Hawaiian Alphabet - Information On Oahu Hawaii

Origins
In 1778, British explorer James Cook made the first reported European discovery of Hawaii. In his report, he wrote the name of the islands as "Owhyhee" or "Owhyee". By July 1823, they had begun using the phrase "Hawaiian Language." The actual writing system was developed by American Protestant missionaries on January 7, 1822.

The original alphabet included five vowels and twelve consonants:
A, B, D, E, H, I, K, L, M, N, O, P, R, T, U, V, W
and seven diphthongs:
AE, AI, AO, AU, EI, EU, OU

In 1826, the developers voted to eliminate some of the letters which represented functionally redundant interchangeable letters, enabling the Hawaiian alphabet to approach the ideal state of one-symbol-one-sound, and thereby optimizing the ease with which people could teach and learn the reading and writing of Hawaiian.
Interchangeable B/P. B was dropped, P was kept
Interchangeable L/R/D. L was kept, R and D were dropped
Interchangeable K/T. K was kept, T was dropped
Interchangeable V/W. V was dropped, W was kept

'Okina
Due to words with different meanings being spelled alike, use of the glottal stop became necessary. As early as 1823, the missionaries made limited use of the apostrophe to represent the glottal stop, but they did not make it a letter of the alphabet. In publishing the Hawaiian bible, they used the 'okina to distinguish ko'u ('my') from kou ('your'). It wasn't until 1864 that the 'okina became a recognized letter of the Hawaiian alphabet.

Kahako
As early as 1821, one of the missionaries, Hiram Bingham, was using macrons in making handwritten transcriptions of Hawaiian vowels. The macron, or kahako, was used to differentiate between short and long vowels.
Modern alphabet.

The current official Hawaiian alphabet consists of thirteen letters: five vowels (Aa, Ee, Ii, Oo, Uu) and eight consonants (Hh, Kk, Ll, Mm, Nn, Pp, Ww, 'okina). Alphabetic order differs from the normal Latin order in that the vowels come first, then the consonants. The five vowels with macrons – Aa, Ee, Ii, Oo, Uu – are not treated as separate letters, but are alphabetized immediately after unaccented vowels. The 'okina is ignored for purposes of alphabetization.

Source: Wikipedia