How to convert .obj files to .mdl files?

Hello all,

I have decided to try to add a new vessel to FSX. I purchased a 3D boat model at TurboSquid in a .obj format. ModelConverterX states that it can convert .obj files to .mdl files, however when I attempt to convert the file using the wizard, I get an out of memory error. Can anyone direct me what to do or where to go to accomplish my objective? I only want to use the models as AI with AI Carriers and, in a perfect world, be able to land on the decks. Is it a reasonable request or am I just way out of my league? Any help is greatly appreciated.

Thanks,

Paul