Balanced yacht and LCF movement when healed in MaxSurf

[Mikey]

Quote from Ian Ditmore in the thread about hull Balance
I think the method referred to by Coozeman is the same as that discussed by designer Cyrus Hamlin in his book "Preliminary Design of Boats and Ships", pages 195-197. His method is to calculate heeled LCF (center of the waterplane) at 30 deg (25 deg for flat bottomed/shoal draft hulls) without allowing the hull to retrim from static upright trim. He then takes the distance between the upright and heeled LCF's as a percentage of waterline length. Hamlin recommends that the LCF should shift aft as the boat heels, but the shift should be less than 1% of DWL.
End Quote

I am trying to check this in MaxSurf by rotating all controls 30 degrees. Does anyone know if it works to do it this way in MaxSurf?

Mikey

[Andrew Mason]

Mikey

Maxsurf is not ideal for this, you really ned Hydromax to do heeled hydrostatics.

If you don't have access to Hydromax, you can do it it Maxsurf by duplicating and flipping the hull surfaces around the centerline, then making each surface asymmetrical. If you don't do this before you do the rotation the mirrored port side of the hull will rotate the wrong way opening up a split in the hull.

If you make the port side of the hull real, rather than just a mirror image of the starboard side then the rotation command will do the right thing.

Once you have rotated the hull you will need to move either the hull vertically until you get the displacement you want, or move the waterline using the Frame of Reference dialog to acheive the same thing.

Hope this helps

[Mikey]

Thanks for quick response Andrew. Yes, works perfectly now.

Mikey