exhaust system design

Discussion in 'Boat Design' started by djsaxton, Apr 16, 2017.

  1. djsaxton
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    djsaxton Junior Member

    exhaust system design for beta 50 hp


    would greatly appreciate your thoughts.
    first my old system see attached (pic 02,52,33)-had 60 hp perkins #4203 repowering with Beta 50hp.
    next plan A system (see attached drawing) with two waterlocks drawing.
    even with the two waterlocks, I don't think they can handle the volume of water in the 2"x9'6 hose. (This is my only waterlock option with my limited space available) my old system makes sense to me as there is no way water can travel from the port side to the STB side muffler. but is a 90 degree bend and aprox 3' rise too much back pressure?
     

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  2. gonzo
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    gonzo Senior Member

    Why don't you leave the exhaust system as it was originally?
     
  3. djsaxton
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    djsaxton Junior Member

    yea that's my thought to, but the beta guy I bought the motor said he wouldn't
     
  4. philSweet
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    philSweet Senior Member

    You've got a couple issues that the Beta guy may not be aware of. First, it's an old IOR design of some sort, and you can cruise for days with the stern squatted down to the waterline. I have fond memories of sailing for three days with my entire engine control panel a foot under water in the cockpit (Catalina 38). So figure the actual waterline as the sheer at the stern. Secondly, even with the highrise elbow, the engine can flood. I think you need to get some professional help from someone who knows your boat very well. (What kind is it BTW, a Lapworth?) I'm with Gonzo - reproduce the old arrangement. Did the Beta guy say why he wouldn't stick with the original?
     
  5. djsaxton
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    djsaxton Junior Member

    Thank you for the reply Gonzo and Phil,

    the boat is a F&C 40 (see attached)

    the Beta guy thought it was an outdated system and quoted ABYC standards and said he would not use it in his own boat.

    I am an circumnavigator and have been in all types of weather (including spreaders in the water) with my old system and have never got water in the motor.
     

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  6. gonzo
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    gonzo Senior Member

    This is a German Frers design, and on top of it built by Frers & Cibils. I would trust the original design and construction. If the Beta guy thinks he can do better, he should provide you with a design he will guarantee to work.
     
  7. djsaxton
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    djsaxton Junior Member

    Thanks Gonzo,

    yes that's what I plan on doing.

    I was questioning my self because of the ABYC standards.

    I have been restoring the boat from top to bottom and have found an amazing level of craftsmanship and design.
     
  8. gonzo
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    gonzo Senior Member

  9. djsaxton
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    djsaxton Junior Member

    Hi Gonzo,

    I didn't think of that -great thinking.

    I posted on the Beta forum and got this answer from Stanley who knows his stuff from what I can tell; and I posted a question, see below

    from Stanley;I think that your standpipe arrangement as used on the old engine should work just fine.
    I would definitely build a new one and also include a new flex section between the engine and the standpipe.
    It won't hurt to fit an anti siphon valve in the water line between the heat exchanger and the water injection point of the standpipe as well. This will also be mounted above the waterline.

    I hope that this helps, Stanley

    Hi Stanley,

    Thank you so much for your advice.

    I have drawn in an anti siphon loop as you suggested.

    but I have a mystery, its been 10 yrs since I pulled the motor and I don't remember what the 1/2" fitting on the upper fitting of the water jacket went to, any thoughts
     

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  10. gonzo
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    gonzo Senior Member

    The anti-siphon doesn't need two hoses in the installation you show. It can simply be a hose that goes higher than the waterline and then has a one way valve.
     
  11. djsaxton
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    djsaxton Junior Member

    thanks Gonzo,

    before the injection point of the water jacket as drawn -correct ?
     
  12. gonzo
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    gonzo Senior Member

    The anti-siphon can be any place between the water pump and injection point.
     
  13. djsaxton
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    djsaxton Junior Member

    Thanks Gonzo, how's this
     

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  14. gonzo
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    gonzo Senior Member

    Looks good. I suppose the valve will be higher than the muffler, but you run out of space for the drawing.
     
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