Thank you so much for your involvement with the Owner's Club Forum! We hope you've gotten some great information and had the chance to interact with other owners on the current system.

Thru Hull Flappers

pascal1972 Member Posts: 7 ✭✭
That's probably not the technical term for them but I have three thru hull fittings for my deck drains and I think the flapper is there to prevent water from flowing into the boat but they seem be just as good at keeping water in. This weekend I had a boatload of kids swimming from the boat, jumping off the front, climbing up on the swim platform travel through the boat, etc, lots of water and it didn't want to drain. Has anyone had a similar experience, can I just remove the flapper? Any other suggestions? 

2001 FD 228 RE 115 Evinrude FICHT
2007 SD 237 5.7L Mercruiser MPI Bravo 3


  • rdcastle
    rdcastle Member Posts: 100 ✭✭✭
    My 2001 GS 201 has no "flappers" but drains very poorly as well. The problem comes from the goofy way the deck drain plumbing is routed. The drain at the helm seat flows back to a "T" fitting where the drain below the rear entry step area and then to the overboard fitting. The problem is that the tubing from the helm seat drain has a dip in it which doesn't allow the water to flow out until it is too full. I am going to open whatever accesses I can and remedy the situation very soon. Those flappers are basically check valves to prevent water from flowing into the cockpit when submerged such as when backing or in a swell situation.
    Rob Castle
    2001 Hurricane GS201 FD
    Yamaha 150 V6 2 Stroke, Oil Injection
  • nquirk
    nquirk Member, Moderator Posts: 672 ✭✭✭✭

    @pascal1972.  Check to see if you have any blockage in the hose (light compressed air would work if available)

    I wouldn't remove it as its purpose is as you've stated to allow water out but not back in so you should look to see if anything is blocking/preventing the water from leaving.

    The technical term for this is a scupper.

    2010 Hurricane SS 188 OB
    2010 Mercury Optimax 200HP / Mercury SS High Five 19P
    2010 Trailmaster SC trailer