AEUK has sub-contracted the construction of three SEA-class Passenger Transfer Boats (PTB) that will equip HMS Prince of Wales to Diverse Marine, based in Cowes on the Isle of Wight and the vessels will be delivered to the RN later this year.
The PTBs are based on Atlas Elektronik’s (AEUK) SEA Class design and is part of a larger contract to deliver a variety of workboats, procured by the RN under project VAHANA. The 13.8m PTBs are certified for up to 34 passengers and have a crew of three – the first vessel ‘Walrus’ is pictured above. Diverse Marine were selected by AEUK to build the boats because of their proven track record with aluminium construction and ability to customise the design. Some of the other SEA Class workboats have already been delivered while others are currently being produced at AEUK’s Platform Integration facilities in Winfrith, Dorset.
Three PTBs are stowed in the large ports side sponsons that overhang from the side of the carrier and are lowered to the water vertically when needed. The PTBs are not intended for tactical use or in amphibious assault role but they allow the rapid movement of personnel to and from shore, this is especially useful where port facilities are too small to allow the carrier alongside. Typically they will take off-duty members of the ship’s company to and from shore as well as transport visitors to the ship. The QEC carriers have a specially designed platform at the stern which allows the PTBs to come alongside and visitors can ascend the permanent companionways up to 4 deck. (The boat bays are highlighted in red on the plan below).
HMS Queen Elizabeth currently carries three of the four ALN-139 passenger transfer boats of a quite different design that were supplied by Alnmaritec Ltd in 2017. These boats all bear the names of famous Fleet Air Arm fixed-wing aircraft including Harrier, Buccaneer, Sea Vixen and Swordfish. With the delivery of the 3 SEA Class vessels: Walrus, (Gannet and Sea Hawk?), the RN will have a 7 PTBs (which allows for a ‘spare’) and the carriers can embark PTBs of either design. The AEUK PTBs are faster, up to 25 knots compared with the 18 knot ALN-139s, have a more modern look and will benefit from the broader logistic support of the more numerous SEA class boats.
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Alnmaritec PTB Buccaneer operating from HMS Prince of Wales, June 2021. The stern platform and companionways can be seen on the right. -
The ALN-139s PTBs have the capacity for up to 36 passengers. -
AUEK has already delivered several SEA Class boats. This is one of the eight 15-metre Officer Training Boats that will be attached to Brittania Royal Naval College and used for officer cadet instruction (Photo: AEUK). -
OTB-01 at anchor in the Hamoaze 14 July 2021. These boats will be used to train officer cadets in basic navigation, seamanship and leadership. The SEA class are of a modular design and the custom module added to the standard hull design can be seen in this image. Cadets can live onboard for short periods and the module contains bunks, workstations and teaching space. (Photo: RFA Nostalgia) -
The SEA class contract also includes the delivery of 13 small 11-metre general-purpose workboats (3 of which will be equipped with a small survey module for embarkation on HMS Echo, Enterprise and Protector). This is SWB-02 anchored in the Hamoaze, 14 July 2021. (Photo: RFA Nostalgia) -
RNMB Hebe is a 15m workboat delivered by AEK to the RN in September 2020 and used as an autonomous mine warfare command vessel (Photo: AEUK).
The SEA Class is another success story for UK maritime industry and has the potential to attract export orders. While obviously not critical to the frontline fighting strength of the RN, the PTBs and workboats are important logistic enablers that carry out apparently mundane but necessary duties to support the fleet. The PTBs will also carry VIPs and visitors to the aircraft carriers, modern, comfortable and fast boats are important in forming a good first impression.
Knows anyone the reason for two different classes of PTBs? I understand that die use of SEA leads to a standardization with the other workboats. But why were ALN-139 purchased?
As a guess the ALN-139 were part of the original carrier procurement program, the SEA class are part of the (newer) replacement program for the old RN (and RLC) workboats and the long deceased fast motor launches. It makes sense to standardize!
The Alnmaritec boats achieved 30 plus knots on sea trials . Alnmaritec owners didn’t push for more orders.
A proper admiral’s launch would have been nice.

Had those on the Massive
Yes. 🙂
It is a shame the budget can’t be stretched to a ‘comfortable’ helicopter for liaison work.
The Admiral’s Barge, Lake Burley Griffin, Australian Capital Territory, Australia; 2011.
[...Built by Norman R Wright & Sons in Brisbane and commissioned in 1993, the Admiral’s Barge is the third vessel to carry the name since the conception of the Squadron more than 30 years ago.
Normally the Barge would see service in the escort of senior Australian officials and foreign dignitaries on ceremonial occasions such as Fleet Reviews and Australia Day commemorations, generally in and around Sydney Harbour. The 2011 Royal visit was an historic occasion for the VIP Boat Squadron and the Royal Australian Navy as the Admiral’s Barge temporarily undertook ‘higher duties’ in service of Her Majesty Queen Elizabeth II.]
Extract from – https://www.navy.gov.au/fleet/ships-boats-craft/other-vessels/admirals-barge
or this
Probably a better spend than £200 million mega yacht.
A proper yacht and a comfy helicopter would be a lot less.
Never heard of this’ comfy’ helicopter ? Cant seem to find any previous mention of one in the services when they had far more helicopters…could they have a single VIP seat for quick fitting ?
If the Royals or Boris visits while at anchor or underway they can land on the deck with their own ( or hired) helicopters. Otherwise its a 2 -5 min hop in a Wildcat or Merlin from a suitable shore site for everyone else.
A comfy helicopter is one that is comfy.
A comfy helicopter………..

A not very comfy helicopter…………
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Thank! 🙂
I was in a rush.
Could these be upgraded for Sea Ceptor?
No problem to arm them as heavy as Type 31!
Type 31s 20 inch guns might get in the way…
There has never been a 20inch gun on a ship nor will there ever be. The closest we have ever came to a 20in naval gun is the WW1 battlecruiser design called incomparable for a 300m long battlecruiser mounting 6 20in guns and travelling at 35 knots. Or perhaps the Japanese A-150 designs.
joke
noun
No mk41s! No phalanx! No guns,,,
Of course not they are passenger carrying vessels. Not amphibious assault ships or escorts. Don’t be ridiculous.
We should include these boats in our official Royal Navy numbers, 70 looks bad! Other navys include these kind of things..
‘Looks bad’. And what purpose would artificially boosting navy ‘vessel’ numbers have, other than to please the uninformed.
Seriously Navy Lookout? This is worth an article?
Yes of course it is. Why not? There are books on ship’s boats.
There are books on dinghies, mate.
I have books on ship’s boats and I have books on dinghies too.
Your question was still pointless.
Mate.