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.

@ 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.

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.

@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?

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.