Ham class minesweepers and the paravanes on the Ton class.

Thanks for the link, it was very, very helpful in explaining what an ‘otter’ and a ‘kite’ were and what they were used for, and the techniques involved in mine sweeping. The reason I’m interested in the Ham and the Ton is because I’m doing some research on the Royal Malaysian Navy [RMN], which operated both – for routine patrols and mine sweeping.

Here ‘s a description from a former RMN man about how the ‘otters’ and ‘kites’ on the Tons [Marhamiru class] were calibrated before wire sweeps could be performed.

First on the agenda was to Calibrate the ‘Otters’ and the ‘Kites’. These are equipments or ‘paravanes’ — to use the correct technical name — used during Mine Sweeping operations. They were rigged with slings and with Three (3) slings it became a ‘Kite’ and applying Four (4) slings made it an Otter. The Otter was for taking the ‘sweep’ wires out and kept at a certain depth, away from the Ship to either the Port or the Starboard quarter. The Kite was for keeping the inner section of the ‘sweep’ wire down to a certain depth. This calibrating exercise is pains taking and dangerous. We repeatedly went ahead and stopped because it’s adjustments were not correct and from the Bridge we could see the Otter or Kite ‘leaping’ out of the water. This is frightening !!!! The wires would be recovered, the Otter winched on board and the settings readjusted. After many trials, the X.O. is happy — these equipment are now calibrated. Now we can practice putting our ‘Wire Sweeps’ out. We would start with just one Sweep to either Port or to Starboard and when confident, both Sweeps to either side would be streamed. Then, another date would be marked for practicing streaming ‘the loop’. The team have to be completely clued up for all these Sweeps and each person must know his particular task. When streaming any of the Sweeps, there are many smaller events happening there all simultaneously and no one can dream or switch off. Your mate could be seriously injured. You would have ‘steel wire ropes’ in tension and have to be watchful all the time. Again, step by step we follow the Instructions from the Manual and when it is all streaming astern correctly, the Electrician makes sure that the Generator works correctly sending the right current and pulse through the thick cables. With success, the boys on the Sweep Deck all receive a ‘Bravo Zulu’ from the Bridge.

Another big aspect about Mine Sweeping is the part played by the Navigator. He has to be accurate with his plotting so that the Ship can clearly mark the ‘channel’ that the Ship had cleared of Mines. One of the best methods for ensuring this is with the ‘laying’ of ‘Dan Buoys’. A line will be drawn on our charts establishing one Boundary Line of the targeted channel area that is to be swept of mines. Then, we practice with the Sweep Deck crew — they have to know when to drop the ‘sinkers’ and the Floats — from the orders from the Bridge. If they drop too early or just a few seconds later, your Dan Buoy will not be on the ‘line’. Practice as they say makes perfect. Soon our ‘drops’ are spot on, but the Captain reminds us that we are practicing in very good weather conditions whilst the real thing may require the Operation being conducted in quite rough conditions. Following this, we practice recovering all the Dan Buoys we had ‘laid’. We time each Recovery as there are standard times that we must keep within.

Something I’m also very curious about is how were mines detected? Were sonars for detecting mines already in use in the 1950’s? Also, were the RNs Tons fitted with a single or twin barrel 20mm Oerlikon?

I’d guess it would be a variant of that on the Tons and an Oropesa sweep, but, would have to dig out a couple of the old Janes books I’ve stowed away to confirm it to be honest.

Until then if you follow the link below and look towards the bottom of the page you’ll see as good a description, and illustration, of the constituent parts of the Mk3 gear as I’ve seen.

http://www.kenthistoryforum.co.uk/index.php?topic=4154.0

There are a few associations covering RN MCMW with online presence which, I take it, you will be familiar with?. I did find an entry by a poster claiming to be the former CO of one of the IMS boats at http://www.shipsnostalgia.com/showthread.php?t=28439. I can dig out some stats etc but my guess is you want to be talking to that chap more!

Good luck.

Edit: Bit more detail here on the basic technique – http://www.globalsecurity.org/military/library/policy/navy/nrtc/14160_ch8.pdf

Thank you! Your description of ther Mk3 gear was a big help as I was very confused as to what it was. As the Ham class was designed only a few years earlier than the Ton it is possible that both had a simliar wire sweep arrangement.

To the best of my knowledge the MK3 gear was an Oropesa sweep. This used a single line tensioned and depth regulated by an Oropesa float and kite arrangement. The cutters, mechanical or explosive, were attached to the wire. There was no separately streamed paravane-equipped cutting line I have ever seen detailed on UK Tons.