Geoff - Sallyport was taking in water slowly during the row to Portchester yesterday, presumably due to the timbers drying. so we left a little water in both galleys and left the bungs in to increase humidity overnight.
What you are doing should could help. Both have had the planks sealed. It a bit of a mystery. They need to have some water in them to see if there is a leak. I will have a look tomorrow. G