To make the explosives for a depth charge, it wouldn't be very effective to try to use our regular dynamite. First and foremost, it's preformed into shape via the rigid paper the nitroglycerin is soaked into. When we stack it on a barge, that's less of a concern, but to try to pack such an explosive into a submerged bomb would be a very difficult task. Though we do have a different material that could be more effective in this application.

  Back when I was developing smokeless powder, I had to try to fine-tune the mixture of nitrocellulose to nitroglycerin. Too much nitroglycerin, and the resultant mixture was too explosive to use as a propellant. Some of those resultant mixtures weren't even solid, and instead were a viscous, sticky gel. One of the problems with it compared to dynamite is actually how stable it is. It needs something else to detonate it, otherwise it just burns slowly.

  Since we plan on dropping these charges down onto stationary clams, we'll need some form of detonator for the whole device. Without flexible insulators, we're not going to be able to use electricity as a detonator. I'm going to start working on some designs for mechanical detonators instead. I'm going to take a couple of days to figure out what mixture is best for us to use for the explosive gel, and instruct the workers to start making and storing it in sealed stone crates so we can start stockpiling the finished product.

  I took five days to decide on an explosive mixture after doing a few tests to determine what mixture ratio would best fulfill our needs. For a mechanical detonator, I'm thinking of utilizing a spring loaded capsule of nitroglycerin to trigger the rest of the explosive. Due to the overall risk involved in the process, I'll probably go with at least one, if not two, redundancies on the firing mechanism.

  For now, I'll tinker with various designs while I clear out more of the fluorite mine. We might also be able to at least use some of the dynamite we've already made in the explosive device, if we're smart about it. 70 tons of explosives will take a bit of time to make if we don't use the existing stockpile, so I should probably try to plan for using at least 10 tons of dynamite per depth charge.

  After 26 days of working on the design and prototypes in between mining, I think I've come up with a reliable detonator design that we can operate from the ship. The design uses three spring-based resetting triggers which would all need to be pulled in unison to release the firing spring that triggers the nitroglycerin. That means that, besides whatever tow lines the explosive will have, it will also need three trigger lines that lead up to the boat. Those triggers will all need to have tension pulled on them at the same time to hold back all three springs to detonate the system.

  The main concern I had with the idea of only using two trigger lines was that there is a chance that a line could end up wrapping around a tow line, and becoming permanently stuck on. Then it would only take a rogue wave or current to suddenly tension the second line for an accidental detonation. In practice, two would likely be enough, but considering the penalty for accidental detonation is likely the loss of an entire ship, I'd rather not risk it.

  I've also drafted a design for the charge such that it can be towed and steered by the ship. While it would probably be easier to drop the explosive from the ship, I'd rather have it dragged out from the bay on a tow line. It's designed to work something like a submarine or torpedo. It'll be long and tubular with some control surfaces operated via cables from the ship. The density will be carefully designed to just barely float, with a single release able to be pulled that causes two cavities to fill with water, making it sink nose first.

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  It's no slouch in size either. To meet all the design requirements, the whole thing ends up being a bit over 30 feet long, and 10 feet in diameter, not counting the nose or control surfaces. That means that building these is going to end up heavily slowing our production of any new ships due to needing steel casings to form the outer shell.

  I spent 15 days getting the roller mill adjusted to produce the necessary plating to start assembling these massive depth charges. I'm honestly surprised that Elora hasn't shown much interest in us killing leviathans as effectively as we are. I'm guessing that it's a combination of hubris and focus on the existing war.

  Basically, the way we've been dealing with leviathans has been a method that would only be viable in the water, and requires them being unintelligent. With knowledge of our massive explosives, all the elves would need to do is avoid them. If you think of it as a technology that is only useful for taking down leviathans, then it's not really a concern. It might be impressive, but it's not a threat. We couldn't even really deploy it as a weapon for breaching walls, as a single martyr with the right kind of magic could detonate it early, causing losses on our side as well, and it appears to be a non-threat.

  The misunderstanding comes from the idea that they're only useful as large bombs. With only a few more materials, we could be going from solid lead shells to high explosive shells. In essence, I think we're actually a little lucky that there is a rampaging demon army right now. The next ten years or so would probably represent the last chance the elves would have to wipe us out. Beyond that point, I think the odds probably fall into our favor, with the deck getting stacked further and further against anyone who might try to attack us the longer time goes on.

  Well, that is up until a certain point. While it would take time to reverse engineer our technology, it will likely happen. At a certain point, I'll run out of advancements that I can speed us through, and the superior population and resources that other nations have will eventually allow them to eclipse us, though that would probably be centuries later.

  I took six days doing some medium scale testing to ensure that things would work the way I expected them to before I returned to the fluorite mine. Considering everything, we'll be ready to do the first test in twenty days or so. The main holdup is actually the construction of the vessels, rather than the explosives themselves. We've also decided to send one of the ships out to deliver a nearly full cargo load before we run the test, just in case something goes wrong.

  Just like with the initial barges, I'll oversee the process to make sure everything goes well before I leave it to others to handle. There are a few things coming down the pipeline later this year that I'll have to attend to, and some of them will likely require even larger stores of fluorite, so I really should try to get as much of it extracted as I can.

  I took ten of the twenty days to extract more fluorite before I went to go work on the depth charge. While I was getting ready to go to the far side of the island, I was updated on the three potential deposits in the mountain that hadn't been checked yet. One was a dud, one led to a small set of pockets of mana crystals, and one led to a deposit of sulfide ores with gypsum surrounding it. The size of the ore deposit isn't very large, but it's better than nothing.

  The same goes for the mana crystal deposit. The smallest crystals will get melted down and reformed into larger ones, but having more crystal trays available for the expanded mining force should be useful. Plus the surrounding stone is useful for further extraction of the hardening metal for either steel or more crystal growth. Zeb has fully committed to sending in the lower level individuals to work as miners to expand our tunnel network and extract resources so these deposits should ensure there is plenty of work to go around.

  After that was taken care of, I spent the remaining days making sure everything would be ready for the first test of the depth charge.