How do you come with this figure of 10 to 20 minutes reload time?
Any source you can share.

For what I have read in several books the reload was far much faster.

Even in Wikipedia they are talking about 3 minutes.

Hedgehog_(weapon)

it may well be, that's why I used the word "estimate". :) I was working from the premise that replacement hedge-hog charges would not be laying around the deck before firing, ready to reload, but would need to be brought up from the magazine. I'd have expected this resupply to occur until they were told to stop, so its the first reload that would be most time-consuming. If you had the new rounds ready and by the weapon, then 3 minutes makes sense. But if not, then 10-20 minutes is probably a better estimate, dropping back towards the 3 minute mark as time goes on. On the other hand, DC's were (erroneously) believed at the time to be far more effective than hedge-hog and as the same people who were resupplying HH's were also bringing up the DC's, it's entirely possible the HH was only used once whilst in asdic contact, with the reload occurring once contact was lost.

I'm simply asking of anyone knows, or can provide evidence for, the reload rates, the rest of it is surmise.

I have found this video with a lot of interesting data about Hedgehogs and it also mentions the 3 minutes.

https://youtu.be/AWJyzPaVQbo

And on this one you can see the loading cadence. Apparently the magazine is just right behind the launcher

https://youtu.be/KGpwRbM3gxU

Most interesting, thanks.

There was a magazine for additional shells but most were held in "ready to use" ammunition lockers next to the weapons they were intended for. The deck gun had racks that held shells all around it, each 20mm had their own lockers right next to the spotlights behind them. Hedgehog had a big ole locker right behind the blast shield of the main gun. So each weapon was always in the ready to be used and reloaded because in war, seconds, not minutes, count.

Hedgehog Progress
 

https://imgur.com/xTHevjOhttps://imgur.com/xTHevjO

I can bet that my pictures would be over sized. But I been working on the hedgehog quite a bit and have set up where you can see two of them next to another. The one on the left with the rainbow colors is there to indicate the fire groups of each shell, the one on the right represents roll compensation and isn't important to be colorized.

https://imgur.com/g7UXnIyhttps://imgur.com/g7UXnIy
I am testing out the gyro stabization of the weapon which it was able to compensate for roll and pitch of the ship. I have the numbers to how much forward and back, side to side the thing was able to compensate but the real puzzle is in the how. I have found out that each of the 6 shells sits on one of 4 cradles and like a baby cradle is able to swing to and fro. This to and fro motion of the cradles is how it is able to compensate for roll. However, I still haven't found how it compensated pitch.

They may not have needed to. The pitching of a ship is generally readable from the observed swell and waves, and of course you have a pretty good idea when the ship is longtitudinally about level. All that would be needed is to commence the electrical (?) firing an instant before the boat is level in pitch? Even a crude "foresight" on the front of the ship, when about level with the distant horizon would be enough to "eye-ball" it....

Hm, I would have expected some form of mechanical gyroscope in play there, at the time. Why wouldn't/didn't it work?

I can't imagine a worse environment for an expensive and delicate gyroscope than being on a rolling/pitching/yawing Flower Class which drops depth-charges. Lots of them.

Much easier to put a mark of paint on the foremast at the height of the horizon as viewed from the bridge (on a flat calm sea) and just slightly anticipate it passing through the horizon as the boat pitches, I would think the latter, which is not prone to damage or hideously expensive, would be the RN's preferred "system" for this...

Even today, the captains of our submarines are expected to be able, and can, rapidly calculate torpedo firing solutions in their heads, rather than being helpless if all the technology falls-over.

Now, I have no evidence that such a "paint on a stick" system were used, but I think it's a pretty fair bet. I don't have the performance figures of hedgehog, but I'd be interested to know, if someone fancies calculating the parabolas, what error in pitch of the boat at firing would prevent a hit, assuming all else is accurate....

Paint on a stick (mast) Wouldn't work due to the fact that the mast is behind the bridge not before. The entire hedgehog was gyro stablized, this much is very clear in a dizzyon of texts, but it doesn't explain how exactly that it was. This is what is still puzzling though I am trying to figure out.

Just a degree off, and I am more than 30 yards off target with pitch. That is either a hit or miss if the time I need to fire is NOW. I am still working at this though have other areas I too can work on till I can gather more information on it all.

I can't tell you how it worked on a ship, but I do have a better understanding than most of how aircraft instrument gyro's work, as a retired ATPL/IR and QFI.

I would imagine, (and this is surmise) you'd have a box of 2 or more gyros on the ship, which generate electrical currents proportional to the movements of the ship around the gyros, and these signals are used to drive electric or electro-hydraulic motors, more probably, to stabilise the hedgehog to local-earth vertical (according to the gyros) regardless of the movement of the ship. I doubt this was on all the time, but rather was enabled once an ASDIC contact was made, and disabled to aid reloading, when ideally you'd want the unit remaining to ship vertical, rather than earth-vertical during the reload.

The other way to do it would be to put a large weight as far below the hedgehog as possible, with a connecting structure. Although less accurate, this would have the benefit of being more reliable. A Flower Class is as about a hostile environment for a gyro as you could devise.

The Yanks used a similar system on remote-barbettes on B29's, so that the gunner in a blister could align his sight with a target, generating a signal which the turrets then attempted to bring to 0 difference electrically. This occurred far faster the greater the deviation, so once in the right area the corrections became progressively more accurate.

Well, I had no intention of picking this up. I've had enough of U-Boats, honestly. But if you get a few sub killers in here that players can man, yeah, I'm in. A Tribal class destroyer, you say?

I forget the numbers now, but Tribals carry a lot fewer DC's than the Corvettes. If ever Tribals are modelled as player-operable, then I can see the Tribals being used by moving quickly to the required position to force the u-boat to dive, whilst 1-2 corvettes move in more slowly to take up the search, releasing the Tribal to regain its previous position in the convoy escort screen...

I'm hoping SEA POWER goes multiplayer, but they're still mulling the idea around. Since DW and before that HARPOON the pickings are slim.

All this just brings home how much things like reloading a weapon varies by conditions (imagine doing that in even Sea State 3) and the motivation and fatigue of the crew.

Human factors in warfare always seem to be the biggest factor.


So much good history in exploring all the cool Escorts!

https://upload.wikimedia.org/wikiped...-236608%29.jpg
https://en.wikipedia.org/wiki/Buckle...stroyer_escort