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  1. #1

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    The Unsinkable ‘Doo

    The Titanic of Sea Doo’s?

    I have read through most Bilge threads on this forum and see a lot of arguing about the cost vs benefit or people claiming it will still sink no matter what.

    That’s B.S. I come from the marine industry, Ive added hundreds of ballast sytems to wake board boats in which we added several tons of ballast weight and dealt with lots of failures and had bad ass pump systems to keep the operator and passengers safe. There is a way to add enough pump to a little ski.... its math. Lets figure out how much water intrusion is possible with a carbon ring or similar failure. At that point we just need to match the pump output and you wont sink. Its cut and dry. Why so much hate for bilge systems?

    Im not a math genius but with a little help on the math..... I promise to do a very detailed how to with pictures on a ST3 Hull that could be followed closely to work on any ski. My install will be 110% true marine grade and a great addition to the forum.


  2. #2

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    I bet you have a lot more battery(s) on board then a tiny pwc battery and bigger pumps. I'm going with no you can't. Pumps only buy you time and usually not very much time....that's if you happen to be close enough to shore or can jump off and support your pwc. Let's say you have a 1000GPH pump, that works out to 3.6 sec per gallons and I bet that is not under any real strain and not pumping up through a hose and out overboard. Lot of people run two...still I don't see two pumps saving you...just buying you a little bit more time.

    Even if you could put a car battery in it or lets say as many car batteries as you could fit in a PWC and run the biggest pump(s)...eventually you'd still run out of battery power and sink. You need to be able to plug the hole long enough to get to shore. If you try to run the motor without a carbon ring water pumps in even faster. The ideal thing would be to have like a rubber plug you could jam in around the shaft...but even that I could see issues with. The newer skis like the TX, you can't even get to that area easily anymore. Also most people don't realize they are sinking until the ski stops running...so even if they have pump(s) it's to late.

    I had a pump in my turbo ski when I blew out the waterbox and I had water up to my head and came very close to totally sinking before I remembered I had a tennis ball in my front bin for just such an occasion. My tennis ball I stuffed in the exhaust exit saved me and it took about 30minutes to pump out the hull so I could tow it back.

    The moral to the story is inspect/replace carbon ring and other surrounding parts as needed. Don't run longer than 60 sec on the hose and never do show off revving...yes it's a thing...so I'm told. A pump is great for pumping out a ski after it's filled with water and is in a spot you can get the water out and figure out what happened. I stopped putting pumps on my skis many years ago...they usually end up dieing anyways. I've had carbon rings last well over 100 hours but I usually replace all that stuff around 100hrs if I have a ski that long.

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  4. #3
    ^^^^ this

    Only thing I have pumps on are X2s and standups.

  5. #4

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    Quote Originally Posted by DinoMite View Post
    I bet you have a lot more battery(s) on board then a tiny pwc battery and bigger pumps. I'm going with no you can't. Pumps only buy you time and usually not very much time....that's if you happen to be close enough to shore or can jump off and support your pwc. Let's say you have a 1000GPH pump, that works out to 3.6 sec per gallons and I bet that is not under any real strain and not pumping up through a hose and out overboard. Lot of people run two...still I don't see two pumps saving you...just buying you a little bit more time.

    Even if you could put a car battery in it or lets say as many car batteries as you could fit in a PWC and run the biggest pump(s)...eventually you'd still run out of battery power and sink. You need to be able to plug the hole long enough to get to shore. If you try to run the motor without a carbon ring water pumps in even faster. The ideal thing would be to have like a rubber plug you could jam in around the shaft...but even that I could see issues with. The newer skis like the TX, you can't even get to that area easily anymore. Also most people don't realize they are sinking until the ski stops running...so even if they have pump(s) it's to late.

    I had a pump in my turbo ski when I blew out the waterbox and I had water up to my head and came very close to totally sinking before I remembered I had a tennis ball in my front bin for just such an occasion. My tennis ball I stuffed in the exhaust exit saved me and it took about 30minutes to pump out the hull so I could tow it back.

    The moral to the story is inspect/replace carbon ring and other surrounding parts as needed. Don't run longer than 60 sec on the hose and never do show off revving...yes it's a thing...so I'm told. A pump is great for pumping out a ski after it's filled with water and is in a spot you can get the water out and figure out what happened. I stopped putting pumps on my skis many years ago...they usually end up dieing anyways. I've had carbon rings last well over 100 hours but I usually replace all that stuff around 100hrs if I have a ski that long.
    With the engine running a single battery setup should keep a pump running. I will do some math later on keeping a 2500 gph pump running but the alternator and battery should keep it running for awhile. If the ski is off then yes forsure there is a time limit but these are all figures that can be easily figured out so you know exactly how much time you have.

    First I think we need to figure out how many gallons of water it takes to sink a ski and have a pump that can exceed that fast enough based on the gallons of of water that can intrude via mechanical failures. Basically the pump out just has to exceed the “pump in”. After that we can figure out the battery and charging system to support this and have a system that reacts fast enough.

  6. #5
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by DinoMite View Post
    ... a tiny pwc battery and bigger pumps. ... Pumps only buy you time and usually not very much time....that's if you happen to be close enough to shore ...

    . Let's say you have a 1000GPH pump, that works out to 3.6 sec per gallons ... Lot of people run two...still I don't see two pumps saving you...just buying you a little bit more time.

    ...eventually you'd still run out of battery power and sink.

    You need to be able to plug the hole long enough to get to shore. If you try to run the motor without a carbon ring water pumps in even faster. ...

    ... most people don't realize they are sinking until the ski stops running..

    .... I stopped putting pumps on my skis many years ago...they usually end up dieing anyways.

    I've had carbon rings last well over 100 hours but I usually replace all that stuff around 100hrs if I have a ski that long.
    I agree that sitting in open water with a rapid and significant leak into the hull and engine not running, eventually the battery will run flat from the bilge pump electrical draw.

    Clearly the hull needs to get to shore promptly, or the engine needs to be running to provide continuous electrical power.

    Or the leak must be stopped.

    Other than the work to install a bilge pump, and the modest cost, what is the downside to having it in there? If it saves the day (and maybe the ski) then it was worth all the hassle and cost.

    If it buys you some time, that may be enough to make a difference. We do not know when or where we might suddenly REALLY want a bilge pump. But if the need arises, it must already be installed.

    How are you seeing bilge pumps fail but you often do not get to even 100 running hours before selling the ski?

    In regards to people not knowing they have a leak, that is what an automatic electronic water sensing bilge pump is for. As soon as it senses water and starts pumping, you can see the water stream exiting the hull. I have my bilge pump exit mounted high on the rear side where the fast water exit stream would be quite noticeable. So the pump is already working even if the rider does not notice immediately.

    I currently use the Whale Supersub SS1212, rated for circa 1050gph. Sure, it will flow something less than that number given hose flow restrictions and head lift, but that is still a lot of gallons per minute. Whatever rate water might be flowing into the hull, the pump is buying some amount of additional float time. 16 gallons per minute, roughly one gallon every four seconds. Out of the hull.

    The SS1212 bilge pump draws about 4.5 amps, so a 19 amp-hour battery could run the pump (assuming fully charged battery) continuously for 3+ hours. Or two of those pumps for over an hour.

    If the engine can be started and at least run at idle, if not some slow forward speed, then the battery will last even longer.

    As the OP said, just how fast is water coming into the hull when the shaft seal fails?

    It might be difficult to actually measure the leak rate, but perhaps a few timing tests would put some numbers on the question. Install one or two bilge pumps into a hull. Remove/disable the carbon seal.


    Float the hull off/above the trailer bunks at a ramp. Stopwatch how long it takes water to reach a certain level inside the hull.
    Pull hull out of water and drain.
    Enable automatic bilge pump, back down the ramp into the water. Measure how long it takes for the water to get up to the same level inside the hull.

    Testing with one and then two bilge pumps would reveal how much pump capacity is needed to make a significant difference in float time.
    And perhaps what pumping rate would be needed to actually keep up with the leak flow.

    I suspect the test results could be interesting.

  7. #6
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by RR697 View Post
    ... There is a way to add enough pump to a little ski....

    ... on a ST3 Hull ...
    In addition to the electrical demand, physically fitting large capacity bilge pumps into the confines of various PWC hulls can be challenging. Finding enough room to sit the pump in the bottom of the hull interior, clear of all the OEM stuff tucked in there, and route the bilge exit hose properly.

    And have the bilge pump installation be robust enough to handle hard riding in rough conditions. PWC hulls can really pound and smack around with violence on the water at speed.
    Last edited by K447; 03-16-2019 at 12:51 AM.

  8. #7
    Looking forward to the installation details. When do you think we might see them ?

  9. #8

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    Quote Originally Posted by K447 View Post
    In addition to the electrical demand, physically fitting large capacity bilge pumps into the confines of various PWC hulls can be challenging. Finding enough room to sit the pump in the bottom of the hull interior, clear of all the OEM stuff tucked in there, and route the bilge exit hose properly.

    And have the bilge pump installation be robust enough to handle hard riding in rough conditions. PWC hulls can really pound and smack around with violence on the water at speed.
    And there you have it folks. Let me also add that usually the outlet is below the water line or close to it, once you start sinking it goes below the waterline causing the pump to work even harder. If you the outlet is above the water line, the pump has to work that much harder. I'll also mention the fact you've put another hole in your ski that water can come in. The hoses and fasteners are not the greatest that come with those pump kits. In my turbo ski (why does it always have to be about my turbo ski) I had the bilge hose a little to close to my exhaust outlet pipe and melted the hose.

    By the way both OEM kits I purchased in the past, the pumps died within a few years. I just stopped buying them. The aftermarket pump I have in my turbo ski which as has been through hell actually still works.

    At one point I did the old pump out a 5 gallon container with the big pump in my turbo ski and I remember thinking I'm basically screwed if I get any substantial leak. I might be able to recreate said experiment now that that ski is in pieces.

    The problem I see is once the carbon ring is blown out your pumping in water way faster than any pump setup that could be put in a ski would be able to come close to handling. Also your sucking air into the pump so your not going anywhere fast. Once you notice your ski is even sinking it's probably to late to do anything about it, the intake pipe is very low on a stock ski and you'll be sucking in water before you have a chance to do much of anything.

    I'm not anti pump, I just have been through enough crap that there is no way I would expect to be saved by even 2 big pumps. They are useful if you can manage not to sink and you can get to a beach or somewhere you can get the ski enough out of the water to pump the water out and fix the issue or plug the hole if possible.

    I'm back to regular maintenance and inspections and the chance you blowing out that seal are super low. I'm on my 8 ski since 2010 and I have never had an issue with the carbon ring setup if everything is aligned probably. I've replaced a few along the way and fixed alignment on some my skis.

    I think this all Much Ado About Nothing.

  10. #9

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    RR697-I applaud your ambition and desire to make a machine better but in this case your efforts will be in vain. The reason is that the design of the thru hull seal for the driveshaft on a Sea-Doo is an "all or nothing" one. With the conventional bearing/packing design that all other manufacturers use, the seal degrades gradually which allows the bilge pump to keep ahead of the leak.

    The carbon ring seal that the Sea-Doo uses can fail suddenly and cause a massive breach.

    The best defense is to ride with proper safety gear, towing and vessel insurance, and a factory warranty. NEVER own a current Sea-Doo that isn't covered by a BEST warranty.
    Last edited by K447; 03-16-2019 at 01:01 PM. Reason: With/without, typo...

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  12. #10

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    I understand that preventive maintenance can almost guarantee a worst case scenario from happening. However to me thats not enough. Also this could end the debate, there is a pump out rate that can prevent sinking.... the question is what size pump is that and how much juice will it take to power and how long can it run with the motor on AND off... lets figure this out instead of continuing the debate of why to do it half ass or not at all.

    We start with the size of any mechanical failures possible, there size and how fast the water can come in. Then how much water the ski can hold. Then add a pump sytem that can support it. Shit you guys are talking about problems like fitting a pump. Theres plenty of room for creative solutions. Such as a water level sensor at the lowest point in the hull and a pump that has a inlet hose and exit hose where the inlet hose starts at the lowest point of the hull. Theres a solution we just need specs and then I can do a build and people can justify if they want to take the steps to make it happen.

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