Which hull type is more stable?

[kach22i]

Originally Posted by Wynand N

stable ....hard chine flat bottom or hard chined V bottom?

Might be something of interest in this old thread:
Lost power in heavy seas - which hull shape?

[lewisboats]

Originally Posted by daiquiri

Hi Terry,

Please find attached a sample dialog screen of Freeship's SSD command. I've circled in red the dialog box where you input the Zcog, and the graph where you read the calculated curves for various Zcog.

As for your second question, it can be corrected manually too - and it is not so difficult. The formula is:

GZnew = GZold - Dz sin(Heel)

where:

- GZold is GZ at the initial vertical position of the CoG, for a given heel angle
- GZnew is GZ for new vertical position of the CoG, for that heel angle
- Dz is the vertical shift in CoG, positive when upwards
- Heel is... the heel angle.

The effect of a horizontal (transverse or beamwise) shift of the CoG is evaluated in a similar manner:

GZnew = GZold - Dy cos(Heel)

where Dy is the transverse shift of CoG. It is positive when contributing to the heeling moment, negative when contributing to the righting moment (canting keel, for example, or a sailor on a trapeze).

Hope it was clear enough. Cheers.

If you are using the original FreeShip...this is not available. You must download FreeShipPlus. Freeship does not have the SSD and the screen that you show. Therein perhaps lies the confusion.

[ancient kayaker]

Yes, so I discovered! Oddly, I thought I had created a post thanking Daquiri and noting the problem, but it somehow vanished into cyberspace. The lack of SSD/DSD curves is not a big problem however, as it is simple to make manual corrections. Thanks to both of you for the help!

[daiquiri]

Oh, I thought indeed we were talking about Freeship+ .
I never understood what's the difference between the two anyways...

[lewisboats]

FreeShip 2.6 is the last version of the original by Martijn...FreeShip+ is a continuation with additional features added by Victor T...mainly in the resistance area but also with stability as we can see.

[ancient kayaker]

I now have the Plus version, thanks for the help!