Gellcoat repairs

[GRIFFON]

I need some advice about repairing damage to the gellcoat on my old waverider.

I have a good match on the gellcoat colour and the small scratches are no problem...........but there is one area where the deck has taken an impact and the gellcoat is badly cracked and lifting

Does anyone know what i should be useing to thicken the gell to a filler like state so it stays in the repair and not on the floor!

I want to be able to rub it down and blend it in with the original finish without having to spray the boat.

Am i wasting my time trying to repair a large area like this?

Should i spray the boat as it would be alot easier for me?

The size of the repair would be about 10cm by 30 cm
Any ideas/help would be great Thanks