The hourglass mode has many issues. For one, it works like a watered down version of arena. Arena failed, so imagine how well this mode will stand compared to arena. Unlike arena, there is only 1 vs 1 ship combat, and you have a chance to be paired up with unfair battles, especially after the 4th consecutive win. Fighting a brigantine or galleon on a solo sloop is just not ok. Just like arena, the game mode is set up to instance 2 players against each other with the mode being separate from the regular adventure unless 1 player chooses to defend. Defending is the best form of interaction for this mode, but sadly it is also not worth it because the rewards for doing so are abysmal. Basically, you get boosted rep for sinking but requires a huge hoard of loot, roughly the size of a fortress haul to start seeing a boost, which ultimately isn't as significant.
This mode is so unfair, and detached from the regular game, that I honestly see it going down the same path as Arena and failing. I hope this isn't the case, I love a good fight, but not if I'm forced to grind it out by repeating the same 3 or 4 game strategies, with players that may end up being sweaty or trolls. The game mode has great rewards but if the gameplay isn't fun nothing you throw at it will work. Now I'm not saying the game mode is boring, far from it, but at the moment it feels like work. I wish I could say that unlocking the curse felt like a successful achievement, but the grind was so bad that honestly I'm not so sure it was. The mode needs more to spice it up, this includes more pve elements such as allowing collected treasure for those that activate the map, allowing treasure to be sold for the pvp faction rep, merging the pvp factions with the pve factions, more weapons or tools for combat, more game modes (such as dig for treasure, or island combat, or 1st to solve a riddle on a large island, team battles, etc)