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great advice, you don't sound like a village idiot to me. i've never seen the vent port you're talking about. Do you have any pics on how they do this? i'm envisioning a line say 3/4 to 1" running from above the water line down to the tunnel. does this sound even close, or did i just steal your title?

 

Yes, that's close.

If you search the refugeforums link I posted, you should find some pics. It is basically just a hole drilled through the bottom of the boat at the leading edge of the tunnel (just inside the front of the tunnel). You can run a pipe up inside the boat - ideal is to run it up into a console if you have one, then put the valve where you can reach it while running the boat. Main thing is to have the opening above the waterline. If you put your hand over the opening while running the boat, you can feel the vacuum.

To test this on an existing tunnel, you can glue a PVC pipe to the inside roof of the tunnel and run it out and up the transom to above the waterline. It doesn't help on all pocket tunnel boats, just most of them. Again, a good cupped prop with large swept blades is ideal for dealing with the aerated water.

 

progress?