Propulsion for passagemaker

Discussion in 'Inboards' started by taniwha, Sep 26, 2012.

  1. taniwha
    Joined: Sep 2003
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    taniwha Senior Member

    I am presently building one of Tad Roberts Passagemakerlite designs. I have not yet installed the engines. Although I have in mind what I want I like to keep an open mind on things. So let me know what you would install and dare to be different: hybrid diesel electric, hydraulic with one engine and two shafts,... whatever let your inspiration work and who knows you might convince me.
  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    The original design will give you the most economy and reliability. Are you looking for innovation for its own sake or trying to improve the design?
  3. taniwha
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    taniwha Senior Member

    I started building this concept because somebody had to do it. Writing thousands of posts on forums does not compare to building the real thing. In the same spirit I am just curious to know what ideas people would come up with in terms of propulsion. The original concept is probably the best but since this Forum serves as an exchange of views and ideas.....
  4. DCockey
    Joined: Oct 2009
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    DCockey Senior Member

    How far along are you with the construction? I looked at your website and since there are no photos I assume you are just starting.

    What are the goals and requirements for the boat and propulsion system? How important is it to you to "dare to be different"?

    An alternative propulsion system will require some rework of the design. Are you capable or are you willing to pay someone who is?
  5. Frosty

    Frosty Previous Member

    Yeah --how far dare to be different do you want --like Elephants on tread mills or not that far. Or maybe not far enough. I like a challenge.

    What about 2 whales strapped to each side?

    We need ground rules like do you insist on a propeller, that would be the whales out.
  6. WestVanHan
    Joined: Aug 2009
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    WestVanHan Not a Senior Member

    hybrid diesel electric-nope

    hydraulic with one engine and two shafts-nope

    I'm sure Tad will know what's best....
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    FAST FRED Senior Member

    The real question is what complexity will you accept for efficiency?

    If your boat needs say 60Hp, 3 GPH to cruise at SL .9 to SL 1.5 an 80 HP honestly rated engine would give the best fuel burn.

    But there would be little excess power for headwinds (so you go a bit slower)in F8 to windward.

    Std prop , 2 blade if you have the diameter , cheapest and easy to install..

    Want more power for the 1% of the time , "to run from storms" it will require double/triple the installed power and reduced efficiency.

    So a CPP would be required to regain efficiency from the mostly loafing engine.

    If you decide you need a wing "get home" engine and or a noisemaker , the choice is more complex.

    The noisemaker could power the main shaft with belt , chain or HYD.

    I prefer hyd as it requires nothing but moving a lever, no bilge crawls with tools/parts in hand.

    An interesting tho more complex setup would be a twin engine with single CPP shaft.

    Dual Tranny is from landing craft but not light..

    This could use engines of 2 different sizes if desired

    .Some folks would pick 2 identical engines so parts can be canabalized when required

    Big engine for wake making inshore, and docking.

    Little engine is noisemaker or propulsion as desired.

    Both engines would be fitted with Hyd to power bow thruster, water maker ,windlass, dink hoist,flopper stoppers or stabilazition gear, refrigeration, scuba compressors , DC alt for the batt and gen head for AC power.

    Gets sorta complex but you could even power the head with a hyd motor.

    How much "efficiency" how much luxury , how much maint?

    Your choice.
  8. taniwha
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    taniwha Senior Member

    Pictures are on the photo gallery:
    Why would you have to rework the design for using eg hydraulic propulsion or hybrid?
  9. taniwha
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    taniwha Senior Member

    The two shaft tunnels are already there as the hull and interior is finished. So we will have to work with 2 shafts.
  10. taniwha
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    taniwha Senior Member

  11. tugboat

    tugboat Previous Member

    Im all for D.E. or hydraulics--coming from a tugboat background--they seem to be the best systems..of course--as with everything else in the universe no pro goes unanswered without a con..

    both systems are more expensive-more complicated and a headache at times...think about this too--costs of running?..unless you r wealthy(you probably are if your able to build one of Tads wonderful passagemakerlites!)then fuel operating costs come into play..

    i could list the advantages and disadvantages for each system but --there will be many other who will soon offer thier opinions about each. stay tuned they are on thier way...

    my quick 2 cents-

    D.E. costly- can use twin screws- but recharging the batts gets very complex. and the wieght of the batts and the complexity for extended cruising makes this almost unviable. plus there are cooling issues for the motors running cont. duty. there is alos shunt wound- pm , and brushless motors, to name a few. all have unique characteristics.


    better than D.E. in mho. less complicated- more costly- the oil alone is going to run you into the thousands.
    depending on the size of your engines--the bigger the engines the more oil needed unless you can keel cool the oil somehow.
    slightly more efficient too than d.e.

    *but dont blow a hose--you'll rememebr that experience for the rest of your life.!

    they do also offer instant reverse, instant response and arguably more manoeuverability and the bonus of two props off one engine--(yes d.e. systems can do this too!)

    but you will lose hp-because the drive motor needs a higher buffer of hp to run the pumps. so there is where the losses are--having said that--they run about 89-92% efficient.

    its more complicated than that as there are two systems closed or open.

    my choice would be steam--because again one boiler two engines..and wood is free!! if you can cut it--but then again--cutting uses fuel..and trucks hauing use fuel too..

    bizarro world option #1

    you could be like some waterworld mcgyver type and cut your own wood on the shores of deserted isles...using hand saws?
    personally id run a boiler off cheap cheap.

    solar will not power a boat -unless you have a huge new mexican type solar array attached to your boat and a windfarm when its not sunny out.

    so it boils down to the least complex most effiecient way to propel a boat..

    power -balanced with economy!--

    go with a single shaft. single prop and an oversized rudder. include a bow thruster if its a larger passagemakerlite--(the plans do come in larger and smaller versions dont they?)

    those are esentially your my opinion
  12. tugboat

    tugboat Previous Member

    yea--and the boat could become a submarine when they decide to dive...too!

    whales hp ais pretty low--like about 2 hp per ton.
    ala Wifried Elmers calcs.

    funny guy!:p
  13. R. Jacobsen

    R. Jacobsen Previous Member

    Two small Deere´s of 4.5 Ltr. each and a CPP by Hundested, or equivalent, are my choice if I would have to propel that boat around the world with peace in mind and on a fair budget.

    Others may choose Cummins of similar displacement and/or power, thats more a choice of taste rather than good reason, but the Deere is a non destructable sort of engine combined with a CPP.

    DE, Hyd. or the so named "hybrid" of any taste have their advantage in some very narrow markets, but passagemaking (read: cruising the oceans in a fast and economical way) is not amongst those.

    A CPP of that size is not as cheap as the cheapest gearbox if one looks just at the price tag, but not much more if the comparison is done fair. The advantages on the other hand are almost indefinite.
    You can load your engine even at idle, you can shift from full to full (ahead, astern) in seconds without destroying the gear, you can travel under sail with engines supporting at any setting of power you want to apply, you can dock easier even with one engine running, and so on.
    Then, a CPP does allow for the biggest wheel possible, within reason, regardless of the engine size installed.
    Though I am aware there are some members around here not recommending CPP´s for no good reason (mainly inexperience), I would beg you to think twice, and then rethink, before you install anything else but a proven CPP system!

    As a boatbuilder I do wonder btw. why that hull is already built and the propulsion not choosen???? That is not only strange, that is close to be named idiotic. Sorry

    If in doubt, search older posts here on CPP systems, the most experienced members have recommended it for ages. Or google "Kastenmarine" and have a look what Michael Kasten has to say on that topic.
  14. Stumble
    Joined: Oct 2008
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    Stumble Senior Member

    For a true Passagemaker I might seriously consider diesel-electric with a primary engine of spec size, and use the house generator for back up propulsion. Without any thought to using the batteries for propulsion.

    This way you have a get home engine so long as the shaft/electric system is operational.

  15. taniwha
    Joined: Sep 2003
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    taniwha Senior Member

    -John Deer is definitely a nice sturdy industrial engine but even the 4,5 l is way too big for my boat.
    -A CPP is also a good idea I just wonder at which time you would get your money out of the investement, would be a nice exercise to work out.
    -Do not worry the propulsion was choosen at design state (you can see it on Tad Roberts'site) as mentionned in my first post I just like to keep an open mind.
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