I think used 1 1/2” ID but that was based on the size of the thru hull and the matching drain above it. Probably about 3-4 inches is all you’ll need. I replaced my cockpit seat drains and am running the same diameter. A little large for the seat drains but no standing water.
Brian

On Mon, Feb 7, 2022 at 15:34 RODNEY BROWN <rnelson204 at gmail.com> wrote:

> Happy Monday!  Looking for some advice, the flexible tubing connecting the
> deck drain (running downward in the lazarette) seems to have given up the
> ghost and is leaking water into the lazarette.  Does anyone know what size
> tubing is needed to replace the old section?
>
> Thanks,
> Rodney