Get it checked out! If this is forward of the main beam this is a stress area (all the loads of of an unsupported bow, rig compression, every wave plowed through etc.). If you have ever seen where cat hulls fail you will know what I mean. I'm also sure most people remember where team philips failed!
It is quite likely that the the knock to the side has opened this up but you need to be sure that there is no crack down into the main hull seam which will propagate with loading. Very simple repair if caught early but remember gelcoat is just a protective coating and not structural, so shouldn't be used to repair any crack going down into the hull seam, just for refinishing afterwards. If your not sure about tackling this give AW sailboats a call.
Cheshirecatman
Totally agree;
Espically as you are in Essex and so may be very close to Andy Webb in Harwich.
It's worth doing as Pepin suggest and finding out if the crack is air tight or not.
It air tight I would suggest keeping a close eye on it, but not panicking right now.
If it is NOT airtight, I would give Andy a ring and ask his advice.
It might be a simple case of running a hacksaw blade thru the bap, hollowing out a little matting and filling with epoxy and chopped strand mat.
As it is in a potentially high strees area I would err on the side of caution and ask advice of someone who can get close to it and have a proper look.
