USD Horns- The long and the short of it

[duckbill]

On a previous thread, "Captain" Tom added the following observation:

captain said:

Most reproduction duckbills I have seen are best suited for the shorter horn. I don't know the exact year the short horn came out but I have a late 60's Aqua Master with the short horns. The rectangular section of the horn where it enters the can is shorter and the round section being closer to the rim of the can halves is why the side of clamp rings have to be cut away to clear the horn. On regulators with the longer horn the rectangular section is longer and does not interfear with the clamp ring.

from vintagescuba.proboards2.com/index.cgi?board=buysell&action=display&n=1&thread=1313

This prompted me to take on a task that I've been wanting to do for some time. Any clue which can help narrow the date of manufacture for any given regulator is a benefit to those who collect and desire to know the history.
When did the shortened horn first appear, and was it a definite transition?
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Here is what I have come up with so far:

First a note- Catalog illustrations are not necessarily good indicators, as good illustrations were reused in subsequent years' catalogs.

Square-labeled RAMs were produced 1966-69, and can have either long or short horns.
The 25th Anniversary gold-plated RAMs (1968) that I have seen all have the short horns.
Royal Mistrals were produced 1965-67, and can have either long or short horns.

So, the short horns were in use by at least 1968 (25th Anniv. RAM), and 1967 (Royal Mistral's final production year).
Longs were in use as late as at least 1966 (RAM).

Therefore, I would say that the short horns came into being somewhere between 1966-67.
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BUT, were short horns used exclusively after they were introduced?

After studying serial numbers (which are assumed to be consecutive for any given regulator model and style) and photographs of dozens of prior Royal Mistral and RAM auctions and other sources, I thought I had an answer. Then I studied the DAAMs and the picture got muddied.

This is my tabulated data (If you see your regulator's serial number on the list, it is because I saved the auction or other source for reference).


L= long horn
S= short horn

Royal Mistral
2045, L
2370, L
2514, L
****, S (see: www.calclassic.org/Regulator/aqualung.html)

RAM
6188, L
8460, L
9089, L
9785, L
10174, L
12386, L
12551, S
15170, S
16343, S
16713, S

DAAM
PICO
200020, L
200799, L
202592, L
203819, L
209662, L
210580, L
212170, L
212254, L
218553, L
222022, L
224286, L

WARNER
233***, L
235749, L (non-mag)
242057, L
242738, L
243361, L
247211, S
250239, L
251895, L
252224, S ?
256725, L
257669, L
262024, S
262208, S
263779, S
263843, L
263917, L

It is possible that damaged cans of the later years were exchanged for NOS stock on hand which may have had the long horns. Otherwise, I can't account for why the latter DAAMs vacillate between long and short horns. It would have been nice to pin a definite year down on the horns so that the serial number sequence dividing point could be determined. Then we could have another reference point to help determine a ballpark year of manufacture based on how far the serial number of a given regulator is from that dividing serial number.

CONCLUSION: I think it is only safe to reiterate that the short horns came into being somewhere between 1966-67.
Thereafter, either length could be found.
___________________________________________________

LONG HORN, face view/side view


___________________________________________________

SHORT HORN, face view/side view

[Captain]

The big question to me is why the change to the short horns.

[JES]

Nice work Duckbill.

Thank you for sharing your research information with everyone.

[nemrod]

Could it be as simple as they were supplied by different vendors?

James

[scubadiverbob]

Terry,

I think my DAAM has short horns. S/N 244125.

Robert

[bsea]

duckbill said:

RAM
6188, L
8460, L
9089, L
9785, L
10174, L
12386, L
12551, S (1970)
15170, S
16343, S (late 1960s)
16713, S

I noticed that you show a 1970 model with a serial number of 12551. I always thought that 1970 was the start of the round label with much higher serial numbers on the can. I'm not doubting your findings, but since I don't have a round label RAM or DAAM, I was just curious about the serial number.

BTW my 2 RAMs correspond to what your data shows.

9485, L
16325, S

[duckbill]

Thankyou for the additional data. The more, the better.

bsea said:

duckbill said:

RAM
6188, L
8460, L
9089, L
9785, L
10174, L
12386, L
12551, S (1970)
15170, S
16343, S (late 1960s)
16713, S

I noticed that you show a 1970 model with a serial number of 12551. I always thought that 1970 was the start of the round label with much higher serial numbers on the can. I'm not doubting your findings, but since I don't have a round label RAM or DAAM, I was just curious about the serial number.

Notice that I said that was the year that the seller said he bought the regulator. He was clearly mistaken, and you are correct. The round label came out in 1970. The seller that said his #16343 was bought in the late 60s is probably remembering a bit more clearly! I have deleted the "1970" reference, as it is clearly misleading. Thankyou for pointing that out.

I added pictures to help show what is meant by "long" and "short" horns. The straight/rectangular cross-section showing for about 1/4" at the horn/box insertion point is the giveaway for the long horn. The short horn tapers right down to the insertion point.

It isn't a matter of the horn simply being set lower. My examples are all flush to the box on the inside. There also seem to be differences in measurements and contours as well.

Notice that the raised ring at the end of the horns is also different. The ring is the termination of the tube on some horns (let's call this the "terminal ring"), whereas the tube extends about 1/8" past the ring on others (let's call this the "inset ring"). I have long horns with each ring type. My only short-horned regulator has the inset ring. I'll go back and see if there is a timeline pattern to this difference. Right now, with mine, I don't see a pattern. My Pico regs have both types, my Delhi reg has the inset ring, and my Warners are all inset ringed, I think. More on this later.

[ralphl]

Another data point:

DAAM
223068,L (Pico)

[SeaRat]

Duckbill,

I have a square, blue label DAAM, Serial #250701, and it has the long horns on it. I also have the top and bottom boxes of what was to be a DA Aquamaster--US Navy Antimagnetic (never assembled), serial #238694 gold label with black background on a black box, with long horns.

Until you brought this up, I never realized that there were two different sizes of the USD horns on the DA Aquamaster and Royal Aquamaster. I thought they had been standardized since the switch from the DA Aqualung and the Overpressure regulators, which had even longer horns. But that did not matter for the duckbill exhaust on those regulators, as they had the screw-on exhaust horn and mounted the duckbill only on the internal part. This explains the problems some of the duckbill valves have caused with leakage due to water pressure. Here's the thread where we discussed that, along with a photo of the inside of my DA Aquamaste bottom box.

vintagescuba.proboards2.com/index.cgi?board=general&action=display&n=1&thread=265&page=1

John

[Broxton Carol]

Here are photos of the horns of various common early usd regs. The first picture shows the short stubby horn of an early green label BROXTON in the 11.000 range.


The next picture is of a BROXTON in the 20.000 serial range. Its the improved one, longer, and with the ridge at the edge to keep the hose in place.


The third picture is of a late DA NAVY horn, in the 57.000 range. Very similar to the BROXTON. Enquire minds want to know...