The spare set of rudders have the holes filled (epoxy?). However, they are identical to the set that is on my H14 which are also Raditch Speedblades. After looking more closely at the ones on the boat I noticed the bottom tips where there is some wear is a darker brown-grey color indicating the white finish does not go all the way through. Would that indicate they might be fiberglass? Thanks.
I've got a pair of "Switchblades" that have some mystery
substrate, similar to what you've described. One, of the pair, had obviously dropped down when trailering and worn through exposing this material. I have no clue what it is but that particular rudder weighs about twice the undamaged one, even after being left exposed to dry out for literally years.
To answer your question, more than likely the outer layer is glass and gelcoat. Chip away at the damaged area in search of fibers.
Sheet In...Max Out
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