USS Harder (SS-568) - Tang class, not Gato

[PaulC]

Can anyone explain the function of the "X" style fins on the stern of the USS Harder in this picture? I noticed them on USS Wahoo (SS-565) too.

[mkeatingss]

They're not 'X' fins, they're

They're not 'X' fins, they're actually sonar domes.
Mike

[tom dougherty]

Mike,
You mean the really

Mike,
You mean the really thin double dihedral fins behind the PUFFS dome? They do look more like some sort of topside upper rudder, somewhat similar to the single rudder you had on Amberjack. What kind of sonar are they?

With those fins, I thought maybe, with it being the late 1950's, they were using Harder for a Cadillac promotion event....
Tom



Edited By Tom Dougherty on 1133299818

[PaulC]

They do look very Cadillac-ish,

They do look very Cadillac-ish, and I used "X' fin style for lack of a better term. From the picture they look stationary but I could be wrong. As I said the are found on other Tang class boats.

They look awfully "fin-ish" to be sonar domes. Some GUPPY boats had upper rudders installed. I've never heard of an X-style upper rudder being used, much less used on multiple boats. Which would lead back to a sonar application possibility...

[anonymous]

Just a guess Paul. The

Just a guess Paul. The dehedral fins are perhaps fixed stabilizers. They are split, instead of one single vertical so flow noise from them is dimminished being located so close to the aftermost component of the passive 'puff' array fin forward of it while making the most of the twin fin surface area vs. a low profile. But I ask myself, wouldn't the fixed puff array itself in effect also act as a directional stabilizer too?

Very precise directional heading might have been essential for the puffs to calculate the target bearing accurately passively. The centerline of the boat being the baseline for triangulating target bearing. This is likely pre-towed array era, where the baseline is the boat length, or rather the distance between the fore and aftermost puff array. Target bearing accuracy could be improved later using towed arrays (a very long microphone cable towed behind), due to a greatly increased baseline calculation.

Steve Reichmuth



Edited By Dolphin on 1133322944