HONWAVE T38IE2 + HONDA BF20.
5 persons. Me and wife 150 kg, 3 kids total 100 kg, 24l tank + 12l spare, some equipment - about 300 kg in total.
Average consumption was 4-5 liters (per hr - more realistic 5l), average speed was below 20 km/h so we can say that per 100 km it was 5*5=25 liters.
We did max trips 20 km one way if I remember.
2015 Greece again (5,4RIB 115 HP engine):
Again the same family but all kids had 170 cm height and kids weight in total was more than 150 kg, me and wife again 150 kg, equipment (snorkell equipment for 5 people include neoprene short suits, fishing equipment for 5 people, some food, spare shoes, many things - I think in total 450 kg include petrol (100l + 20l spare)
Average speed was between 40 km/h and 50 km/h (mostly near 50 km/h)
Usual trips 60-80 km one way
Average consumption 2km per 1liter so about 50 liters per 100 km
- on the same distance consumption was 2 times greater use RIB
- speed average was 2 times more than SIB
- average range was more than 3 times
I used to love my SIB but:
- I do prefer jockey seats or stand when drive -> 0 problems with my back (I had such problems uses SIB)
- Kids are much bigger every year (now boys have 175 cm)
--- I doubt if be able to handle family on HONWAVE 3,8 again + equipment
- We do like very much to explore coats, islands by boat so minimum range one way is 50 km usually max 100 km so use RIB is out of question now
OK, to be honest boat total cost almost 3-4 times more ...