I think you may have a tough time making a case that a safe containing gold to be used for buying horses
was on either gunboat. It makes no sense that Union seamen needed horses when their job was to defend
the blockade of the Gulf of Mexico. Interesting link though.
The first link, the official naval records also says:
Order of Commodore Palmer, U. S. Navy, to Acting Volunteer Lieutenant Loring, U. S.
Navy, commanding U. S. S. Wave.
U. S. NAVAL HEADQUARTERS
No. 148 Canal street, New Orleans, La., May 4,1864.
SIR: I have received your letter by the Ella Morse.
So soon as the object of the expedition has been accomplished you
will return to South West Pass with the Granite City and Wave and
report to me by telegraph.
You understand that you were sent there to assist the army in get-
ting stock, and to pick up recruits for the Navy. When, in your
opinion, you have accomplished these things, you will obey your
orders as instructed above.
There are so many records! The first link above is one of numerous links/records.
Others:
The Wave and Granite City received orders on April 15 to proceed to Calcasieu Pass to buy 250 head of cattle and 200 horses from Jayhawkers. The brigands had stolen the livestock from area farms. The Wave arrived on April 24 with gold for the purchase. It bombed an abandoned Confederate fort at the mouth of the river and was led to anchorage two miles upstream, opposite the home of Duncan Smith, a Union sympathizer. Smith was on board the vessel and acted as guide...
The crew jettisoned valuables, including the ship’s safe which contained gold to pay for the livestock.