opinion of Beta Marine diesels

Discussion in 'Diesel Engines' started by BelleCanto, Oct 5, 2013.

  1. BelleCanto
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    BelleCanto Junior Member

    Okay, so the simplest setup is heat exchanger engine cooling, with dry stack venting......simplest referring to ease of maintenance, fewer hull penetrations, no freezing temperature issues, but maybe a trade off in esthetics. Is this correct? I'm assuming the heat exchanger system is a closed loop containing antifreeze?
     
  2. michael pierzga
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    michael pierzga Senior Member

    I dont know that maintenence cycle of dry stack. It does need to be maintaned. Unburnt hydrocarbon, soot, accumulates in the dry exhaust....lays soot balls on your deck and presents a fire hazard . Mufflers need to be renewed. Thermal packing on the pipes needs to be renewed.

    It would be worthwhile for you to travel to the waterfront and speak with fisherman who run dry exhaust. They can give you installation and operation tips.

    common marine exhaust insulation

    http://www.heatshieldproducts.com/marine/marine-exhaust-insulation/marine-exhaust-insulation

    The dry system will be constructed of welded steel tubung. since the tube is rigid and the engine jumps around on its mounts , you will have to include one of two flexible steel belows in the system to absorb vibration and deal with expansion and contraction.

    http://www.tonyporterfabrications.com.au/gallerytwo/main.php?g2_itemId=43

    Im not sure what type of soot collector is typically being used or if you need one for 25hp instalation
     
  3. michael pierzga
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    michael pierzga Senior Member

    Concerning dissipation of heat , one of the biggest challenges on small craft is the creation of all weather air inlet and exhaust for machine space ventilation. You should think about this. These vent must handle a substantial volume of air to cool your machine space.

    cool air is fed into the machine space down low and hot air is vacumed up thru a vent up high and expelled.

    you must never blow cold air over a hot surface or you will raise the temp of the machine space.

    I didnt review the link from transport Canada concerning marine exhaust. could be helpful. Regulations are important.

    http://www.tc.gc.ca/eng/marinesafety/tp-tp1332-section9-960.htm#1

    Also contact boatdesign net contributor IKE.

    IKE is ex US Coast Gaurd and runs a website aimed at helping home builders conform to regulations. I cant remeber the website.
     
  4. BelleCanto
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    BelleCanto Junior Member

    Yes, the heat dissipation problem occurred to me. I'm thinking there would need to be an engine compartment venting blower for this, which would also take care of pre-ignition fumes. I read the transport Canada document......fairly basic, mostly common sense. I will follow up on the USCG info. I'm pretty sure the dry stack is best for me, I just don't want to have a stack enclosure that ends up being a foot thick. Thanks.
     
  5. FAST FRED
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    FAST FRED Senior Member

    >Okay, so the simplest setup is heat exchanger engine cooling, with dry stack venting......simplest referring to ease of maintenance, fewer hull penetrations, no freezing temperature issues,<

    There are 2 style of heat exchangers , a keel cooler is a pipe in the water run along the hull. The engine is cooled by the water the boat is in and uses only the normal existing engine coolant pump. It is normally antifreezed so no main is required in freezing weather .

    The heat exchanger mounted on the engine uses sea water with a pump you install to keep engine coolant on the other side of the exchanger cool.This MUST be winterized.

    This style usually also uses the sea water to cool the exhaust , so the need for risers to keep it from the engine cylinders.

    A water cooled exhaust manifold is usually used with the sea pump heat exchanger.

    The water cooled exhaust manifold could be used on a keel cooled vessel but are hardly necessary as insulation requires no servicing or replacement and is way cheaper.

    Some believe the wet manifolds will make a quieter engine room , but proper sound proofing is far better , .

    Google Soundown
     
  6. michael pierzga
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    michael pierzga Senior Member

    With noise, a wet exhaust turns into rubber hose as it exits the boat. This rubber absorbs sound and vibration.

    An all steel hard pipe dry system need special attention and shock mounts to isolate noise and vibration..

    keel coolers work well. proper instalation is important. some hull shapes are difficult
     
  7. BelleCanto
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    BelleCanto Junior Member

    I'm going to have to find boats with all systems and see what they look like....I really like the idea of a wet exhaust...no heat issues, quieter.....but I looked at drawings of this setup, and it looks like you need a minimum of clearance between the manifold and the underside of the deck, in relation to the waterline. Also, its an extra pump....more moving parts. Obviously its doable, because I've seen a lot of small boats with water cooled exhaust.
    What is the best type of gear drive/transmission? Sail drive looks good to me.....
     
  8. FAST FRED
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    FAST FRED Senior Member

    Sail drive looks good to me.....

    Sail drive is very fast & easy to install , so many mfg will select it or a pod drive to lower the expensive labor for the install.

    Sadly a dozen different metals being submerged 24/7 is how a battery is made.

    Long term (over 5 years) the tried and true simple shaft and propeller are the cheapest in terms of maint and repair.Running gear from the 1920 era is still in use.

    >I really like the idea of a wet exhaust...no heat issues, quieter<

    You may not like it when running downwind and the exhaust stench fills the boat and cockpit.
     
  9. michael pierzga
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    michael pierzga Senior Member

    Saildrive like ,everything else in the world ,has its plus and minus


    Since saildrive is so compact the hull piercing and powerplant can easily be installed into a water proof engine room.

    On the negative side is life cycle maintence. ive never seen an OLD saildrive
     
  10. BelleCanto
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    BelleCanto Junior Member

    Point taken about the longevity of the shaft and prop set up, FF and MP...I was thinking that a sail drive may be too similar to a stern drive for me....and I don't know about you, but it seems to me I've seen more boats laid up with stern drive issues than anything else. Back to the exhaust.....is fume blowback a bigger issue with wet than dry? Because that would be an issue in a pleasure craft.
     
  11. michael pierzga
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    michael pierzga Senior Member

  12. FAST FRED
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    FAST FRED Senior Member

    ..is fume blowback a bigger issue with wet than dry?

    The dry is well above the top of the boat , even higher if there is a fly bridge.

    Where ever the exhaust comes out of the hull aft or midships , the breez from that direction will blow the exhaust aboard.

    Fast boats with aft exhausts can run away from the stench , but it is usually 1/2 MPG to get the speed up.
     
  13. BelleCanto
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    BelleCanto Junior Member

    Thanks Fast Fred, ....sounds like dry stack is for me...now, if I only had a boat!
     
  14. nkurb
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    nkurb Junior Member

    In my experience, there are inherent problems with running dry stack exhausts on low cylinder engines. The small diesels do tend to bounce around a lot, even with the best motor mounts. The problem lays with the need to absorb this vibration through the exhaust system. The use of flexible steel pipe is required. Problem is, these can sometimes crack at the 'folds'. Vibration being transferred to the hull can also cause problems.

    You have to be aware that diesel exhaust can reach upwards of 900c. Managing that can be difficult in small craft.

    In my opinion - the easiest system for small engines is a wet exhaust with heat exchanger. Just keep on top of cleaning your water filter and checking impeller and zincs. No big deal really. Everything is much, much cooler. Heat management and vibration is a non-issue, but can be difficult in other systems.
     

  15. FAST FRED
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    FAST FRED Senior Member

    One advantage of purpose built marine engines is many smaller ones will have a hand crank, and de compression levers , so can be hand started.

    This is not done on lawn equipment as power cords and barrery chargers and replacement starters solve the problem.

    I have a great low time Volvo MD 7 B complete wit 2-1 tranny and starter , ready to install.

    With a proper lift muffler this can be very quiet in operation..

    17 HP at 2600? rpm , in most boats at 1800 it sips 1/3 a gal an hour or so.

    PM me if interested $2500 .
     
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