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Old 10-03-2013, 08:08 AM   #1
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Dripless Shaft Seals and One Bilge Pump

I am a newby owner of a 1984 Grand Banks 42. Managed to run it from Ft Lauderdale to Ft Myers but did experience first problem with a failed starboard drive coupling. Owl Creek just completed the fix. I did not take on any water when coupling failed, thank goodness - but here is my question: I have dripless seals and have a single bilge pump. I've heard that when dripless seals fail, they do so catastrophic compared to traditional packing seal. Can a single bilge pump adequately handle dripless seal failures and is it wise to add a 2nd bilge pump?

Final leg of my trip is Sarasota to Texas. Have 3 week planned fuel tank replacement job before heading to Freeport, TX. Want to make sure I have all bases covered before trip.

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Old 10-03-2013, 08:42 AM   #2
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Really depends but even a conventional packing tube failure can overwhelm a single bilge pump...even a 2000gph capacity pump....

I would say that I would feel comfortable with around a true 4000gph capacity on a boat like long as I think I can catch and stem the flow pretty quickly. No bilge pump system is going to handle a true just has to handle what gets by your prelim damage control.

So just as important as bilge pump a system of checks and gear that allows you to detect little problems before they become big and quickly when the big, bad stuff happens. Then you have to know your boat ad what you have on hand to slow the water ingress.

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Old 10-03-2013, 09:36 AM   #3
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As additional precaution I ran a beak of 4200 caulking between the shaft and the SS collar incase the seals fail.

I would be more concerned about the bellows than the seals as the seal and collar fit the shaft very closes, so there is not a big cap between the two. I installed and additional 2000 gph bilge pump just in case with high water alarm.

I have a blue paper towel under the drippless and one of the things I check when in the Engine Room. I have blue paper towels through out the bilge so if there is a wet towel its easy to find the general area. Just follow the dark wet blue towels.
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Old 10-03-2013, 09:43 AM   #4
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A high water alarm is also a great item to install in the basement.
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Old 10-03-2013, 12:11 PM   #5
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On a 40' boat you really need a second bilge pump for redundancy, not only volume. This is especially so, if you leave your boat unattended for a week or longer at a time.
Over the years I can't tell you how many times, I have discovered one of my three bilge pumps was not working on a visit to the boat. Float switches fail, fuses blow, moisture gets to a connection. The pump is only as good as the last time it ran.
Larry B
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Old 10-03-2013, 01:11 PM   #6
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When cruising offshore (good advice for near shore too) check your ER including shaft logs hourly. You should have no water appearing from a dripless system. As Psneeld says, detecting those little things early will save you a bunch of grief.

Do you know the age of the packing system? If not, service professionally ASAP per the book.
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Old 10-03-2013, 03:05 PM   #7
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The PSS bellows is easily inspected for cracking and other warning signs. Mine second bellows is 6 years old and still like new. The one I replaced previously as a preventative maintenance measure did not need changing either after 7 years.

I do agree strongly that you can not have too much bilge pump capacity, especially since they do not perform as rated unless you have a nominal discharge pressure head.
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Old 10-03-2013, 04:15 PM   #8
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One other thought that has helped me is to shoot your packing glands with the IR heat gun during ER checks, that way you can tell early if a problem is arising, it saved my bacon on a previous boat where the packing gland got way too hot.
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Old 10-03-2013, 08:41 PM   #9
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Paper towels in the bilge should perform very well to plug your bilge pump intakes if you do get a leak...

I used foot powder to detect leaks. I couldn't think of another aerosol powder that came in a only puts a very thin layer of powder down. Makes any oil or water leaks obvious.

It smells nice too!

Check one of my other posts, a bilge pump with a head of 4 feet or so puts out about HALF of what the pump is rated for. Also, if you run on batteries not an alternator, the lower voltage cuts that down even more. To add insult to injury, if you get the polarity on the pump wrong you lose another 20%. Spend the 500 and buy a Honda trash pump. It might save your boat and maybe even some lives. Don't forget to buy some gas...
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Old 10-04-2013, 05:26 AM   #10
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>Can a single bilge pump adequately handle dripless seal failures and is it wise to add a 2nd bilge pump?<

It is doubtful that an engine driven 2 inch Jabsco will keep up with a failed bellows.

Maybe 4 or 5 electric pumps , and some luck.
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Old 10-04-2013, 08:27 AM   #11
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You should also carry emergency self-fusing "rescue" tape. In the unlikely event of a bellows failure ( a crack??) simply bind it up with tape - even duct tape will help in a pinch, but rescue tape should do the job quite well. Still do not think there is much risk of the bellows going south unless you never inspect it and it is very old, especially in a slow shaft trawler. Biggest risk I see is an external catastrophic event that damages the prop, the prop shaft and the shaft seal.
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Old 10-04-2013, 12:01 PM   #12
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We have two bilge pumps mounted in the sump, one higher than the other. The first pump has a high water alarm that is very loud. While at the dock, the first bilge pump failed and set off the high water alarm while the second pump took over the pump duties. No emergency, just a collection of sea water from the shaft logs. Yes, I still use packing as I am a firm believer in "KISS."
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Old 10-04-2013, 04:04 PM   #13
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One thing to check is if cooling water from the engine to the seal assembly is used is to be sure the water is flowing. The first time I checked mine, a Tides Marine dripless seal, after owning the boat a couple of years there was no flow at all, there was a build up of crud blocking the inside a 90 degree hose fitting on the cooler. I cleaned it out and got full flow. Tides Marine recommend disconnecting the seal end of the hose and sticking in a bucket and running the engine to see if it is working OK. I believe this is more critical on high speed turning shafts than our trawlers but it is an easy check to do.
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Old 10-04-2013, 08:51 PM   #14
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A very inexpensive little item which can be a big help for a dripping shaft is the wax seal which sits between the commode and the drainage pipe (in your house, of course). You can get one at Lowe's or Home Depot for a few bucks. I used one when replacing the packing gland in the sailboat, and nary a drop of water came through. (Obviously of no use when the boat is running, of course).


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