stupid thru-hull measurement question

[squishface]

I'm shopping for a replacement thru-hull and seacock, but I'm confused about how they are labeled. The hole is about 1/2 inch diameter, its 3/4 inch if I measure the width including the threads. Do I buy a 1/2 inch or 3/4 thru-hull?

(I remember reading somewhere that you measure the hole, but the site says "thread size", so I'd think you measure the whole thing, hence my confusion)

[negrini]

Usually their label refers to the hose/pipe conection size. A 1/2 inch thru-hull will need a little more than that when cutting the hole on hull. There are some bulky ones that require a bit larger hole. You probably have a 1/2 inch one, but best way is to measure it.

[rikhall]

I have made the same mistake. My suggestion:

If possible (not always possible) take the old one out and take it to you favorite chandelier. Then you can compare side by side.

A good and worth while project.

Cheers

Rik

[7Psych]

What's the size of the hose? That usually helps if it's a 1/2" hose through hull fitting, the hole would be the size of the outside measurement...which could be 3/4" overall.

[brak]

thru hulls and other fittings are measured according to "nominal pipe size". this is more or less an inside diameter of the fitting. I.e. the hole in your thru-hull will be about 1/2" in diameter if it is labeled as a '1/2" thruhull'. Outside diameter of all fixtures will vary of course (what's an outside diameter of a seacock anyway? ). For thruhulls outside diameter is about 1/4-1/2" more depending on size.