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Hull side Thru Hull Fittings for A/C etc

Discussion in 'Technical Discussion' started by Maxwell, Feb 4, 2019.

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  1. Maxwell, Feb 4, 2019
    #1
    Maxwell

    Maxwell Senior Member

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    My boat is in the process of getting the hull repainted and to prepare, we removed all thru hull's (for sinks/AC units etc) from the hullsides and need to replace them once the hull is finished. I'm planning on sticking with white nylon material as a lot of them are located in the white boot stripe of the (flag blue) hull which will blend in better than stainless. Outside of making sure I purchase the same type/size of fitting from an angle or straight perspective, is there anything that I need to know before I purchase? Are there any manufacturers or distributors that are better than others for these items?

    Appreciate any suggestions...

    Max
  2. Capt Ralph, Feb 4, 2019
    #2
    Capt Ralph

    Capt Ralph Senior Member

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    Look for Marlon fittings if you must stay composite. Nylon should not be trusted that close to the water line.
  3. menkes, Feb 5, 2019
    #3
    menkes

    menkes Member

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    Do not use nylon under water.
    Use poliuretan, it sticks much better and stronger.
    You might have more time & effort taking it off and cleaning the area next time you want to remove it, but it's worth the effort.
  4. Capt J, Feb 5, 2019
    #4
    Capt J

    Capt J Senior Member

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    Cabo use to use Bronze and prep and paint right over them. The paint stuck and that is what I would do.
  5. Pascal, Feb 5, 2019
    #5
    Pascal

    Pascal Senior Member

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    I ve used SS thruhull. I Prefer them to Marelon
  6. Capt Ralph, Feb 5, 2019
    #6
    Capt Ralph

    Capt Ralph Senior Member

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    Our L2 project used stainless.
    Looked great in the boot stripe.
    Installed still 4 to 8" over the water line.
    I still lean to Bronze or Marelon for zero maintenance. The S S may require some polishing from time to time.
    Last edited: Feb 5, 2019
  7. PacBlue, Feb 5, 2019
    #7
    PacBlue

    PacBlue Senior Member

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    The common nylon thru-hulls you see at marine hardware stores will degrade over time and fail due to UV exposure. The nipple will shear from the flange when you least expect it and then the excitement begins. You begin filling up the bilges with a/c circulating water or seawater can enter if it is too close to the waterline.

    Within a foot of the waterline always use bronze with an accessible shut-off ball valve.
  8. Capt Ralph, Feb 5, 2019
    #8
    Capt Ralph

    Capt Ralph Senior Member

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    Are you stating Nylon or glass infused Marelon?
    I'm pretty much against the Nylon fittings.
    Forspar Marelon thru hulls do pretty well above the water line.
  9. Maxwell, Feb 5, 2019
    #9
    Maxwell

    Maxwell Senior Member

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    Sorry I used the term Nylon by mistake. I believe the existing fittings are Marelon. I'm going to get a stainless fitting or 2 to set in and see how they look. If they're good, I'll go that route, otherwise will stick with the Marelon. The boot stripes and hull sides have been painted, and the boat is just waiting for the clear coat now so installing bronze then painting isn't an option.

    Appreciate everyone's input as usual!

    Max
  10. PacBlue, Feb 5, 2019
    #10
    PacBlue

    PacBlue Senior Member

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    Nylon.
    I do prefer metal within 12" of the waterline though.
  11. Capt J, Feb 5, 2019
    #11
    Capt J

    Capt J Senior Member

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    You can paint the bronze ones before installing them. It's easy if you're so inclined to go that route.
  12. captholli, Feb 6, 2019
    #12
    captholli

    captholli Senior Member

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    These new Bronze through hulls were installed then sanded bright , primed with 545 epoxy primer and then top coated with Awl-Grip by using a pre-valve system. As you can see, minimal masking and impact on the surrounding surface by using a medium pre-valve for acceptable results on small areas. Bronze accepts primers and top coats very well when prepped properly.



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