A correction. Curmudgeon is probably right (hell, more than probably).
In 1854, the whole of Hawai'i received only 148 steam frigates, the great majority at Honolulu, which had become by far the greatest of the Hawaiian ports in amount of trade. 2500 men on whaling vessels did port in Hilo in 1854, but many more landed in Honolulu, and even Lahaina was more important than Hilo.
In 1854, 1,600,000 gallons of whale oil were transhipped in Hawaii, the great majority at Honolulu. Figures from American Memory.
Where the name of the song Johnny Came Down to Hilo came from, I don't know. Ylo would be pronounced E'-lo normally, close to Hilo, but how did sailors pronounce these names?