Sea Strainer

[Oran]

I need to replace the gasket on the sea strainer for my Pearson 27. I am having a hard time identifying the part since the engine parts source says that this part was installed by the boat builder and my Pearson 27 manual does not show this as a part for the boat. Any clues out there?

[Last Resort]

If you have the original, probably brass, it's time to replace the whole unit and put in a modern one that you can see through and deal with much easier.  I changed mine a decade ago to a Vetus model

https://www.vetusmarine.com/store/p/228-Strainer-Type-140-3/4.aspx

and love it.  There are many different manufacturers of this type of strainer.
It's an easy swap. Just match up the hose sizes to the model you need and all set.