Alarms at 1:15am Follow up

Six months ago I bolted awake at 1:15am to a shrieking high bilge water alarm while we were 50 miles south of the Grand Banks, in large seas, on passage from Newport, RI to Kinsale, Ireland. The quick summary is we got the problem resolved, but it took 11 hours, and we learned about a few changes we could implement that would make Dirona safer. This write up is about what we decided to do.


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I bolted awake at 1:15am to a shrieking alarm. We were 50 miles south of the Grand Banks, in large seas, on passage from Newport, RI to Kinsale, Ireland. I ran upstairs to the pilot house and Jennifer, at the helm, just said “high bilge water.” Yuck. Better than fire but far from good news. I ran back down stairs to get to the engine room and, yes, conditions there certainly do warrant a high bilge water alarm. I hadn’t even stopped to put clothes on yet but in the short time between the alarm firing and me arriving in the engine room, the water had come up above the bilge and the port side engine pan that forms the walkway around the engine was already awash.

 

The rest of the story is up at Alarms at 115am. The quick summary is we got the problem resolved, but it took 11 hours, and we learned about a few changes we could implement that would make Dirona safer. It’s been six months since that morning with the alarms and we now have all the changes implemented. This write up is about what we decided to do.

The first issue is the aft storage lockers will flood in very rough sea conditions. This by itself isn’t really a problem. The things we store in that locker can get wet, but the real problem is, if that locker fills up a few inches, water will flood down below through the shore power cord re-tractor storage opening. This raises two questions: 1) why is the locker filling? and 2) why will a flooded locker allow large quantities of water into the boat?

The locker is filling because it has a one-inch drain hole. We have had the boat for eight years and we often see some water in that locker, but rarely much and it hasn’t been flooding below. The locker drain is there to help nuisance water get out so the locker contents don’t stay wet all the time. This actually works fine, but every year or two a wave fills the cockpit and, when this happens, the locker floods through the “drain” and some water gets below. On the night in question, the sea conditions were both fairly severe and quartering, and the cockpit was filling every 60 to 90 seconds. This means there was always 12 inches of water in the cockpit so the locker would eventually have 12 inches of water as well.

The flooded locker was dumping large quantities of water into the boat through the down the 2-inch Glendinning shore power cord retractor pipe that passes through the locker floor. The pipe has a collar around it to help keep water out but, in these conditions, water was just about always above the collar. Once the locker has more than 1.5-2 inches of water, it floods below. Under these fairly rare conditions, we essentially have the 1-inch drain hole from the cockpit pouring directly into the boat. A 1-inch hole at 1 foot of depth will bring in 19 gallons per minute or 1,140 gallons per hour (from: http://www.whsyc.org/Flooding/Flooding.html). This doesn’t sound like much until you see how fast the engine room fills.


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We addressed this problem in two different ways. First, we installed small boat self-bailing transom plugs. These are essentially one-way valves that allow a small boat to seal when it’s sitting in the water but to allow bilge water to drain out when the boat is up on plane. We put one on each locker and these valves will allow water to freely drain from the locker but, in those times when the cockpit fills, water will not run into the locker. This means the locker will be clear and dry under normal circumstances and won’t be allowed to fill when the cockpit does. Thanks to mvdirona.com blog readers Greg Moore and Dave Berliner who recommended this approach.


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This check valve seems like a pretty effective solution but we also added an extra level of redundancy. For this we sealed off the shore power cable retractor hole using an alpine boot gaitor. Gaitors, for those that haven’t used them, are waterproof boot extensions that can be wrapped around your leg and velcroed together to prevent water from rushing down your boot tops when walking through snow or high water. We installed one on the cord retractor hole. Strictly speaking it should never do anything but, if for any reason, the locker flooded, this would reduce the flow below to a trickle if any at all. Thanks to mvdirona.com blog readers Rod Sumner and Paul Wood who suggested this mitigation.


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At this point, we’re back to our usual dry bilge. We keep the bilge dry so we can see any leaks quickly. We also test the bilge pumps annually but part of the problem was the main bilge pump had a failed valve. These Jabsco 34600-0010 pumps have a few weak points, the most annoying of which is the inlet and outlet valves have ferrous metal rivets that hold the rubber flapper in place. Unsurprisingly, these valves fail and testing annually really isn’t sufficiently frequent. But, even if you test them daily, they can still fail an hour later. The only way to trust these pumps is to change the valves frequently.

We considered that option but it doesn’t seem practical or efficient and the valves are fairly expensive. Instead, we installed a Rule 3700 in the main bilge with an automatic float valve only a couple of inches above the often-faulty Jabsco pump. We initially planned to use a Rule 4000, but the 3700 was a better fit in what is a very tight spot. We already did have a Rule 3700 high-water bilge pump installed that produces excellent volume (our bilge pump design is described at Fighting Water Ingress). But we learned from this incident that it is mounted way too high in the bilge to serve as a primary high-volume dewatering system since it doesn’t even turn on until the main bilge is nearly full. It’s tough to see that much water in the bilge and feel like things are still under control. We left it in place as an additional level of redundancy.

We now use the Jabsco 34600-0010 pump only to dry the bilge. If there is more than a couple of inches of water, the Rule 3700 takes over and it’s capable of moving 3700 GPH. It moves a lot of water. So much that the original leak would have just turned on this pump every 2 or 3 min for 15 to 20 seconds and would easily have handled this leak.

Fortunately we have two very loud bilge alarms since one of them didn’t work that night. We suppose this is fine since the reason we have redundancy is we want to be absolutely certain one will work. But, for something this important, we ended up deciding we wanted to have three high water detectors so we installed yet another one.

Closely related to the bilge high water alarms, we also have pump cycle counters mounted on the dash, but we wanted to make sure these absolutely get noticed. Now when the bilge pump cycles more than 3 times in 1 hour, our control systems will illuminate a red warning light on our Maretron N2kView display and send email to both of us.

For added safety, we added a red warning light in the engine room when the new Rule 3700 bilge pump operates, and a manual switch allowing the pump to be operated by hand if the automatic float fails. And when the pump operates, the control system will send email, generate an audible alarm, and display an indicator light on our Maretron N2kView display.


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Click image for a larger view

We also have a Pacer SE2IBL hydraulic bilge pump that can move a prodigious 180 gallons per minute. It’s a beast, but is not self-priming, so care is needed to pump out the bilge without pumping down to the point where the prime is lost. We get great security from the volume of water it can move but, ironically, its volume is a problem as well. You need to turn the pump on, dump the water, then shut it quickly off again. This is easy if you can watch it pumping, but the switch that controls it is up in the pilot house so what should be a simple job ends up taking two people. We installed a second control switch in the engine room so the pump can be operated by a single person with a view of the bilge. Of course, it’s also controllable from the pilot house.


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Click image for a larger view

When we said earlier “we installed a Rule 3700”, we oversimplified slightly. It actually doesn’t fit in our bilge. Access to the lower bilge in our boat is limited below the prop shaft and 5 through-hulls. The pump can’t be dropped in through all that mechanical gear so it needs to be assembled in place like a ship in a bottle. In order to install the pump, the base had to be removed and then it had to be worked into the bilge but held high enough that the base and float valve can be installed. Then the outlet plumbing had to be installed and the pump lowered to its operating point at the bottom of the bilge. Each section of the outlet plumbing had to be added in sections since the entire assembly is too large to install in a single operation.


Click image for a larger view

Click image for a larger view

Click image for a larger view

Click image for a larger view

In the pictures you can see some of the obstructions but it’s hard to do them all justice. The bilge is just barely wide enough for the pump at the bottom. Halfway up, there are through hulls for the generator, wing engine, hydraulics, and HVAC cooling. Above those near the top of the bilge is the 2 1/4-inch main prop shaft. Once installed, the Rule 3700 fits nicely and works super well


Click image for a larger view

Click image for a larger view

Due to tight quarters in the main bilge, the design we chose for discharge is to have the new bilge pump share the 2-inch pump hose with the manual bilge pump. We put the manual bilge pump and the 3700 in series rather than in parallel. Essentially the 3700 replaces the pickup for the manual pump and discharges inline through the manual pump. And the manual pump draws through the 3700 pump.

It’s an unusual configuration, but we’ve filled the bilge and the manual pump output is indistinguishable from the test prior to installing the 3700. We again filled the bilge and the 3700 output is about 3x and perhaps 4x the output of the Jabsco pump. It’s a simple design that seems effective and is fairly easy to install. Well, it would be “easy” except for having to install the pump like a ship in a bottle. That required some patience but, otherwise, the job actually was easy.

In the first picture below, James is starting the Rule 3700 install by pulling up the extremely stiff hose from the manual bilge pump that we’ll use as the discharge hose for the new pump. The second picture shows the grate at the end of the hose where the manual bilge pump picks up from the bottom of the bilge. We cut off that grate and plumbed the hose into the new Rule 3700.


Click image for a larger view

Click image for a larger view

 

In summary, the changes we made to address this issue were:

  • insert self-bailing transom plugs on the two cockpit locker drains
  • seal off the shore power cable retractor hole with an alpine boot gaitor
  • don’t rely on the low-volume and low-reliability Jabsco 34600-0010 for anything more than bilge drying
  • install an additional Rule 3700 just above the main bilge-drying pump
  • illuminate a red warning light in the engine room when the new Rule 3700 bilge pump operates
  • when then new the pump operates, the control system will send email, generate an audible alarm, and display an indicator light on our Maretron N2kView display
  • install a third bilge high-water detector
  • when the bilge pump cycles more than 3 times in 1 hour, our control systems will illuminate a red warning light on our Maretron N2kView display and send email to both of us.
  • install a second hydraulic bilge pump control switch in the engine room for single-person operation.

In many ways, this is a lot of work for a problem that only happened once in 7 years. But this is life critical equipment and we intend to own the boat for many more years to come, so it feels worth it.

 


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9 comments on “Alarms at 1:15am Follow up
  1. Patrick Walsh says:

    I served aboard the USS Archerfish SSN-678 and we used sonoprobes for bilge level alarms which had no moving parts. A centrifugal pump was used for routine bilge pump outs but we also had a monster DC motor which drove a multi-stage centrifugal drain pump for major bilge or compartment water evacuation. Your fixes are sound and exhibit a good defense in depth strategy which is critical to keeping water where you want it. Well done sir.

  2. Gary says:

    Wow, gasping while reading this! I get elevated when a spider trips my fire alarm at home…nothing more noxious than piezo buzzer alarm in the middle of the night….glad you reconciled this one…but, lucky enough you are youthfully agile and able. 100 lbs ago when I used to teach water skiing, we would be tasked occasionally to pull up other little speed or ski boats by attaching toe line to bow hook and opening the transom drain plug and just pull and the water flies out….the key is bing agile enough to clamber in to the back of the freshly floated hull and put the plug back in and lock it down….those little plugs! Well done, both of you!

  3. Patrick N46 Noeta says:

    So #4 pump thru the Edson hand pump in series is placed at the end of the pick up for the Edson pump where the strainer is located?

  4. Rod Sumner says:

    James and Jennifer:
    Thoroughly enjoyed the write up. All these mods should eliminate “Alarms at ?? hour”!!
    In the fourth photo is the pipe with the green wire and white tubing (on the left of two) sealed as the one of the right appears to be?
    In the 13th photo there are two shut off valves.
    Should these be labelled just in case? I have found the Brother P-Touch labelling system produces excellent waterproof labes of all different sizes, fonts and colour combinations – Just a thought!

    • Hi Rod. It looks like you are right that the pipe with the shore power and bonding wire aren’t sealed off with calking. The pipe will prevent any water getting below until it’s deeper than 4″ in the locker but it’s not hard to calk that pipe top. I’ll do that.

      The shut off valves in picture #13 are labeled with easy to read tags fiberglassed in beside the through hulls.

      Thanks for the careful review Rod.

  5. Michael & Frances, N40 Coracle says:

    James, Jennifer,

    Thanks for taking the trouble to complete the story. As you know I have a close personal interest!

    I counted 5 bilge pumps discharging through 4 thru-hulls:
    1. Jabsco
    2. Pacer
    3. Rule 3700 #1
    4. Rule 3700 #2 + Edson hand pump in series

    I assume pumps 1 and 4 use original thru-hulls installed when the boat was being built. Where do pumps 2 & 3 discharge?

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