Calculus is very integral to a lot of technical subjects, and the Navy is made up of lots of machines and technology, so might want to take it. Otherwise, you could limit yourself career-wise. Having taken it will also help you to differentiate yourself from other officers and help with integration into more technical fields. But I went off on a tangent there...
One key thing needed to not struggle with calculus is solid mastery of ALGEBRA, trigonometry, and geometry, but in particular the algebra. A lot of what trips students up with calculus isn't the calculus itself per se but the algebra needed to solve the problems. If your algebra is so-so, get one of those Schaum's guides for college algebra and work through that. Algebra, trigonometry, and geometry are to calculus what language arts are to writing (and arithmetic is like the abc's). You won't be able to write essays, prose, creative writing, etc...if you can't properly construct sentences and paragraphs. If you passed algebra/trig/geometry but with so-so grades, get that stuff down to second nature or you WILL struggle with calculus.
Having slogged through the full Calculus sequence, Differential Equations, Undergrade Statistics, Graduate Statistics, and Graduate-level matrix calculus, I will say that I now see the benefit of the theory work because it has helped me see the applications of the different techniques across multiple disciplines. That said, I do think math should be more applied for the majority of majors, including engineering. Some schools actually teach it this way with engineering or economics professors actually teaching the courses instead of math professors. Going through grad school, I realized that the problem with most math classes is the professors themselves. They are usually very mathematically intelligent and can "just do it" whereas most students are either not yet at that level or their brains are more verbally/linguistically-oriented. Being one of the latter (Strange for an engineer), I had to work with my professors to build logical heuristics and process diagrams so that I could step through each problem and their permutations. They often struggled to explain it to me when they just "saw it" and could intuit most of the math in their heads while I would often get tripped up every time they did not explicitly state and show what they were doing even it was just simplification of the equation. It was difficult but we made it work.
I am wanting to make a joke about the stereotype of engineers not being good at spelling
Yes, knowledge of the subject vs ability to teach are two ENTIRELY different things, and unfortunately, a lot of professors don't realize this. Another problem is that the teaching can be a side issue for the professor, as research is their main job, unless it's one of the rarer schools where teaching is the main focus and the research secondary.
Proper instruction of calculus, unless the person is very bright, I believe actually has to be more applied at first simply because most people will not be able to understand the proofs for the different parts of calculus, and that is what separates Real Analysis and Complex Analysis from regular calculus (i.e. regular analysis). Because in analysis, you go back to the very beginning of calculus and now learn and work through all of the proofs.
