Leaks in pylons

While sailing last week in a race on our H16 we were overtaken by a Prindle 15 with 3 sailors on board. I already had the feeling that things didn't go as planned.
When returning to the beach, we found that the starboard-hull carried enough water to fill a medium-size bathtub.

When doing the airpressure-test it showed that the pylon closest to the rearbeam had a leak. The foam-like substance used to fill the center of the pylon wasn't sealed by the silicone-kit. As far as I can see, the foam-like substance doesn't let any water through, although the substance is compressible.

Any of you guys has an idea how to repair the pylon without putting silicone between the pylon and the corner casting ?

Thnx

My question.

I doubt that a leak in the pylon could account for that much water. There is also an intended vent built into the pylons. Usually the forward ones.

I would look at the hull bottom, keel for wear and a possible leak. That is a ton of water!

You can seal the pylon by coating the top of the foam with silicone. If you don't want to pound the boat apart to get at the top of the post / foam you could inject 2 part floatation foam into the bolt hole.