Flapper Style Scupper Valve

[boatnamesue]

Giving serious consideration to installing the flapper style scupper valves on my '76 170.  Important details to note...I keep my scuppers plugged 100% of the time while the boat is on the water.  With the weight of my 115hp, the waterline is just below the scuppers.  However, if my 15 gal baitwell is full, the scuppers are under the waterline. 

My concern is will these flapper scuppers truly operate as a one way valve.  Applying simple physics, while hull is stationary the pressure exerted by water outside the hull is greater than inside hull, thereby keeping the flaps closed.  So in theory the flappers should remain closed when scuppers are submerged.  But I'd prefer to rely on actual performance results verses theory.  I'd hate to drill holes into the transom for mounting the flappers and then learn that they don't operate as advertised when the flappers are submerged below waterline.

I know there are a number of members here that have installed the flapper style scuppers, so I'm hoping to hear some feedback.  Preferably from those whose scuppers are like mine...resting just above waterline, and below waterline when weight is added aft to hull.

[Woodeneye]

My experience with this style is that were "ok" (tended to leak a small amount like a dribble) for a while , perhaps 6 months, then the rubber began to deteriorate and they never really seated/sealed properly again. So I guess if you  are prepared to replace them every six months they would be ok.

[theFunsmith]

I am also interested in a flapper type scupper that works well. We crab hard over here, and seaweed, grass and other debris coming in on traps is a real consideration. I would like to be able to hose that stuff right through a scupper, and I can only see the ping pong type getting fully plugged with crap immediately.

[mshugg]

My concern is will these flapper scuppers truly operate as a one way valve.  Applying simple physics, while hull is stationary the pressure exerted by water outside the hull is greater than inside hull, thereby keeping the flaps closed.  So in theory the flappers should remain closed when scuppers are submerged.  But I'd prefer to rely on actual performance results verses theory.  I'd hate to drill holes into the transom for mounting the flappers and then learn that they don't operate as advertised when the flappers are submerged below waterline.

As I said, I like the flap type scupper.  As long as the flaps are in good shape, they work well.  That said, I’m not of the opinion that any scupper valve is designed to keep the boat from sinking which is kind of what you’re asking it to do if your scuppers remain under water. Some water will seep past the flap, and wave action will pull the flap away for a moment with each wave.

I had the flap scupper on my AS 170, and they worked great.  But I had the 90 HP OMC 2 stroke (302 lbs), and the bolt on transom baitwells that we’re weight neutral at rest.  My deck sat just above the waterline at rest, and my scuppers were out of the water except if someone stood right at the transom or with the rise and fall of waves.

[wingtime]

The TH marine ball scuppers work much much better in my opinion.  They seal better and more evenly than the flapper styles do.  Also they last a long time.

[boatnamesue]

Appreciate all the input guys!  Wing...the ball valve style isn't an option for me.  I regularly throw a net on grass flats, then wash down deck after, so sea grass blockage of the ball valve is inevitable. 

[wingtime]

FYI the TH marine ball scuppers are a two piece design that allow you to take them apart for easy cleaning. 

[CTsalt12]

Had better luck with ping pong style. As someone mentioned, the flappers are very susceptible to rot.  I've had my PP scuppers for at least 4 years.  Very easy to clean, I actually don't even mount the cover with a screw so I can take it off by hand and quickly clean in a pinch.