It might sound like a good idea to have a patch that can be G3 continuous at it's edges but looking at you prop design, it would be extremely difficult to use. Solidworks can do this but looking at your model you would need four patches. Now, which one would you do first? The first one is going to have two curves as two of the edges. These can only have G0 (positional ) continuity. Then when you put the next patch in, you face the same problem on at least one edge. The resulting surface may well not be what you want. These type of patches (certainly in my experience with SW) are normally used to close a hole that has been delberately cut out to remove unwanted geometry.