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Rich Ahlberg
9/13/2026 11:41 AM

Hi,


I just read the article on placement of a thread drain keel plug... excellent article!


Does anyone know a good source of the drain plug referenced in this article? Here's the reference: "To make a drain hole for a threaded removable plug, a flange from a 1” brass coupler was epoxied into the hull"


Thanks!


Rich

Christopher Dehart
9/13/2026 6:35 PM
I went back and forth with the idea of a garboard drain plug but ultimately decided to glass the hole and re drill when I haul out next.
In order to get the water to drain properly the hole is so low that it leaves little room to properly install a through hull with a plug.

Christopher Dehart
9/13/2026 6:35 PM
I went back and forth with the idea of a garboard drain plug but ultimately decided to glass the hole and re drill when I haul out next.
In order to get the water to drain properly the hole is so low that it leaves little room to properly install a through hull with a plug.

Ward Woodruff
9/14/2026 7:56 AM
My preferred method of a bilge drain hole is:

From the inside aft, bottom area of the bilge, drill a 1/4” Pilot hole with a 3/8” angle drill. 

From the outside, using the pilot hole, drill a hole sized for a 1/2” pipe tap. 

Obtain a 1/2” pipe tap and a stainless or brass pipe plug with a 3/8” hex socket head. 
Use a 1/2” pipe tap to tap threads into the fiberglass. The tap and plug are tapered. Test the tapped hole size as you go to check the fit of the plug. 

You are done when the tightened plug is approximately flush with the outer surface of the hull. 

We have had experience with this method for over 20 years on multiple Ensigns with good results.  

Go to Amazon for the drill, tap and plugs. 

Ward Woodruff
413-847-0620 Cell
Ward Woodruff
9/15/2026 9:51 AM

Here is an example of the drill and tap to produce the threaded drain hole at the bottom of the bilge. This allows forming a threaded hole directly in the fiberglass wall of the side of the keel at the bottom of the bilge. You wi need a 1/2” pipe plug with 3/8” recessed hex to plug the hole.

Jonathan Gorbold
9/14/2026 8:39 AM
Hi Rich,
I wrote the article along with Pete Kogut from Canandaigua.
I have fitted this brass bung to 3 boats and while it takes some work to fit, it has worked well for me over the past 20+ years.
I like it as it provides a big opening to drain the water and other miscellaneous stuff collected in the Bilge.
So, I made the female threaded part from a 1" NPT brass coupler that you can buy from any good plumbing store. They also come in Bronze.
I cut the coupler in half and filed some notches around the outside edge of the coupler flange to provide a good mechanical lock to the epoxy,

Use thickened epoxy to bond this drain plug into the keel making sure the flange face is flush with the keel surface.

The bung is a countersunk 1" NPT half inch drive plug you can get also from the plumbing store. I cut the top off this so that it is flush with the keel surface when installed. This reduces the drag by the exposed bung. Take care to leave enough of the 1/2" square drive hole for the bung removal tool!

I do use some boat calk sealer on the thread when installing the bung.

Hope this helps.
Rich Ahlberg
9/15/2026 8:15 AM

Thank-you!


Rich

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