The bay where you can anchor is known to local sailors as Nishihimura bay. Five and a half miles S of Upolu Point you'll see a small cove with manmade rock wall on the N face of the cliff. This wall was built for the ralroad that once transported sugar along the kohala coastline. Inside the cove, you should drop anchor where the bottom is sand, readily identifiable by the lighter, turquoise color of the water.
Anchor in about 30 feet of water.
Southerly kona winds would make this anchorage, and virtually all others along the Kona coast, uncomfortable.