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Thread: CD tug help!

  1. #1

    Default CD tug help!

    My brother-in-law has 21 ft C-Dory tug with a 3 cyl. diesel motor. I dont know the size or pitch of the prop, but the boat tops out at an 11-12 mph cruise @ 3000 rpm. He would be happy if he could get 15-16 at 2500 rpm. Could we install a prop that would achieve this? And how could we find out which prop to go to? Thanks...dirt.

  2. #2
    Member NewMoon's Avatar
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    Would that be the Ranger R-21EC tug? He might try contacting the Ranger folks for advice.

    http://www.rangertugs.com/r/contact.cfm
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  3. #3

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    Quote Originally Posted by dirtface View Post
    My brother-in-law has 21 ft C-Dory tug with a 3 cyl. diesel motor. I dont know the size or pitch of the prop, but the boat tops out at an 11-12 mph cruise @ 3000 rpm. He would be happy if he could get 15-16 at 2500 rpm. Could we install a prop that would achieve this? And how could we find out which prop to go to? Thanks...dirt.

    Go to the c-brats site. You will find very good support there. But, with that said. A lot of people want to go faster in their tugs. But, they are tugs for goodness sake.

  4. #4

    Default I forgot that the cdory tug guys have their own site now.

    Go to tugnuts.com

  5. #5

    Default

    Quote Originally Posted by dirtface View Post
    My brother-in-law has 21 ft C-Dory tug with a 3 cyl. diesel motor. I dont know the size or pitch of the prop, but the boat tops out at an 11-12 mph cruise @ 3000 rpm. He would be happy if he could get 15-16 at 2500 rpm. Could we install a prop that would achieve this? And how could we find out which prop to go to? Thanks...dirt.
    1. Check the sites mentioned above.

    2. You can make anything go fast if you apply enough horsepower and burn enough fuel. The tug hulls are designed to go slow with good fuel economy.

    3. Somebody, somewhere said that the F4 Phantom was proof that you can make a brick fly if you strap on big enough jet engines. But only the US military can afford to do that.
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  6. #6
    Sponsor potbuilder's Avatar
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    Quote Originally Posted by dirtface View Post
    My brother-in-law has 21 ft C-Dory tug with a 3 cyl. diesel motor. I dont know the size or pitch of the prop, but the boat tops out at an 11-12 mph cruise @ 3000 rpm. He would be happy if he could get 15-16 at 2500 rpm. Could we install a prop that would achieve this? And how could we find out which prop to go to? Thanks...dirt.
    You need to find out what RPM that engine is supposed to turn at wide open throttle and then prop to that number. If you add more diameter or pitch to the prop trying to go faster you will only be lugging the engine and wearing it out sooner then instead of going faster you will only be going to the bank for a new or rebuilt engine.

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  7. #7

    Default Tugs like that just don't go fast.

    While it is just speculation, I would be very doubtful that turning slower is going to result in more power. Most diesels in that size range are at their max hp (only 30 hp if I remember right) at about that 3000 RPM, give or take.

  8. #8
    Member captaindd's Avatar
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    What type of hull does it have? If the boat is a displacement type hull you may already be at its top speed.

  9. #9

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    I beleive it is a displacement hull. And I beleive he said 3000 rpm is WOT. Is there a prop shop around we could talk to?

  10. #10

    Default

    Quote Originally Posted by dirtface View Post
    My brother-in-law has 21 ft C-Dory tug with a 3 cyl. diesel motor. I dont know the size or pitch of the prop, but the boat tops out at an 11-12 mph cruise @ 3000 rpm. He would be happy if he could get 15-16 at 2500 rpm. Could we install a prop that would achieve this? And how could we find out which prop to go to? Thanks...dirt.
    According to the C-Dory site, the top speed is 13 mph. Good luck going faster with a 30 hp motor......turn it faster or turn it slower, it just isn't giong any faster.

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