Ishigaki - Hateruma + ferry discounts?

Hi,
I was trying to find out info on the island of Hateruma, reading there are 3 daily ferries from Ishigaki, but the ferries are prone to cancellation often because of waves and winds.

I want to confirm if this is true or any changes.

Then there are a lot of other islands around Ishigaki. Are there any "ferry pass" (like JR pass) or so that could benifit visiting many islands? Or at least any sort of return ticket discount?

1)
Such super convenient pass is named "Island hopping pass アイランドホッピングパス" in this ferry company,
http://www.aneikankou.co.jp/articles/detail/28
also round(往復: oufuku) discont(割引 : waribiki) is usual.
http://www.aneikankou.co.jp/water_routes
"片道 katamichi" means oneway.
"税込み zei-komi" means including sales tax(8%).
"障がい者" means passengers with handicap.

This is EN .ver (download PDF file).
http://aneikankou.co.jp/languages/e_index.html

2)
The cancellation rate of the ship changes, depends on season.
Bc their ferry is not so large, the cancellation standard (waves and winds) is not the same as a large ship.
You also can send e-mail to ferry company. (you can find e-mail address jump to page bottom)

Also Okinawa is famous for the way of typhoons than main land of Japan, but weather forecast tells us.
https://en.wikipedia.org/wiki/Typhoon
This is one of sample of tyhoon route forecast.
http://kawazuweather.com/wp-content/uploads/2017/08/dr_20170803_215837...
This is the table of record that tyhoon landed in Japan.
http://www.data.jma.go.jp/fcd/yoho/typhoon/statistics/landing/landing....
About 30 typhoons occur in a year born in southern asian sea,
but the number reaching Japan is only one third or less,
however, some of them are very strong and dangerous like this, must escape to safe place.
https://youtu.be/ZJ3s3yWAfOQ

Put this into Google translate for the prices in English. It does not work through the main page....

http://www.aneikankou.co.jp/articles/detail/28

Thank you. Seems like a nice deal :)