Are Scupper Drains Supposed to be Above the Water Line?

[Toothpick 10]

I have seen some photos of Gradys with the scupper drains just above the water line and some photos with the scupper drains just below the water line. Are these scupper drains supposed to be above the water line, and it is a sign that the motors are too heavy if the scuppers are submerged?

 

[Fishtales]

I think they should be above the waterline. There was the switch from 2 to 4 strokes and some models were caught in between updates. Other factors include fuel load, extra batteries and gear. Some folks load them down fairly well. The only risk is if the line should burst, then you could have an issue. I would look for the thru hulls with a check value ball or maybe put them in-line if I had the issue.

 

[Toothpick 10]

Thanks Fishtales. Does anyone else have information on this?

 

[magicalbill]

Yes I do.

I had a 232 Gulfstream with twin 200 4-strokes and my scuppers were 3/4 submerged at all times. I owned the boat for 11 years and it never mattered; the cockpit always drained, even when I was hosing the deck with the boat in the water.

Now, as Fish says, if a hose was to burst, that would be problematic, so for that reason, I would certainly opt for them being above the waterline or close to it, but in real world everyday conditions they drain even if partially submerged.

 

[ROBERTH]

Mine have always been just under the water and never have any issues. Even with 2 fat guys in the corner, no water comes up in the cockpit, likely the flappers help with that. I have the 200 HPDI 2 strokes, so it appears this model, this is pretty normal.

I did replace the plastic thru hulls with SS and new Hoses, so bursting is unlikely.

At one time, I added 2 additional group 31 batteries to the transom for a total of 4, but since moved 2 up under the helm area to help get some weight off the transom. This did bring the waterline down about an inch.

Seems on the Grady's this is not a real issue so far.

 

[DennisG01]

Good points above about a hose leaking. But aside from that...

Should the scuppers be above the waterline? Yes. Do they "have to be" in order to work? No. They can be completely submerged and still work - the key factor here is the height of the cockpit floor compared to the waterline. As long as the cockpit floor is above the waterline, water will not seep up into the cockpit since... gravity works. Any number of reasons could explain why they are below the waterline and a number of them were mentioned above. Others could be that as boats get older, they get heavier (moisture retention)... an addition of an engine on a bracket will do it, too.

However, another downside to scuppers being below is that you could get growth on the scuppers and even in the hose. Keep up with your anti-fouling paint and it will help that, though.