Supra SL Owner's Manual page 40

Center Drain Plug
On V-drive models the center drain plug is accessed via the
access cover in the center floor panel.
It is extremely important that the drain plug is always checked
before starting the engine. The drain plug should be secured
in place using a wrench.
DO NOT start engine until center drain plug is checked and
secured in place.
©2017 Skier's Choice, Inc.
Rear Drain Plug
The rear drain plug is located at the back of the boat, near the
bottom of the transom (See photo). It is extremely important
that the drain plug is always checked before starting the
engine. The drain plug should be secured in place using a
wrench.
DO NOT start the engine until the drain plug is checked
and secured in place.
DO NOT try to install the drain plug while the engine is
running.
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