FAQ
=> Generic Regular Expression (regex) Formulas
=> Replacing in a specific zone of text
The “zone” you want starts with <p (BSR) and ends with </p> (ESR). You want to find newlines using FR=\R in that zone, and replace with a space character as the RR .
Actually, since your lines are also indented, then FR should probably be \s+ – which would collapse one or more whitespace inside the tags (whether spaces or tabs or newlines or unicode whitespace) into a single space each).
When I replace each of the bolded BSR/ESR/FR/RR with the values I listed, and did a Replace All, it converted
<p align="justify" >The captain and the crew were taking care of the last details when someone remembered that there was no ice in the boat, nor the necessary amount of beer. A volunteer was found and he rushed to buy all that was needed. Soon he was back with a big bag full of ice and a dozen beers and other refreshments.</p> <p align="justify" >The captain decided that everything was ready and we should board the boat and sail. Five minutes later we watched the little harbour getting smaller and smaller. The trip to Ayiofarango had just started.</p>to
<p align="justify" >The captain and the crew were taking care of the last details when someone remembered that there was no ice in the boat, nor the necessary amount of beer. A volunteer was found and he rushed to buy all that was needed. Soon he was back with a big bag full of ice and a dozen beers and other refreshments.</p> <p align="justify" >The captain decided that everything was ready and we should board the boat and sail. Five minutes later we watched the little harbour getting smaller and smaller. The trip to Ayiofarango had just started.</p>