alternative easy to do ballast?

got a fairly small outboard boat, and looking for something to use as ballast- not real keep on fatsacks due to lack of space at the best of times... only usually have 3-4 people come riding at most, due to lack of space mostly...

have considered chucking 1 or two 50 liter water bottles up the front, or something, but other than that, kinda stumped...

any suggestions?

talk to the guys at your local tyre place to save youa couple of months worth of old wheel balancing weights

When I first tried this stuff out I used spring water bottles. They were 10 litre squarish bottles (about 22 lbs each). I think I loaded about 15 of them into the back of a 16' Charger with a 130 hp Yam. My son could go wake-to-wake but I couldn't.