What do you call this?

[TiggerToo]

... and where can one buy a replacement?

 

[sailorman]

shell vent
any swindleries

http://www.bing.com/search?q=shell+vent&form=OPRTSD&pc=OPER

 

[chewi]

... and where can one buy a replacement?

View attachment 37870

unscrew it and bash it back to shape if its an achor locker drain.
You will bend the new one as well if you have a swinging mooring.

 

[VicMallows]

You will bend the new one as well if you have a swinging mooring.

Why?

 

[sailorman]

Why?

Too much scope on the strop ????

 

[chewi]

Why?

Arriving in a chop at some time or other ,the tender will modify it.