I've been gathering inspiration for a map based on the American Rhine Crossing at St. Goar. However, can the Source engine handle a river crossing? I know it can handle boats in water, but would DoDS be able to handle moving boats across a river? If not able to move back and forth, at least be able to do it once before moving the spawn to the far side of the river?

A larger scale idea of what I'm going on, both pictures are from the St. Goar crossing:
http://img513.imageshack.us/img513/6524/crossingrhineriver18934gu.jpg
http://img297.imageshack.us/img297/3308/crossingrhineriverassaultboat1.jpg

Basically, being able to load up a boat with troops, move across the river, and then be able to return to the far side to pick up the next wave of reinforcements. If being able to transport between sides isn't possible, then would at least having a few of the larger, motorized boats(second picture) crossing once be possible?

You would deffinately be pushing your luck with that, it would be a huge strain in singleplayer so I hate to think of what it wuld be like in MP

I'd say save yourself some pain :P

I'm not talking about recreating Operation Plunder in it's entirety, one or two boats would be more than enough for a full server. It's not something I'd base my map around, at most it'd just be something to spend some free time working on.

Would there be any way to tie a boat to a track and do it that way? It wouldn't have to have any physics applied to it, it'd be carried along a specific path.

func_track train. Have a look around for some tutorials on how to use trains (just a generic name). You can parent prop_dynamics to some invisible moving brush with func_tracktrain tied to it. Entirely possible, just the same as how trains move in HL2.

Though, a map like that is pretty hard out, the water would have to be tuned right down, or made so that the Allies can't see over the edge of the boat to see the water close up...

The first wave came in on rafts, a la Nijmegen from A Bridge Too Far. After that, the next waves came in on LCVPs. The first wave would be rather hard to do. For one, it was at night. The Germans(the US crossed from St. Goar to St. Goarhausen, a village directly on the opposite side of the Rhine from St. Goar) set river barges on fire. This made the rafts clearly visible, and then they started drawing 88 fire. The fire, the river, and the shells landing in the river would be far too much for Source, let alone a multiplayer game.

The river would only be 300 yards wide(~10,000 units), so an LCVP intro could probably work. Would there be any way to throw some tracers over the heads of the players in the LCVPs?

A very nice account of the crossing:
http://www.89infdivww2.org/combat/rhine4.htm

If you want this to work in MP then I suggest having the intro very short. The para maps took way too long :o

IMO if it is all scripted and made properly it could look good and work well too.
-Make the fire a point based light, not a dynamic. Fire sprites don't use up a lot of processor but dynamic light would.
-Splashes would also be sprite based so as not to hog anything.
-A single soundscape would lower sound processing
-As posted before, the inability for the river crossers to see the water would then enable low quality (or even texture based) water to be used.
-Tracers... not totaly sure how.. perhaps env_beams or something?

It can be done!