Mk13 to Mk41 Launcher Conversion for Oliver Hazard Perry Frigates

A Mk 13 Launcher with a Harpoon missile on its rail. Photo courtesy of Wikipedia Commons.
A Mk 13 Launcher with a Harpoon missile on its rail. Photo courtesy of Wikipedia Commons.

In researching about these Oliver Hazard Perry (OHP) Frigates, one question that came to my mind was, “Is it possible to upgrade the OHP’s Mk13 launcher to the Mk41 Vertical Launch System (VLS)?” Much of the OHP’s firepower comes from its Mk13 launcher and ability to carry 40 medium-sized missiles, but the launchers have been deactivated by the United States Navy (USN) on all its ships due to obsolescence of the SM-1 missiles and to save on operating cost. The Mk13 is VERY cool to watch due to its fully-automated firing and loading system as can be seen by the video below, but it did have its share of disdvantages also.

‘Mk13 Launcher vs. Mk41 Comparisons’
First disadvantage with the Mk13 launcher is that it is NON-REDUNDANT, you only have that single launcher to launch all 40 missiles. If something happens to that launcher, whether due to battle damage, or whether it malfunctions on its own due to some reason, then you lose ALL of your missile capability. Hence you need to take very good care of that launcher, frequently conducting tests and preventive maintenance to ensure that it is working and that it will be working when you need it. It also has a lot of moving parts, all the worsened by the fact that it is moving heavy, 700 kg missiles at a fast rate in various directions. It also has to withstand high temperatures and shock during firing, hence the parts are subjected to large amounts of physical stress, making frequent maintenance necessary.

Second is that it launches missiles at a fairly slow rate, only 1 missile every 8 seconds,[1] or a maximum of 7 missiles per minute. This is not very ideal against saturation missile attacks, and even more so against saturation attacks by SUPERSONIC Anti Ship Missiles (AShM)s, which are slowly going into service in various major navies around the world. Because of their speed, these supersonic missiles will cut down even more on a ship’s available reaction time, increasing their chances of scoring a direct hit. Third, it can only launch one type of missile at a time, meaning it has to wait every 8 seconds to switch from firing a Harpoon AShM to a SM1/2 Surface to Air Missile (SAM), for example, which could be detrimental under some combat conditions.

The newer Vertical Launch Systems (VLS) like the Mk41 is virtually everything the Mk13 is not. It is naturally redundant since each missile can be launched from its own container, hence damage or malfunction to one or more launcher will NOT render the ship without missile capability; It can launch missiles a lot faster at around 1 missile per second per module[1], and using various modules you can launch different missiles at the same time. It has no moving parts, making maintenance generally easier and the system much more reliable.

The boringly plain and simple VLS launchers on a ship's deck. Photo courtesy of Wikipedia Commons.
The boringly plain and simple VLS launchers on a ship’s deck. Photo courtesy of Wikipedia Commons.

So its just natural to wonder if it is possible at all to upgrade the OHP’s Mk13 launcher to the Mk41? It turns out that it may be possible to do so, as we shall see.

‘Factors to Consider’
The 3 INITIAL factors to consider here would be the SPACE, WEIGHT and COST of upgrading the launcher. First would be SPACE, is there enough space for the Mk41 launcher to be installed on where the Mk13 is placed? If so, how many “modules” can be accommodated in that space? The Mk41 VLS comes in “modules” with 8-cells each where 1 or more missiles can be stored in each cell, depending on the size of the missile’s Outside Diameter. Here is a picture of an OHP in service with the Australian Navy (AN), the HMS Sydney, upgraded to accept a Mk41 VLS:
Mk41 on OHP

The AN opted to retain the Mk13 launcher and put a single Mk41 VLS module ahead it, for reasons that are not very clear (probably cost). As you can see from the picture, there seems to be ample room for 3 additional Mk41 modules to be placed where the Mk13 launcher is. If you add in the Mk41 module already in front of it, you can theoretically have 4 modules or 32 cells in total. Not as many as the Mk13’s 40 medium sized missiles, but close enough.

Note that the Mk41 installed on the HMS Sydney is the “Tactical” version or size. The Mk41 comes in 3 sizes: Self-Defense, Tactical and Strike, which is basically the same as “Small, Medium and Large”. The systems are the same in width, they only differ in length to accommodate shorter to taller and bigger missiles. The Mk41 Tactical does protrude a bit from the deck of the OHP, but not too much to be a concern.

‘Weight and Cost’
Next factor to consider would be the WEIGHT of the systems. An empty Mk 13 launcher weigh 61,000 kg.[1] On the other hand, 3 empty Mk41 modules in place of that single Mk13 launcher weigh in at a combined weight of 43,635 kg (14,545 kg each[2] times 3), which is actually LIGHTER than the Mk13 system by around 28%, so this actually SAVES the ship some weight. There is the issue of BALANCE, as the difference in weight is quite large at 28%, but I feel this could be offset by the FOURTH Mk41 module, which weighs an additional 14,545 kg bringing the total weight of the 4 Mk41 modules to 58,180 kg, quite close to the weight of the Mk13, and thus should probably not be much of a concern anymore.

Last would be the issue of COST. Each Mk41 module costs approximately USD 4 million[3], so for 4 Mk41 modules that’s USD 16 million for the modules alone. The following work then need to be done:
– Remove material from the deck;
– Remove all of the Mk13 launcher parts;
– Installing all 4 Mk41 modules;
– Installing auxilliary systems for the Mk41

Estimating cost for this is tricky, the best we can do is make some sort of a “guesstimate”, say USD 8 million for all of the work done. That would then bring the total costs to around USD 24 million for each ship.

‘Unknown Factors?’
So, from the above exercise, upgrading the OHP’s Mk13 launcher to the Mk41 launcher seems to be doable based on the factors discussed. The big question now is, “How come nobody has done it so far”? The OHP is in service on 10 different navies all over the world, and NOT A SINGLE ONE OF THEM has done anything like this up to now. Australia, in upgrading their OHPs, opted to just upgrade/replace all of its sensors and auxilliary equipment plus add in one Mk41 module[4] to the tune of over USD 226 million per ship[5]. USD 24 million to add to USD 226 million isn’t much, only around 10% of the cost per ship, so why was this not done?

Other factors could be in play why this is so, like:
– Cost, my “guesstimate” above for removal/installation costs above could be low, and that it would be much more expensive for the above work to do;
– Time, perhaps the whole operation could add weeks or months to do;
– Engineering issue, there might be some in-depth engineering issue us mortals do not know about that the Naval Engineers do

‘Additional Missile Canisters’
As a footnote, additional missiles can be carried in canisters, similar to the setup the Taiwanese did with their OHP-derived Cheng Kung class Frigates to carry their Hsiung Feng AShMs. They bolted on 2 4-cell Canisters just behind the bridge, with each 4-cell Canister angled at around 45% facing to the sides. Additional strengthening was done in that area to support the weight of the canisters. This would bring the total number of missiles that an OHP could possibly carry to 40, maintaining the OHP’s formidable “Combat Persistence”.

A model of Taiwan's OHPs showing the location of the Hsiung Feng AShMs just behind the bridge. Photo courtesy of Solomon203 thru Wikipedia Commons.
A model of Taiwan’s OHPs showing the location of the Hsiung Feng AShMs just behind the bridge. Photo courtesy of Solomon203 thru Wikipedia Commons.

‘Parting Shot’
So how would I arm an OHP with 4 Mk41 modules (32 cells) and 2 4-cell canisters (8-cells)? Well, first I would leave the 28 cell for long-range area defense Surface to Air Missiles (SAMs) like the SM-2 Standard Missiles (or maybe even SM-6, if possible). And then I would leave 4-cells for point defense Evolved Sea Sparrow Missiles (ESSMs) quad-packed per cell[6] for a total of 16 missiles. And then I would leave the 8 canister cells for Harpoon AShMs. So now you have an OHP with modern weapons, and packing incredible “Combat Persistence” for Anti-Air Warfare (AAW), but still maintaining good Anti-Ship capability.

Its really strange that no work towards replacing the Mk13 launchers for the Mk41 has been done so far, which is too bad as doing so would’ve made modernized these OHPs weapons capability, making them more viable for service for at least a decade or so more with some of the navies of the world.


[1] U.S. Navy Guided Missile Launcher Systems,

[2] Vertical Launch System Mk41 Tactical-Length Module, 2013-08-17_Vertical_Launch_System_Mk41_Tactical-Length_Module

[3] Lockheed Martin Receives $16 Million Contract to Provide MK 41 Vertical Launching Missile Systems for Australian and Spanish Navies,

[4] Thales FFG Upgrade, 2008-10_Thales_FFG_Upgrade

[5] Adelaide-class frigate,

[6] Evolved Seasparrow Missile (ESSM) (RIM 162D),

8 thoughts on “Mk13 to Mk41 Launcher Conversion for Oliver Hazard Perry Frigates”

    1. Thanks, USSHelm. Interesting that both navies used the same upgrades, then just stopped at that without doing the full Mk13 to Mk41 conversion. Also I noticed your link gave a different view of the Mk13 and Mk14 installations, this one from the side. Thanks again.

  1. Would you say it does make sense that we acquire those OHP and upgrade them like what you suggested? They seem to be reasonable. The question is would the US give us a couple? I would assume is that we use it sparingly like maybe just around the Palawan area if the Oyster Bay is fully functional to minimize the gas-guzzling COGAG. Or maybe in the Luzon area facing the WPS. My point is its a perfect deterrent, would you agree? I like your analysis.

    1. Thanks for liking my blog. IMHO, the OHP is just too expensive to maintain. Using the ship sparingly will mean less training and familiarity of the crew with the ship, hence the overall effectiveness of the ship will also do down. There are other options out there, some defense blogs talked about getting South Korea’s Pohang Corvettes, which would be a good option, aside from more Hamilton cutters …

  2. The reason this hasn’t happened is hull geometry. Simply put, the OHPs were ‘shrinkwrapped’ around the combat systems that were embarked, and had no room for growth over their lifetime (this is why the self-defense length VLS that is embarked on the Australian and Turkish ships sticks out so far above the deck). The areas around the Mk 13 launcher are in use, so filling out those spaces (as you could at most get one 8 cell block in the existing hole for the Mk 13) would mean reducing the volume used for something else on the ship – and that’s a dicey proposition at best.

    Also, because the Mk 13 is so short (it’s sized such that the only missiles it can take are the Harpoon and Tartar/Standard-MR family) you can’t fit the longer SM-2ER and SM-6 into any VLS you fit. To make matters even worse, the casing is used as a part of the strength frame for the bow, and the removal of this would necessitate the rebuilding of the entire bow, which gets very expensive very quickly (note that the US ships that lost the launcher arm didn’t lose the casing or the under-deck equipment).

    The Alternate Wars GMLS page ( has a lot of good primary source material on the USN GMLS systems and is useful for working on hypotheticals such as this one.

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