Peppermint
New member
Below is a precise of a case from Australia.
Resistance to shear forces in composite structures is a bit of a nightmare to calculate and if your searching for lightness it’s pretty critical.
Also interesting to note that. If a yacht is constructed for sail training the inspection cycle during construction and the standards of that construction are rigorous. Whereas, if a yacht is brought into sail training post-build i.e. secondhand a visual survey is all that is required.
“The NSW Coroner has recently completed his Inquest into the deaths of two (of the six) members of the crew of the yacht “Rising Farrster”, a Farr 38 owned by "Flying Fish Leisure Management International (LMI)", a UK based organisation, and built by Binks Yachts of South Australia in 1993.
The Coroner found that both deaths occurred as a result of drowning when the keel of the yacht separated from the hull causing the vessel to capsize.
“Rising Farrster” was on a sail training passage from Southport, Queensland, to Sydney, NSW after having previously made the passage from Sydney to Southport, when she capsized off Evans Head. The wind was about 20 knots with a 1.5 metre swell.
The cause of the capsize was established to be that the fin keel separated from the hull unexpectedly; within 15 to 20 seconds the yacht had capsized.
The primary cause of the failure was inadequate hull shell thickness in way of the keel washer plates.
The 1986 revision of the ABS guide does not properly account for the shear loads at the edge of the washer plates in the case of “Rising Farrster”. In fact the 1986 ABS required minimum hull shell thickness of 6.8 mm is only 37% of the 18.5 mm of thickness required to produce a safety factor of 2 on shear stress in way of the washer plates.
The 1996 (sic 1994?) version of the ABS guide does not properly account for the shear loads of the washer plates in the case of “Rising Farrster”. To comply with the later revision, the hull shell laminate in way of the washer plates would have been required to be a minimum thickness of 27 mm.
His Worship's relevant recommendation is "The Australian Yachting Federation (now known as Yachting Australia), in conjunction with the Yachting Association of NSW, and yacht clubs endeavour to contact owners of light displacement yachts fitted with fin keels subject to pre 1994 ABS approval, to provide them with a précis of my summing up, findings and recommendations at inquest in order that appropriate decisions can be made by owners as to checking and/or modification of yachts."“
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Resistance to shear forces in composite structures is a bit of a nightmare to calculate and if your searching for lightness it’s pretty critical.
Also interesting to note that. If a yacht is constructed for sail training the inspection cycle during construction and the standards of that construction are rigorous. Whereas, if a yacht is brought into sail training post-build i.e. secondhand a visual survey is all that is required.
“The NSW Coroner has recently completed his Inquest into the deaths of two (of the six) members of the crew of the yacht “Rising Farrster”, a Farr 38 owned by "Flying Fish Leisure Management International (LMI)", a UK based organisation, and built by Binks Yachts of South Australia in 1993.
The Coroner found that both deaths occurred as a result of drowning when the keel of the yacht separated from the hull causing the vessel to capsize.
“Rising Farrster” was on a sail training passage from Southport, Queensland, to Sydney, NSW after having previously made the passage from Sydney to Southport, when she capsized off Evans Head. The wind was about 20 knots with a 1.5 metre swell.
The cause of the capsize was established to be that the fin keel separated from the hull unexpectedly; within 15 to 20 seconds the yacht had capsized.
The primary cause of the failure was inadequate hull shell thickness in way of the keel washer plates.
The 1986 revision of the ABS guide does not properly account for the shear loads at the edge of the washer plates in the case of “Rising Farrster”. In fact the 1986 ABS required minimum hull shell thickness of 6.8 mm is only 37% of the 18.5 mm of thickness required to produce a safety factor of 2 on shear stress in way of the washer plates.
The 1996 (sic 1994?) version of the ABS guide does not properly account for the shear loads of the washer plates in the case of “Rising Farrster”. To comply with the later revision, the hull shell laminate in way of the washer plates would have been required to be a minimum thickness of 27 mm.
His Worship's relevant recommendation is "The Australian Yachting Federation (now known as Yachting Australia), in conjunction with the Yachting Association of NSW, and yacht clubs endeavour to contact owners of light displacement yachts fitted with fin keels subject to pre 1994 ABS approval, to provide them with a précis of my summing up, findings and recommendations at inquest in order that appropriate decisions can be made by owners as to checking and/or modification of yachts."“
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