Click for Ocean Alexander Click for Walker Click for Westport Click for Mulder Click for YF Listing Service

Heavy Carbon Sooting On Transom

Discussion in 'Technical Discussion' started by captTPT, Aug 27, 2011.

You need to be registered and signed in to view this content.
  1. captTPT

    captTPT New Member

    Joined:
    Jul 12, 2009
    Messages:
    20
    Location:
    Eugene, OR
    No, I don't have pressure guages at the secondary filters. I have been running 30 micron Racors. My secondaries are 10. The Racors are available in 2, 10, and 30. Would you switch to 10's?
  2. K1W1

    K1W1 Senior Member

    Joined:
    Sep 30, 2005
    Messages:
    7,388
    Location:
    My Office
    Hi,

    I would certainly try a set of 10's if there is nothing between there and 30, this will at least catch most of what would normally get through to your secondaries.

    Are any finer ones available for the secondaries?

    If you are only bunkering from a well maintained supplier and using automotive diesel you should get a long life out of the secondaries even if they are the same size as the primaries.
  3. captTPT

    captTPT New Member

    Joined:
    Jul 12, 2009
    Messages:
    20
    Location:
    Eugene, OR
    K1W1 I travel to places where I am forced to occasionally obtain fuel from smaller harbors I don't know with all the associated problems. It has been my understanding that sequencial filtration using larger pore primaries (30) followed by smaller secondaries (10) is best. The rational being a much larger total surface area available if you suddenly obtain contaminated fuel. If you place 10 micron primaries and 10 micron secondaries you eliminate the secondaries as filtering units. Never having used your suggestion I have no idea how frequently I would be changing my primaries.
  4. Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    14,432
    Location:
    Fort Lauderdale
    I would try a set of 10 micron fuel filters. What condition is your bottom in? Growth on your bottom and running gear would limit rpms and cause the smoking condition you're experiencing as well.
  5. captTPT

    captTPT New Member

    Joined:
    Jul 12, 2009
    Messages:
    20
    Location:
    Eugene, OR
  6. Pascal

    Pascal Senior Member

    Joined:
    Feb 29, 2008
    Messages:
    8,120
    Location:
    Miami, FL

    what kind of boat/size? there is no way you can be on plane at 13.5kts... at that speed, most boats are just pushing a big wave, putting a heavy load on the engines.

    either slow down to hull speed or get the boat on plane, which is likely to be at least 15 to 16kts (water speed, not GPS!)
  7. dennismc

    dennismc Senior Member

    Joined:
    Jan 29, 2009
    Messages:
    1,175
    Location:
    Vancouver BC
    Soot

    I purchased my 70 ft Stephens MY in Ft Lauderdale in 1991, boat had sat for 2 yrs prior to a refit one year prior to my purchase, I had the fuel polished by "experts" and since then to now, after 6000 hrs on my 12 V 71N's, I have never used anything other than 2 micron Racors, the fuel tanks seem now to be 95% clean as polishing cannot get behind all the baffles etc, I change them twice annually whether they need it or not, the only failures I had were in the Bahamas and Panama due to some water in the fuel where we were really close to full shutdown and all during high seas conditions.
    My experience based on 19 years operation, ymmv

    I also use 2 micron on my Hatteras in Florida and they sure clean up the fuel as the p.o. had a Captain who seemed a bit slow on fuel maintenance.
  8. K1W1

    K1W1 Senior Member

    Joined:
    Sep 30, 2005
    Messages:
    7,388
    Location:
    My Office
    Hi,

    I do not know the characters who wrote that or were mentioned in it but what is written needs to be taken with a grain or two of salt.

    Using the Racor Vacuum gauges will give you an indication when the filters begin to foul long before any damage occurs to your fuel system.

    If you get used to seeing the needles in a certain position at the same speed a variation in pressure (an increase in vacuum) can easily be noticed and monitored.

    I have run CATERPILLAR 3516 Engines with Triple Racors - two in service and one standby for many thousands of hours and have never had to actually change a Racor underway and only done them on hours when doing the oil change at 1000 Hr intervals. I change the engine mounted ones at the same time both primary and auxiliary.

    I have by the end of the 1000hrs had all three in service a couple of times as the vacuum has increased and the fuel pressure on the engine has dropped a bit.

    One of these engines typically burns around 50 us gals an hour at cruise and pumps at least double that amount as it uses a lot for injector cooling and lubrication.

    I use a biocide at bunkering time and run the fuel centrifuge 24/7 polishing the fuel.
  9. jhall767

    jhall767 Senior Member

    Joined:
    Jan 14, 2010
    Messages:
    319
    Location:
    Middle River MD
    It's not the fuel filters. It's too much diesel not too little. It might be the air filters. I'd definitely check them though because they will have sucked some of that soot in.

    Running at that speed the engines are overloaded. Most likely they are overloading each time you climb a wave. Speed up, slow down or change the props.
  10. Capt Bill11

    Capt Bill11 Senior Member

    Joined:
    Feb 27, 2006
    Messages:
    1,458
    Location:
    Sarasota/Ft. Lauderdale FL

    I like Dennis use 2 micron elements in most of the boats I've run if I have a choice. If I was worried about not having enough surface area on the element I just go up one size on the filter or go from single to dual filters.

    I also believe running a boat in rough weather does a better job of cleaning the fuel and fuel tanks than so call polishing does. Unless you can fully access the insides of the tank and it's baffles.
  11. captTPT

    captTPT New Member

    Joined:
    Jul 12, 2009
    Messages:
    20
    Location:
    Eugene, OR
    Wow. This is great! So many different opinions. I, unfortunatly have very little experience with marine diesels (2 1/2 yrs), although quite experienced in engines in general. I am, however, aquiring it rapidly. I'm therefore dependent on "expert" opinions for this type of information. One might think Bob Senter, who wrote that article, with 25 yrs experience at John Deere Marine Propulsion would carry some weight. Steve De Antonio also. But what I read here is very different. Sure would be nice if there was some real science out there. Does anybody know if there is any? Or is this just different ways of skinning the cat and all work? Hope it doesn't take me 10 years to just figure it out on my own!
  12. Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    14,432
    Location:
    Fort Lauderdale
    The information you are getting right here in this thread is all very good and from some of the best in the industry. BTW, how much soot are we talking about here? Is the transom slightly discolored or Black?

    What condition is your bottom in? If you have growth on the hull and running gear (propellors/shafts/rudders etc), it will not only slow you down, but also cause the sootiness and loss of rpms. If your engines top out at 2800 rpms, you should be cruising them at 2200-2300 rpms and on plane (you may need to use the trim tabs to achieve on plane).

    I have usually seen a lot more vaccuum on the racor's before seeing black soot, like in the neighborhood of 15" of vaccuum or at least 10". Engineers have told me that 30 microns don't allow the water to drop out and into the bowl in racors and it's best to run 10 microns. 2 microns may or may not be too fine, depending on your fuel quality and they could fowl very quickly.

    I agree with everyone else's sentiments regarding fuel polishing and really like the Diesel Kleen "Clear Tank Diesel" additive to take care of Algae.

    KIWI- Here in the US we do not get Automotive diesel fuel bunkered. Fuel that is bunkered is generally High Sulfur offroad diesel 99.5% of the time. The only way to get Automotive diesel fuel in your boat's tank would be to fill it up with fuel from an automotive gas station either by taking the boat there on a trailer, or fuel cans, and it's about 10-20% higher in price.
  13. captTPT

    captTPT New Member

    Joined:
    Jul 12, 2009
    Messages:
    20
    Location:
    Eugene, OR
    No, its not black by any means. I polished the entire stern and transom and double waxed it. Looked beautiful. Later that day ran for about 4 hours with a few periods of idling while going through locks. After that the transom was sooty grey. The dam stuff doesn't wash off either. The bottom has some algae present. I dove under and inspected the shafts and props. They are completely clean. Since that time I have quickly brought up on plane and run at 2350 (80% WOT) which is Volvos recommended cruising rpm. Definitely a lot less soot when running at that rpm. However, I have not had this happen before. Sound like multifactorial process. I certainly appreciate all of your advice.
  14. Bamboo

    Bamboo Senior Member

    Joined:
    Dec 19, 2008
    Messages:
    934
    Location:
    Palm Beach, FL
    Wax holds soot much more than an unwaxed transom. Use a cleaner on the transom but no wax and it'll be less black. If the moderators allow it- I use the Collinite #920 to clean.
  15. captTPT

    captTPT New Member

    Joined:
    Jul 12, 2009
    Messages:
    20
    Location:
    Eugene, OR
    Bamboo- thanks for that info. I noticed that. I coated the gelcoat with heavy Carnuba wax. It was like the soot absorbed into the wax. Have to re-polish to get out. Is the Collinite simply a cleaner or does it provide any type of protection? After cleaning with the Collinite, what kind of coating will help protect from soot. My moorage is in the flight path of the Portland Airport so I'm fighting soot all over my boat all the time.
  16. Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    14,432
    Location:
    Fort Lauderdale
    It's just a cleaner, no protectant. I prefer to wax all of a gelcoated boat, including the transom. I usually spray rolloff on the transom and brush it around lightly to spread it, let it sit a few minutes, brush and rinse off and it should take all of the soot off. With the diesels you have, you are going to get some discoloration of the transom after running for a while. What speed does the boat do at 2350? 13.5 knots is probably not a good speed to run, you're most likely better off staying at 10 knots, or closer to 20 knots and on plane.......
  17. captTPT

    captTPT New Member

    Joined:
    Jul 12, 2009
    Messages:
    20
    Location:
    Eugene, OR
    At 2350 the boat will run at about 16 knots.
  18. Capt Bill11

    Capt Bill11 Senior Member

    Joined:
    Feb 27, 2006
    Messages:
    1,458
    Location:
    Sarasota/Ft. Lauderdale FL
    Try using a polymer product on you transom instead of wax. Something Zaino.

    Soot will come off much easier with just boat soap and if you have use a detergent or degreaser to remove the soot you will not strip the polymer off in just one wash like you would with wax.
  19. captTPT

    captTPT New Member

    Joined:
    Jul 12, 2009
    Messages:
    20
    Location:
    Eugene, OR
    Thanks. I'll check that out.
  20. captTPT

    captTPT New Member

    Joined:
    Jul 12, 2009
    Messages:
    20
    Location:
    Eugene, OR

    capt J would you comment on the concept that 30 micron filters immediately become clogged with debris and effectively filter out at a much smaller size right away. With the assumption that other size filters do the same, a 10 becomes smaller and a 2 becomes obstructed quickly. I do not have a polishing system and I buy fuel from unknown sources, so I assume there is garbage in the fuel. In fact, I see it on my Racor filters so I know this is happening. Hard to know what the effective pore size quickly becomes but certainly has to be much smaller when you begin to see any pressure change.