Garboard drain plug

Nov 4, 2025
4
Catalina 36 MKII tall rig South Haven
This is my first post. I hope to get first hand knowledge from other owners of boats like mine. I apologize in advance for rookie posting mistakes. I'll learn.
I have a 1996 Catalina 36 mkii tall rig wing keel with a keel stepped Zspar furling mainsail. I am slipped in Southwest Michigan. I keep my boat in a cradle, shrink wrapped, on the hard during winter. Every year I get almost 25 gallons of rain water down the mast into my bilge. This creates the obvious moisture problems (ice, condensate, mold). Question: Has anyone installed a garboard drain in their bilge? What type? Where did yo locate it? Has it been a success? I am thinking of installing one with hopes it will allow rain water to drain out of my bilge and not accumulate over the winter. I have seen different types a) a t-handle brass plug which installs inside the bilge and b) a 1/2 in brass square threaded plug which installs on the outside of the hull. That one attaches the flange to the hull with 3 screws. I suspect the core needs to be sealed with an epoxy after drilling a hole through the hull to the bilge. I guess a proper sandwich type thruhull with inside and outside flanges aren't used here. I'm guessing the tricky part is finding the best location to get the most water out. thinking would have to be the lowest place in the bilge yet exit above the keel. I am thinking the bilge compartment in the salon, lowest point, (thats where my bilge pump is) or the section just forward
 
May 1, 2011
5,218
Pearson 37 Lusby MD
Not a Catalina, but . . .

1/2 in brass square threaded plug which installs on the outside of the hull.
Mine's installed on the outside of the hull. You're looking for a bronze fitting.
thinking would have to be the lowest place in the bilge yet exit above the keel. I am thinking the bilge compartment in the salon, lowest point, (thats where my bilge pump is) or the section just forward
Mine's as far aft as possible in the bilge and exits above the keel.

Welcome to the forum! :beer:
 
Apr 1, 2004
179
Catalina 34 Herring Bay Chesapeake, MD
That's a lot of water fo just the mast. Try also asking on catalina36.org good luck
 
Jan 11, 2014
13,325
Sabre 362 113 Fair Haven, NY
Only use Bronze, brass below the water line will fail in any application.

Use the type where the plug screws in from the out side. Water pressure will work with you on this.

Don't use the type with a T handle. It can anything floating, line, seaweed, trash. Use the flush plugs with a ⅜" square hole. A ⅜" ratchet fits and allows you to tighten and remove the plug easily.
 
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Jan 1, 2006
7,740
Slickcraft 26 Sailfish
I'm not a Catalina owner but I think the hull is not cored. It would still be important to seal the laminate to prevent water ingress into it.
 
Apr 18, 2012
46
Catalina 400 MKI 67 LaSalle,Mi
We have one on our C400. The previous owner installed it a couple of inches from the bottom of the bilge. I remove the bilge pump from its mount so it doesn't freeze in the remaining water. Seems to work as it is supposed to as long as I remember to put it back in before launch.
 
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Nov 4, 2025
4
Catalina 36 MKII tall rig South Haven
Thanks for all your replies regarding my original post about the garboard plug. Yes, 25 gallons is a lot of rain water. It may be a little less as my estimate was based on pumping out about 6 or 7
- 5 gallon buckets over 1/2 full . That is a pretty large bilge. I am moving forward with this project. The plug I chose is a Perko bronze flanged fitting on the hull with a square headed 1/2 in threaded plug. Appears to be the one most chosen according to chat GPT. My boat is in fresh water from May to November and gets VC17 bottom painted every spring. I will however look for ideas on solving the problem of water in the mast (a foam dam inside the mast above the deck with weep holes above the dam, maybe) but that will be another postThanks all for replies and I'll be participating in this forum more often now.
 
Jan 11, 2014
13,325
Sabre 362 113 Fair Haven, NY
I will however look for ideas on solving the problem of water in the mast
This is pretty much an insolvable problem. There are too many openings in the mast for rain to enter to effectively seal them and some can't be sealed, halyard sheaves, halyard exits, and so forth. Foaming the mast and drilling drain holes might work, but more holes in the mast doesn't seem like the best idea.
 
Sep 24, 2018
3,782
Catalina 30 MKIII Chicago
Drill a pilot hole from inside the bilge to outside to determine the location. If you get it wrong, it's pretty easy to inject some thickened epoxy. If you get it right, bust out the big bit
 
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jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,671
CAL 35 Cruiser #21 moored EVERETT WA
I will however look for ideas on solving the problem of water in the mast
Are you sure it is coming down inside the mast? You may have need of a Mast Boot.

If it is coming down inside the mast you do not want to stop the water inside the mast (i.e. a dam). That will lead to corrosion of the mast from the inside. Better to let it drain into the bilge and then drain the bilge.
 
Sep 24, 2018
3,782
Catalina 30 MKIII Chicago
Id put a small dam in the luff track and a boot on the outside. 20ish gallons seems excessive for a mast leak but then again, mine is deck stepped
 
Nov 4, 2025
4
Catalina 36 MKII tall rig South Haven
Thanks for your input. Ok no dam inside the mast. There is no boot. Was wrapped with tape and I removed it because didn't look good and probably not real effective. Remember the boat is unattended for 6 months of heavy rains and melting snow. During sailing season and the batteries are hooked up the bilge pump takes care of rain
 
Nov 4, 2025
4
Catalina 36 MKII tall rig South Haven
Thanks, that Waterboot looks nice. I may try that in the spring time. A boot right now while I'm shrinkwrapped is kind of redundant but it may help prevent rain intrusion during the sailing season. Thanks for the tip.