Odd Pipe Size Fittings

[Troubadour52993]

My genset overboard dribbles (some of the) water down the hull, with the resultant stains. The overboard for the main engine has a lip that extends out, so any dribbles drop straight into the water.

Upon inspection, the genset overboard fitting appears to be similar to a deck fill fitting, in that it has threads on the ID. I had the brilliant idea to thread a short extension tube into the fitting, allowing water to run down the tube and drip off without running down the hull.

Unfortunately, the 1-1/2" and 2" fittings I got at Home Depot don't fit, it's between them, something like 1-3/4", which of course I can't find anywhere in any material.

Anybody have any ideas for me to eliminate the drips before the next overhaul when I can change out the fitting?

[limmer]

measure exact dim. inside with caliper and go to a contractors distributer for plumbing materials. Not Home Depot or any other hardware store.

[GordMay]

You may have a metric discharge fitting.
Metric Pipe is usually available in 40mm & 50mm.
40 mm ≈ ±1.57"
50mm ≈ ± 1.97"
1.75" ≈ ±44.45mm

One inch equals ±25.4mm

As limmer suggests, try a plumbing wholesaler, or industrial supply house.

[James S]

Depending on where you're at and what your time is worth....machine shops are a great resource and may be cost effective.

[svcambria]

Nominal diameter of a 1.5" pipe is actually 1.9" (48mm). a 2" pipe diameter is 2.38" (60mm). There are American NPT and NPS and British standards as well as metric. Through-hulls are usually straight pipe thread - no taper.
You can go crazy pretty quickly trying to guess what's going on - I second the recommendation to measure the ID of your fitting and head for a contractor's distributor.

Michael

[Blue Stocking]

I had this same problem with exhaust soot on the transom. I got a scrap of 1 1/2" copper tube (pipe) split it lengthways, filed opening in pipe to tight fit and tapped it in with small overhang. Works perfect.