|
|
General HydroStatics
Ship Stability Software |
|
Command of the Week
(New or interesting aspects of GHS that you may not know about) |
|
SEA /ROLLTANK
(Requires GHS version 17.02 or later with SK) |
|
John Bonn, our favorite unsuspecting naval architect, who no doubt reads every single word of every single COW, called us one recent afternoon because he was deeply troubled by something.
"John, it is good to hear from you. It has been some time." "Yes, I've been spending a lot of time pretending to work from home. But, I have a new job in the pipeline." Although it wasn't unusual for John to be deeply troubled by a new job, we assumed that by reading every single word of every single COW, what on Earth could he possibly be missing? "Have you ever heard of a roll tank?" "Why yes, John, we have." "Well, I need to analyze the effects of one of those in some seakeeping work." John went on to explain that he doesn't know anything about roll tanks, because, frankly, there is nothing about them in any of the COWs. Of course, we sympathized with his dilemma, but we also had some good news to share. "Well, John, we've actually had support for roll tanks in GHS since version 17.02, but we never told anybody about it, save our families and close friends." "Am I not one of your closest friends?" Replied John. Quickly changing the subject, we explained to John that we would send over an example run file by the end of the day. Including a roll tank in a seakeeping analysis requires only the /ROLLTANK parameter on the SEAKEEPING command. It would look something like: |
|
`... set up geometry, condition, and wave
load (rolltk.c) 0.69 `load roll tank so sea /head:90 /data:withtank\re,ta /rolltank:rolltk.c |
|
However, unlike some methods, the GHS logic uses the modeled roll tank geometry, so you'll need to model the tank in the GF and pass the component name to /ROLLTANK, as shown. We won't get into how to design an optimal roll tank here (we know John won't be pleased), but if the tank is tuned to the vessel's natural frequency, you'll see significant attenuation of peak roll amplitudes: |
|
| As for the run file we promised to John, you can find that here. |
|
Questions, comments, or requests?
Contact Creative Systems, Inc. USA phone: 360-385-6212 Fax: 360-385-6213 Office hours: 7:00 am - 4:00 pm Pacific Time, Monday - Friday Mailing address: PO Box 1910 Port Townsend, WA 98368 USA Click here for an index to this and previous COWs |