Cummins Marine Diesel Repower Specialists › Forums › Boats & Repowers › 1990 Wellcraft 33′ Sports Bridge Re-Power

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  • June 18, 2021 at 3:39 pm #116653

    Jeff Sevier
    Participant
    Vessel Name: Life is Good
    Engines: 6BTA 250hp
    Location: Oxnard
    Country: USA

    Howdy all, I bought this boat with a pair of 300hp 3600RPM GM 6.5L supercharged diesels, Hurth 630 A 2:1 gears and 20×22 props. Im going to re-power, looking at a pair of Cummins 6BTA 210hp and using my same gears and props. I have 2″ freshwater thru hulls and 5″ exhaust. Please let me know if you see any potential problems with this set-up. The boat is the same hull as the Wellcraft Coastal, approx weight 16000lbs. Thank you!

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  • June 29, 2021 at 9:17 pm #117352

    Larry Massa
    Participant

    Jeff,

    I have a 1995 3300 Coastal with tower. It should be very comparable to your Sports Bridge. Last time on the lift the weight was more like ~17,000# with light fuel and water. Mine had the same GM 6.5’s which were subsequently replaced with 6BTA 300 CPL 1613’s. 300hp@2,800rpm. The transmissions were replaced with ZF-63A’s with 1.56:1 ratios. The propellers are 3 blade Michigan Dyna Jet Nibral 20″ x 19″ with a light cup. At WOT and moderately loaded it will make ~26kts@2,950rpm. It comes up on plane very easily with no smoke. I’m sure it is too lightly propped and I’m leaving a couple of knots on the table, but I like the idea of 20+ year old engines running easy.

    I do have some concern over the smaller 210hp engines you have chosen. These boats were all equipped with 340-350hp gasoline or 300-370hp diesel engines from the factory.

    If faced with a repower today, I’d likely choose 6BTA 330’s or 370’s. I’d like to see a bit higher cruise and 30+kts top.

    Best of luck on your project!

    June 20, 2021 at 2:49 pm #116700

    Tony Athens
    Moderator
    Vessel Name: Local Banks
    Engines: QSB 6.7 550 HP
    Location: Oxnard, CA
    Country: USA

    WANT GOOD HELP? Then I need to know everything / exactly what your current running gear is———————-That’s everything behind the engine.

    June 20, 2021 at 11:46 am #116694

    Jeff Sevier
    Participant
    Vessel Name: Life is Good
    Engines: 6BTA 250hp
    Location: Oxnard
    Country: USA

    Thank you Tony. I think that is the biggest concern I have. I have no idea how the boat performed with any of this equipment. The boat was not running when I got it.
    I’d really like to go with the Cummins 6BTA’s but, regardless of HP, they are rotating at 2600rpm. Do I look at changing my gears and props or start looking at Yanmars and Volvos to get the RPM higher to match what I already have?
    If I go with Cummins what gears and props should I be looking at?
    Thank you again!

    June 20, 2021 at 7:00 am #116689

    Tony Athens
    Moderator
    Vessel Name: Local Banks
    Engines: QSB 6.7 550 HP
    Location: Oxnard, CA
    Country: USA

    How are you going to compensate for 1000 less RPM?. Currently at 3600 your props spin 1800 RPM.. With the Cummins you’ll see 1300 prop rpm… Yes, less HP tp, but that is major…. What do you know about the props on the vessel now and the speed of the boat at 2600 RPM thru 3600 RPM?

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