For which reason the testing of, for example, aircraft wings involves a ton of calcs, myriads of expensive sensors, and extensive mandatory stress cycles. In terms of boats, designers should really apply 3 load calcs/tests: maximum normal load limits, ultimate load specifications, and finite element model calculations (FEM). Is this done in practice? (i) and (ii) are, but (iii) is not.
Because FEM testing returns us to the problem of models need be calibrated and validated empirically, which implies testing samples and test mock-ups to destruction under controlled environments. This doesn’t happen with pleasure boats and there simply isn't the data for cutting-edge vessels. Not through any fault of the designers, because a detailed knowledge of the materials is necessary and laminates are still not rigidly controlled enough and are subject to too much human error and variance to accurately model in the ultimate stress sphere.
In fact, the strength and characteristics of laminated hulls can vary widely within the same production line. Not to mention the changes in dynamic loading that could have been brought about by the reinforcement and design retrofitting applied to both HB and PRB.
NOBODY is blaming anyone here, such is the nature of budget-constrained pioneers, but there's something going on here and other competitors with similar boats are taking note.
Here's wising everyone a safe journey from here on in. As for "Yes we Cam!"
....it seems like you truly Cam!!
These vessels have all been designed by 'expert' design teams, but expert in this sense means the use of theoretical frameworks calibrated in imperfect empirical data. Pure theoretical models are not possible to fully constrain as there are simply too many variables.
For which reason the testing of, for example, aircraft wings involves a ton of calcs, myriads of expensive sensors, and extensive mandatory stress cycles. In terms of boats, designers should really apply 3 load calcs/tests: maximum normal load limits, ultimate load specifications, and finite element model calculations (FEM). Is this done in practice? (i) and (ii) are, but (iii) is not.
Because FEM testing returns us to the problem of models need be calibrated and validated empirically, which implies testing samples and test mock-ups to destruction under controlled environments. This doesn’t happen with pleasure boats and there simply isn't the data for cutting-edge vessels. Not through any fault of the designers, because a detailed knowledge of the materials is necessary and laminates are still not rigidly controlled enough and are subject to too much human error and variance to accurately model in the ultimate stress sphere.
In fact, the strength and characteristics of laminated hulls can vary widely within the same production line. Not to mention the changes in dynamic loading that could have been brought about by the reinforcement and design retrofitting applied to both HB and PRB.
NOBODY is blaming anyone here, such is the nature of budget-constrained pioneers, but there's something going on here and other competitors with similar boats are taking note.
Here's wising everyone a safe journey from here on in. As for "Yes we Cam!"
....it seems like you truly Cam!!
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