Lcg & Vcg

[fmmarco]

Hallo:

I`m looking for a method to estimate the LCG and the VCG of a modern 40' cruiser sailing yacht.

Someone knows a formulae, or same method for aproximate this values in preliminar stage of designing?

Thanks a lot,

Fmmarco

[SailDesign]

If the boat is floating to its lines, then the LCG is , by definition, at the same position as the LCB. If you guessed wrong, though, the boat will never float to its lines.
Bottom line here is that there is no way to estimate it. Weights will be where the will be, and you just have to calculate it the old-fashioned way - by adding up the weights and centres, and designing a hull to fit.
Just one of the little hidden skills of design.

VCG? Same problem!

Steve

[Guillermo]

SailDesign gave you a clue to LCG.
A very, very rough estimative of VCG, is around waterline.
But I agree with SailDesign: You should perform a weights estimative, fit lines to match and so on back and forth.
Cheers.

[MikeJohns]

fm marco

This seems to be a perrenial problem these days . You are designing a big boat with no idea whatsoever about the design spiral ? Is this a design just for learning or do you plan to build it?

Perhaps start with "How to design a boat" by John Teale it is a good gentle introduction for the newbie.

If you can get the numbers from a similar boat of the same construction it will be the best initial guide.

Cheers