Fishing boat 30m and 2 Engines

Discussion in 'Boat Design' started by Nisham, May 19, 2014.

  1. Nisham
    Joined: May 2014
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    Nisham Junior Member

    Hi. I'm currently designing a 30 meter fishing vessel for pole-and-line fishing. As far as I have seen all the traditional designs have one main engine and a typical stern curves. What are the main advantages of those and can't I alter it to instal two engines?
    Thanks in advance.
     
  2. gonzo
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    gonzo Senior Member

    Price is the first concern. What advantage would twin engines give you? Also, single engines have a single propeller deeper and tucked under the hull. That has less probability of getting lines tangles.
     
  3. Nisham
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    Nisham Junior Member

    Thank you. True. Also struts and stern modification must be a hassle which may not be worth. I was only thinking of speed alone and as i have checked the fuel consumption of engines are almost proportional to the HP. So thought the running cost may not be an issue but the initial cost and maintenance perhaps.
     
  4. FAST FRED
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    FAST FRED Senior Member

    So thought the running cost may not be an issue but the initial cost and maintenance perhaps.


    Two engines usually are far harder to service because of the space constraints of the engine room.

    As well as double the cost for oil, filters (fuel & oil) , belts ,,,,,,,stuffing box and tranny maint.
     
  5. Nisham
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    Nisham Junior Member

    Great help. Thank you!
     
  6. PAR
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    PAR Yacht Designer/Builder

    Maneuverability is greatly enhanced with twins. How is it that you're "designing" a nearly 100' long fishing vessel and asking such basic questions about propulsion and hull form alterations to accommodate a twin shaft arrangement?
     
  7. Nisham
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    Nisham Junior Member


    Thanks. know the general advantages/disadvantages of the twin engines. Twin engines may not always cost more fuel. Volvo 600 fuel consumption rate is same as total of two 300HP Engine's fuel consumption rate. The speed will definitely increase with double engines than a single one for many reasons as you know. Well the initial cost, installation and maintenance is definitely a problem. As so far I havn't seen a twin screw fishing boat it's going to be new for me and I want to check if there is anything i'm missing. That's why i thought it might be good to ask before coming to a conclusion.

    Thanks again
     
  8. PAR
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    PAR Yacht Designer/Builder

    Given the same HP for a single to twin conversion, the twin will always use more fuel, always cost more, will always have more drag associated with it, so it'll be slower too. A twin installation is heavier, further burdening the hull form.
     
  9. Nisham
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    Nisham Junior Member

    Thanks that's a lot of information.
     
  10. PAR
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    PAR Yacht Designer/Builder

    This "information" is all but obvious and something you should have learned a long time ago, if attempting to design a vessel of this size. This is why I've questioned you abilities previously in the thread. Simply put, if you have to ask these questions, you are unqualified to design a 100' craft.
     
  11. FAST FRED
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    Most engines operate more efficiently when heavily loaded than when loafing.

    Twins can be done to solve this with a transmission that mounts two engines and allows 1 or both to powert the shaft.

    OTS , its been built for landing craft for 1/2 century.

    The neat trick it to use engines that can have the service items , pumps , filters etc mounted on either side, so there mounted on the Outside of the power package when installed..
     
  12. CBD Boat Design
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    CBD Boat Design Junior Member

    Two engines vs single engine in a fishing boat... In my opinion depends of the size the boat and the operational requirements.

    For power requirements of less than 700hp probably is more economic install one engine big than two smallest. Because when you thinks in power requirements more bigger is not ever true.

    The engines biggers of 700hp in continous operation ratings are very big, very expensive (buy and manteniment) and complex of installation. (Not is the same one shaft line for one engine of 400hp or for 800hp) The same with propellers, exhausts...


    For other hand i think that one propulsion of 600hp is too small for one boat of 30m

    If you make exhaustive numbers (not sensations) you will see than the diference with double propulsion is not big and the win in maneurability, safety and fiability is big.
     

  13. Nisham
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    Nisham Junior Member

    I haven't read them yet as I am going slow because this is a project of my own. I just said thanks to appreciate the links not necessarily the information is totally new to me (yet to know).

    I admit that I lack information and mostly experience in this field which is why I am here. I am a new graduate in Naval Architecture. Yes I am kind of new to the practical world. The projects I have worked were mostly motor yachts. Knowing that there are experts with lot of experience here I asked. Most of the times the best tricks/shortcuts comes from the experienced people.
     
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