Strip planking thickness

Discussion in 'Class Societies' started by DUCRUY Jacques, Jan 22, 2011.

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DUCRUY JacquesJunior Member

Hello,

I find a formula in the ABS ORY rules for calculate the thickness of a carvel planking : is this formula valuable also for the traditionnal strip planking ?

This formula is not very clear for me :

t = 1.09 * (4.2 - (1.13 L^0.25)) * s * ((0.001 Fh/St)^0.50

with St : admissible stress (for example for mahogany 8 * 0.4 = 3.2 Kg/mm²

It seems to me that the result is a irrealist thickness (too much ?).

Is my interpretation correct ?

Have a nice week end

Jacques

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rwatsonSenior Member

Generally, the term "strip planking" is associated with fibreglass inner and outer cover.

Without the fibreglass "skins", strip planking *is* Carvel planking

Maybe you were referring to Clinker Built V Carvel Planking ?

eg http://en.wikipedia.org/wiki/Carvel_(boat_building)

Last edited: Jan 22, 2011
3. Paul KotzebuePrevious Member

Strip planking refers to narrow planks with edges nailed and/or glued to each other. Carvel planking has caulked seams. Carvel scantlings should not be used for strip plank construction. ABS ORY design pressures can be used to derive strip plank scantlings using the same principles as cold molded construction, with the planking treated as a unidirectional material with no strength perpendicular to the direction of the grain. ISO 12215-5 has specific guidance for strip plank construction scantlings.

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DUCRUY JacquesJunior Member

Thank you very much.

If my understanding is good, in ISO 12215-5, the admissible stress is :

for cold molded : modulus of rupture * 0.30 * 0.5 (FOS)

for strip : 1.6 * 0.07^0.5 * modulus of rupture * 0.5 (FOS)

and the good formula for thickness :

t = s ((0.5 Fh)/(1000 st))^0.5

But the rule for strip planking is not very clear in ABS ORY !

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