Hi,
For structural and aesthetic purposes I'm planning on carbon skinning the deck of my sailing dinghy. The deck is currently marine ply.
However, I wondered if I could take the opportunity to do some weight saving at the same time by drilling a series of large holes out of the play before skinning.
If I do this, how can I skin? Can I cover the holes with something light such as vinyl or masking tape prior to skinning? Will this be enough to support it whilst it cures without showing imperfections? Will the bonding to the remaining ply be sufficient?
OR is there a specialist product that can be used to bridge the holes before skinning?
I have attached a (very) rough sketch to give some idea of what I'm talking about.
Many thanks in anticipation.

I'm not certain that tape or some other adhesive film would provide the best solution here, as you'd need to take up some of the surface you intend to skin with the edges of the tape and it could get also get a bit messy if the epoxy starts to seep underneath the tape and loosen it

It feels like the neatest and most straightforward approach would be to cover the whole thing and then make the holes. You'd be wasting a bit of material but I'm sure that the time saved would be worth it. Be mindful also that the skinning is unlikely to add a great deal in terms of strength, so carefully consider how much is safe to take away in terms of the hole drilling

Thanks for the reply. I fear I may not have described the final outcome I want properly. I don't want any holes in the carbon skin, only in the plywood below (and that's purely to save weight)

You could cut out the plywood and replace it with PVC foam of the same thickness, then skin over the new surface.

You would have to make all the hole/patches really smooth before you skin over the lot and that would take some time too. Sounds like a lot of work to me.

Ah, apologies, as I now understand your intention better

If the deck is not overly large, then perhaps bonding a ready-made sheet of carbon to the deck once you've cut your holes might be the easiest solution. Skinning is very labour intensive to get good results and, even if you happen across a clever solution for temporarily covering the holes you'd likely find that the carbon above the them wouldn't stand up well to too much load-bearing, unless the holes are very small.