Good day, sir!
I've been facing a problem in Maxsurf Stability. No matter how I define my tanks, they are including some of the appendages' volumes into their volumes. By appendages I mean the rudders, keel coolers, propellers nozzles and shafts and skeg. Obviously if I "Recalculate Hull Sections" unselecting the appendages surfaces, then the tanks are correctly built, trimming to the hull's surface. However, I need the appendages to run the stability, and once I add the appendages surfaces to hull sections, the tanks are again messed up including some of their volume, going below the hull's bottom.
I've tried hiding the appendages in Stability before defining the tanks. I've tried calculating hull sections without the appendages, creating the tanks and recalculating the sections later. I really don't know what else to do. Would be really glad if you could teach me on how to understand what is happening and how to solve it. One big weird thing is that, as you can see in the pictures below, not the entire appendages are being taken into the tanks' volumes, but just some part of them.
I'll be looking for a reply. This is really urgent for me.
Thank you very much!
Hi Gabriel,
There are two ways you can do it:
The first way is the simple way and will probably suffice here. Create tapered tanks by defining different limits for your tanks at the aft end from the forward end:
With these values, you can create a tank whose top or bottom slopes fore-aft. Or sides slope Port-Stbd. The one you can't do is slope the bottom or top from port to starboard. It looks like you would be able to choose limits where this worked for your model.
Your next option is to use boundary surfaces. This involves creating surfaces in Modeler that provide limits for the tank. Take a look at this video on using boundary surfces for tanks: https://www.youtube.com/watch?v=wDIZb8QKWl8
Now - there are also some difficulties in modelling what you have. One of the rules for Stability is that we need to be able to form closed contours at each station to calculate the area. We can have multiple contours, such as 2 catamaran demihulls or a bow + bulbous bow. In your case, there is the hull plus rudder or hull plus propeller shaft.
The limit is that we can't have those multiple section lines one inside the other. So you can't have the outside of your prop nozzle plus the inside of your prop tunnel. There are two ways you can model those prop nozzles:
- Make a small split in your nozzle so that it becomes a single contour that links from outside to inside.
- Only model the outside of the tunnel as buoyant volume, and then make a non-buoyant volume (tank) for the inside section.
Regards,
James
James, hello,
Thank you very much for your attention and the reply!
It seems it worked out for me hiding some of the appendages in the Stability before setting the tanks, even though it didn't work before. Plus that, defining boundary surfaces for some tanks also helped me with that.
Thank you so much and happy new year!