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The Ins and Outs of Frozen Thru-Hulls

This is just a small piece of a bigger story. After 18 years of loving our Ranger 33, Summer Sailstice, we’ve finally decided to move to another boat. A few weeks ago we closed on a 1989 Sabre 38 MkII. Despite working with Latitude 38 over the past 30 years, it’s not often we get into the details and paperwork of buying and selling or learning the systems aboard a new-to-us boat.

Some of the many differences between the two boats, besides being simply five feet longer and somehow a lot bigger, are the added systems and creature comforts of the Sabre. The Ranger was pure simplicity, with only a couple of yarns on the shrouds to help us figure out which way the wind blows. The Sabre is very well equipped with a refrigerator, inverter, chartplotter, cabin heater and more. Some of the more mundane but critical pieces of equipment are the thru-hulls — all 10 of them.

Sabres have a reputation for being solid, Maine-built boats, and it’s obvious, as we crawl around to learn how it all works. Unfortunately, one of the other solid things is six of the 10 thru-hulls that haven’t been rotated in a couple of years. The boat needs hauling for bottom paint, so now is the time to fix them.

Sabre 38 Mk II frozen thru-hulls
This frozen thru-hull is as solid as the Sabre. The good thing is, should the thru-hull fail, each one already has the correct size bung secured next to it.
© 2020 Latitude 38 Media LLC / John

Our question is, do you rotate all your thru-hulls regularly? How do you get frozen thru-hulls unstuck? Do you just replace them? Besides being frugal, we just don’t like filling up landfills with  ‘perfectly good’ stuff. They look well made and should be able to work again.

Solid thru-hull
Another very solid installation of a now very solid thru-hull.
© 2020 Latitude 38 Media LLC / John

Besides getting all the thru-hulls unstuck we also have to find out where they all are. The good news is the previous owner left a very good layout with the location of each thru-hull. Every boat should have one of these aboard in an easily accessible and visible place. Do you?

Sabre 38 Thru Hull Diagram
We have a great thru-hull diagram taped inside the chart table.
© 2020 Latitude 38 Media LLC / John

Fortunately, all the thru-hulls are stuck open, so the ins and outs are working as intended. Sinks and scuppers drain and the engine cools, but that’s not very reassuring to us or our insurance company. Getting them working is at the top of our list of “things to do” as we learn about our new boat.  Figuring out all the buttons on the chartplotter will come at a later time.



  1. Greg Clausen 4 years ago

    I have a reminder on my calendar once a month to go through the boat and open and close the valves check other plumbing issues etc. on the boat as part of its regular maintenance. I think if I was hauling the boat like you are I would just replace them all for peace of mind there’s a big debate on what kind composite brass etc. I’m not sure which route I would go maybe the composite. I like the idea of the chart showing the through holes

    • Neil Ramsey 4 years ago

      I switched to Trudesign 7 years ago and wouldn’t use anything else. They have never been stiff, even after 5 years closed and I don’t have to worry about corrosion or maintenance.

  2. Kim Paternoster 4 years ago

    We had those same thru-hulls when we bought Prudence. We ended up replacing all of them because those ones are kind of hard to deal with. Also, we added some long “bars” to the thru-hulls so they can be easily accessed. Sabre is an awesome builder, but those weren’t the most accessible (i.e. raw-water for instance).

  3. Max 4 years ago

    I close all four thru-hulls on my boat every time I leave the boat, so they get rotated at least once a month – usually more. To insure that I don’t forget to open the engine cooling intake thru-hull, I keep the engine key on the handle. The one exception to this is the waste-overboard through hull, which is always closed as I don’t take this boat outside of the bay very far. I think I’ve moved it a bit after pump out to see that it works, but that’s only been done once or twice over the last few years.

  4. Rick Johnson 4 years ago

    I’ve had fairly good luck using a heat gun for a few minutes and then tapping with a hammer while putting as much force as I can manage on the handle to reposition stuck bronze thru hull valves. Good luck.

  5. Candy 4 years ago

    I operate all my seacocks monthly as well as the y-valves for my bilge pump & head discharge. I agree with Greg about replacing all of them just for peace of mind. Talking with your surveyor for recommendations whether to stay with bronze or go with composite seacocks might be a good idea. The amount of corrosion in the pictures makes me wonder if there has been a leak from the hose or if the bonding wire connection is ineffective. Neither situation is good. The diagram of seacock locations is a great idea.

  6. Pat Broderick 4 years ago

    Bronze sea cocks can be refurbished, but a little Internet research into the brand and reputation of these would be in order. As would a consult with a trusted marine surveyor or yard expert. However, my first inclination would be to replace with synthetic sea cocks. Bronze can be recycled nicely; no land fill.
    Another concern for an older boat are the hoses. A friend with an older Sabre recently discovered badly deteriorated hoses which were as old as the boat.
    One sea cock looks like there’s been leakage around the hose/clamps — and the hose looks a little “puffy.” The hull area around the intake looks like it’s been cleaned. Does the maintenance log say when the sea cocks or hoses were last addressed? Did they pass your purchase survey this way? Can you ask the purchase surveyor about them?
    As long as you’re “looking” take a look at all the hoses and both ends. Oh the joys of buying an older boat, no matter how well-built its reputation!

  7. Greg 4 years ago

    We ended up removing as many thru hulls as we could on our Cal 39. Down from 13 to 8. We operate them as needed (close them when leaving the boat etc.)

  8. Andy 4 years ago

    The thru-hull diagram is required for boats racing in any of the long distance ocean races (TransPac, Pac cup, Tahiti etc.) as is a long list of other “good to have” safety gear…

  9. Ben Shaw 4 years ago

    Ah, such a common conundrum. I too am looking at replacing all the thru-hulls on my new-to-me boat… ALL 13 OF THEM!! After looking into it I’m leaning towards the glass-reinforced composite fittings as there is no worry about electrolysis.

  10. Doug Gibson 4 years ago

    You appear to have Spartan seacocks with a tapered cone design. These are still made today by Spartan Marine. I have the same seacocks in my 1987 Cape Dory. Yes, they are a pain to service. I have also considered replacing them with new, modern seacocks, but I quickly realize I have better things to spend $3K – $5K on for the boat (even more with boatyard labor). The good news is that even the most ‘frozen’ seacock can usually be restored. Remove the nuts holding the tapered plug and gently tap with a rubber mallet/wood block. A little PB Blaster can help. Here’s a link to a great description on the full process to service these seacocks.

  11. Martin Thomas 4 years ago

    The pic is of a Spartan seacock on a Sabre, perhaps the galley seacock. These are excellent seacocks which if maintained will outlast you. We have a Sabre 34 II with these and disassemble and greases them at each haulout ( 2-3 years) . Access is a major issue but it you had them on a workbench it would take 15 minutes each.
    To unstick the frozen ones, use heat and cold and PB Blaster daily over several days. If you are in the water have the diver plug the hole and have at it. Trying to move the handle while hot and after marinating in PB blaster combined with tapping the threaded end with a wooden or rubber hammer will eventually work. Take the nut and washers off and protect the threads by replacing the nut leaving it proud of the threads. if you can remove the screw used for the bonding wire you can squirt PB blaster in there too. Bring your profanisaurus. Most Important of all join the Sabre List and search the archives for frozen seacock.

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