NE Dory - Gash on Plank

Greetings!  I recently purchased a used/completed NE Dory.  There is a gash on one of the planks that spilt it about 8 inches on the outside and inside of the vessel.  I'm seeking best practices and recommendations from other builders on how to tend this damage.

Many thanks!

Scuzzy

 

CORRECTION - the damage is on panel 3.

Pictures?