Splashing water is always a tricky thing to create realistically in Maya because it requires intelligent particles that will detect collision between one another, so that for example, you could fill a container with pouring water, like a glass for example. The same applies to an object like a boat skimming across water.
One solution is to generate particles like a grid, using a creation expression, on your water surface. So, it is not a soft body and will not kill the computer. You can now deform the surface in anyway you like best and the particles will maintain their position on the surface. So now you can create a collision event that will emit splashes of particles when the surface particles come into contact with the boat. Using this method you could also creat a secondary collision event when these new particles hit the water surface, to simulate splashing.
Now obviously, the splash particles will not deform the surface, and you certainly don't want to use softy body dynamics to do so.
So what you could do, is make an expression to put into the secondary collision event script box, that will create a non-linear ripple deformer with set attributes in the position of the particle (using velocity coords) effecting the surface for a set length of time.
So now you have an animated ocean using one of many techniques. Lots of ways to animate your object across the surface, and you now have water spray, AND splashing, and ripples. This again is very intensive on the cpu (but no-where near that of softbodies) and you will need to cache the particles. Once you have it lookin ok, you could bake the annimation of the ocean, so it is purely shape animation, no more need for wave deformers or anything, so it should playback in real time.
Now wakes and water deformation up the under-hull of the boat are a different matter altogether, This again is because of Maya's very crappy particle system. It can be re-written, but it ain't easy, and you certainly don't wanna go programming fluid dynamics, which is what was done for Perfect Storm and the smoke systems in Black Hawk Down. There are systems available to do the job for you if you have access to it. RealFlow and Realwave is an exellent system supporting ultra-realistic fluid and wave systems. It runs entirely outside of Maya (import your scenes in) and is therefore very fast campared to the alternatives. Another system is Arete's Digital Nature Tools plugin for Maya, which is pretty awsome. Unsurpast realism on waves and oceans and water of any kind really, with built in control of wakes from boats, foam particle systems, liquid systems, ripples, environments and even its own renderer. It is also very easy to use and self explanatry. It does however have its limits because again, the liquid part of it is still based on Maya particles. Check out the website galleries and movies to see :
http://www.areteis.com
http://www.nextlimit.com
~Pootang~