Self-Bailing Bung on Tinnie

[Karsten]

I searched the forum for "Self-Bail Bung" (and variations) but couldn't find any threads, so I posted this thread.  If this has been discussed in depth before, please just list the thread number (or link) and I'll chase that discussion down.

My situation:  I am about to re-fit two bungs low down on the transom of a 5.4m aluminium runabout (under waterline).

However, I see there are things called "Self-Bailer" bungs for sale - see attached photo.

So, my questions:

1) I know in theory they should, but does anyone have experience that these actually work, and work well?    Will opening this bung while I'm travelling at around 10kt empty bilge water  (realise 10kt is not very fast) ?

2) Will a "normal" one inch bung (very common), when installed to unscrew to the inside of the boat, have the same effect at the same speed?   

3) The special "self-bailer"  bung has a rubber flap - will this keep the water out even when the boat is not travelling forward (ie. if you suddenly slow down with the bung open)?   

Appreciate any full or part answers.

 

Edited March 5, 2017 by Karsten
Typo

[NaClH2OK9]

I don't have first hand experience with these but would not trust them. They look so likely to have sealing issues that they would cause more problems than they fix. I like the idea of bungs sealing the water out not getting me in trouble due to bits of debris keeping them open. 

[Karsten]

@NaCIH2OK9:  Get what you're saying about risk, but do you mean sealing risk even when the Bung is screwed in shut, or ONLY while it's screwed out to activate self-bailing?

[NaClH2OK9]

I mean when activated. 

But if the water level in the boat is less than the outside level then the water pressure won't let the water out anyway. 

If at 10knots your on the plane it will probably work but do you want to be sticking your hand down there with a running motor? 

Sounds like a lot of faff when you'd want a bilge pump backup anyway. Just my opinion. 

[Karsten]

My bilge pump always leaves about an inch of water, so would be good to clear out under the sole when the boat stays in the water for a week or more.

Yes, I wouldn't like sticking my hand near the prop, but I'd install the bung to screw in/out from inside the boat.

[Foghorn]

I had a set of self draining bungs, the ones with the long rubber tongues, I found that they leaked when you were drifting for a while, great if you are constantly on the move only.

[rickmarlin62]

if I have read correctly the bungs are designed to work from outside..so if you mount internally it will let water in as it will be under pressure..over the years ive seen many types of self draining systems and have never seen one that works 100% of the time so in a 5.4mtr boat mount a bilge pump as far back and and central as possible..as you mentioned you were going to remove the bung from inside I would assume you have access...rick

[Trailcraft43]

Yeah those long rubber tounge ones can get a small stick or forign object stuck in them and water will pour in.

Id steer clear of self drainers.

I like to know the bungs are water tight.

Less dramas the better. 

[Karsten]

@ Rickmarlin62:   The Tenob product in the picture has two versions, one is made for interior install.  I have good access to my stern bilge - in fact I insist on it.

@ Noel, Foghorn and Trailcraft43:   Thanks for the feedback - seems you should expect these to LEAK when the drain plug is out.

It is starting to look like the only sensible way to use them would be to unscrew the plug, travel forward for a bit and then screw the plug back in firmly when the bilge is empty.  So really the internal rubber flap is of little value.

 

[rickmarlin62]

call me old fashion but I find it easy to flick a switch and watch the water pour from the hose..also it saves having to start and travel to get rid of water...maybe the question should be where is the water coming from ?????

[Karsten]

"...where is the water coming from"

Can come in from splashes, but mostly from rain - esp when I keep my boat in the water for several days in a row during a holiday break or long weekend.  As mentioned, i have bilge pumps but they leave an inch of water, so I just wondered how these self-bailers do on motorboats.  Most sailing dinghies have them and they work well there.

[frankS]

I'm with the rest of the guys, total waste of time and as rickmarlin said, Where is the water coming from in the first place ? and have a reliable bilge pump. Debris gets stuck in these things and allows water in.

 

Frank

Edited March 5, 2017 by frankS

[rickmarlin62]

all these style of drain plug only work when you are travelling at a speed great enough to have bung level above water level..if you cant get on the plane and let the water out at speed there is no reason to try and install these "gadgets"..rick

[Fab1]

Does it matter that much if there's 1" of water left in the bilge after using the bilge pump/s?

Those bungs are one more thing that can fail in my opinion but it's entirely up to you if you want to install them.

Cheers.

[Hooked-Up]

trim it up, get the nose up as high as you can whilst bilge is running so all the water pools at bilge, still wont get it all out but pretty much.

[NaClH2OK9]

I think this one is done to death. Horses to water. 

[brad_tate]

I'm with Hooked-Up. When my boat is on the water and it has rained overnight I turn the bilge pump manually on first thing in the morning and deliberately push the bow up without going on a plane for a couple of mins to empty as much water as I can. That leaves a pretty minimal amount in the bilge.