You think YOUR boat is heavy, take a look at this one.
http://www.okinawa.usmc.mil/Public%20Affairs%20Info/Archive%20News%20Pages/2006/060512-hari.html
Click on the "high res" link for a better look.
I count 32 paddlers, 2 steersmen, a drummer, and a "cheerleader". And if there is a slower looking hull design out there I have yet to see it.
Their time for 400m? Almost 4min. Nasty.