John...I don't really know what to tell you...they are pretty industrial and do beat the metal up a bit...it might be to aggressive and hard to control adjacent damage to surrounding areas depending on what areas of the boat your really trying to de rust.
I have not used a hand held sand blaster like Saber posted...but I see it requires quite a bit of air @ 10 CFM which is not much less then my big sand blaster uses at 13/15 CFM so if you want to go the sand blast route
you can borrow that tool....and my portable air compressor
...you will however need 2 to supply enough air...I do have two but my gas powered one through a rod and I haven't bought a replacement 5 HP motor
for it yet.
All I can tell you is if you want to give the needle scalier a try you can or go for the for sure way and blast it.
Keep in mind sand blasting is messy so I don't know if your going to be allowed to do this in your slip/marina.... nor if you would want to!...the sand ends up bouncing 20' sometimes so it will land on OP boats if your not careful.....Maybe that's the advantage of Sabers small gun?
me what you want to do/try and I will help you all I can.