I'm having the same problem but only when trying to simulate lots at the same time.
Here's the model and some pics.
When I have only one oar there's no problem but with all of them the program crashes.

NOTE!

In this model I didn't attach the jonts and motors to the model yet.

Argo oar 2 animated.png

Argo oar 2 animated1.png

Argo oar 2 animated.skp