Paddy,
ben tornato !
Io mi rivolgevo, come sempre, ai coloro che vogliono iniziare questo hobby e non tutti hanno il computer a disposizione e le competenze per usarlo.
Quindi resto fedele al gesto manuale che tutti possono applicare velocemente. Questa é la ragione delle innumerovoli foto fatte con descrittivo della operazione eseguita.
Negli USA, Dave Acree,
Center Of Effort
suggerisce il metodo di spinta laterale di un modello senza vele ed immerso in una piscina.
Per fare più 'complicato' un'altro ha fatto la stessa ricerca del CAD o CLR o CLP facendo inclinare la barca aggiungendo un peso in cima all'albero tanto da far inclinare il modello intorno ai 30° e poi spingerlo lateralmente fino a trovare il punto di equilibrio. Lo farei, ma non ho la piscina !.
Scusa il francesismo, per 'ardente' intendo 'orziera'
Ciao
ClaudioD
PS
fra le tante cose ho trovato anche questo che per te sarà più familiare
:Wind,
There are two methods to calculate the center of lateral plane: In Autocad, and with scissors, paper, pencil, and a triangle scale (what could be referred to as the kindergarten method)
AutoCad: Assuming your profile is in AutoCad, a 2-D drawing, using a polyline, trace around the entire underwater profile area. With the REGION command, declare the polyline a REGION (Type REGION on the command line, and select the tracing polyline as the region). Set the Origin of the drawing at some convenient point on the drawing, such as the front end of the waterline (TOOLS-NEW UCS-ORIGIN). Then on the command line, use the MASSPROP command to determine the mass properties of the region (MASSPROP, select the region you just created) and a window will pop up with the mass properties of the region. Included in those properties will be the centroid coordinates of the center of area (or mass) from the origin. Using those coordinates, you can put a point or a set of cross hairs at the centroid location.
Kindergarten method. Print out to scale a copy of the underwater profile on a piece of paper, and glue it to a piece of cardboard such as the back of a tablet of paper. Cut out the paper and cardboard outline of the underwater profile with a pair of scissors. Bend the profile slightly with a smooth curve from one end to the other so that it is not perfectly flat. Place a triangle square on a flat table, and balance the cutout on the triangle square so that the bow extends one side, and the stern extends the other side. Balance it perfectly, and with a pencil, mark the upper edge and lower edge where the top edge of the triangle is. You should have two little pencil marks on the cutout--connect them with a straight pencil line using a straight edge (the triangle scale, for example). Now you have a line of position, just like in celestial navigation, going somewhere through the center of gravity (area) of the cutout. You need at least one and preferrably two more lines of position. Rotate the cutout about 45 degrees one way, then 45 degrees the other way, and repeat the balancing and marking process, and drawing lines between the hash marks. You should now have 3 lines of position that all cross at the same point. If you have done a poor job of balancing, you will have a little triangle drawn by your 3 lines and you'll have to do it over again until the lines all cross perfectly at a single point. This crossing point is the center of area. You can measure the coordinates to the waterline and the forward end of the waterline.
I hope that helps.
Eric
__________________
Eric W. Sponberg
Naval Architect
St. Augustine, FL
(904) 460-9494