Steering drain through hull

Jun 2, 2014
453
Catalina 30 mkII - 1987 Alamitos Bay Marina, LB, CA
Want to replace this. I have a 87 mkII.
is there a standard size thru hull?
assuming this was original?
looks like about 1” to me. But I’d have to get my calipers and/or pull it first.

Do you recommend just pulling it first then go search for the replacement? Or can I get something ahead of time?
Any other advice?
C6B98918-789C-433F-AE4A-8F692770E65B.jpeg
9E3AC350-3C32-4686-BA19-DDCDF750BD12.jpeg
 
Feb 26, 2004
21,959
Catalina 34 224 Maple Bay, BC, Canada
Take the hose off and measure that first. Then measure the size of the outside of the thru hull. The look in a West Marine or Defender catalog and find one that matches.

Or ask the C30 guys at their Io Group.

Good luck.
 
  • Like
Likes: Ward H

Ward H

.
Nov 7, 2011
3,129
Catalina 30 Mk II Barnegat, NJ
I think I would start by measuring the OD of the hose. If the hose is 1" OD you know the ID will be about 1/4" less. (1/8" wall of hose x 2)
Common sizes are 1", 3/4", 5/8" hose barb with 1", 3/4" and 1/2" hole size. (hole size and hose barb size is the same except for 5/8" hose barb with 1/2" hole size.
Then compare to offerings on WM and Defender as @Stu Jackson suggest.

If I had to guess and I wasn't risking the sinking of the boat, I'd buy a 3/4" hose barb thru hull. If the boat was at risk while I searched for one I'd buy the 3/4" and 5/8" hose barb thru hulls and return the one I didn't use.

Or follow Stu's suggestion and pull the hose.

The photo looks like a mushroom head thru hull was there at one time and the current has a smaller head. So I wouldn't go by what is on other C30s.
 
Jan 7, 2011
2,923
Oday 322 East Chicago, IN
Can’t quite envision where that thru-hull is or what it is for, but it appears that it is above the water-line.

I replaced 8 thru-hulls on my 1988 O’Day 322 over the winter. I had 4 different sizes of thru hulls for cockpit scupper drains, propane locker drains, lavatory sink drain, and bilge pump drains.

Unfortunately, it seems that the manufacturers have changed some of the dimensions over the years, so a thru hull for a 1” ID hose has a different size “body” and required that I drill out the hole a big bigger. In fact, I think the 3 smallest sizes all had the same “body size”. And the largest thru-hull had a body that was smaller diameter than the one I was replacing…
065927D5-7991-4FBC-8765-FF67FE068D84.jpeg IMG_0264 2.PNG

So, my recommendation is to remove the hose and measure the hose connection (hose ID) and the body OD (which indicates the size of the hole in the boat) and see if you can find an approximate match.

I bought mine here on SBO. But be aware that the body OD dimension is not given in the specs…I called to try and verify….unfortunately I was not given the correct info and had to enlarge the holes in the boat for 2 of the 3 sizes I was trying to match. Turned out not to be too difficult, but an extra step I was trying to avoid by buying the right size.

Greg
 
Mar 9, 2020
27
Catalina 30 MkII Oyster Bay NY
I’ve replaced mine. It s a 3/4” through hull but you should measure yours to confirm. Fairly easy job but involves a little bit of boat yoga to reach the hose and connections. it’s easier with the boat on the hard but doable while it’s in the water. Also put some sealant around the through hull before you tighten down the nut.
 
Jun 2, 2014
453
Catalina 30 mkII - 1987 Alamitos Bay Marina, LB, CA
It was a 3/4 hose barb thru hull. There’s only one size WM sells in the marelon and it fit perfect. The threads OD were 1”. I used 4200 to bed seal the new one.
this is the drain for the steering quadrant. The old thru hull was nylon and cracked. It was also pretty loose when we removed it. It cracked off pretty easily too.
C96BD3B2-9325-4BDD-BB9B-151B7846FD54.jpeg
 
  • Like
Likes: Ward H
Jan 7, 2011
2,923
Oday 322 East Chicago, IN
It is a good idea to check all of the other similar thru hulls. They get brittle with age and are prone to crack as you noted.

Greg
 
Jun 2, 2014
453
Catalina 30 mkII - 1987 Alamitos Bay Marina, LB, CA
The anchor locker has the same one. I know that one leaks a little. But it is far less often under water. Plan on changing that one next. First step was to find the one putting random water in the bilge.
 
  • Like
Likes: Ward H
Jun 2, 2014
453
Catalina 30 mkII - 1987 Alamitos Bay Marina, LB, CA
Replaced it with the Marelon mushroom one. WM had it in stock. It was the 3/4" barbed thru-hull and measures 1" for the hole. Sealed it with 4200.
thruhull.jpg
 
Jun 2, 2014
453
Catalina 30 mkII - 1987 Alamitos Bay Marina, LB, CA
And lastly, it appears to have solved the mysterious water in the bilge.
 
  • Like
Likes: d-marko