Surface drive for v6 ford

Discussion in 'Surface Drives' started by jamesp2k, Aug 8, 2010.

  1. jamesp2k
    Joined: Aug 2010
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    Location: england

    jamesp2k New Member

    Heres what im up against...

    I have a rocca 600 sports boat (20 ft weighs about a ton and a half) a knackered old omc leg and a good ford v6 engine my idea is to go surface drive rather than leg. To make it more intresting im going to try and make the drive myself. any advice on design or anything aka gearbox type, prop size/pitch and anything else like that.

    Look foward to some help

    James
     
  2. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

    Look at Lancing Marine surface drives (LM-14). Their catalog shows a drawing with dimensions. A very simple construction, once you've obtained the material, you can weld it together in a weekend.
    If you're a good welder you could construct it all from stainless steel.
    The only expensive parts are a gearbox and a prop.
     
  3. jamesp2k
    Joined: Aug 2010
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    Location: england

    jamesp2k New Member

    Surface drive v6 ford

    Cheers for that, how would i work out the prop size and with that design would the boat not 'walk a bit'. oh what size shaf should i use same as the lancing spec?
     
    Last edited: Aug 9, 2010
  4. CDK
    Joined: Aug 2007
    Posts: 3,324
    Likes: 148, Points: 63, Legacy Rep: 1819
    Location: Adriatic sea

    CDK retired engineer

    Put that question to Mike Bellamy at Lancing Marine. He wrote me a few years ago that he is very satisfied with his twin LM14 cabin cruiser, using Ford puma diesel engines. He claimed a significant increase in performance compared to stern drives.

    They designed the LM14 for engines like yours and can advise you which gear ratio to use. As far as I know they only offer one solid hub nibral 14" prop for this drive.

    I decided to design my own tunnel drive system which still isn't performing like I hoped it would. You have to accept the noise and vibration that belong to surface piercing. I found it unacceptable but tried it with 3 blade props and was afraid everything would fall apart.
    Last week there was a large RIB here with 5 blade props and 2" shafts: I didn't see any parts falling off, but it was quite noisy.
     

  5. jamesp2k
    Joined: Aug 2010
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    Location: england

    jamesp2k New Member

    I have now managed to source a borg warner 1:1 gearbox but am struggling to located a adapter plate to connect to my engine any ideas on sourcing a second hand one since like i said trying to keep cost down. One other thought i have had is do i need to fit a angled plate on the transom for when going astern to ensure that prop wash/thrust goes below the boat as opposed to hitting the stern.
     
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