"An amazing role model to his peers and our young junior rugby players. We were very lucky to have him as part of our club.
"Our thoughts, love and prayers go out to [the] family, long-time members and supporters of our club. Our collective hearts are hurting so badly for you all."
Matamata College Principal Alan Munro said Billy, a Year 9 student at the school, was strong academically as well as in sports.
"The school was shocked and saddened to hear of the accidental death of Year 9 Matamata College student Billy Crabb yesterday afternoon," he said.
"Billy was a positive all-round student with strengths academically as well as on the sports field.
"Well-liked by his peers and staff and his loss of life has hit our school and wider community hard.
"The school is handling this tragedy as best we can, and our Incident Response Action plan has been actioned to support staff and students.
"Guidance staff have been on hand to support students and this will continue during the week ahead.
"Our thoughts and prayers are with the family during this difficult time as they are with the families of other boys involved in this tragic accident."
The boy's last photo on Instagram showed him waterskiing five days ago.
Many friends and family had posted messages on the images saying rest in peace and posting heart emojis.
Matamata Intermediate School principal Debbie Currie confirmed the boy was a former student.
"We are devastated by the tragic loss and as a school, our hearts go out to his family," she said.
Emergency services were called to the scene at Pauanui Beach about 3.45pm.
An Auckland Rescue Helicopter Trust spokesman said the teenager was being towed on a sea biscuit, when a wave hit the towing boat and spun it around.
The teen, 13, and another friend were subsequently hit by the boat's propeller.
The 13-year-old was killed and the second teen, a 16-year-old friend, suffered multiple lacerations and was taken to Waikato Hospital in a serious condition.
A Waikato DHB spokeswoman said the patient was now in a stable condition in a general ward.
Maritime NZ said an investigation into the incident was underway.