Mike,
Keyhole slot is where a key is inserted to start the boat. Pg 9 #127
Tank Coating is epoxyproducts.com NSP 120 / NSF 61 Approved Potable Water Epoxy. Read the MSDS.
If anyone is prone to using this product for this use: I do not advocate the use of this product for drinking water.
I will, after the tank is set up, and flushed a couple times, fill it with water and keep it in there for 8 weeks or so, after which I'll have it tested for the specific chemicals that might have leached from the epoxy. If something shows up I will run it thru a carbon filter and test the water again.
I do not trust THE chemical industry nor THE regulators to come clean with the consumer. The coating is applied outside of laboratory control by an unlicensed, untrained, probably-guilty-of-something (PGOS) individual. It is best to be wary of approvals and claims and the language used to describe attributes and limitations of a product. IMCO the only approvable containment for potable water is mineral glass. Haven't found a paint-on version yet. Nearly ALL plastics have been proven many times over to be a gamble or downright dangerous. Not sure about bakelite.