Build it Cool.Tiltable,Retractable.

Discussion in 'Outboards' started by tom kane, Jan 2, 2015.

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  1. tom kane
    Joined: Nov 2003
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    Location: Hamilton.New Zealand.

    tom kane Senior Member

    If you do a lot of boating in shallow water and are tired of looking after your outboard against rocks and sandy bottom why not make it tilt-able, lift able so
    when you run aground the outboard will lift straight up and keep the prop horizontal so it will work better in shallow water. You can use the same principle with a stern drive.

    When an outboard that is just tilt-able hits bottom the power is still on the prop and the gear case is is in danger of damage.
    If the outboard can lift up under the power of the prop the shock is reduced and lifting an outboard for trailering is more convenient.
    The unit can be preloaded to make it easier to rise.
    It would be easier to handle than a long tail or mud boat arrangement.
     

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  2. CDK
    Joined: Aug 2007
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    CDK retired engineer

    Draw a vector diagram of the forces acting on the swivel points; you will see a considerable downward component. Add the weight of the engine and it will be clear this is not a viable idea, there will be more load on impact instead of less.

    For a stern drive the principle is downright impossible, the input shaft allows no vertical movement unless a second pair of universal joints is present.

    On my Yamaha F100 I just press the "up" button to make sure the gear case doesn't hit anything. No need for insane swivel arms that put the prop further behind the transom and increase the transom load.
     
  3. Mr Efficiency
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    Mr Efficiency Senior Member

    The shroud around the prop creates plenty of drag, reminds me of the surf lifesaver IRB 25hp outboards, designed to not chop off swimmer's limbs. They just tilt up when they hit a sandbank, without the need for other modification.
     
  4. tom kane
    Joined: Nov 2003
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    tom kane Senior Member

    build it Cool and Sexy.Tiltable,Retractable

    You have not read the thread properly or thought through the possibilites. The weight of the motor is counter balanced. The thrust of the prop pushing on the leg frame protector on striking the bottom ensures the motor rises.
    There have been many lift able outboard transom brackets on the market.

    For a stern drive you use a Pivoting Drive Shaft and a sliding jack plate
    Your Yamaha F100 tilts backwards at the wrong angle increasing the transom load and pushes the transom down and is useless at a tilted angle to propel the boat forward and the tilt mechanics are to slow to lift the outboard quickly.
    Swivel points are set up to lift the outboard when the when it strikes the bottom.
     
  5. tom kane
    Joined: Nov 2003
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    Location: Hamilton.New Zealand.

    tom kane Senior Member

    build it Cool and Sexy.Tiltable,Retractable

    The shroud creates some drag but they are used and accepted ( 10% speed loss) with racing Thunder Cats and life saving teams and are accepted for their safety factors.
    When outboard tilt up and backward in shallow water they loose thrust and steering control when it is most needed to get to deep water.
     
  6. tom kane
    Joined: Nov 2003
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    tom kane Senior Member

    build it Cool and Sexy.Tiltable,Retractable

    When an outboard is in operation all the dynamics change and the weight of the outboard changes on the transom. Outboards have clamps to stop the outboard from jumping off the transom as has happened to many people.

    You can have a jack plate that just slides up and down and does not pivot as the thrust and lift of the prop takes the weight of the outboard from the transom (very pronounced with S/P props) so if an outboard can lift up freely it will do so and it can tilt back as well to protect it from damage if provision is made for that.

    You can increase the area of the anti cavitation plate to get more effect so the outboard rides on the surface trailering behind the boat.

    If you want to test the principle loosen your transom clamps and power ashore and see where your ooutboard finishes up.
     

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    Last edited: Jan 7, 2015
  7. tom kane
    Joined: Nov 2003
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    Location: Hamilton.New Zealand.

    tom kane Senior Member

    build it cool and sexy.tiltable,Retractable.

    Anyone with experience using outboards in shallow water would soon see
    an outboard does not tilt up and back while there is power on the motor which drives it into the sand bank like a rotary hoe and creates a lot of damage, but it is impressive and exciting.
    The reason for having a sliding or pivoting jack plate is to make the outboard easier to control and be available at the right angle to push the boat forward when there is more water available like waves.An outboard is useless tilted in shallow water and even very inconvenient anywhere.
     

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  8. Mr Efficiency
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    Mr Efficiency Senior Member

    Not entirely useless tilted in shallow water, you can get enough forward thrust to edge along slowly.
     
  9. tom kane
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    tom kane Senior Member

    If you do want a bit of extra thrust and speed to overcome wind and tidal drift and open up your throttle the outboard and the back of the boat is pushed down if it has enough water depth and that increases the draft otherwise it just creates a lot of spray.

    Mr Efficiency and others are any of you experiencing a host of pop ups and advertising banners and other interference when longing into boatdesign.net????
     
  10. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    No mate, no pop-ups etc. You might have picked up a virus or malware.
     
  11. whitepointer23

    whitepointer23 Previous Member

    Yes. I clicked myarks latest barge photo yesterday and have had my laptop taken over by advertising spam and I can't get rid of it. I don't know if myarks post had anything to do with it or if it was coincidence.
     
  12. tom kane
    Joined: Nov 2003
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    tom kane Senior Member

    Thank`s for replies on spam. I installed free Avast software at computer workshop before Christmas and had never had so much rubbish taking over since and I spent ages cleaning up but it is still there. All my browsers are invaded. And my computer up graded it`s self to windows 8.1

    I thought it may have been firefox (just up dated) add on as that is what the top banner indicated. I get music running I don,t want as well. And demands that I up date my video player and my computer is slow and about to crash..but it just slowed right down..so I un installed Avast free security and it cam right for a while. There are green colour links displayed on my boatdesign pages where pop ups appear. Lovely pokie running at bottom of page now.
    Another computer workshop on 17 this month but I do not have much hope there.
    Other computers running Linux do not have any trouble.
     
  13. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    If you get into the "manage add-ons" section of your op system, you may see some recently installed stuff you can disable. Google the name of it first to see if it is safe to disable or delete.
     
  14. tom kane
    Joined: Nov 2003
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    Location: Hamilton.New Zealand.

    tom kane Senior Member

    thank`s Mr Efficiency, I don`t have any add ons and also checked plug- ins there are three there marked ( unknown. Research) Cisco Systems,inc 1.1 which may be troublesome
    I think they show in installed programs too I will check. Unbelievable that anyone thinks they have the right to do such malice.
    I have never had trouble without computer security using anything other than the software that came with the computer in the past and think all free software is more a danger than anything.
     

  15. tom kane
    Joined: Nov 2003
    Posts: 1,766
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    Location: Hamilton.New Zealand.

    tom kane Senior Member

    Thank`s Mr Efficiency I have no add- ons and checked plug- ins and there are three there that may be troublesome.I think they are in the installed programs so I will check them out.
     
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