1975 O'Day 25 Gated Thru Hull (Under Galley Sink)

JoeWhite · Jun 26, 2024

The thru hull is definitely below water line. The missing hose is an indication that the thru hull is broken. I vote for working on it only when she is on the hard in case it decides to fall apart while you are testing it.

kappykaplan · Jun 26, 2024

JoeWhite said:
The thru hull is definitely below water line. The missing hose is an indication that the thru hull is broken. I vote for working on it only when she is on the hard in case it decides to fall apart while you are testing it.

pgandw · Jun 26, 2024

On my ODay 25 (1979?), the through hull for the sink in the head was above the water line by a couple of inches. Both the ice box and the galley sink fed into the pipe which contained the centerboard pennant. None of them had valves or seacocks, which proved problematic when the hose popped off the thru hull for the sink in the head when we were pounding going to windward on starboard tack - which immersed the thru hull and flooded the cabin before we realized what was happening. Another time surfing down waves squirted a lot of water up the centerboard pennant pipe into the sink, the bilge, and the ice box. I extended the cb pennant pipe up to the cockpit, and installed seacocks on all 3 connections.

Fred W
ODay 25 1979-1993
Stuart Mariner 19 2022 - present

Timm R Oday25 · Jul 1, 2024

Our Oday 25 is a 1981 . The through hull under the galley sink originally had the ice box and sink drain .
The factory installed a gate valve.
While on the trailer I replaced the gate valve with a bronze ball valve .
When replacing the valve , I teed a fitting in so that a bigger bilge pump now situated inside the step empties into the drain .
Originally the bilge pump was teed into the sink drain across from the head . It wasn't hard to get water to come back down into the boat .
The tube for the centerboard went up to the cockpit . This tube was completely seperate from any other throughulls

Project_Mayhem · Jul 23, 2024

For future reference, you can see water come up through the ice box drain in mild waves when the valve is open. My boat came with a ball valve. It was quite pitted when I removed it over the winter. Cost for a new 3/4" one from Groco was around $50.

jmallett · 2025-11-03T03:16:06-0800

GreggS said:
Hi. Just bought an old O25 and launched it last week. So far, so good. But I would like to do a few projects including replacing the water lines and getting the sinks working again. There is one thru hull, so I've read, under the galley sink. The sink drain hose is removed and the gate closed on the valve. My question is: Can I mess with this while it is in the water or should I wait until it's pulled for the season. I would think that the thru hull exits above water line, but I have not traced it yet. Anyone have experience with this? Thanks

Gregg

I had a similar situation on my 25. I attached a length of tubing to the peacock to bring it above the water line. I opened the sea cock and poked a flexible rotor router thing through to clean it out. Next I closed the sea cock and replaced the tubing to the sink drain. This only works if the sea cock can be operated.

If it won't operate then the way to fix it without taking the boat out of the water is to swim down and insert a bung. Then the sea cock can be replaced.

I am assuming the thru hull fitting irmtself is not leaking as that would have been obvious.

The other problem I had was with the ice box drain. This was teed into the sink drain but because of the small internal diameter of the tee kept blocking up.
I removed the tee and ran the sink drain directly to the sea cock and drained the ice box via a separate length of tube into the bilge through the hole surrounding the sea cock.