I think the answer would be "probably not". Even if you assume that the propulsion techniques were additive, stacking three or four methods that each alone can achieve less than 1% of the speed of light certainly isn't going to somehow get you to above 10%. As cjameshuff points out, adding additional propulsion systems also adds to the mass of the craft. So if anything, two propulsion systems together woould be less than twice as effective as either one alone, not more than twice as effective. If you put a second motor on your boat, you'll be able to go faster than you could with just one, but not twice as fast.
Originally Posted by vcf123
Conserve energy. Commute with the Hamiltonian.