Anti-Torpedo Nets

©Phil Russell

This article by Phil Russell (PhilipR@BTinternet.com) first appeared in "Battlefleet", the Journal of the Naval Wargames Society, and appears here by permission.

I had always assumed, quite wrongly, that anti-torpedo nets had been an ineffective encumbrance, however the more I researched the more I became aware of the important part they played in the defence of capital ships at the turn of the century. Nets remained effective, although relatively unproved, for over 30 years and it was only in the last decade of their life when past their usefulness that they acquired the bad press which has marred their memory of this simple yet effective defence.

Introduction

When the Whitehead locomotive or self-propelled torpedo made its appearance in about 1873, urgent consideration was given towards a suitable method of protecting capital ships from the menace. Progress was initially slow, as the torpedo's threat seemed limited by its slowness and short range. By 1885, however, the torpedo boat had arrived, capable of delivering a much improved Whitehead torpedo reaching 30 knots and holding 200 lb of gun cotton. By the time Dreadnought was completed in 1906, the Hardcastle torpedo then in use reached a speed of 33 knots, and had a range of 7,000 yards.

At first, with torpedo ranges measured in only hundreds of yards it was assumed that attackers could be kept at bay by a combination of searchlights and quickfirering guns. However, as technology progressed, the increasing threat from the torpedo was not underestimated, and warship designers moved quickly to develop improved means to safeguard against it. A major innovation in capital ships was the addition of longitudinal 'Torpedo Bulkheads'. Running from the after machinery spaces to the forward and flanking boiler and machinery rooms, these were set far enough inboard to prevent being breached by a torpedo exploding against the shell plating. The outboard space could be coal filled, but was more effective if left void, giving the explosion space to vent itself. However in their original form, they did not cover all of the important areas of the hull, and were limited in value.

Thornycrofts of Chiswick pioneered the fast steamboats from the early 1870's. The Admiralty was quick to recognise that these fast boats when armed with the new Whitehead torpedo were a real threat to the British Battlefleet's superiority by making the traditional strategy of blockade off their coasts impossible. Besides which they were relatively cheap; whole flotillas could be built and manned for the cost of a single ironclad.

History

The idea of anti-torpedo nets rapidly followed the introduction of the locomotive torpedo. Experimenting against a hulk, numerous devices were tried out for catching torpedoes and rendering them harmless before they ever reached the ship. The most successful of these was galvanised wire net with an 8 inch mesh weighted at the foot and hung out around the ship from 40 ft booms; the depth of the nets when thrown out in to the water was to corresponded with the ship's keel, with the nets hung vertically whilst at rest and extended about 4ft above the water. In 1874 tests these nets arrested all torpedoes fired.

A British Admiralty Torpedo Committee set up to enquire into all aspects of torpedo warfare reported in 1876 that due to the threat of torpedo boat attack "none of our large vessels could remain for any length of time during war off an enemy's coast...". The defences recommended were, "patrols of 'guard' or picket boats around the fleet, electric lights concentrated in beams by dioptric projectors which can be pointed in any direction, a machine gun armament and nets of galvanised iron hung around each battleship from projecting 40ft spars". All these were adopted by ironclads, together with greater internal watertight sub-division of ships, also recommended by the committee. The following year 1877 HMS Thunderer was the first operational ship to be fitted with experimental torpedo nets.

In 1884 experiments by both the British & French Navies indicated that while ships were being fitted with large numbers of quickfiring small calibre guns there was no evidence that these had the power to stop a torpedo boat. In fact most hits were obtained only once the attacking boat were well within torpedo range. It looked as if booms and nets were the only available defence for ships at anchor and that at sea only high speed would ensure safety. There was no need to deploy nets whilst underway as the torpedo was only a maximum of twice the speed of the ship so could be out manoeuvred.

These early nets where of the Bullivant type named after the London company which manufactured them and made up of steel wire rings 6 1/2 in. diameter joined by smaller steel rings, forming a continuous crinoline and weighed only 1 lb per sq. ft. They were slung out on 40ft long wooden booms, far longer than traditional boat booms, connected to the ship side by a simple heel fitting and triced up high above water by stays from the derricks or mast heads. Extended trials proved that despite their perceived limited stopping ability they were capable of stopping, without damage, the slow 14 in torpedo, which it had been feared might explode and destroy the net.

The booms were carried along the sides in turret ships, but usually stowed inboard in broadside ships except for a pair triced up at the bow and the stern. The cumbersome crinoline, stowed around the edge of the upper deck, took a long time to get fixed into position and longer still to restow, and could only be used with the ship at anchor. Additionally being stowed on the deck edge the nets were prone to damage in bad weather sometimes being completely washed away.

During 1885 the Resistance was prepared for a series of trials on the effect of guns & torpedoes and the protection against them. The ship was moored fore and aft in Portchester Lake. One of the main objects of the trial was to test the effectiveness of torpedo nets and to determine the minimum distance from the hull at which they would be effective. On 21 September 1886 a 80lb charge was exploded 30ft from the side which shock her but caused no damage. This seems to have been in the nature of a calibration shot to see that all was well. On 22 September, the torpedo vessel Vesuvius fired an old pattern 16in torpedo with a 91lb charge from her bow submerged tube against the nets which were still rigged 30ft from the ship's side. The range was a mere 100 yards, both to ensure the torpedo hit in the desired place and that it impacted the nets at high speed. The explosion was impressive but the damage was very localised, one net supporting boom being unshipped, there was no damage to the ship.

Since the value of nets had been demonstrated, it was possible to use static charges, hung from a boom, rather than the expense of real torpedoes. A charge was exploded at 20ft, which caused no damage. The next charge was detonated at 15ft from the side and caused some minor leaks in the shell plating. There was then an interval until the new series of trials started on 9 June 1887 which was intended to try a new heavier design of Bullivant net. This used steel booms which were only half the weight of the old wooden design and with stronger and hinged heel fittings. It was so designed that it could be got out or stowed very much more quickly than the older nets. Once again Vesuvius was used to fire a 16in torpedo which tore the net but did no damage to the ship. On the 10 June a 220lb charge was exploded 30ft from the side and 20ft down. The only damage was that some net booms were bent.

The lessons learned from these trials as given in the Naval Annual were:

Nets of the type in service will stop a Whitehead torpedo and, if this explodes 25ft from the hull, there will be no damage to the ship.

The new design of Bullivant net is equally effective and far easier and quicker in operation than the existing type.

These test results were confirmed in fleet manoeuvres designed to test defence against torpedo boats. Flotillas attacking at night never succeeded in getting closer than 800 yards to the ironclad squadron at anchor before they were discovered and the only 2 torpedoes to travel in a straight line to their target were caught in the nets which had been swung out to catch them.

In the design of Mars (1894) the torpedo net shelf was experimentally lowered a deck and ran below the casements and the booms ran out nearly flush with the water, in which position it proved far more satisfactory - especially when the heavy grommet net of stouter wire and consisted of closely interlaced ring 2¹/₂ inches in diameter and weighing 5 lb per sq. ft. was adopted. Added to which, if damaged in action portions of net could not foul the guns. The crinoline was only partial, the extreme bow and stern being kept clear so that a ship could proceed slowly with nets deployed and if damaged a net would be less liable to foul the propellers - although in later classes, having inward turning screws, this risk was increased due to the in flow into the propellers. So fitted, a ship could proceed slowly without the nets being swept to the surface and was safe at sea. In 1906 the Channel Fleet with nets down steamed at 6 knots.

With the improved (lower) main deck net shelves and booms stowed along the side of the ship, 'Out Nets' became an evolution which could be performed in an astonishingly short time, the nets being dropped and swung out into position on their 30 ft booms in 10 seconds and refurled, with the aid of steam powered windlass, onto the shelves in a minute. The record times which were even less, were recorded in the Venerable in 1905. However these times should be viewed with some scepticism, as they would be achieved through some highly unorthodox priming. Times of 2-3 minutes are more likely to have been achieved in action.

But the coming of the torpedo with a net cutter fixed in its nose posed a serious threat. Net cutters to deal with the heaviest mesh were of (1) the pistol type evolved by the French, which discharged automatically upon hitting the net, and (2) a scissors type as used on Japanese torpedoes to cut the net. The former worked well enough experimentally, but did not score much success under realistic conditions. The closer mesh of the later nets apparently defeated the scissors cutter, to such an extent that both in the German and Royal Navy's heavy nets were regarded as more or less torpedo proof. Elsewhere opinion as to the utility of nets varied between nations. France discarded nets; the Russians fitted them in some ships and not in others; for a short time they were carried in the Italian Duilio and Italia classes; and the Americans ignored them never adopting this form of defence.

During the Russo-Japanese war nets were used effectively in only one instance, namely, in December 1904 by the battleship Sevastopol. That vessel, at the end of the siege of Port Arthur, was anchored outside the harbour in a position where she was sheltered from the fire of the Japanese batteries, but became exposed to persistent attacks from torpedo boats. She was lying near the shore and had her nets out along both sides and an extra net around the bow, but the stern was left unprotected. Two destroyers were assigned the duty to ward off enemy attacks in the region between the ship and the shore, and two smaller torpedo boats were stationed near the ship, one each side. Land batteries co-operated in the defence.

From 11th to 16th December Sebastopol was exposed to numerous night attacks. The Japanese employed no less than 30 torpedo-boats, of which two were lost, and it was estimated that altogether 104 torpedoes were fired against the ship. Most of the torpedoes missed or remained hanging in the nets, where several of them exploded, but the nets were repaired in the daytime. One torpedo, however, which exploded in the nets near the bow, produced a leak in the torpedo room, and another damaged the compartment forward of the collision bulkhead, the nets having yielded to such an extent that the explosion took place near the hull. The ship settled by the bow. The two last torpedoes that struck the ship were fired at close range against the unprotected stern: they damaged the rudder and produced a serious leak under the quarterdeck, so that the aft end of the ship sank until it touched the bottom. The leak was repaired, the ship again floated, and finally, on the last day of the siege, she was take out to deep water and sunk. The nets did good service in this case, but it must be admitted that the circumstances were exceptional.

The Japanese in peacetime had practised steaming with nets out, but did not do so during the war. They gained practically no experience in repelling torpedo attacks owing to the lack of Russian enterprise, but after their attacks on the Russian ships at Port Arthur the inadequacy of partial net defence was realised. Japanese battleships carried the same sort of protection as the RN, and through about 60° of arc the nets gave no protection whatever; for another 100° or so they only slightly reduced the size of the target, and should the broadside be turned to an attack so as to get the benefit of the maximum length of net defence, the maximum of risk was invited by the offer of the unprotected ends.

In the flagship Mikasa an extension of the crinoline around the bows and stern was temporarily fixed, but later discarded. No reports of nets having fouled screws were received.

By the time of Dreadnought in 1906 it was said that the torpedo net defence, devised by Captain Bacon, was the most elaborate and complete system fitted to a warship to that date, yet needed only 2 or 3 minutes to drop the nets from a stowed position. The net defence ran for three-quarters of the length of the ship along the upper deck level. The weight of the entire installation was about 100 tons.

In 1907 advances in the propelling engines of Whitehead torpedoes doubled the available propelling power of the torpedo and adding about 10 kts to the maximum speed which for the first time was to give them sufficient punch to penetrate net defences. The days of the torpedo net were numbered.

Provision for anti-torpedo nets within the Royal Navy's capital ship designs continued until 1911 when the King George v class (1910 Estimates) were the last to enter service with anti-torpedo nets fitted, and although they were provided for the succeeding class of Iron Dukes (1911 Estimates), they were only fitted to Iron Duke during her trials period and were removed before she commissioned. Nets were discarded in all following designs. Those already fitted in ships were progressively removal from all class but some were retained as late as 1916, even though it was accepted by then that they were of limited value except for moral and as a seamanship evolution to keep ship's company's well drilled.

By the outbreak of WW1 torpedo nets had disappeared from all but German and British Navies where they could still be found on many capital ships. At the beginning of the Gallipoli campaign in spring 1915 the pre-dreadnought battleship Goliath was torpedoed and sunk by the Turkish torpedo boat Muavenet whilst engaged in shore bombardment. Then the first U-boat arrived and quickly disposed of the Triumph and Majestic. All three ships had anti-torpedo nets deployed, but these proved no match for latest generation of torpedoes.

The torpedo that sank Majestic passed clear through the nets without being checked. As the ship sank several men were drowned after becoming entangled and trapped in the very nets designed to protect them. Again in the case of HMS Triumph, the nets did not prove effective. According to some reports, at least 2 torpedoes were fired in succession from the submarine against the same part of the net. The first torpedo cut through the netting, and the second passed through the hole made by the first. The ship was hit amidships, capsized after nine minutes, and sank 20 minutes later. Again it was said that a number of men were caught up by the nets when the ship turned over. These reports may not be quite accurate, but it is certain that the Triumph had her nets out and they were ineffective. From this point the Royal Navy had to accept they had no effective defence against the torpedo and finally abandon the centuries old principle of close blockade.

The Germans retained nets until after the Battle of Jutland. However their experiences during the battle were that their vulnerability to shellfire and the possible consequences far out weighed any remaining benefits. The gunnery officer of Derfflinger wrote of the damage received in battle:

"The after torpedo net had been shot away and was hanging over the port screw' the ship had to stop for several minutes at the height of the battle 'How many times had were cursed at not having rid ourselves of these heavy steel torpedo nets, weighing several hundred tons. As we hardly ever anchored at sea they were useless, and in any case, they only protected part of the ship against torpedo fire. On the other hand, they were a serious source of danger, as they reduced the ship's speed considerably and were bound sooner or later to foul the propellers, which meant the loss of the ship. For these reasons the English had scrapped their torpedo nets shortly before the war - we did not do so until after the battle of Skagerrak (Jutland) and only then as a result of our experience."

Before the end of the war torpedo-nets had disappeared in both in the British and the German Navy. In the event, nets had proved useless at stopping the latest generation of torpedoes and afforded no protection even when the ship was stationary.

Nets in Operation

The deployment of nets was relatively straightforward. On the command 'Out Nets' the lashings securing the nets were removed and the booms swung out with the nets remaining furled until the booms were secured. The nets were then lowered in a controlled manner until fully unfurled into the sea. Of course corners could be cut hence some of the record times recorded. Nets could be allowed to unfurl uncontrolled as the booms were swung out. However the wire nets could cause serious damage to the paintwork! Recovery was the reverse and utilised winches and bradling davits to brail up (furl) the nets. However all did not always go according to plan as this account from HMS Armageddon in 1915 shows:

"At Anchor, tried to furl our nets but through breaking a winch, could not brail up so we weighed and proceeded with nets out. We got barely 6 knots out of the ship."

Both evolutions were manpower intensive so times would have been significantly extended in an action scenario. Nets tended only be used when the ship was lying still or going at very low speed; at higher speeds they would rise and become ineffective. When the ship moved the drag and sway of the nets, was sufficient to constrain the vessel speed to a maximum of 6kts.

Epilogue

Advances in torpedo technology soon rendered nets obsolete and with no hope of stopping a hit attention turned to minimising the out come of a hit - hence the torpedo bulge compartmentalisation for large ships. In fact the first proposals for improved internal sub division to minimise the effect of torpedo attack had been made in 1884 - only a few years after the nets themselves were introduced.

Although nets disappeared from ships heavier static nets continued to be used to protect anchorage's from submarine and torpedo attack throughout both WW1 and WW2 most famous being the 3-tiered nets that protected the Tirpitz and nearly thwarted the X-Craft attack. The RN policy of using nets to protect anchorage's continued into the late 50's when the last dedicated net layers was paid off.

For forty years from 1876 to 1916 anti-torpedo nets contributed to the protection of the battlefleet from torpedo attack. That they lasted so long stands as a testimony to their usefulness especially within the ordered nature of the Royal Navy where they were viewed as much as a method for developing ships companies as they were for defence.

It is worth pointing out that anti-torpedo nets were used once again, by British merchant ships, during the Second World War. The article by L. Norbury-Williams - Ships With Steel Skirts, in Warship 1989 goes into this in detail. Volume 72 Number 3 (1986) of The Mariner's Mirror contains an interesting note by Austin Farrah, which explains that the heavy nets used by British capital ships were intended for harbour defence, and that they were not intended to be streamed while steaming.

Mike Potter (potter4@att.net) adds:

A still more recent use:
Late in 1978 the Argentine fleet deployed to invade three disputed islands at the eastern entrance to the Beagle Channel. A Chilean surface action group lurking in the islands about 100 miles to the west almost certainly included Condell and Lynch. To obstruct the Chilean ships' Exocets Argentina's aircraft carrier 25 de Mayo draped anti-torpedo nets, retained from dreadnoughts launched in 1911, from her flight deck. Pope John Paul II agreed to mediate the issue. [source: Robert L. Scheina, Latin America: A Naval History 1810-1987 (Naval Institute Press, 1987), 184-87.]

Bibliography

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4. Hovgaard W, Modern History of Warships, Conway, 1978.

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9. Tarrant V E, Jutland - The German Perspective, Arms & Armour, 1995.

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