Table:
text: Port vessels of the Royal New Zealand Navy
Tugs and tow boats
Tugs and tow boats
Name_ Dates Grt Propulsion Port Notes_
Arataki  i 1948-84 74 320 bhp diesel, 10 knots (19 km/h)  US Navy harbour tug
Arataki  ii 1984-99 143 1100 bhp diesel, 12 knots (22 km/h) Timaru harbour tug
Hipi 1942-56 39 100 bhp diesel, 8 knots (15 km/h) Auckland Towing lighters
Kahanui 1942-45 207 800 ihp SR TE coal, 11 knots (20 km/h) Wanganui harbour tug
Manawanui  i 1948-52 74 329 bhp diesel, 10 knots (19 km/h) Auckland US Navy harbour tug
Meola 1961- 19 76 bhp diesel, 9 knots (17 km/h) Auckland work boat
Toia 1926-49 423 1250 ihp SR TE coal, 12 knots (22 km/h) Wellington World War I Saint class naval tug, a notable salvage tug

Question: Among the Royal New Zealand Navy's port ships, which is the only ship used as a workboat?