Depends.

Removing it means more work, buying more glass cloth.

Leaving it adds weight & a measure of increased durability. And the necessity of balancing the weight by doing the same to that panel's opposite number, meaning buying more glass & likely epoxy as well.

This your first build?

Do you compete or simply enjoy watercraft recreationally?

Want it as light as possibie?

Were it my build I'd swallow my pride, do the same to that other panel, get on with it.

We learn from our mistakes, and those made by others....

i have built shearwaters....not the shearwater sport.

so let me ask a clarifying question.  by fibreglass on the wrong side, do you mean the strip of fibreglass tape that is used to reinforce the back side of the puzzle joint prior to assembly?   or do you mean you glassed the whole panel?

if its just the tape, then yes, use a heat gun, soften the glue and remove the tape.  its very easy to do......heat the epoxy with a heat gun and use a metal spatula or wide chisel at an oblique angle to lift the glass tape/soft epoxy off the surface.

if you glassed the whole panel, i would leave it.  it won't have any signficant negative effect.

on the scale of screw-ups, this one may feel big to you but it won't make the top ten around this forum.   glassing the wrong side of a piece is pretty common....(happened on my last boat).

h

   Yup it was the tape on the back of the puzzle joint. This is my very first build and I figured I would probably make a mistake or two. I was actually surprised you don't have to glass both sides of the puzzle joint to start but I am sure there is a reason for that. Thank you for your prompt replies.

The exterior glass takes care of securing the outside of the joint.

Laszlo

I thought about asking whether full-panel got glassed by mistake or just a p-joint. Figured worst-case answer most informative reply.

After reading Laszlo's, I agree: no worries! No Big Deal. Enjoy your project both in the building of and later use!