I'll be driving too, with a dishwasher in the boot, but room for 3-4 passengers (let's say 3 cos there'll be a reduced amount of boot space for gear)
25 attending - 3 don't need lifts - 6 drivers = 16 passengers
16 passengers / 6 cars = 2 cars with 2 passengers, 4 cars with 3 passengers
16 passengers / 5 cars = 4 cars with 3 passengers, 1 car with 4 passengers
CONCLUSION:
Evan, you needn't drive all the way out to the boathouse cos it's out of you're way and we can fit everyone in 5 cars.
Cillian, don't worry about boats for your car, we'll be using ICU/WW boats so we don't need to bring a bot per person.