The name Thetis was chosen from Greek mythology for the Mk.IV+ by Barbara Hobson. Father of Achilles, Thetis had the power to create a shield around those he loved. "We have designed a vehicle with that in mind," Peter Hobson said, "To protect those people we put in harm's way."

Based on research conducted both when designing the original Hobson ALR Mk.IV proposal and subsequently evolving the better protected military specification Ranger derivative, in Thetis, Hobson Industries has been able to create a vehicle which they believe better shields its occupants than any previous steel bodied armoured Land Rover, and, through incorporating the latest design and materials technology in strategic alliances with other specialists in associated fields they have been able to increase protection level while maintaining operational payload.

Thetis has been designed to deal with multiple threats and attacks from above, below and all sides, ranging from bullets and improvised weapons through to petrol bombs and fire scenarios.

For example, the Dawson Roof overhead protection principle has been improved and integrated into a one-piece design which also assists in fire protection for the occupants in the type of situation often encountered in urban civil disorder, and indeed witnessed frequently, during the Jasmine Revolution which swept through much of the Arab World in the first half of 2011.

The original Dawson Roof concept came about following the first successful attack on an RUC vehicle with a 'drogue bomb' improvised explosive device, which peeled the roof of a Hotspur armoured Land Rover in Dawson Street Belfast on 9th August 1987. Questioned about his Dawson-derivative roof

"I won't go into the details of the Mk.IV+ roof suffice to say that it is a multi-layer design that works on the spacial armour principle. I've done most of the research on this for getting this armour system going. What we've done with Thetis is raised the height of the body and used a Dawson-derivative design, because of the weight, to give us more height and of course a smoother surface for flammable liquid to run off. It is basically the same as the original concept of a multi-layer design except ours is also impervious to 7.62mm fire." Peter Hobson said.

"We improved the side gig design considerably", Peter Hobson continued, "and now it's an integrated part of the vehicle. It is designed to disintegrate on explosion so it's actually sacrificial but the outer is made out of exactly the same material as they make the top hats for the Land Rover Wolf so it is designed to crush in an accident without giving shards out. It is actually quite an expensive piece of kit, being layered and autoclaved, and of course it meets Road Traffic Act legislation for collision, which is important. We can't use the bath spray type technique on it because it would shatter in shards. As it's designed to be sacrificial we want it to actually tear apart."

On the Mk.IV+ Thetis the outside surface is coated with fire retardant paint throughout and the design has very few seams through which flammable liquid can get into the vehicle. The paint coating used in the wheel area is designed so that when it catches fire it bubbles up and actually creates a barrier of inert gases. The rubber tyre can still burn but because the wheel has Tyron run-flats fitted the vehicle can be driven out of trouble and burning rubber no longer poses a threat to the engine compartment.

Another area of major fire vulnerability was the front of the vehicle. On earlier vehicles, the RUC had tried lots of remedies to try to stop flammable liquid getting in but Hobson's took a completely different approach.

What the Company did was look at the way that fluids react when they are in motion and they realised very quickly that if he could make a labyrinth seal and get the angles of the inclined planes correct what would happen was the fuel would hit the bonnet area and joint between bonnet and cab and simply run off rather than seeping in.

A labyrinth seal is like a maze for flowing liquid, which uses all its energy up trying to get around, therefore Hobson's created a completely new bonnet designed so that liquids would run onto the sides of the wings and then off down the side of the vehicle rather than into the gulley below the screen or under the bonnet edges.

There is no rubber at all to catch fire on the Mk.IV+ Thetis bonnet and only the labyrinth seal design is used to prevent ingress of liquids, but the engine can still breathe because air comes from a separate location.

Hobsons combined the experience of BF Goodrich from the racing car industry, with Peter's experience in the Royal Navy, to ensure that anything which carried flammable liquid on Thetis is protected from fire with a unique patented Fire Protection system. Although armoured Land Rover fuel tanks are explosive proof, later models are plastic so they had to make a shroud and wrap it in fire protective material, of the same sort that firemen use in their suits, to withstand 1000 degrees for at least a couple of minutes.

Such protection allows the vehicle to be driven away from fire without worrying about the fuel tank igniting, but this also means that any plastic fittings in the fuel lines need to be changed and the lines themselves have to be shrouded and shielded. The bottom of the fuel tank also has to be protected against blast.

Hobson Industries has teamed up with joint venture partner Line-X of America to run spall liner trials with them. Originally the chosen material came in as a backing spall liner for the floor and as a secondary guard for the inside, but by working with Line-X they produced a fire retardant material.

Hobson's were then granted one of only three military licences by Line-X to apply this new fire retardant spall liner type material and the inside of the Mk.IV+ Thetis is therefore uniquely sprayed with this compound. The spall liner itself is lightweight and will absorb energy very fast and still keep its rigidity. Like all materials used in Thetis Mk.IV+, this lightweight spall liner is also fully compliant with end of life disposal requirements.

Through careful use of materials Hobson Industries has dropped the standard vehicle down from nearly 4.0 tonnes to 3.2 tonnes kerb weight, to allow a fully crewed gross vehicle weight within the 4.0 tonnes approved by Land Rover. Hobson's also completely redesigned the braking system on the vehicle in conjunction with Alcon to not only meet the 4.0 tonne target but to also cater for 4.4 tonnes GVW.

In addition, the Company has worked with Alcon as a joint venture to design the braking system for the new vehicle and as a result it is far superior to anything that is currently fitted to armoured Land Rovers. However despite uprated springs, better shock absorbers, reconstructed anti-roll bars and a better braking system they still had a vulnerable underside to the vehicle.

The Mk.IV+ Thetis has a military specification STANAG Level 1 floor at half the weight that would normally be considered appropriate and this gives considerable savings on weight as well as providing a solution which greatly exceeds B6 protection level.

Hobson's also worked with Romag, makers of bullet resistant security glass, on the weight reduction programme. Armoured glass is both very thick and it's heavy, so working with the knowledge they had of Northern Ireland vehicle attacks Peter realised that the biggest threat was actually from a sniper round and so developed a glass to meet NIJ 0108.01. This glazing solution not only easily stops a 150grain sniper round at 3000 fps but also caters for another common threat, which is, ball bearings fired at the windows to crack the glass and take the vehicle out of service.

This secondary threat is addressed by provision of a potted glazing system with the glass being sheathed in its own frame meaning it is just a matter of unscrewing a few screws, taking the old glass out, and inserting a new cassette in double sided tape to make it waterproof.

"My cassetted glazing system design gives an easy stop for a high powered sniper round, which is what the primary threat would be. If a ball bearing is fired at it, because its front face is a heavier glass it is less likely to shatter, but if it does the cassette system allows it to be changed literally in minutes and the vehicle can then be returned to service." Peter Hobson said.

"Hobson Industries Mk.IV+ Thetis has therefore been a rethink from top to bottom. With complete redesigns for all of the armour shell, all of the improved Dawson-derivative roof, all of side gigs, all of spall liners, all of the bonnet and wing petrol bomb protection, all of the suspension and all of the braking system, plus redesign of seventy percent of the fire protection system. I am confident that my design is the best current solution for those requiring a comparatively benign appearance armoured Land Rover type of vehicle for high threat level public order situations." Peter Hobson concluded.

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