Maxsurf tank modeling

Hi all,
I'm a new member here and would really appreciate if anyone can help me with this.
Now am designing a Self propelled Barge, for this i have to model tanks. when i generated tanks its showing as it in the picture attached.. can anyone help me to generate tank fully..

 

Check your surface of the hull is correct or not, also the direction of surface !

 

I think if you remove checkpoints that exist in the angular area, you'll get a very good tank surface.
On the other hand, I do not think you need to define a new surface to the outer side of the tank. You can use the same hull surface.