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How to vent a cabin-mounted day tank on a Catalina 30?

Discussion in 'Ask All Sailors' started by patrickkidd, Dec 5, 2017. Add this thread to a FAQ

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  1. patrickkidd

    patrickkidd

    Joined Nov 15, 2015
    214 posts, 8 likes
    Catalina Catalina 30
    US Sausalito, California Richardson Bay, CA
    Hello!

    I am trying to figure out how to vent a diesel day tank for my new diesel cabin heater. The tank is mounted inside the on a bulkhead on the beam of this Catalina 30 (see attached photo) and will be filled via transfer pump from the main tank. I am not familiar with thru-deck hardware, spillage concerns when heeling over, etc. I can only imagine that venting to the cabin will make the cabin smell like diesel.

    I know that the water tank vent goes through the deck up into a stanchion which has a hole drilled into the side. Seems like running a tee into that vent potentially exposes the water tank to diesel overflow. There is another stanchion next to the spot where I want to mount the tank - should I drill a hole and vent the tank there? Or should I run the vent along the top of the cabin all the way back to the main diesel tank vent on the transom? Or is there some vent I device can buy that I can install right through the deck that won't let water in?

    Concerning heel: I am surprised that sea water does not enter my fresh water vent mounted into the stanchion at full heel.

    What considerations I should make for venting a day tank?

    Thanks!
    -Patrick
     

    Attached Files:



  2. Ken Cross

    Ken Cross

    Joined Oct 24, 2010
    1,420 posts, 147 likes
    Hunter 30
    US Everett, WA
    No experience here, but I'd assume it vents like an engine fuel tank.
    Ken
     


  3. Michael Davis

    Michael Davis

    Joined Jan 5, 2017
    273 posts, 70 likes
    Beneteau First 38
    Ca Saturna Island B.C. Lyall Harbour Saturna Island
    I had the same tank on my E-28+ but in the cockpit locker. Just used a high loop out of poly line for a vent. Never any problem unless I didn't pay attention when filling it. ( I didn't have my settee cushions right under the tank fortunately)
     


  4. Michael Davis

    Michael Davis

    Joined Jan 5, 2017
    273 posts, 70 likes
    Beneteau First 38
    Ca Saturna Island B.C. Lyall Harbour Saturna Island
    How do you plan on plumbing that? You'll need a long fuel line from your main tank then a shorty to the heater.
    I think I would put the day tank in a stern locker and run the fuel line in the bilge, up inside the locker ahead of the heater and through a small hole in the bulkhead to the heater metering device. I know that takes away from storage but you don't have to live with it inside.
     


  5. patrickkidd

    patrickkidd

    Joined Nov 15, 2015
    214 posts, 8 likes
    Catalina Catalina 30
    US Sausalito, California Richardson Bay, CA
    The purpose of the day tank is to gravity feed the heater. I am pretty sure that the place I have planned for it is the only place it will fit.
     


  6. Michael Davis

    Michael Davis

    Joined Jan 5, 2017
    273 posts, 70 likes
    Beneteau First 38
    Ca Saturna Island B.C. Lyall Harbour Saturna Island
    From the pics it looks like your heater may be a little higher than mine was but my tank was mounted right under the deck aft. and I had no trouble with it. 5200 a piece of 3/4 ply against the hull and screwed the tank there. I know they are shiny et.al. but I think you would be happier if it wasn't in your living space. IMHO
     


  7. patrickkidd

    patrickkidd

    Joined Nov 15, 2015
    214 posts, 8 likes
    Catalina Catalina 30
    US Sausalito, California Richardson Bay, CA
    Can you elaborate on where you put the pump, lines, etc? What kind of lines did you use?
     


  8. Michael Davis

    Michael Davis

    Joined Jan 5, 2017
    273 posts, 70 likes
    Beneteau First 38
    Ca Saturna Island B.C. Lyall Harbour Saturna Island
    Main tank in the 28 was under the 1/4 berth. Ran the fuel line across to the port side ( through a filter) then up to the pump ( pump will lift 6 feet) into the tank. Outlet ran down to the bilge. Through the under settee storage into the hanging locker the heater is mounted on. Used marine grade diesel fuel line for all. Pump was mounted on the same board as the tank.
    P.S. Primary racor was right beside the main tank so came off the second outlet of it.
     


  9. patrickkidd

    patrickkidd

    Joined Nov 15, 2015
    214 posts, 8 likes
    Catalina Catalina 30
    US Sausalito, California Richardson Bay, CA
    Yeah, I don’t think sure a gravity feed from the day tank to the heater would work with the tank mounted aft. At the moment I am thinking I should run a vent straight back along the top of the cabin to the main tank vent on the transom which exits at the same height.
     


  10. Ron20324

    Ron20324

    Joined Jan 22, 2008
    5,717 posts, 396 likes
    Beneteau 323
    US Annapolis MD
    Hhmmm... How about just small a vertical tube with a shutoff valve when not in use?
     


  11. Michael Davis

    Michael Davis

    Joined Jan 5, 2017
    273 posts, 70 likes
    Beneteau First 38
    Ca Saturna Island B.C. Lyall Harbour Saturna Island
    You could also not use the day tank and run straight off the pump. That's the way it is on our first 38. Pump is under the foot of the aft berth, heater is on the heads bulkhead. You hear the pump if you listen for it but it disappears pretty quickly. No need for a vent then.
     


  12. patrickkidd

    patrickkidd

    Joined Nov 15, 2015
    214 posts, 8 likes
    Catalina Catalina 30
    US Sausalito, California Richardson Bay, CA
    Yeah, that was the reason for the day tank actually, to avoid having to hear the pump. Call me picky :)
     


  13. Michael Davis

    Michael Davis

    Joined Jan 5, 2017
    273 posts, 70 likes
    Beneteau First 38
    Ca Saturna Island B.C. Lyall Harbour Saturna Island
    Same reason I put one on the 28. I was disappointed that this boat didn't have one too but your brain stops hearing the pump after a minute.
     


  14. Michael Davis

    Michael Davis

    Joined Jan 5, 2017
    273 posts, 70 likes
    Beneteau First 38
    Ca Saturna Island B.C. Lyall Harbour Saturna Island
    Your pic show the metering valve about 30 inches below deck level so gravity should work just fine if you mount the tank just under the deck. Distance from the tank doesn't matter.
     


    LloydB likes this.
  15. patrickkidd

    patrickkidd

    Joined Nov 15, 2015
    214 posts, 8 likes
    Catalina Catalina 30
    US Sausalito, California Richardson Bay, CA
    You may be right. I am just having trouble finding a straight enough path for the fuel line to the heater. But anyway, it's a good idea.
     


  16. Michael Davis

    Michael Davis

    Joined Jan 5, 2017
    273 posts, 70 likes
    Beneteau First 38
    Ca Saturna Island B.C. Lyall Harbour Saturna Island
    Don't worry about a straight line. Rubber fuel line goes anywhere.
     


  17. patrickkidd

    patrickkidd

    Joined Nov 15, 2015
    214 posts, 8 likes
    Catalina Catalina 30
    US Sausalito, California Richardson Bay, CA
    I was thinking more in terms of avoiding section where the gravity-fed fuel line has to go through a section of rise. It is hard to find a way where every turn is downward over that length.
     


  18. Michael Davis

    Michael Davis

    Joined Jan 5, 2017
    273 posts, 70 likes
    Beneteau First 38
    Ca Saturna Island B.C. Lyall Harbour Saturna Island
    A long as you don't go back up higher than the tank you will be OK.
     


  19. LloydB

    LloydB

    Joined Jan 15, 2006
    347 posts, 9 likes
    Macgregor 22
    US Silverton
    After having drained several fish tanks and a rain filled cockpit from time to time it still amazes me how high a siphon will pull through a 50ft 3/8" hose.
     


    Michael Davis likes this.
  20. thinwater

    thinwater

    Joined Mar 26, 2011
    1,635 posts, 193 likes
    Corsair F-24 MK I
    US Deale, MD
    Not the potable water vent. I'm hoping that was a joke.

    One possibility would be to run the vent back to the main diesel tank. In that way, if you overflow by loosing track of time, it just goes in a loop.
     


    Michael Davis likes this.

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