Yes it is, just that it is suspended in a gel. I do not think the gel would help with the cleaning of sails.

If you use the Oxalic Acid you can make it as mild as you think it should be.

I do agree that you should post prepare the hulls after using the Oxalic acid. You can use wax if you like, after all that is what the boat comes with, release wax. Some other, and I think better, choices are to use something with PTFE (teflon) in it.

Come to think of it I think it may be time to do my boat for the year. Thank you for the reminder.

Later,
Dan