I need Help finding a plug.

[Slick Willy]

I have been looking for a transom drain plug for an older mirrocraft 12 foot aluminum deep v boat. The drain hole has male threads and requires a "cap" style fitting to screw onto it. I have tried a 1/2" galvanized cap and a 5/8" flare cap both of those were too small. I then went out and purchased a 3/4" pvc cap and a 3/4" galvanized cap, but this time these two were too big. I am currently using a wine cork that I shaved down to fit into the hole, but I am always worried that it is going to pop out and flood the boat. Any help or ideas would greatly be appreciated.

 

[rbh]

Re: I need Help finding a plug.

did you try the expanding rubber style, has the flipper on the end
rob

 

[Slick Willy]

Re: I need Help finding a plug.

I have not tried the the ones that fit inside with the switch on top, no. I did not think that I would be able to find one large enough. Do you think that the threads are just for show? I am attaching some pictures to give you guys and gals some help.

 

[rbh]

Re: I need Help finding a plug.

ok then, I am going to have to go with the fitting is probably from the plumbing store, trying to remember, is it npt thats the threads for plumbing???
you might want to try the hardware store for a brass cap.
sorry but thats all I got right now.
rob

 

[RWilson2526]

Re: I need Help finding a plug.

you're pics are tiny so its hard to see but it looks like maybe somebody installed a through-hull fitting in the back. I believe the threads are there to hold that retaining nut that keeps the fitting tight to the transom. I know that the threads on fittings like that are not NPT (by the way the threads of galvanized vs pvc vs stainless are cut to national pipe thread so you dont have to buy different kinds thinking they are different) I forget what you call them but the theads are kind of blunted at the end which stops NPT style threads from meshing. (edit: I just remembered I think they call it a running thread)

anyway even though the threads dont mesh up It should be close to a standard size pipe od. Does the 1/2" galv cap come close but just doesnt seem to screw on more than a thread or two? if thats the case you probably can get a pvc cap,lube it up good and twist it on with a wrench and it will cut the threads in the cap to match what you got.

 

[Slick Willy]

Re: I need Help finding a plug.

The only one that seemed to be really close to the diameter was the 5/8" brass flare cap that I bought, but even then it wouldnt thread. Sorry for the tiny pics, they were too big before so I just went with the thumbnails, I cant stand resizing pics on what amounts to basically dialup speeds.