principle dimenstion control

[raheeb23]

dears,
can somebody help me finding a complete document in principle dimensions issues in ship buildings. for example.

how to control breadth? how to do half breadth measurements? what tool should be used?

and all other principle dimensions: sheer, camber.....height.....block alignement control.

also does any body have any idea how to control workshop centre line Vs block centre line.


thanks,
raheeb23

[Stephen Ditmore]

Do you mean how to establish what the parameters SHOULD be in the preliminary design process?

Or do you mean how to build a vessel accurately once you have a set of plans in hand?

[raheeb23]

dears,

i mean how to build a vessel accurately once you have a set of plans in hand?

as you know steel vessels are build by blocks, but how to insure the accurancy of these blocks? how to insure the sheer iam obtaining? how to insure the camber iam obtaining? how to insure the basic dimensions such as half breadth at defferent locations.....?

thanks,
raheeb23

[Stephen Ditmore]

Thanks for clarifying, Raheeb. Unfortunately I don't know the answer. I'd have done better with the other question.

Anyone...?

[marshmat]

Very careful measurement. CNC is becoming increasingly popular to ensure that everything fits perfectly. But you need the experience with measuring and building, in order to know what to do. Books can help but nothing beats time on the shop floor
The simple fact is, though, that one can't simply jump into boatbuilding and expect it to work flawlessly. It's still many years as an apprentice or shop worker, for most people, before they can become the shop foreman.

[jehardiman]

Marshmat has is correct. Only skilled shipwrights can do that. And no amout of technology (e.g. lasers, which won't work on large ships BTW as the hull follows the curve of the earth) will help the unlearned.

Edit to add. Also, how tight of control do you really need? Temperature changes alone are 0.5cm per 30m in steel. I expect the finished length of 150m vessel to be +/- 10cm just from allowable weld fit-up. Remember, in large steel shipbuilding, you may design it on a computer to 0.0001mm, but the machine/man that cuts the plate will have a 1 +/- 0.5 cm throat in the torch and the welder will fit it up 0.5 +0.25/-0.5 cm.