Landing crafts complying with MGN 1752 (M) [MCA load lines]

Good afternoon everyone.

Currently I continuously have an issue designing small ((L)<24m, mostly around the 10m range) landing crafts for the UK, under Workboat code edition 3 - category 3. These landing craft require stability booklets and therefore require to comply with the MGN load lines. The loading capacity of these vessels is dramatically reduced compared to when I design them under CE, because of the following reasons:

1. These vessels are outboard powered, so the deck height of the motor well is relatively low.
2. These vessels are required to have a straight deck (or with a small incline for self-draining) for easy on and off loaded at the bow ramp.
3. The vessel cannot have a forecastle because of the bow ramp (eventhough the gunnel and the bowdoor provide full enclosure of the freeboard deck).

These three factors contiuously cause a large addition due to the deviation of standard sheer, addition due to bow height, and I cannot reduce the freeboard due to the % off effective superstructure length.

These vessels have plenty of additional W.T enclosed spaces above the freeboard deck, which add to buoyancy and sister vessels have been sailing around for years (a surveyor praised the stability of these vessels to me personally during testing).

I was hoping someone here has dealt with this problem in the past and could direct me to a possible solution.

 

Im a little confused.
Since any vessel under 24m there is no requirement for an International Load Line Certificate or a Load Line mark. Loadline Rules regulation 9, para 1.7.2 & 1.8.2.

Thus all you need to do, is comply with MGN 280 v3.

 

Perhaps the reference to,

Maybe Earganon meant to type a '>' instead of the '<'.
The outboard motor well shouldn't be a problem as you can partition of the motor well from the rest of the cargo area so that even if the cutout does dip below the waterline, there is no danger of swamping.

Which is the deck, in this case? The cargo or payload deck is below the catwalk, or below the main deck, I assume. What shape do you want to make it?

Does a flying bridge qualify?

-Will

 

This is not correct, see The Workboat Code Edition 3 Section 13.2.1.

"13.2 Minimum Freeboard for Vessels which carry greater than 1000 kg of Cargo
Section 13.2 applies to vessels which carry cargo, passengers, industrial personnel, or any combination thereof, for which the cargo element exceeds 1000kg, and which are not rigid inflatable boats, inflatable boats or boats fitted with a buoyant collar.
13.2.1 Vessels to which 13.2 applies must comply with the Merchant Shipping(Load Line) Regulations 1998 (SI 1998 No. 2241), as amended.

See MSN 1752 (M), as amended , Schedule 5 Table B and calculation for ships <24m
and noting the corrections for Type B ships “other than timber freeboards” that are required for lack of superstructure, lack of sheer, block coefficient, depth and bow height shown in Schedule 4."

As you can see in MSN 1752 (M) (my appologies I wrote this incorrectly as MGN in my earlier post) created a formula to determine the tubular freeboard for vessels below 24m.

This was what I used to do up to about 2023, since then the MCA no longer accepts this standard for all vessels below 24m (see The Workboat Code Edition 3 Section 1.11), with the exception of yachts/pleasure crafts (this was stated to me directly from MCA accredited surveyors).

That is not the issue, the issue is that the motorwell causes a huge deviation with the standard sheer profile, increasing the overall freeboard unnecesarrily.

These vessels are usually only 8 to 12 metres, there is only room for 1 main deck, the payload is fastened onto the freeboard deck during transit. The sheer line of the deck is either parrallel to the keel or inclined at 1 to 2 degrees to assist with the self-draining of the deck.

Landing crafts of this size are usually either build with a simple wheelhouse, or a console with a T-top at the aft of the vessel. I can't see how this could be counted as a the forecastle.

I think for clarrification I will get a link to a simple landing craft image from google as a simple visualisation.
https://www.boatnation.com/wp-content/uploads/2023/03/53260698b8654c4c7f720f698-2.jpg

Thank you all for thinking along with me.
Earganon

 

I am used to versions 1 and 2, not used v3 since it came into force. I know there are "some" issues with it.

I am a bit confused by what you have and what you need, as it seems to be related to just stability calculations?.....an image/profile view of what your facing will help greatly.

Problem with MCA is, ask 2 surveyors a simple question, and you'll get 2 very different replies. Not helpful. It all depends which office and which member of staff you end up liaising with..

 

Edition 3 has been in effect since last summer, eventhough MSN 1752 (M) was already a requirement for vessels with a cargo capacity over 1000kg in edition 2 (but as you said; back then you could use MGN 280 as an alternative).

My problem is that the design of landing crafts has become near impossible, under the current MCA requirement of determining the freeboard according to MSN 1752 (M).
The reason I posted this issue was, because I know landing crafts continue being designed and build in the UK. Therefore, I hoped someone here found a work around. For example, I know that the Norwegian Maritime Authority allows for a reduction to the bow height penalty according to https://www.dco.uscg.mil/Portals/9/DCO Documents/5p/5ps/NVIC/1986/n10-86.pdf?ver=2017-07-13-103958-573 . I do not know if the MCA allows for any modification of MSN 1752 (M) and my attempts trying to contact MCA or their accredited surveyors never go anywhere.

I see the cargo capacity of these vessel drop by half, because of the corrections for lack of sheer, lack of superstructure, and the bow height.

For example the added image of a 12m landing craft went from about 4tons cargo (when determining with CE) all the way back to 1.5 tons (when determining with MCA).

Please note the pictured waterlines are not the accurate waterlines of this vessel, more a rough indication to show you the order of magnitude we are talking about.

This is my experience as well, however I have heard this from both Mecal and Lloyds.

 

Can you please quote the rule reference to which is causing you issues.

 

MSN 1752 (M) - SCHEDULE 4 - PART 1. - paragraphs 5.10 and 11. to 16.


Landing crafts of the size I am talking about have small wheelhouses or are console boats with a tent frame for bad weather.



This reduction is not viable for ships below 24m and even if you could interpolate down landing crafts cannot have a forecastle.




These landing crafts have an outboard motor well and a straight single deck, creating a massive deficiency of standard sheer.



Because the minimum bow height is measured from the deck and not the gunnel to the summer waterline, this causes a similar issue as with paragraph 15.

I hope this explains my issue more clearly.
I would like to restate my aim for this thread: I am looking if there are any workarounds , which designers are applying in order to get similar vessels accepted by the MCA.

 

Not really, no. Since you're quoting pretty much the whole part, not the 1 single ref or 2 that are causing you an issue.

As I read it, WBCv3, 13.2 says: "...Schedule 5 Table B and calculation for ships <24m and noting the corrections for Type B ships.."

So This shows:


Thus, being less than 24m, you then apply:



That's it.

 

Ad Hoc I really appreciate that you are thinking along, but this is incorrect. That formula is merily to determine the Tabular freeboard baseline of the vessel before the corrections for Type B ships “other than timber freeboards” that are required for lack of superstructure, lack of sheer, block coefficient, depth and bow height shown in Schedule 4 (as required by WBC Edition 3 13.2). Therefore, I did quote what the issue is, the whole part is the issue
I honestly wish it was that simple, but I had a stability booklet denied once because of the incorrect application to the strict wording of these corrections to the tabular freeboard.

I will restate my issue again as specific as I can:
With landing craft vessels under 24 metres the additions to the tabular freeboard (as presented in my previous post) require me to drastically reduce their cargo capacity. The freeboard is unnecessarily increased, because of these ships were not meant to be included for load lines, and therefore ship's shape causes massive issues (single decked vessels, small wheelhouse, outboard powered and so a low aft deck, and a bow ramp removing the option of a forecastle). I learned that other flag states alow for specific corrections to the load lines freeboard, taking into account varrious 'non-standard' ship types/shapes (see link from a few post back for example).

My aim is to ask you:

1. Does anyone here know if MCA would accept a specific external (meaning not directly stated within the MSN 1752 (M) or similar notices) correction to the load lines determined required freeboard?
2. Does anyone here have any experience getting their below 24 metres craft over 1000kg cargo capacity vessels verified by MCA in an alternative manner.

I am willing to accept if the answer to both questions is no.

 

Im sorry but your reading is not correct.

Section 13.2 applies to vessels which carry cargo, passengers, industrial personnel, or any combination thereof, for which the cargo element exceeds 1000kg, and which are not rigid inflatable boats, inflatable boats or boats fitted with a buoyant collar.

Thus, if your vessel falls into this definition, then it clearly states in 13.2.1: looking at the superscript ref of #36....which states: "..
36 See MSN 1752 (M), as amended , Schedule 5 Table B and calculation for ships <24m and noting the corrections for Type B ships..."

Ergo, if your vessel is <24m, that is all you need to do.

This is not clear at all.
How does your cargo capacity reduce, other than just quoting the rules...since you have not explained exactly what clause and its effects of with or without said compliance.
Either you're seriously over thinking this, or I am dumb as a bar of soap.

Freeboard is just a vertical distance above the waterline....if this is being reduced, change the beam and/or draft of the vessel, to carry what you need.

You need to remember, the role of MCA is to prevent any vessel from going to sea. If a vessel does not go to sea, it is a safe boat.
Thus your role, as the NA, is the navigate around their rules to satisfy your SOR whilst still satisfying MCA.
A design is a series of compromises, not an absolute. If you are approaching this as an absolute (as you appear to be), you'll go nowhere.

 

Again not true, I understand how you could read this. But if you request a surveyor to verify your stability booklet and the freeboard mark is placed at a freeboard determined with the following formula, they reject it outright (you may tell me incorrect, but it has already happened once to a vessel).

You are misunderstanding the tendering process of these vessels. A client comes to a shipyard and says: "Hey I have seen this vessel on your website. I want a copy/one similar to that of LxB, clearance height "H", 2o to 30kn, and with a cargo capacity of 'X. So the beam and the moulded depth are only rarely adjustable. Therefore, if freeboard increases, allowed displacement decreases, leading to a reduced cargo capacity. Likewise when raising the depth is an option at all, now we are making these vessels more unstable in the loaded conditions, because the cargo they wish to carry always is stored ontop of the deck, usually COG half a metre up to a metre. Now the vessels the client is referencing to are perfectly safe (and considered perfectly safe anywhere else in Europe) landing crafts sailing in and around the UK without issue for years. However, they were certified before 2023, when the surveyors working for MCA started strictly adhering to the requirements set by the Workboat Code, no longer accepting CE or MGN 280 as alternatives. The same vessel 8m certified safe up to a cargo capacity of 2.5 tons (one in the UK and a different one in the Baltic), but after WBC 3 suddently reduced to 800kg, how does that make sence.

Also a misunderstanding, I am not approaching this as an absolute, but recognised surveyors like Lloyds and especially Mecal are approaching the rules as written as an absolute.
Sadly the rules as written do not take into account the required shape of a small landing craft and gives issues that I have specified earlier. No leeway is allowed, no alternative analysis to prove that the vessel is perfectly safe allowed. The only possible acceptable route is an in depth risk assessment, which might still take more than a year to get a response on.

The purpose of this thread was to ask if someone here know a valid way to navigate around their rules in a safe and secure manner. I asked it here, because I hoped someone here may have had a similar experience.
Clearly this is not the case and I think we might as well end this discussion, because it is not going anywhere.

 

In the point 16 (Corrections for minimum bow height), there is a comment that gives a "Carte Blanche" for the "Assigning Authority", that may be the key to the trouble: "The freeboard shall be increased by such amount as the AA may determine in each particular case". In practice, this leaves the designer to subjective interpretations, no matter what the guides or rules say. Guess that's very convenient for the "Brexiteers; lets arrange a few trapholes so we can avoid EU competition......"

I have not studied the MSN in detail, but I've seen a number of those "landing crafts" and I'd be very careful with a full load in any seas with significant wave heights. The freeboard is low, and the freeing ports are often not enough to clear deck fast enough from green water coming in over the bow (and that happens even in EU cat "C-waters"). The boat in the linked photo is typical, where the above-deck side structure will hold a lot of water, and there's only one little opening each side to be seen.

So, if the average height of the cargo deck is counted, could you get around it by increasing by a "step" just aft of the superstructure entrance? Then cover the outboard bay and hang the OB on a bolted bracket (no increase of hull length...). On top of that, make the side structure above deck tight; that increases the average deck level as well, ooor...?

Anyway, I've had my fights with ignorant surveyors that cannot read their own rules and I will follow your struggle with interest, good luck!

 

Then that is what you need to say to the client – the new rules will not allowed it.

Rules are not meant to make sense….i have 2 CTV designs running around the North Sea- all perfectly safe. But now, new rules came in, requiring my new sister designs to have ballast water treatment, on a small boat. Make zero sense, it is not a large super tanker. And yet…no matter how much I protest, I must comply. Adds a lot of weight and cost and takes up a lot of space…

Indeed, that the nature of ambiguous rules.

Ditto.
I have had one surveyor accept XX…and yet another reject the very same.

Fair enough.