View Poll Results: Be honest!

Voters
94. You may not vote on this poll
  • Absolutely

    59 62.77%
  • I must think about it, but I'm sure I can tell

    23 24.47%
  • I must think about it, but I might miss some

    10 10.64%
  • Not a clue

    2 2.13%
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Results 131 to 135 of 135
  1. #131
    Join Date
    Apr 2011
    Location
    Boat- SoF
    Posts
    3,224

    Default Re: Can you tell off the top of your head...

    Where does the little 12 mm pipe I have marked in red go ?
    Looks like a typical shaft seal T ?
    https://imgur.com/a/8SZqO

    Mikes got V drive g box ,s so will they be cooled via there own seacock in s —- under the engines ?

  2. #132
    Join Date
    Mar 2002
    Posts
    14,766

    Default Re: Can you tell off the top of your head...

    Quote Originally Posted by Portofino View Post
    Everything when running is kept with temp tolerances.
    Well it seems to work using 80 odd degree sea water to cool the g box oil.
    Actually I don't think that seawater can reach a temperature anywhere near that, regardless of inline vs. V engine architecture.
    Both the aftercooler and the heat exchanger are designed to use a large quantity of fast flowing cool fluid (sea water) to lower the temps of air and cooling liquid respectively.
    So, in order to keep your cooling liquid around mid 80s, the seawater is bound to be MUCH cooler, even after flowing out of the HE.

    Coming to think of it, I half recall to have read that the normal temperature increase of raw water between the inlet and outlet of the cooling circuit is between 10 and 15 degrees.
    And if that is true, the g/box oil in your setup is being cooled (roughly) by 40 deg sea water rather than 25 - no big deal, I suppose.
    Regardless, yup, as I said by no means I was suggesting to fix something that ain't broke!

    With my post #124, I just thought to mention the explanations I got after asking what's the point of having separate pickups for shaft seals - which was the (very sensible) question raised by mikef.
    But obviously, there are many ways to skin this cat...

  3. #133
    Join Date
    Mar 2002
    Posts
    14,766

    Default Re: Can you tell off the top of your head...

    Quote Originally Posted by Portofino View Post
    Where does the little 12 mm pipe I have marked in red go ?
    Looks like a typical shaft seal T ?
    https://imgur.com/a/8SZqO
    Good question, but I'm afraid I don't know the answer.
    In fact, I don't think to have it in my non-CRM engines, though at the moment I can't be positive about it, because I don't have a pic showing that point.
    The previous drawing which I posted (which is related to pre-CRM engines) seems to support my memory, anyway.
    If you look at it, the only T connections downstream of the raw water pump are the in/out for the gearbox cooler.
    Regardless, I don't think it has anything to see with shaft cooling, considering that it's going upward, towards the inner part of the cylinder banks, where the HP fuel pump is located.
    Maybe CRM engines have an heat exchanger for cooling fuel? 'Dunno, just guessing now.

    Quote Originally Posted by Portofino View Post
    Mikes got V drive g box ,s so will they be cooled via there own seacock in s —- under the engines ?
    This is tricky.
    In mikef boat, there isn't a separate V-drive, because his engines are mated with gearboxes whose shaft exit is reversed and angled downward.
    In other words, his gearboxes integrate the V-drive in a single box.
    This is the reason why I would be surprised if they were cooled just by the dynamic sea water flow, which implies no cooling at all unless the boat is moving.
    Btw, such solution implies a rather poor cooling also at low speed.
    In fact, some previous Ferrettis (like whitelighter or markc boats) used the separate BPM v-drive which I've also got on my DP.
    That is widely recognised as a bomb proof unit, but in Ferretti installations it was "only" dynamically cooled by its own seacock.
    And sometimes, that could lead to overheating after cruising for longish periods at slow D speed (I half recall that whitelighter experienced that).
    Another reason why I don't expect mikef integrated g/box & V-drive to be cooled that way.
    But it's just a matter to wait for him to check and let us know, I reckon!

  4. #134
    Join Date
    Apr 2011
    Location
    Boat- SoF
    Posts
    3,224

    Default Re: Can you tell off the top of your head...

    Yes you are right re seawater HE exist temp
    I have the raw water pressure guage on the MMDS buy not its temp
    Only engine coolant in the closed circuit

    Anyhow fascinating stuff how they manage it all - successfully I might add
    TBO they MAN are quite sophisticated when you scratch about

  5. #135
    Join Date
    May 2001
    Location
    Broken Brexit Britain
    Posts
    44,306

    Default Re: Can you tell off the top of your head...

    Quote Originally Posted by MapisM View Post
    In mikef boat, there isn't a separate V-drive, because his engines are mated with gearboxes whose shaft exit is reversed and angled downward.
    In other words, his gearboxes integrate the V-drive in a single box.
    This is the reason why I would be surprised if they were cooled just by the dynamic sea water flow, which implies no cooling at all unless the boat is moving.
    Btw, such solution implies a rather poor cooling also at low speed.
    In fact, some previous Ferrettis (like whitelighter or markc boats) used the separate BPM v-drive which I've also got on my DP.
    That is widely recognised as a bomb proof unit, but in Ferretti installations it was "only" dynamically cooled by its own seacock.
    And sometimes, that could lead to overheating after cruising for longish periods at slow D speed (I half recall that whitelighter experienced that).
    Another reason why I don't expect mikef integrated g/box & V-drive to be cooled that way.
    But it's just a matter to wait for him to check and let us know, I reckon!
    All correct including about the BPM units. I had those on my Ferretti 46 and at slow speed they got so hot that you couldnt put your hand on them. I have checked through all my photos of my current boat and I have no photo which confirms exactly how the gearboxes are cooled so my answer to this question will likely have to wait until I next visit my boat which is likely to be Easter

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