Generally using some Vaseline should greatly help reduce the onset of blisters. It helps to greatly reduce friction and stops them from forming and I can attest to it's ability to prevent blisters from personal use as I used to suffer from blisters quite badly before I started using Vaseline.
I don't seem to get blisters on the inside of my hands anymore even when I haven't done so in awhile. However
I get blisters sometimes on the webbing between my thumb and pointer fingers on either hand.
It def. sucks but I am not sure if it is position or not. Generally happens when I am rowing something to small for me.
Yes, I do have blisters from training, but they are worth it. Try using microtape. All my crew uses it. It's a type of tape that sticks to your skin and acts as a second skin to prevent your hands from blistering or protect the blisters. Through I don't like that that much, really, but it works.