The recommendation is that one puts an aptly sized softwood plug next to each through hull, attached with twine.
Teak plugs that don't soak up water and swell won't work, since the movement of the hull and water pressure will pop them out in short order. Softwood that soaks up a lot of moisture is perfect, since they will expand and become hard remove, as you learned. I know of no teak plugs for stuffing through-hull holes, only of small teak plugs for plugging screw-holes in teak decks.

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