The Paddle Boat That Struggles

This is why I havent really uploaded anything for a while.. I keep trying different paddle types and sizes...
I sadly added thrusters (all set to half strength) to help it get momentum..
If you have a better paddle design, or want to make one; then read these rules below:
1. No Thrusters.
2. No bigger than the largest wooden beam size. (from one blade to the opposite end.)
3. Must be able to move forwards and backwards.
4. If you want a challenge, make it able to push 5 maxed out weights worth of cargo.
5. Dont change any of the red/gray plastic beams or the bottom of the boat (the wooden beams part of it)
6. If you do Rule 4; Please try to put the cargo bay in the back of the boat. If you want more room, then also use the very front of the boat as well.

Anyways.. Make sure to comment your Ideas if you have any!