Through Hull Replacement, Part 1: Removal of Old Through Hulls

The old through hulls, soon after their removal
In the refitting of a sailboat, especially one that is almost forty years old, a keen eye and a patient disposition are necessary allies in the struggle, the many costly skirmishes of which often reveal unexpected opponents and thus unexpected delays. This article, and the many that follow, document, in pictures and words, the various skirmishes I fought in my effort to replace the original through-hulls in Oystercatcher, my Ericson 25. What began as a simple inspection of these original through-hulls turned into a simple, or I should say seemingly simple, replacement of them. Likewise, what began as a simple replacement, turned into a protracted project, comprised of one sub-project then another, then another. Through much of this project I relied upon the advice of Don Casey, This Old Boat, 2nd Edition, and Maine Sail, that ubiquitous, yet somewhat mysterious, boat maintenance and electrical mastermind, whose postings pepper the various sailboat forums, and whose wisdom is often distilled on his own website, Compass Marine. Yes, I frequently relied upon Don Casey and Maine Sail, but I also had to figure out quite a few things on my own. There are likely others, who have faced similar challenges. Therefore, for the sake of remembering how exactly I approached this project, and for the sake of assisting others who might undertake this same project at some point in the future, I have written this multi-part article on the subject of through-hull replacement.
The original MSD (Marine Sanitation Device) in Oystercatcher
The first phase of this multi-phased project involved the removal of the old through-hulls. Based on what I had read, I knew that there would be no sure-fire way to know the condition of the original through hulls in Oystercatcher without removing them from the hull and inspecting them closely. It was my understanding that hidden corrosion can lurk deep within the bronze itself of bronze through-hulls. In other words, that which can appear to be stout and robust can in fact be thin and weak. Given that I was in the process of a thorough refitting of Oystercatcher, I knew I did not want to leave this part of the boat untouched. Therefore, I resolved, albeit with some reluctance, to pull the through-hulls from the boat.
Original MSD (Detail), with red hose leading from the raw water intake seacock
A necessary precursor to the pulling of the old through-hulls from the boat was the removal of the old hoses and seacocks. In the Ericson 25, as in many other boats, there are two through hulls and seacocks in the head. One serves as the raw water intake, the other the outlet for waste. Below we see the raw water intake seacock. It was very easy to remove this seacock. A few turns with a wrench at the base, and it was free. I won't go into the details of all that was wrong with the plumbing here and elsewhere in the boat. If you'd like to read more, see my earlier article, "Plumbing, Original."
The seacock for the wastewater outlet was just as easy to remove. All I had to do was turn it just a tad. I'm pretty sure that these seacocks in the head were not original to the boat, since the Ericson 25 manual speaks of the boat being plumbed with gate valves.
If you're curious to know what a gate valve looks like, look no further than the picture below. Here we see one in the cabinet beneath the galley sink. This piece of hardware was just as easy to remove as the seacocks.
My young helper, in the picture below, demonstrates the internal workings of the gate valve.
The removal of the through-hulls was equally easy. Fortunately, no slack-jawed lame-brain had installed them with a permanent adhesive such as 3M 5200.
To remove the through-hulls, I used the method suggested by Don Casey, This Old Boat, 2nd Edition. I used a scrap piece of a 2x4 and a long bolt. At the time, I thought it was funny to label this contraption, as if I had purchased it from West Marine or some other place. I also thought it would help me keep track of this through-hull-pulling-kit, if I ever needed to use it again.
Below we see the original waste outlet through-hull soon after its removal. Fortunately, the bunk of the trailer did not hinder my work. In case you're wondering, the ID (inside dimension) of this through-hull was 1.25 inches. Most through-hulls are 1.5 inches ID. In Part 2 of this article I will describe how I addressed this problem.
The previous owner had joined the seacock to the through hull with Teflon tape. There's nothing wrong with this. Notice, however, how little of the Teflon tape is marred from the joining of these two pieces of hardware. It appeared to me that there were only several threads holding the seacock in place. Not good.
The raw water inlet for the head is pictured below. The bunk of the trailer did not present a problem for the removal of the through-hull. It would, though, present a problem later when I had to resize this hole.
The through-hull for the raw water intake had an inside dimension of 1/2 inch. As I would soon find out, the norm is 3/4 inch. This would be another issue that I would later need to address. One other thing . . . notice how large the flange of this through-hull is relative to the size of the threaded section? This flange is much larger than the flanges on the flush-mounted through-hulls manufactured today by Groco, the brand I would later choose for replacement parts. This meant that I would need to need to resize the chamfered hole, i.e., the tapered hole, in the hull to accommodate the new flange. Of course I didn't know all of this at this time. I was simply pulling out these old through-hulls for the purpose of inspecting them.
The waste water outlet for the galley sink was very close to the bunk of the trailer. Nevertheless, I was able to extract the through-hull.
This galley sink through-hull had a normal 3/4 inch inside dimension. It's flange, in the picture below, appears to be of a proper proportion doesn't it? Not so fast. I would later discover that the 3/4 inch ID bronze through-hulls manufactured by Groco do not have a flange this large. Therefore, I would need to resize the chamfered hole, i.e., the tapered hole, for the new through hull . . . and yes . . . the trailer bunk would hinder me in my efforts.
After I had removed all of the through-hulls, I laid them out in a sunny location, so that I could inspect them well.
Using a Dremel, I removed some of the bottom paint from the surface of the flange for the purpose of determining whether or not the bronze had a distinctive pink color, which would indicate that the zinc in the bronze had been depleted and corrosion was taking place.
It was around this time that I initiated a thread on the Ericson Yacht Owners Forum to get some advice as to how I should proceed. The title of the thread, as you see from the link below, was as follows: "Installing New Flush Thru-Hulls in Original Chamfered Holes."  By this point, I was already working under the assumption that these through-hulls were compromised and that I would need to replace them with the smaller flanged Groco through hulls. I should note that I had, around this time, carried the old through-hulls to the local West Marine and compared them to the new Groco through-hulls that were sitting on the shelf in the store.
If you've clicked on the above link and read the series of postings in that thread, you will have noticed that, in one of those postings, Maine Sail advised me to clean up these old through-hulls before condemning them. Perhaps in cleaning them up they would reveal a uniform color - that's what Maine Sail suggested.
I cleaned them up as well as I could with the Dremel, and it seemed that the flange itself was not uniformly colored. Of greater concern to me was the widespread pitting that I found in the flanges of all the through-hulls. With this in mind, I listed to the advice of Emerald (an owner of an Ericson Independence 31 and an Ericson Forum moderator). Emerald said that on an earlier boat he owned he had replaced all of his old plumbing fixtures except his original through-hulls. As it turned out, this was a bad decision, because he ended up breaking off one of his through-hulls when installing a hose on the barb for this through-hull's seacock. I had heard enough. I decided that the most prudent course of action would be to replace these original through-hulls with new ones.
This ends this first posting on the removal of the old through-hulls from my boat. The many steps I took to replace these original through-hulls on Oystercatcher, my Ericson 25, are the subject of the numerous postings that follow.