Thru hull in hanging locker

[jerridsc]

My A25 has a 1” below waterline thru hull opening inside where the hanging locker will go. What is it for?

Thanks,
Jerridsc

[dkirsop]

Salt water intake for the marine toilet.

[DesertAlbin736]

I believe that's flush water supply line for a marine toilet.

20171115_103931_resized.jpg

[kerrye]

I use it for lake water to the bathroom sink.

[Dieselram94]

Does anyone know what threads these through hulls are? Someone installed a standard brass looking valve and I want to replace with the proper bronze. Several on the boat like this, hoping there all just standard pipe thread?

[WillieC]

A little experimentation is called for. BSP and NPT are close. For example my Volvo Penta engine has 3/8" BSP threads on the raw water pump. I know this because it is new and the sticker on the pump said so. Over the years several of the old pumps have been crossed with NPT and lots of tape. If they are wrong, they only thread together about one thread. If correct, they will go a good couple threads before the taper takes over. Of course, any boogering of threads will throw that off. Good luck!
Also, any replaced, (at least in USA), through hulls will likely be NPT.

[Desertboater]

The typical thru hull thread is a straight thread to allow the retaining nut to screw all the way down to the hull. There is an excellent write-up about thru hulls by "Compass Marine" at the following:
http://www.pbase.com/mainecruising/seacock_primer

[tribologist]

The threads i measured have been BSP. They only differ 1 tpi on 1/8, 1/4 and 3/8”

1/2” is the same pitch but thread profile is different. 55 vs 60 deg for nps. Defender will sell either. The issue you might have is damage to the threads if they forced the valves on...

NPT was not common in Sweden at that time (besides in refrigeration, not now either)