The next question I would ask is what is the pattern?
I personally use stanchions but the block approach is an attractive one for a big beamy ship. Otherwise you need more than one row of stands fore and aft and it gets a little weird.
But the practice of modeling blocks bears no resemblance to actual practice or only a distant one.
Initial construction docks usually contain elaborate fixtures to hold the parts together during assembly.
Subsequent dry docking is a very busy and usually somewhat messy looking affair. The dry dock master who is a true expert in things big and heavy devises a layout of towers of various height formed from prepared pedestals, cribbing of timbers and all manner of pads that correspond to the main structural members inside the hull itself.
Our task is a different one than avoiding breaking the back of the ship. Here we have the happy task only of making something that looks attractive and properly substantial. The example posted is a nice one. The modeler has used square shapes in one piece crossways, and spaced them closely. They give the effect of supporting something big and heavy. You can see though where if the blocks were spaced their own thicknesses apart, it would increase the apparent weight of the ship.
It looks to me as though they are cut to sort of mimic the plan form of the ship. This has a certain grace to it, however I would probably make them all the same length as it would look a little more " real" to me.
But it's entirely a matter of taste.
Most but not all ships at least as the model companies make them have a keel of constant depth. Some don't though and this needs to be considered, esp on something like a schooner.
As far as attachment I think it's always a good policy to make the base solidly attached but removable in some fashion. A couple of self tapping screws from underneath the base plaque should do it, in drilled pilot holes of course.
Two more thoughts and then I will shut up. Make the base bigger that the boat. And be really careful drilling holes on centerline if it's a join between two hull halves or fuselage halves etc. Really bad things can happen if the drill bit bites. Start small and go carefully.
Good luck I look forward to seeing your model.