Drain Plug Help! Please!!

Hello, great forum and I can't wait to get my tin boat out for some fluke! Unfortunately my drain plug bung is holding me up.

The boat is a 1975 MirroCraft 16'. The boat didn't come with a drain plug, so I purchased your standard 1" plug. Well it won't fit, I cleaned out the hole, plug is loosened all the way and even threw some grease on it.

What has me stumped is the hole on the boat has ribbing on the inside of the hole all around it, and they run front to back. It looks factory, or someone took a round file and screwed my hole over.

Do I take a 1" drill bit and run it through the hole? Other people with these boats, what does the hole look like and what kind of plug does it take?

I'll try and take a picture later. I have my water pump kit, and after that is done this is the only thing keeping me off the water!! Please, any help will be appreciated!!

if it has threads like for a bolt, there are some drain plugs that bolt in with a wrench

IF YOU CAN DRILL IY OUT TO 1" AND BUY A RUBBER PLUG FOR IT I THINK THAT WOULD BE THE EASIEST FIX, I HAVE AN 80-SOMETHING MIRRO CRAFT AND IT HAS A RUBBER PLUG HOPE THIS HELPS

Keep us posted on the solution. I have a threaded drain plug as well, and would like a backup just in case. Those 1" rubber universal plugs are too small.

WHAT DOES THE ID MEASURE ON THESE DRAIN PLUG HOLES? IM KINDA CURIOUS, YOU CAN ALSO USE A RUBBER FREEZE PLUG FROM AN AUTO PARTS STORE. THEY MAKE ALL SIZES.

I don't think the hole ever had threads in it... It has ribbing that run front to back, not around the hole. It looks cast in the tube.

I think drilling to 1" is my best solution also... Going to play with it in a bit and will try and post a picture later. Thanks for the replies.

Can you ask the previous owner what they used?

1 inch too big, is 3/4 too small? That seems to be another standard size when you google it.


From the mirror craft web site faq , might be something to check out too:

Can I order parts factory direct?
If your MirroCraft boat is older than 3 years, it may be necessary to contact MirroCraft parts and service department. In doing so, it is absolutely necessary to provide the serial number. No order will be serviced without the serial number. Most parts are available up to 10 years.

Don't mind the pitting, I think it's mainly old paint.


It's hard to measure a hole that's not round. But I guess I need to measure from two points.
This looks cast in the tube to me, it doesn't look like someone could have done it with a file.
A 1" drill bit is looking better and better to me. :?

I post a picture of my screwed up hole and no one wants to touch it!! haha... I guess a 1" drill bit is in my future. :?

It's hard to tell from the picture, but it sure looks like its made this way and not just screwed up by someone with a file.

I have a threaded plug on mine but if it were me, I would buy a rubber plug and drill the hole to fit the plug you buy. From the picture it seems hard to have anything fit in that shape and create a good seal. Good luck!

JUST MAKE SURE THE 1" DRILL ISNT TOO BIG AND WIPE OUT THE ENTIRE TUBE ALLTOGETHER THEN YOU WOULD HAVE A REAL MESS! DID SOMEONE PUT IN A BED LINER OR SOME OTHER COATING IN THERE IT LOOKS LIKE IT RAN INTO THE PLUG HOLE!!

BOB350RX said:

JUST MAKE SURE THE 1" DRILL ISNT TOO BIG AND WIPE OUT THE ENTIRE TUBE ALLTOGETHER THEN YOU WOULD HAVE A REAL MESS! DID SOMEONE PUT IN A BED LINER OR SOME OTHER COATING IN THERE IT LOOKS LIKE IT RAN INTO THE PLUG HOLE!!

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I don't think a 1" will take much meat out at all... But I will measure the OD and make sure before I start drilling!! It's definitely the tube that's bumped out like that.

Is the hole the same diametor(sp?) from inside the boat to the outside? i guess what i am saying is does the plug fit if you try to install it from the inside or the outside of the boat? good luck. Scott

Any Menards around you? I counted 12 different boat plugs of various sizes at my local one earlier this afternoon. In the nuts and bolts section.

Ohh man,,, what an afternoon. First, no the plug fit the same, either way I tried to insert it. From inside the boat or outside.

I took a 7/8" stepped bit (biggest I had) and went to it. Went right through and made a pretty smooth hole. Tried to insert the plug and it was not quite there. I noticed some weird "marks" inside the hole at this point, right where the weird ribs had been inside the hole. So at this point, I had to keep going right?? :roll: So I took a dremel bit and lightly went around the inside of the hole.... well the weird marks grew a bit and I realized the "ribbing" had been factory and were in fact welds. Well the plug fits in now, and it seals water.

I'm just really worried the two pipe halves they sandwiched the hull with and then welded around on the inside is going to separate and my plug and hole bung is going to fall into the bay. I pulled and wiggled the plug a bit while it was sitting full of water... Like I said, no leaks and the plug is in. I guess it stays this way for the remainder of the fluke season.

I KNOW THEY MAKE KITS TO REPLACE THE WHOLE DRAIN PLUG YOU MIGHT WANT TO RESEARCH THAT AND GET ONE, IN CASE I WOULD COME UP WITH A PLAN NOW SO YOU CAN BE READY IF IT FAILS ON YOU, KEEP SOME DUCT TAPE IN THE BOAT JUST IN CASE GOOD LUCK!!

I had a screwed up drain plug bung, almost identical to yours, in a boat I owned once. Took it to a local dealer and he had a drain bung swedging tool and new drain bungs of various lengths and diameters. I used a 1 1/8" (one and one-eighth inch) drill to drill out the old one. We coated the new bung and the inside of the hole in the transom with a liberal amount of Marine Tex epoxy and swedged in the new brass bung. Worked perfectly and it never leaked a drop the whole nine years I owned that boat.

Well I had the boat out today! No leaking or falling out drain plugs, so that was good! But I still don't like it, and I will change the drain tube eventually. Thanks for all the replies!

Keep an extra plug with you or plug it from inside. mine can only be plugged from the inside.When i bought it ,it had a real small chain attatched to the handle on the plug to the knee brace. You could always carry an emergency tampon in the tackle box :lol: .
Good luck with everything Scott

F150fish said:

Keep an extra plug with you or plug it from inside. mine can only be plugged from the inside.When i bought it ,it had a real small chain attatched to the handle on the plug to the knee brace. You could always carry an emergency tampon in the tackle box :lol: .
Good luck with everything Scott

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I'm definitely only putting the plug in on the inside! I guess I should have something just in case... I went out yesterday without anything to even bail if I had to! :roll: