Marine propane gas conversion

Discussion in 'Propulsion' started by dockdave, Jan 11, 2009.

  1. dockdave
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    dockdave Junior Member

    Noticed that my local garbage company now sportin a shiny new PROPANE fueled truck . I thought these infra-structure changes would take some time.
    My question ; Is it feasible to convert existing recreational boats to this as a fuel source, specifically outboard powered vessels?

    DockDave
     
  2. marshmat
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    marshmat Senior Member

    Probably yes; many existing gasoline engines are easily converted to run on propane. Taxis and police fleets have been doing it for a while around here. An older two-stroke outboard can burn darn near anything (my '94 Johnson is rated to handle 67-octane gas, I didn't know they made fuel that crappy!)

    Propane aboard a boat, though, is a fair bit more difficult than propane in a car. The fuel is gaseous at ambient pressure, and slightly heavier than air, so it tends to pool in the bilge. Not a problem in a car, where any vapour that drifts down will just blow away. But in a boat bilge it's more likely to blow up than blow away. Hence why, on boats that use propane to run the stove, the tanks are usually mounted in a separate compartment on deck or hung off the transom.

    So it's technically feasible, but the safety issues that come with storing propane on board can be significant and costly to overcome.
     
  3. dockdave
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    dockdave Junior Member

    Thanx Matt, figured storage to be the main issue.

    Sideways to original ?

    Would propane fueled outboards have much better thru hub emissions than standard gas?

    Thanks for any input


    Dockdave
     
  4. masalai
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    masalai masalai

    Do you not read? add the propane tank and prepare for a very explosive future .... BANG.... just once and no more boat and most likely people nearby....
     
  5. Tcubed
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    Tcubed Boat Designer

    I don't know what kind of boat Dave means but i will say -
    That is definitely an issue with a decked boat but in a completely open boat like a skiff or dinghy, any slight breeze will blow it away so i would say it should not be a problem.

    Myself i am looking into building an wind/solar electrical system for our house that will store hydrogen and oxygen to power a fuel cell as well as the car and the skiff.

    So then it will be technically a wind powered boat, although it runs with the outboard on the transom.

    Advantage though with hydrogen is it is buoyant in air. The disadvantage of hydrogen is it is difficult to compress enough.
     
  6. rasorinc
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    rasorinc Senior Member

    Propane is not the answer, Natural Gas is. It is lighter than air so rises not sinks. Done a lot of research on CNG compressed natural gas and presented proposals to companys re: conversion. Storage and compressability are the problem.. Natural gas particles do not like each other and to gain any storage you have to compress to 3,600 psi and that takes thick tanks. Propane on the other hand compresses at about 189psi. The answer is ANG absorbed natural gas where a medium in a storage container absorbs the gas at around 600psi. NATURAL GAS IS 1/3 THE COST OF PROPANE. USA will soon start going this way on vehicles in a rapid manner. Conversion costs + absorbing tank under $1,200 US Stan
    PS engines that run on propane or naturaL GAS SHOW HARDLY ANY WEAR AT 100,000 MILES--THEY RUN FOREVER. USA is blessed with ample natural gas for decades. Honda is the only firm to make a CNG vehicle--11 gallon tank--zero trunk space.
     
  7. apex1

    apex1 Guest

    Nono.............;)
    Volvo v70........................and you can still store the honda in the trunk.:D

    Regards
    Richard
     
  8. CDK
    Joined: Aug 2007
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    CDK retired engineer

    Many years ago I converted my Glastron Bayflite to run on propane by adding a reductor valve/evaporator and an injector tube in the venturi. A very simple operation on any old-fashioned Mercruiser or Volvo.
    The propane bottle must stand upside down so the gas leaves the bottle as a liquid, otherwise the bottle freezes in minutes and the gas flow stops. The experiment had little practical value, there where (are?) no fuel stations at the waterside. With the high consumption rate of these engines you need several bottles: a day trip involved a lot of weight lifting.
     
  9. FAST FRED
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    FAST FRED Senior Member

    Propane is about 95,000 btu /gal Gas is about 120,000.

    So price it by HP and it is expensive.

    The best use of propane would be in a seldom used gen set.

    Longevity of diesel, with little maint as the propane does not leave behind varnish from non use .

    Added that E- gasoline can not be stored for even 30 days , and the propane is not harmed by years of storage.

    FF
     
  10. CDK
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    CDK retired engineer

    Here in Europe propane / butane is the cheapest fuel available, less than half the price of gas or diesel because it is taxed with VAT only. That's why in countries like Holland a lot of passenger cars are offered with an LPG installation ex factory. The governments increase the road tax with 275% for these vehicles, making it interesting only for high mileage drivers.
     
  11. dockdave
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    dockdave Junior Member

    I appreciate all the information.
    My plan is to run my 19' seaway w/'87- 88hp johnson on the bottle.
    Partly because marinas tack on an additional 80-90 cents per gal (gas or diesel). Generally if you have a diesel powered vessel and the marina does not offer it, you can have it trucked in, and no one has a "GAS" station on the water around here.
    Secondly, why not.

    Does anyone have theories or knowledge on the emissions.

    THANX
     
  12. Boston

    Boston Previous Member

    sure
    the carbon emission per million btu is about
    52 kg for propane
    68 or so for gas
    73 for diesel
     
  13. dockdave
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    dockdave Junior Member

    After that one Nascar race I thought i would never speak these words

    THANX, Mr Boston.
     
  14. CDK
    Joined: Aug 2007
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    CDK retired engineer

    I do not know what an 88 HP Johnson is, but it sounds like a 2 stroke outboard.
    One particular aspect of liquid gas as engine fuel is the need to warm the evaporator. You need access to the cooling water outlet and feed that to the evaporator. If you want to discard the carb and use only propane, the engine must be allowed to idle until the thermostat opens and warm water becomes available, otherwise the water present in the evaporator will freeze immediately. An alternative would be to install an electric heater that works only during the first minutes after a cold start.

    I assume the Johnson has oil injection in the manifold?
     

  15. Boston

    Boston Previous Member

    there is a huge range of benefits
    everything from 7 to 70% when you consider alcohol from various sources used in various ways as compared to gasoline

    as opposed to a straight up 23.5 percent reduction for propane

    Im talking to the alcohol group ( no not AA ) about making alcohol from seaweed and what its yield might be
     
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