Spikes and negative trends in displacement curves

I have noticed some negative spikes in displacement/volume curves for appendages when the waterplane reaches very near to the top of the appendage.
All these appendages have tumble home. This may be significant, though two other sections with very similar tumble home had no spike at the chosen depth increment.
I repeated the runs with finer depth increment and the spikes are there. In some cases multiple spikes, all very near to the top of the appendage
There are also cases where there are several negative spikes and some draught ranges with a general negative change in calculated volume with increasing draught.
These appendages (with the general negative trend)are admittedly oddly shaped, and I suspect that the algorithm is interpolating badly in these areas.
Cheers,
Peter


Negative Spikes

Hi Peter,

These bugs I think are all related to an error in the section area calculation routine. A copy of the model and log file would help greatly in resolving.

Many thanks

John

jamac
Site Admin
email - info_at_naval-architecture_dot_co_dot_uk


Copy of model

I have already sent you the model file (the catamaran).
Do you need a different log file to the one I sent?
Cheers,
Peter


Model File Rcd Thanks

Hi Peter,

Model file recevied thanks. Can you send the log file after you run a load case that gives you problems. A set of hydros or description of hydro case you are having problems with would alos greatly help thanks.

Have a great New Year.

Best Regards

John

PS Have posted that image you were looking for elsewhere on KN description and will include in the next issue of the manual.

jamac
Site Admin
email - info_at_naval-architecture_dot_co_dot_uk