To see as much of the world as we can,
Using the smallest carbon footprint we can,
Spending the least amount of money we can,
Making as many friends we can.

Team Red Cruising

Through Hull Exercise

The Whitby design has a fairly large number of through-hull fittings. They let water in (and out) of the boat in a controlled fashion. For fittings below the waterline, we have huge bronze valves — sea cocks — to be sure we can close off the hole in case a hose fails.

We never expected oysters, though. They're tricky little devils.

bronze through-hull
One of the big, bronze through-hulls

You can see the essential elements of the valve here:

A flange at the bottom that bolts through the hull. A run of pipe screws into that and reaches out into the outside world.

A giant lever to open and close the valve.

A piece of bronze pipe where we can put 1½" or 1⅝" hose. Yes, we have two sizes. Choose wisely.

In this picture it's hard to see the two little plug" on each side. These give you some access to the internals.

The original design for a Whitby 42 had the following:

  • Two sea cocks forward for the MSD (Marine Sanitation Device — the toilet) and sink.

  • Three sea cocks amidships for the galley sink, a deck drain and the "water box" that has all of the incoming water. (Engine cooling, head flushing, refrigeration cooling, etc.)

  • A small one amidships for the macerator pump output.

  • Three sea cocks aft for the cockpit drains, the aft MSD, and the aft sink.

Nine, all told. Add two for air conditioner output, and we're at 11 holes into the water. Each with a valve and a hose.


First things first. When we bought Red Ranger, the A/C output hoses did not have sea-cocks on them. I fixed this ASAP. A hose without a cutoff valve is an accident waiting to happen.

A few years later, we realized we didn't use the A/C very often. At anchor, we rigged breeze catchers. At the dock, we found the fans were adequate. And the aft A/C in particular, only seemed to cool the bilge. We don't want to carry it around. We took it out and sold it. This simplified the plumbing and pumping under the floor, also.

For a large boat like Red Ranger, it's common to have "Y" valves for the MSD's. Waste can go to a holding tank or it can go straight out to sea. In much of the US territorial waters, the holding tank must be used and the waste must be pumped ashore. Off shore, however, the "Y" valve can be switched and the head pumps overboard.

Because the previous owner planned on staying in Chesapeake Bay, the "Y" values were not installed. The through hull was put in, but it was capped off. The heads only flushed into the holding tank. This means the through hulls for the holding tanks are left perpetually closed.

We replaced the MSD (with it's water flush drippy pump) with a composting toilet.

If you're keeping score, this eliminated two through-hulls: the aft MSD and the aft A/C. We had Deltaville Boatyard pull out the giant bronze fitting (and the little plastic fitting) and seal up the holes.

Later, we removed the forward A/C. We didn't use it, either. Why carry it around?

Latest Updates

Recently, we had the Drain Hoses redone, eliminating another through-hull. We had Phipps and Osprey here at Herrington Harbour rebuild the drains. They pulled out another giant bronze fitting (and the little plastic fitting) and sealed up two more holes.

oyster in through-hull
This oyster took up residence in the through-hull

The deck drain on the starboard side was always slow. The drain on the port side leaked into the engine room.

Now we know why the starboard drain was slow.

That's an oyster.

It's living inside the valve. Once upon a time, the forward head sink didn't drain well. We were in the Bahamas and I used a screw-driver to get rid of the oyster living there.

In Chesapeake Bay, I wasn't too motivated to dive in the turbid waters to dodge jellyfish and inspect the openings.

Today, Red Ranger has seven holes through to the ocean.


These things are super robust and very reliable. You can see the core of the valve is a giant, machined cylinder of bronze. The body, similarly, is a casting with the inside machined to match this tapered core cylinder.

All it needs is a little marine grease to keep it moving.

Which leads to the annual through-hull exercise.

  1. Open the floors to inspect all seven devices.

  2. Check the hose clamps. (Double clamps below the waterline.)

  3. Apply grease by putting a ⅛" NPT Zerk fitting into the drain holes and pumping in grease. (Only when the valve is open. Greasing a valve that's closed doesn't do anything.)

  4. Operate the lever.

Step four can be really, really hard. Six of the seven through hulls are readily accessible. A pipe wrench can be used for leverage to move the bar. The main water intake valve is one we use fairly regularly, and it's hard to move without some extra leverage.

Through-Hulls in their natural environment

One valve is almost inaccessible. It's under the aft cabin ladder. You don't reach down through the floor. You open the aft head, lay down, and reach over the top of the drive shaft to get at the handle.

In this picture, you can see the body — with the core removed. The bright line in the bottom of the picture is the drive shaft. The shadowy thing on the left is a prop-lock brake.

On the top of the picture is a tiny rectangle of light. This is where the old aid conditioner access used to be. The hole is barely large enough for a wrench. That's a 1⅜" socket on the ½" drive wrench.

Under the aft ladder
The tiny hole under the aft ladder

When we bought Red Ranger, I rebuilt all the through hulls that I could get to. At the time, there was an A/C unit on top of this, and I couldn't get at it.

There was a fair amount of banging and clanging, but — as you can see — we eventually got the valve apart, cleaned it, greased it, and reassembled it.

All of the through hulls have been checked and greased and they all operate.

There are a few more things to do. We should be in the water soon. I hope. With new drains, and no oysters.