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Converting Gas to Diesel

Discussion in 'Carver Yacht' started by CyberTiVo, May 26, 2010.

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  1. CyberTiVo, May 26, 2010
    #1
    CyberTiVo

    CyberTiVo New Member

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    I have an opportunity to pickup a 2001 396 really cheap, but it has gas motors. I have not considered gas an option in the past. However, at this price I might be able to make the switch and still come out ahead. Am I crazy? What all needs to be changed? I am planning on getting Cummins 6BTA 370's, Kohler generator, transmissions & props. Are the drive shafts different? Anything else I am missing; on the surface this seems like all I need. Someone with more experience than me would know better.
  2. Capt J, May 26, 2010
    #2
    Capt J

    Capt J Senior Member

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    Generally when converting from gas to diesel the prop shafts will have to be changed and stuffing boxes. You will also need a return line on your fuel tanks, probably larger starting batteries, and a few other items.......
  3. NYCAP123, May 26, 2010
    #3
    NYCAP123

    NYCAP123 Senior Member

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    What brand 396 is that? (I'm thinging Carver or Silverton?) I very much doubt that a 10 year old 39 footer would be worth the cost of converting (certainly not either of those). For starters consider the care this vessel has recieved from an owner who would buy a 39 footer with gas. Then you have to understand that the diesels, etc. will probably cost way more than you could ever sell the boat for. Finally, if you don't do everything right (including possibly beefing up the supporting structures) you could have a very expensive piece of junk. A conversion like this is generally reserved for a classic or something special that you're in love with.
  4. Capt Fred, May 26, 2010
    #4
    Capt Fred

    Capt Fred Senior Member

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    I do a little work on a Carver 396 and have converted a different gas boat to diesel. The Carver engine room is beefy enough and looks to have the clearance for this conversion. The shaft is 2" in diameter and the stringers are solid. The exhaust is at least 5". This boat runs a ZF transmission with a 10 degree down angle. It would be a lower cost conversion given that you do not have to change the shafts and beef up structure. This change over would be expensive unless you did it yourself and you could save more by getting used diesels. My conversion was approx $23,000 for twins and a genset in 2000. Don't forget that your takeout gas engines and genset have value.

    I'm happy I did the conversion on my boat but would still be trying to recoup the expense if I would have gone with new engines and had a yard perform the work. I nearly doubled the range on my boat which is very important to me and also I travel into Mexico to locations where gas is not readily available.
  5. CyberTiVo, May 26, 2010
    #5
    CyberTiVo

    CyberTiVo New Member

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    What brand 396 is that? - Carver

    I very much doubt that a 10 year old 39 footer would be worth the cost of converting (certainly not either of those). I'm thinking I can do it for around $30K; there are many for sale in the $150K range with the diesels I am looking at.

    For starters consider the care this vessel has recieved from an owner who would buy a 39 footer with gas. The boat is in very good shape.

    Finally, if you don't do everything right (including possibly beefing up the supporting structures) you could have a very expensive piece of junk. Since Carver sold many of these with diesels, shouldn't the boat structure in the engine compartment be the same?

    My last boat was a SeaRay 450 Sundancer with 450HP CATs; that is what I am used to; don't think I would be happy with the performance of gas. Had to sell, $ issues. Would like to a nice boat again (Aft cabin - better layout), but can't spend $130-150K:(
  6. CyberTiVo, May 26, 2010
    #6
    CyberTiVo

    CyberTiVo New Member

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    Thanks CaptFred

    I do plan to do the work myself. I have seen rebuilt Cummins motors around $10K each. Any idea what the transmissions would cost?
  7. CyberTiVo, May 26, 2010
    #7
    CyberTiVo

    CyberTiVo New Member

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    Thanks Capt J

    Yes, batteries and small cost items are no big deal. I'm just looking for some big "got ya".
  8. Capt Fred, May 27, 2010
    #8
    Capt Fred

    Capt Fred Senior Member

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    Without do an exhaustive study I see some ZF 220 in the 3K range and of course the price will vary up and down depending on quality.
  9. CyberTiVo, May 27, 2010
    #9
    CyberTiVo

    CyberTiVo New Member

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    I was wondering which series. I have been looking at the 63 & 80 trying to figure out which one I need. The Cummins 6BTA's have 330 or 370 HP; Carver used the 370 HP models. The horsepower chart for the ZF 45, 63 & 80 is a little confusing. Have not heard of the 220; I will look further. Thanks for the input!:)
  10. ScubaPete, Aug 3, 2011
    #10
    ScubaPete

    ScubaPete New Member

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    I know this is an old thread, but I was wondering if you did the repower with Cummins diesels. I have a 406 with the 330hp 6BTA's and love it.