Re: Water Intrusion and watertight bulkheads


Danny and Yvonne SIMMS
 

Hi All.

if you want to convince yourself about the inadequacy of bilge pumps in the case of a hull breach remove your speed log from the through hull when the boat is in the water.

It is down right scary how much water comes in FAST from that relatively small hole. The idea of massive capacity 120 or 230 volt pumps sounds good till you consider Murphy's' law. What can go  wrong, will go wrong, at at the worst possible time. Batteries don't like being under water.

What situation would necessitate that huge volume pump? You can bet not a quiet controlled one. Panic and mayhem may prevail. Gen set wont start. inverter fails, someone in panic gets it all wrong. 

The captains Amel watertight bulkheads make all the sense in the world. But does all your crew know where the locking bars are, and how to fit  them? Do you know where they are so you could put your hand on them in an instant.

Do the valves on the bilge piping that passes through the bulkhead operate, or are they frozen?The water tight bulkheads  will buy valuable time while you find a method to pug the hole. Above the waterline, cushions stuffed in. Below the waterline a more compressed plugging. Large holes, fothering which is drawing a sail or something similar over the outside of the hull.

Certainly large pumps are great but just one of the methods needed. 

Joel is it true that at an Annapolis boat show years ago they flooded the front cabin on a SM and showed the boat could still sail? 

Regards

Danny

SM 299 Ocean Pearl

On 03 May 2021 at 03:37 Mohammad Shirloo <mshirloo@...> wrote:

I recently finished reading the book 66 days Adrift, where a boat was "attacked" by a large pod of pilot whales 1000 miles into the passage between panama and Hawaii and the boat was lost due to water intrusion in the main salon area, in a matter of minutes. I have always thought about the survivability and resilience of our Amels in different scenarios. I have the following questions and hoping the answers are within our group.

  1. Will there be sufficient buoyancy to stay afloat, if there is a large breach in the salon area and the forward and aft bulkhead doors are secured?
  2. Are the forward and aft bulkhead areas watertight only to a certain height about the cabin floor, or could the entire volume be flooded without water intruding into the engine compartment or the salon area. This would be important if there is a large breach at the cabin top, thus allowing the volume to be filled by waves or the boat is inverted.
  3. I have thought about and there has been some discussion about carrying an auxiliary pump, in order to buy some time, in case of a major leak, so that a temporary repair can be implemented. The following chart shows the amount of water flow by hole size and depth of hole. As you can see, at even 2 feet below the water line, a 1.5 inch hole is sufficient to overcome any pumps that we have been discussing in the group. Has anyone come up with a viable design of an engine mounted/operated trash type pump design, or maybe a larger electric pump that could utilize the full  output of the generator (11KW) to allow for significantly more pumping capacity.

    Boat Flooding Rates in Gallons per Minute

    Depth of Hole Below Waterline

    Diameter of Opening or Hole

    1 in

    1.5 in

    2 in

    2.5 in

    3 in

    3.5 in

    4 in

    1 ft

    19.4

    43.8

    77.9

    121.7

    175.3

    238.6

    311.6

    2 ft

    27.8

    62.5

    111.1

    173.6

    250.0

    340.2

    444.4

    3 ft

    33.9

    76.3

    135.7

    212.0

    305.3

    415.6

    542.8

    4 ft

    39.3

    88.4

    157.1

    245.3

    353.5

    481.2

    628.4


Any and all other thought sand plans to add to our tool bag to help in similar situations, would be appreciated.

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