I am no expert but all I know is that an outside patch did not last any time on my tubes which is why I ended up with the drastic solution that I did! I have a couple of outside patches above the waterline further up the tubes towards the bow. Maybe a pro tube repairer could get a patch to withstand the water battering it all the time, but I couldn't!
A Boat is a hole in the water, surrounded by fibreglass, into which you throw money...
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