Bondo the keel!
Has a gap from where it meets the hull.
It's recommended to use Bondo.
Which is a auto mobile body filler!
There is a lot of sanding.
Required after you Bondo the hull.
When I built Serenity aka Jersey City by Dumas.
I remember having to do the same procedure!
The folks at Dumas. Say the Bondo won't crack.
Well mine did, it was a small crack.
which I used zap-a-gap on!
Note:
Mix the Bondo (P38) just right. So it doesn't crack later on!