Center of weight – how to implement

[Andre Langevin]

I have Delfship PRO 3.2 and have used it for hydrostatics of a 45 feet sailboat. I wonder if it would be possible, and with which extension, do enter the weight of the steel plate and obtain a center of weight, then being able to adjust the ballast for the boat to float even on the water ?

Regards,

André

[MICHAEL KERR]

Hi Andre,
In the layer properties you can nominate the thickness of hull and superstructure materials and its cubic weight, the results can be viewed in View–>hydrostatics–>under hydrostatics report in the Layer
Properties section the totals and centre of gravity are shown. For all other weights such as interior furnishings, ground tackle, tanks (water and fuel) engine, crew, winches etc etc etc and there COGs, the Load Cases module is designed for this purpose. You can also add the COG of the yachts ballast.
I use the Tanks module to add the ballast to the keel because it treats the keel as an other tank and the lead weight fits exactly inside the keels interior walls. In the Tank module you can nominate the cubic weight be it water, diesel fuel, lead, concrete or iron.
In the Load Case module all tanks created in the Tanks module can be auto tranfered in to Load cases and LC will balance the yacht or ship for you and provide you with a detailed report including Stability Curve and you can import Windmoments and Windsilhouette and also if your vessel passes IMO Stability Criteria which I dont fully understand.
Mind you, if your only designing one yacht most of this can be done with pen and paper, if you have the time and your maths is a lot better than mine.
Mike

[Anonymous]

Hi Mike,
I got input problem with loadcase,as I have seen in the manual I change thickness of the shell and density of plate as 0.08;7800 so the result has come with weight of the hull…
But i have no idea how i can make this result get into loadcase,in the loadcase lightship weight is shown as 0
then it affects my result of loadcase as well.
Could you give any ideas how i can make this work???
do i have to enter more info like height of gravity center of hull??

Regards,

Baran

[MICHAEL KERR]

Hi Baran,
for example, mild steel weights 7850 kg/m3 so it would be entered in the Density column as 7.850 , (lets say plywood weights 368 kg/m2 so it would be 0.368) , if your steel thickness is 10mm that would be entered in the Thickness column as 10.00 after you enter your density and thickness press Enter so its locked in, then go to Design Hydrostatics, you will see a list of all your Layers, they will include Layer Name, Area, Thickness, Weight and the 3 COGs, this will be automatically transfered to Load Cases under Lightship. Let me know how you go ?

Mike

[Anonymous]

Dear Mike,

I did as you said but after entering shell thickness 10 in design hid. report hull weight is shown as around 700000 tonnes then i changed it again as .01 maybe because of my version it has never been locked so i found a way to put this weight in loadcase “list of weight items” though seems like a find a solution afterwards i got better loadcase results…of course some values like VCG and LCG have entered depending on my estimation earlier…

Thanks a lot

[MICHAEL KERR]

Hi Baran,
Im starting to get a bit confused, only because I cant see what your doing, if its alright with you, could you send me your file and Ill run it through my hull modeller and loadcases for you. Then I can send it back to you.

mike101@exemail.com.au

Mike

[Anonymous]

Allright there aint no problem for me to send the file..
My version is 4.03 do i have to change it?? or you ll be able to open any “.fbm” file??

Baran

[MICHAEL KERR]

Hi Baran,
I have the latest version 4.27 according to the update manager so as long as its 4.27 or earlier it should be OK.

Mike

[Author]

Posts