Input on gelcoat problem

I will appreciate if anyone can let me know why this part of the kayak deck came out with the problem as seen in the image.
There are 19 fittings like the one in the picture and only on this one there is a problem but I've seen the same in the past in a couple of others.
The temperature inside my workshop when I spray it was 15-17oC and I used 2.5% catalyst.
The gelcoat however was relatively old (5 months).
Any input is very much appreciated.

Thanks

 

The gel coat is thin in that spot, it's not uncommon.

 

Thank you @ondarvr ,I will be more careful next time!

 

@ondarvr any tips how to repair that part easier? The problem is that due to been very little gelcoat on either side of the problem if I start sanding it will rip off the "good one" as well.
It happened in another one deck that I had the same problem.

 

You can apply more gelcoat, sand and polish. No one will ever notice.

 

Do you have a drier on your air line?

 

Barry, I don’t understand what you want to say

 

If you are spraying it you need to ensure that no water comes out of the gun. So is there a drier in the line? If not, you can get the odd water droplet and even occasionally, depending on the type of compressor, some oil can get into the line and ruin the finish

 

Yes there is a drier.
My question is about the repair now actually.
I am spraying more carefully now and didn’t had the same problem but I got already a couple of decks that they had the problem like the picture above that need repair.

 

That is a tuff spot.
Fill with thick gelcoat.
Slice off the excess when it has almost set.
Spray with gelcoat.
Polish