I did this project when first purchased our 34 22 years ago. What you describe sure sounds like VC tar to me. PO used VC 17 paint (fresh water) with VC Tar as barrier coat that had eroded in many areas. Used chemical stripper very sensitive to heat and humidity and very toxic. Apply stripper, put on paper plastic sheeting so does not dry, let stand for X time and strip off. Found a heavy plastic scraper worked well to remove. Must wear protective clothing or will get chemical burns on skin and respirator for toxic fumes. Bear of a job but got to clean gel coat with minimal sanding / fairing required. 6 coats epoxy barrier coat and still going strong.
John and Maryann Legacy III 1982 C&C 34 Noank, CT
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