... Other bav 39s I have looked at have a mix of deterioration but noticeable is the surplus sealant protruding from around the washer except on the one with the lead keel.
...
Someway in your photos it look like..
Maybe once there have been some sealant but not anymore ?
Could it be possible. Keel is reinstalled ? One reason or another.
Attached some pics.
Our B39 with standard cast iron keel.
I think that yellow sealant under the washers is not sealant at all.
It looks more like some kind of clue.
Very hard. More like epoxy than flexible sealant like sikaflex.