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Mast leak h40.5 Solved!

Discussion in 'Big Boats' started by Rich Stidger, May 16, 2018. Add this thread to a FAQ

  1. Rich Stidger

    Rich Stidger

    Joined Feb 10, 2004
    2,758 posts, 227 likes
    Hunter 40.5
    US 1997 h40.5 Bristol, RI
    Three years ago I pulled the mast in my h40.5, and ever since then I have had a water leak down through the wire bundle that is inside of the mast. I was not present for the mast re-stepping (that was a mistake) and the wires were not successfully sealed by the yard.
    Not wanting to pull the mast again, I attempted several times to seal the wires from inside the main cabin, and no attempt was successful until now.
    The wire bundle comprised of the VHF cable, TV antenna, wires for the steaming, fore-deck and anchor lights, and the signal cable for the wind transducer pass through a piece of PVC tubing that is sealed through a hole in the mast step. This PVC tube is just long enough so that the top end inside the mast is about 1" above the base of the mast step. In theory, any water that runs down the inside of the mast would run out of drain holes at the mast base before it could become deep enough to enter the top of the PVC tube.
    However, if water runs down the wires, there must be a complete seal between all of the wires and the inside of the PVC tube otherwise the water will run through the tiny passages between the wires and leak out into the cabin. This is the problem that I had.
    So this spring I was determined to re-seal and stop this leak once and for all.
    I pulled the PVC tube out of the mast step and into the cabin. I cleaned off most of the old sealant from the wires and the tube. This was surprisingly easy. I then laid all of the wires to be parallel and placed a hose clamp snugly to hold them in place above where the PVC tube will be secured. Using Sudbury Elastomer 321 Sealant, I liberally applied the sealant to each individual wire for a length of 4", and as each wire was coated with sealant it was laid back parallel in the bundle. After all of the wires were coated thoroughly, a couple more hose clamps were snugly applied over the 4" length. After this was cured (24 hours) I replaced the hose clamps with wire ties and then coated the outside of the wire bundle with more sealant - twice. After another day a final coating was applied and the PVC tube was slid up over the bundle and the wire ties and more sealant was applied at the top of the bundle and over the top of the PVC tube as well as up into the bottom of the PVC tube. A wire tie was placed at the top of the bundle that would stop the PVC tube from moving upward on the wires when the entire tube was pushed up into the mast. A day later, the outside of the PVC tube was coated with this same sealant and the tube was pushed up until it was just 1/8" down from the cabin top. This position put the top of the PVC tube about 1" above the mast step. It was left to cure for several days.
    Finally I tested by hosing at the bottom of the mast and found no leaks. Previously pouring water around the mast base did produce leaks coming between the wires inside the cabin. Then I climbed up the mast with the hose and poured water into one of the halyard exit slots. I observed lots of water being expelled from the weep holes at the mast base, but no water inside the cabin.
    I think I have nailed it. Attached are some pictures during the process.
    I know that other h40.5 owners have had this leak problem and other Hunter boats may have the same method of cable pass-thru.

    I think the secret of sealing the wire bundle is to apply sealant to each wire and lay the wires parallel with more sealant around each wire so that there can be no spaces between the wires for water to pass.
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  2. jssailem


    Joined Oct 22, 2014
    5,897 posts, 2,061 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA

  3. Rick D

    Rick D

    Joined Jun 14, 2008
    6,563 posts, 164 likes
    Hunter Legend 40.5
    US Long Beach, Shoreline Marina, CA
    Wow, nice job Rich! I've never had mine down, but when I do I'll know what to do. Thanks.

  4. artboas


    Joined Jun 1, 2009
    1,096 posts, 69 likes
    Hunter 49
    ca toronto
    More ideas

    Ok, I solved my 40.5 leak in a very different, and somewhat sneaky way.
    Yes, the original pvc pipe was problematic.
    It was , as you mentioned, supposed to be proud of the mast step, so that water wouldn't drain down.
    But, I didn't want to pack the pipe with sealant, as it was a bit of a guessing game, and it would make pulling the spar again very tricky
    Here is what I did:
    I took a small plastic funnel and cut a hole in the spout just big enough for all the wires to go through.
    I inverted the funnel, (spout facing masthead), and passed all the wires through.
    Then, I packed the spout with 4200.
    When I installed the mast, I simply led the wires down the pvc pipe, and made sure the open end of the funnel sat on top.
    All water running down the wires simply ran down the outside of the funnel, and drained out the mast step

    Important note!!!!
    One of the reasons that the 40.5 mast will still naggingly leak into the cabin liner is because a ton of water literally builds up inside the mast (in a bad storm it can be significant), and overflows the pvc pipe.
    Drill drain holes between your mast base and the deck step plate !!!!!
    I put in two 1/2" holes, and the water literally pours out when a storm hits.

    Rich Stidger and Rick D like this.
  5. Rich Stidger

    Rich Stidger

    Joined Feb 10, 2004
    2,758 posts, 227 likes
    Hunter 40.5
    US 1997 h40.5 Bristol, RI

    Good idea about the funnel, but you can only set that up when the mast is down. But I will look at drilling a couple more holes for drainage.

  6. artboas


    Joined Jun 1, 2009
    1,096 posts, 69 likes
    Hunter 49
    ca toronto
    Yes, the holes are critical.
    Little tough to do neatly. I ended up using a small file to clean up the hole.
    If memory serves me, the best place to drill is on the forward edge, but don't quite me,
    It has to be a spot where the mast extrusion is clear of the mast base "shoe"

  7. Michael G

    Michael G

    Joined Jun 13, 2004
    84 posts, 0 likes
    Hunter 40.5
    US Hampton,Virginia
    Rich, great job and thanks for the information. Please submit it and put it in the modifications section .