I could´nt find any good information in the www about sailing boats cruising between Cartagena/Colombia and Panama via San Blas, so I did some research and got this list.
I thought, this could be useful for you guys. You´ll find all telefon numbers email adresses… inside.
You can book directly on the boat (thats usually cheaper) or you ask in hostals or restaurants for information – they charge a comission (so called deposit) of 25usd.
Cheers
Phil