The rewards between plundering and convoying are vastly disproportionate, a maximum of 150 coupons can be achieved daily from plunders! that is five times more then the measely 30 coupons one can achieve from the single SS convoy that they are allowed to take for free.... and why is this? no good decent reason at all!
Now, it isnt just the rewards difference that is terrible.... its the fact that on some servers people struggle to get there SS plunders simply because there isnt enough people... or those people that doing Convoys are so turned off from being attacked and then only getting 15 coupons... thats TEN TIMES WORSE!!!! then a plunderer who is already vastly stronger then they are because of the better rewards.... and will forever be infinitely stronger as they get vastly more rewards making it impossible to catch up....
So I suggest you remove the ingot cost and remove the SS convoy limit! this would benifit both plunderes and convoyers alike! plundering would still have a better maximum reward, but it would also be faster to complete, convoyers would als benifit from this in more coupons for even the smallest chance of catching up!