Welcome Stee,
I agree that your grandfather's model of the Leon looks to be very nicely done and is well worth preserving. I find that the best way to transport a finished model is to secure the base to a flat piece of wood large enough to serve as the bottom of a box. You will also want to ensure that the hull is well secured to the base. The sides, ends and top of the box can be wood (if your only interest is in shipping it safely) or plexiglass (if you want to build a permanent display case). If you are shipping it commercially, make sure the box is clearly marked as being "fragile" and "this end up".
Your grandfather's model is almost certainly based on Harold Underhill's "Plank on Frame Models", a two volume treatise for serious modelers, which takes the reader, step by step, through how to complete a model of a very nice little Norwegian sailing ship. It also happens to be the source for my first attempt at scratch modelling many years ago, so it was enjoyable seeing another modeler's version of this ship. According to Underhill the Leon was built at Larvik in 1880, with a home port of Porsgrund and she spent most of her life rigged as a brigantine, but was later cut down to the schooner rig as shown in your grandfather's model. She spent most, if not all, of her life sailing the North Sea until October 30, 1915 on a passage from Granton to Porsgrund with a cargo of coal, she developed a leak which could not be controlled, and she quietly sank from under the crew with no loss of life.
Jim Hastings
Rapid City, SD, USA