SUBSIM Radio Room Forums

OK...let's see if I can get to everything in one post...first some social commentary...

BigWalleye...I really did think that you knew what you were talking about (you're from northern WI too...it's self-evident!), and perhaps it just didn't come out right...but I'm easily confused anyway.:huh:

Sailor Steve...I do recall that you mentioned your Navy RM days in another thread; particularly the delightful times you had, trundling bags of shredded documents to the fantail to toss them overboard, in calm and peaceful seas of course.:haha:

J0313...It's good to hear that you had the opportunity to know your Grandfather and hear his first-hand accounts of the war. I had a few relatives to tell me their stories; my Dad was an Electrician's Mate in a Pacific Fleet DE, my Mother was in the Marine Corps and worked at USMC HQ Henderson Hall in Arlington, I had two uncles in the Army/Army Air Force in Europe, two in the Marine Corps in the Pacific, another was a Navy Flight Surgeon and my maternal Grandfather was in the Navy in WWI, a Plank Owner in the battleship NEW MEXICO. I never got a single one of them to write down any of their stories, but I'm trying to do that from memory to pass on to my kids/grandkids, along with my own content.:cool:

Redmane...As one of my grizzled old Chiefs used to say "perzactly!" You can pulse the transmitter completely on/off (not good for the equipment though) or just vary the pulse width. Also, you're very welcome...all of you are welcome, of course; I hope it is interesting, if not useful information. Nothing is more wasteful and wasted than unshared knowledge.:know:

So, back to business...

First item...wavelength is the most obvious reason for differences in capabilities...frequency bands are assigned to nations by international treaties...even valid during time of war (that way makes "snooping" easier too y'know!). If the Deutchers were using their lower authorized HF frequencies (longer "short" waves) and we were (still are, when we use them at all) using our authorized higher HF frequencies (shorter "short" waves), they could get reception at deeper depths than we could. Push the freq down to 3MHZ and the wavelength is up to 100m; IIRC our old Fox Broadcast freqs were as high as 10-12MHZ, which brings the wavelength down to 25-30m or so. But also realize, that in any case the depth for good reception will usually be less than the theoretical depth. Variations in salinity, temperature, density and plain old "crud" (plus "critters") in the water cause interference and signal strength attenuation; even if your gear is perfectly designed, flawlessly manufactured and incredibly well-maintained, you will seldom experience "design performance" specs. Being able to move in three dimensions through the water column means a submarine can pass through several water masses with significantly different characteristics in a matter of minutes.

Second...they relied more on clean CW (carrier wave) Morse code, while we really fell in love with SSB/DSB (single sideband/dual sideband) multiplexed Morse code transmissions. They could send a lot of slow, reliable dits and dahs on CW and encode deep meanings into short "words", whereas we could easily lose a lot of the encoded "intelligence" in garbled multiplex transmissions. So we would be forced to seek better reception at shallower depths.

You have to think about the antenna length too; they're not hauling a 100m wire a couple of hundred yards behind the boat (like we/they do today), but the German fore and aft wire antennas look to be about 15m antennas with a "wired gap" of 10-15m between them. If I couple the bow and stern wires and the gap in series, I've got a 40-45m half-wave antenna good for 6.67-7.5MHZ, 80-90m wavelength (take her down and tune in Radio Berlin).

Early USN wire antennas were a little longer individually, but couldn't be coupled in series. With the more complex transmission modes and the frequencies we used, they needed to function as full-wave receiving antennas at depths that didn't achieve the "theoretical" maximums of 20-30m. You will also see that the long wires running to the "T" poles fore and aft were typically taken down when leaving on patrol. At the faster underwater speeds the Fleet Boats would typically run at (battery capacity differences, not actual speed limitations), those long straight wires attached to tall poles on the decks fore and aft would make a lot of noise and cause drag. Instead, they'd use shorter wires from the shears to the conning tower sides or cigarette deck railings. The USN also opted for "improvements" (as we are s-o-o-o-o wont to do) and started completely removing long wire antennas by mid-war, leaving the boats with only 1/2 wave and 1/4 wave wire and rod antennas or whips with tunable couplers to adjust the frequency, which add attenuation losses and meant the depths for good reception were even shallower.

Last but not least (whew!) the most important factor might well be the way in which the boats and their entire support and command network were designed and intended to be employed by those two very different Navies.

The KM U-bootwaffe was utilized in precisely the way it was planned and built for, a commerce war in the Atlantic. The operational doctrine required reliable and frequent two-way communications between BdU and each/every/all the boats. Regardless of being surfaced or submerged and at any depth (er...survivable depth, that is), the U-Boat had to be able to receive broadcast messages as well as specific message orders/instructions 24/7. Their equipment was designed for that purpose and functioned as intended.

The USN Fleet Boats were designed and intended to be used as a Scouting/Screening Force for the Battle Fleet. Although they did get some cleverly obtained "additional capabilities", they were initially equiped with medium-range radio communication capabilites in order to coordinate/cooperate with the Battle Fleet Commander Afloat. Even after the "blessing" of Pearl Harbor caused a complete and total revision of that Pacific War Strategy, the radio communication capabilites of the submarines fit perfectly into the USN way of conducting unrestricted submarine warfare. Our boats were much more "lone wolves" and their Commanding Officers (once the pre-war strategic/tactical crap was knocked out of them) had no need to report contacts to HQ or to get detailed instructions for coordinating attacks on convoys (some of that did come later, though the doctrine was still very different from the KM's methods).

OK...did that cover most or all of it? I was up 'til midnight reading the flurry of replies and comments/questions, but didn't have enough caffiene on hand to make even a game attempt to write this before going to bed. But, it's laundry day today and this was something to do while waiting to tend to the shifts from washing to drying to folding and putting away (yes dear, I'll be right there).

Have a nice day all...:salute: