Fighting Water Ingress

Click image for a larger view

Besides a fire at sea, few things are more frightening for an ocean-crossing vessel than uncontrolled, and potentially undetected, water ingress. Safety Digest, published by the Marine Accident Investigation Branch (MAIB) of the British Department of Transport (, often contains reports of small boats sinking in minutes. Many might have been saved had their captains realized water was rising in the bilge. These stories prompted us years ago to install a high-water bilge alarm in our previous boat for early detection of excessive bilge water.

In building and rigging our current boat, we focused on high volume pumps, reliable switches, and the provision to manually engage with lots of backups, including alarms and even backup alarms. For pumps, we have a lot of protection and we like having a lot:

  1. Jabsco 34600-0010 pump with an Ultra Safety Systems UltraSwitch Senior Float Type Level Switch model UPS-01-24V. The Jabsco pump is the first level of protection in the main bilge. It will self-prime at 7.8ft and move 10.8 gallons/minute at zero feet of head. This doesn’t sound like much, but unlike many pumps, it actually will produce its spec. The valves need periodic replacement but we forgive it for that because we haven’t seen anything else on the market that we would be willing to replace it with.
  2. Alarm if the Jabsco primary falls behind (ear-splitting).
  3. Backup alarm if the Jabsco falls behind and the primary alarm fails (also impossible to sleep through).
  4. Flashing blue strobe light high up on the outside exhaust stack to let others know the boat is in trouble if we aren’t around.
  5. Rule 3700 pump above the Jabsco, with its own UltraSwitch. This Rule pump will move 60 gallons/minute into zero head.
  6. Pacer SE2IBL bilge pump turned on manually and driven by hydraulics. The Pacer is rated at a prodigious 180 gallons/minute and, having watched it, the pump really delivers the goods.
  7. Honda WH15X portable crash pump. The Honda can pump 98 gallons/minute and is similar to what the US Coast Guard drops in to help save sinking boats. The pump we chose has 30% less capacity than the pump used by the Coast Guard, but it can also be used to deliver a pressure blast to fight fires. Even 100 gallons/minute is an incredible sight. The picture at the top of this post shows the pump spraying water a distance of over 100ft. Saltwater is not ideal inside a boat, but it is effective, and there is lots of it at sea. We would only do this if our lives were on the line and the boat was about to be lost.
  8. Edson model 638AL manual pump. The Edson pump can move one gallon/stroke with volumes up to 30 gallons/minute, has a dry-start suction lift to 12ft, and can pump up to 50% solids.

PAE installed the UltraSwitches on the main bilge. These are fairly dated switches—they have been around forever—and may not be better than the current-generation semiconductor switches, but they have for years been the Cadillac of float-switches. They are super simple, reliable, and battle-proven. We’ve never had an issue and they always works when tested. We like them but are not against the newer systems—we just don’t know them as well.

We annually test the Honda portable crash pump, ensure it’s running well and pumping at full-volume, and change the oil and fuel. It’s always ready to go with new, stabilized gasoline and a fresh oil change. When we tested the hydraulic bilge pump, we discovered two things quickly: 1) the pump will not pump without a prime, and 2) when it does have a prime, it’ll move a prodigious amount of water. When testing it, we filled the main bilge to just below the oil pan and the pump cleared it all in under 60 seconds and shot a 2-inch stream of water out the side of the boat for more than a slip’s width.

The hydraulic bilge pump must be mounted below the water-line to self-prime. And if the boat is heeled over, even if the pump was mounted below the waterline, it might not be when it comes time to need it. Therefore, it must be kept full of water and ready to go. Keeping it full of water is difficult though. Engine rooms are hot and water quickly will evaporate, so it needs to be filled frequently. We instead fill the pump with RV anti-freeze which doesn’t evaporate and keeps the prime indefinitely. Another approach is to tee the pump into a guaranteed source of pressure water to fill it when needed. We prefer the RV anti-freeze solution because it’s simple and doesn’t require any manual interaction.

We had an “opportunity” to test most of these systems in a real-life water-ingress situation where we rolled 69.1 degrees while crossing an ocean bar in Australia. As the boat was knocked over on its side, a breaking wave from above forced enough water through one of the cockpit air intakes to fill the engine room bilge six inches above the floor to within two inches of the engine base. All the high-water bilge alarms activated, and the pumps had been running continuously since the knock-down. But when we checked the engine-room, it was still fairly deep. The hungry hydraulic bilge pump was able to drain the entire bilge in seconds.

We strongly recommend the Pacer pump and some form of high-volume crash pump both be part of a multi-tiered defence against water ingress. The Pacer pump also is available in an electric version for non-hydraulic boats.


2017.06.10 Update

In crossing the North Atlantic in the spring of 2017 we saw some of the most difficult conditions we have encountered thus far in our world-rounding trip (North Atlantic Gales). The conditions were not actually bad enough to be frightening except for a couple of mechanical problems, one of which allowed considerable water to enter the boat (Alarms at 1:15am).

In spending a half day fighting the water ingress, we learned several important things about our bilge dewatering systems. The first is the primary bilge pump is not that reliable and doesn’t pump that much volume. The second lesson is the high-water bilge pump, although it produces excellent volume, is mounted way too high in the bilge to serve as a primary high-volume dewatering system. The third lesson is a confirmation that the hydraulic bilge pump moves absolutely prodigious amounts of water, but ends up being a two-person job to operate. It pumps so fast it can easily run dry and/or lose prime so someone needs to be down in the engine room to monitor it while a second person operates the off/on switch in the pilot house.

These are the changes we plan:

  1. Don’t count on the low-volume and low-reliability Jabsco 34600-0010 for anything more than bilge drying.
  2. Install a Rule 4000 pump just above the main bilge-drying pump. This will be the new high-water bilge pump (primary bilge dewatering system). We will leave the Rule 3700 in place as the backup high-water bilge pump.
  3. Install an off/on switch for the hydraulic bilge pump in the engine room at the pump to allow single-person operation. We’ll leave the pilot house switch in place as well.
  4. Install a third high-water bilge alarm. We had no faults, but this experience underlined that catching these problems early could be the difference between success and failure so we want triple redundancy.


If your comment doesn't show up right away, send us email and we'll dredge it out of the spam filter.

13 comments on “Fighting Water Ingress
  1. I have 2, 14ft boats, and this Shoreline bilge pump kicks butt getting the water out. I just put battery clips on the neg. and pos. ran some 1/2″ PVC and made a rubber adaptor and clamped in on and was off and pumping.

  2. Scott says:

    Just a comment on the Honda dewatering/firefighting pump. In the Navy, a key lesson was don’t wait to use salt water on a fire because you don’t want to ruin stuff. Use it early, as soon as a single extinguisher doesn’t put out the fire.

    • Yes, no question you and the Navy are right on that one. I’m sure it would be hard to go after a fire using destructive saltwater but time given up waffling before using salt water could end up losing the boat. That’s a tough decision that I hope we never have to make but there is no question that fighting fire using the most aggressive means early substantially increases the chances of success.

  3. Gary Reed says:

    Hi James. Timely post as we begin to transition to full time live aboard. Quick question re Honda crash pump. I see from your earlier post you apparently have sufficient suction hose to drop over side for water supply. I was wondering about storage. Infer from your post that you maintain full gasoline tank so “immediately available”. Given gasoline, where are your storing? Assume top side deck box or equivalent? Assume dangers in lazerette or other mechanical spaces dangerous as well as not being “immediately” available ?

    • We carry gasoline up on the boat deck. We have two easy to handle containers that we use to fill the small motors with and two large containers with which we fill the tender or the small gas containers. It’s the small containers we use to fill the honda pump.

      Ideally, the bulk gas storage would be stored lower in the boat but the cockpit was the only other choice and we use that space in two many ways that are incompatible with gas storage.

      We keep the Honda pump with about 1/4 tank of fresh, stabilized fuel ready to go. That enough to get it started and give time to fill the pump while, at the same time, minimizing the amount of gas inside the boat to a very small amount. The Honda burn rate and tank are pretty small so 1/4 tank is a very small amount.

  4. Alex Goodwin says:

    James, so this is the active part of your defences against water ingress? The passive bit being your overwhelming love and affection for fluid leaks of all sorts – jumping on little leaks like hoboes on ham sandwiches before they become big ones.

    So if you’re in a situation where all those pumps going full-banger can’t keep up (and thus taking on >369 gallons/min), you’re most likely en route to a total loss anyway?

    • I like your characterization on my hate for leaks of all sorts regardless of how small. Excellent.

      You outlined two classes of defense: 1) keep after even the smallest leaks so there aren’t problems brewing, and 2) have well maintained and tested pumps on board. Another line of defense of patching. We have wooden wedges, large foam wedges, tarps that can be pulled down the hull on the outside, wood and 5 min epoxy, marine board, rubber gasket material, large hose clamps, etc. This latter approach combines early detection with many redundant alarms and lots of materials to possibly be able to correct the problem. Many commercial boats and some recreational boats carry bags of cement as well. This is reported to quite effective. We’ve considered it but haven’t yet done it at this point.

      • Alex Goodwin says:


        Glad to see you got a giggle out of my characterisation.
        My goof – as you pointed out, you actually have three defence layers against water ingress, one passive (hoboes, ham sandwiches, etc) and two active – one in best Ken Thompson tradition (brute force having an elegance all of its own) and one tackling source of problem (when in doubt, bung a bung in it).

        Would those wedges be left unpainted, the better to swell up, absorb water, and seal whatever hole they got bunged into?

        Along similar lines as your pump test, how can you practice/test your repair gubbins?

        • Alex, we don’t practice stopping up holes a good argument can be made that it would be a good idea to at least talk through different strategies, where we store the gear, and when we would use each. It’s a good suggestion.

          • Alex Goodwin says:


            May have been a dumb question, but I asked in light of your other writings (such as “LEAKS? HAMILTON SMASH!“) where you prefer to have failover/mitigation/repair strategies tested and practiced in advance. That way, you have time (and lack of stress) to find and fix any weak spots.

            Also a reflection on people doing what they’ve practiced when under stress, not what is logical/sane/pants-below-waist/etc.

            • It is true that untested solutions have a very good chance of not going as planned. But it’s also true that the reason we have a boat and tour the world is to have fun so there are bounds on how much time we are willing to invest in the third level of disaster mitigation.

              When your life is on the line, it sounds irresponsible not to invest without bounds on all possible disaster mitigations regardless of how unlikely but there really are only so many hours in a day, some get spent on the day job, some get spent on boat systems, and there have to some left for fun. Primary and most secondary mitigations get good attention but there are practical bounds and everyone needs to make their own call on where to draw the line.

              • Alex Goodwin says:

                Well, as it’s literally your neck, you’re best positioned to draw that line.

                Figured I’d ask a couple of dumb questions and end up learning something.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.