246 open with yanmar prop

Discussion in 'Diesel Dudes' started by Bach Wilson, Jul 7, 2020.

  1. saltwaters

    saltwaters Active Member

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    Are you aware that all Yanmar tachs read 100 rpm high? Your 3300 is actually 3200. You can confirm this by getting a phototach. All diesel engine manufacturers recommend max rated rpm plus 50 - 75 when heavy (full fuel, full water and all of the other stuff you take with you on a boating trip.) At a minimum you need to increase rpms by 150.
     
  2. Bach Wilson

    Bach Wilson Active Member

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    I don't have a yanmar tach. Mine reads from the alternator. I installed a new tach last month. I have no reason to believe its reading high.
     
  3. saltwaters

    saltwaters Active Member

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    That's a better option than the yanmar tachs
     
  4. Bach Wilson

    Bach Wilson Active Member

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    That was part of the reason I created this thread because I did not have an operational tach at the time. The bottom is just a little bit dirty right now at the 3300 number. When I ran it wide-open throttle it was more about checking the operation of the tach tha really trying to do a scientific study on what it was capable of. Looks like I’m got a fishing trip for this weekend and I’ll do some more trial on it then.
     
  5. TheBoat

    TheBoat Well-Known Member

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    What Brand, type of bottom paint are you using? Depending on the Harbor I have gotten anywhere from 6 months to 4 years out of a paint job. I pressure wash it but still hate the painting part. Its just plain Nasty, Always where old cloths that you can just throw away after.
     
  6. Bob williams

    Bob williams Member

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    Getting a good record of what the boat does at the pins with your current prop is info the guys at acme or Michigan wheel will need from you. With all that info acme prop was able to hit the nail on the head first try when i re-powered my 219 open 2 years ago. They offered to ship props back and forth until the numbers were right but there was no need to.
     
  7. TheBoat

    TheBoat Well-Known Member

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    I used to like to deal with a little place in Salem Mass called H&H Propeller, You could bring in your old prop and they would rebuild it to make it perform how it needed to. at the time I had a 30 ft Downeaster with full 3 ft keel single screw that would do 18 kts with 10-12 Divers and lots of tanks onboard. running Dive Charters out of Gloucester,, MA and that boat took out a lot of lobster pots with props constantly hitting them, especially night trips. Its lobster Pot landmines along the New England coast. One of the reasons I like the Shamrock 246 Tunnel drive is it does not get wrapped up in pot warp and I can run really shallow waters where the lobster boats cant go.
     

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