ISU Crew alumnus, made a throwaway to kind of illuminate this for some of y'all since most people here have absolutely no clue what rowing crew is like.
When you get into the boat your feet are essentially put into shoes that have velcro straps over top with a pull cord. It was pretty windy on Sunday. I haven't found data that looked terribly reliable but it appears from what I can see that the wind was roughly 12~~ mph with gusts of up to 20 mph which would be considered unsafe rowing conditions. Anything above 12 knots( about 13.8 mph) and you don't wanna take the boat out. Above 10 knots can be kinda risky. Additionally the water must have been cold as hell. The ice allegedly just cleared in the last couple weeks on Little Wall. Even though it warmed up in the afternoon that water still would have been very cold.
As for how calm the water was, if there's gusts and the water is choppy it is HARD to keep that boat steady. It's not like riding in a motorboat. You're CLOSE to the water and you've got a giant oar, if you "crab" (get the oar stuck on a stroke) you can throw off the set of the boat and since you're so close it's easy to take on water. I've rowed on Little Wall and can confirm that it does have some pretty intense cross winds. Ideally you'd row on a river to avoid the situation but there's nowhere suitable to take a boat out closer to Ames. The two rowers who passed were new rowers. They very likely didn't know exactly how to react when the worst case scenario happened, or panicked. It's hard when you're strapped in. Just rowing is hard your first few times. If they were novices, they're more likely to not know how to control their oars, set the boat (keep it steady), how to react right away, etc. Just getting into a boat the first time is learning a whole new set of language in order to pilot it.
Once your boat flips it would also be very hard to get it over if you've got the oars in there without a good sense of how everything is working mechanically. If it's cold, add panic and shock to that.
All things considered, I don't think they should have been out there in the first place but hindsight is 20/20. Given the conditions and the circumstance I have a very easy time imagining how it could happen. Seen quite a few people saying what they SHOULD have done on these forums but all in all, please be kind. Two families lost their kids. Three students are going to be traumatized for the rest of their life over this. It's a sad day for my organization. It's a sad day for ISU.