Here is a way that I find gives a passable ballpark number.
After completing a row, export the data file (e.g. .csv or .fit) from the rowing machine to your computer. Next, upload the file to rowsandall.com from which you can synch the data to Training Peaks. In Training Peaks, go to the rowing workout and click on the Analysis button where you can get all the data to calculate the TSS.
As you may be aware, Training Peaks defines TSS as follows:
TSS = (sec x NP® x IF®)/(FTP x 3600) x 100, where
“sec” is duration of the workout in seconds,
“NP” is Normalized Power®,
“IF” is Intensity Factor® (a percentage of your FTP; in other words how intense the effort was),
“FTP” is Functional Threshold Power (your best average power for a one-hour race or test),
and “3600” is the number of seconds in an hour.
Example for 2,000m row
Duration: 7:51 or 471 seconds
FTP: 250 W (note: cycling FTP)
TSS = (471 x 210 x 0.84)/250 x 3600) x 100
TSS = 9.2
Note: In the above example, Training Peaks uses bike FTP. From what I gather, an athlete’s rowing FTP is typically 15% to 20% lower than cycling FTP. Assuming in this example that the athlete’s rowing FTP is 200 W (i.e. 20% lower than cycling FTP), we get a higher TSS value.
TSS = (471 x 210 x 1.05)/200 x 3600) x 100
TSS = 14.4
There is a substantial difference depending on which FTP is used. The rowing TSS is 37.5% higher (i.e. 14.4 vs. 9.2) due to a larger IF and smaller FP.
I am not sure why Training Peaks defaulted to using a bike FTP instead of rowing FTP to calculate TSS for a row. Logically, a rowing FTP produce a more applicable TSS value (apples to apples). I’ll check with Training Peaks if there is some way that the software can select the appropriate FTP value depending on the activity or ask them to build in that functionality if they don’t yet have that. Anyway, I hope you find this useful. Cheers.