If the propulsion system is that great and we can save considerable cost over nuclear, why haven’t we adopted it?
Because the only thing that limits nukes is food.
Change systems? Disrupt political patronage and cash flow? There is no profit in that!
If the Military Industrial Complex is known for anything it's saving the taxpayer lots of money, right?
They still have to surface to recharge their batteries. Nuke boats are much more efficient.
If the propulsion system is that great and we can save considerable cost over nuclear, why haven’t we adopted it?
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A good legitimate question that has more than one answer.
First, time underwater can translate to distance underwater. When patroling the water around your borders distance is not important. When patroling the entire world then the Nuclear power makes a lot more sense.
Second, these are small submarines and carry a relatively small weapons payload. I’m not denigrating their abilities they are very effective weapons platforms but the US Subs have a much larger weapons load and crew and therefore need a much larger propulsion system. We kept diesel boats for several deades after the nuclear boats were developed but they outlived their usefulness in time. The SSBN (what used to be called Polaris and Posiden boats) are twice as long and and have more than twice the beam of the small boats. It takes a lot of energy to push these boats at 25 knots for days at a time, all the while making oxygen and water.
Third, we have a system of permanent sonar hydrophones planted in the oceans around our country, the quiet is not quite as important for home defense. The newer nuclear subs being developed are much quiter than the nuclear boats I served on and quieter than the boats in service now.
So, yes these little boats are really great for what they are made for but they serve a different purpose than our boats. We have learned a lot from these little boats and will match them for noise soon.
Thick headed DOD. Not as versatile as a nuc boat. But perfect for some roles. Biggest disadvantage is that they do not cost as much.
Historically, electric (battery) boats did not have the range that nuclear boats did. They are great for littoral defense and very difficult to hunt. The needs of the US have been historically to be able to project power as opposed to our own coastal defense, so we have focused on nuke power and quieting to have the range, stamina, and stealth to do the mission. If an electric system comes along that can match those capabilities, we might be inclined to switch over. I dont think the range and endurance without coming up; to snorkel at some point has been matched yet, but electric is getting better all the time.