Has anyone had experience of blisters/osmosis on a Seal 28?

I first noticed blisters on haul out in 2007, not too many but quite large in diameter (perhaps 2cm?). When burst they have the classic vinegar smell so definitely osmosis related.

After reading up on the topic I decided not to do too much in terms of dealing with the blisters, and relaunched. A couple of years on, they don't seem any worse so probably I won't do any major treatment of acne removal this time around either - although I'm having a survey done for insurance purposes next week so it depends also what the surveyor says.

Having read up on osmosis on the internet, there seem to be as many different opinions as web sites on the topic, so I just wondered if anyone has specific experiences on a seal.

Chris