Just finished my first marathon row!!! Thank you everyone for inspiring me to get it done, including Concept2 for ranking the workout (and sending me a pin!), and Butch91, Citroen, and ArmandoChavezUNC of the Forum for advising me on drinking water during longer rows without disrupting pace. I was able to finish in just under 3:30, besting my target.
This row was for my Aunt Helen and the fight against breast cancer, and I've asked for donations to the Breast Cancer Emergency Fund http://bcef.org/ "for Kathleen Antonia's Marathon Row, 08/14/12" (copy and paste to comment section). BCEF makes sure 100% of donations goes to the people it serves, relying upon volunteers for staffing needs, so thank you in advance for helping so many meet basic needs while they fight breast cancer ... and of course it's tax deductible. (the direct link for donations is https://www.givedirect.org/give/givefrm.asp?CID=11484 )
Thanks also to the Forum and other athletes for advising me on how best to recover: an immediate hot bath with Epsom salts and a mile swim the next day (no rowing, no weights). I feel great!