Electronic charting without a serial port...
I had a similar problem on my laptop in that it did not have enough ports for all my intended applications. On the internet I found a product called "edgeport" that I bought for 100$ from the manufacturer. Its a box (110v powered) that you plug into a usb port. It provides 2 rs232 ports, a couple of usb ports and a printer port.
I think the name of the manufacturer was "inside out networks". A google search on "edgeport" whould find them.