RSS Independence damages hull after hitting underwater object near Pedra Branca
By Margaret Perry, Channel NewsAsia | Posted: 21 July 2009 2336 hrs


SINGAPORE: A Republic of Singapore Navy patrol vessel sailed into trouble on Tuesday afternoon while on a routine patrol in Singapore waters.

At 3.04pm, the RSS Independence was near Pedra Branca when it hit an underwater object and sustained damage to its hull.

A Mindef statement said the crew carried out damage control measures.

After further inspection to ensure it was safe, the RSS Independence is returning to base.

All the crew are safe.

The Ministry of Defence is investigating the incident. - CNA/vm

Just a note, RSS Independence is one of the 12 Fearless class PVs. She appears to be one of the six of that class that is not equipped for ASW operations and has no sonar as a result.

http://www.naval-technology.com/projects/fearless/

The reporting raises more questions. Is the underwater object an existing hazard to navigation? Or was it new?

Pedra Branca is not called white rocks and has a lighthouse for no reason. My guess is the craft probably hit a rock.

The questions that could be raised would include:

(i) What was the route the Independence was taking. Was it in standard/designated sea lanes or did the craft venture into dangerous waters. If so, why?

(ii) Who was manning the craft during that time.

I think the concept of hydrofoil would be useful in a future design to tackle littoral waters as the small draft will enable lower risk (not no risk) navigation. Sea Fighter lite, anyone?

Something like the USN's Pegasus class? Lovely boats, those.

Was looking for military hydrofoils and came across the Italian Sparviero. They look almost cartoonish imo.


Is the Sea Fighter considered a hydrofoil?

the officer of the watch siow liao...lucky no lives were lost...

Anyone knows whether RSS Couragerous is back into service after the last incident?

It is use as a training "tool" for raw naval recruits and NCCs at a desolated corner of Changi naval base.

I stand corrected. Sea Fighter is actually a SWATH design or small water-plane area twin hulled which is applicable for larger vessels. Hydrofoils are more for smaller vessels.

Both SWATH and hydrofoils work on reducing the water area of contact.

Ah, I see. Thank you. I wasn't quite sure myself.

Don't Hydrofoils and/or SWATH designs work on reducing the draft of a vessel only at high speeds? In low speed applications, they still sit in the water in a similar manner -> similar draft.

Might apply for hydrofoils but not for SWATH.

http://usaboatreview.com/archives/2009/swa...wath-ships.html

Basically, for SWATH designs, its only the structs that supposed to sit in the water. Having said that, SWATHs might have deeper drafts in general but there are designs to minimise wetted hull areas.

But I think from a cross sectional view, the front end facing cs is a lot smaller than traditional single hulled vessels ie less likely to hit objects if the vessel is moving forward and backwards.

There are projects like the Susitna that have variable hull designs.
http://www.onr.navy.mil/media/article.asp?ID=113
http://www.globalsecurity.org/military/sys...hip/e-craft.htm

As to hydrofoils, its like driving car. High speed = more dangerous. Low speed = more reaction time. There will always be sotongs who during low speed can still langgar somebody but sotongs won't be commanding RSN vessels (except the sotong who commanded the courageous). Having said that, there's a number of shallow draft hydrofoil designs.

I think you're confusing the standard catamaran with SWATH, SWATH design is basically two seperate hulls joined together and are only used in larger ocean plying vessels, not littoral boats.

Does this look like 2 hulls joined together?

http://en.wikipedia.org/wiki/Sea_Fighter

Maybe you should google the abbreviation for SWATH and the difference between it and a standard catamaran like the HSV-X1.

interestingly, the RSS Independence's CO - a MAJ Chew Chun-Chau - was featured in last Sunday's ST Scholar's Choice. he's a SAF Merit Scholarship receipient with a Masters in EEE from Imperial College London.

we'll see what the investigation turns up and if anyone is censured.

btw, the MINDEF statement does not rule out a collision with something man-made, eg. a submarine. that said, KD Tunku Abdul Rahman has not yet arrived in local waters.

I reckon the waters around Pedra Bracna should not be that deep...underwater rock? Or even wreckage??

I heard that submarines transverse across the area need to be surfaced.

Pls see my post dated Jul 22 2009, 12:58 PM as to the abbreviation.

As to SWATH, the HSV-X1 as you have claimed is a semi-SWATH design. See brochure on JHSV.

http://www.austal.com/files/delivery/JHSV-11x171.pdf

Ah, but then you claimed that for a SWATH design "its only the structs that supposed to sit in the water", while I don't really know what a "structs" is I simply take it that you are actually referring to struts instead.

Of course that is untrue as SWATH vessel actually sits on a pair of submerged pontoon-shaped hulls unlike a standard catamaran and such design only makes it effective for larger ocean plying vessel. In which you responded by remarking...

Which infact it does...

Actually I think you're being anal about the whole thing.

It is the struts that sit on the water. If you're going to be pedantic about spelling, sure, I don't claim to be spelling bee champion. Didn't think it was a requirement for this forum.

You say it actually sits on hulls underwater. So what? Those "hulls" are not exactly the same "hulls" in a standard ship design aren't they?

One can claim a catamaran has no struts. Its just 2 hulls in the water with no struts. What's the point?

But I don't get your point beyond arguing spelling and phrasing and starting with an assumption of confusion.

-----------------------------------------------

Ultimately, despite the argument over spelling and jargon phrases, the thrust of my argument which incidentally is that a SWATH design should provide a smaller amount of under-water cross section as compared to a standard-mono-hull design? I don't think you're really interested in this aren't you?

Man-made could just as easily be something dumped into the water e.g a container etc.

It may even be worse if our submarine hit it instead...

Well, I'm not the one that starts this off with his little sarcastic remark.

Frankly speaking, not at all.

The question + link wasn't meant to be sarcastic. It was addressing your claim that the difference between a catamaran and a SWATH is that one has 2 hulls being joined together (ie SWATH), the other doesn't (ie catamaran).

But in reality, both the SWATH (as per the sea fighter design) and catamaran are 2 hulls being joined together (if you claim that the things the struts are sitting on are hulls). This debunks your first post.

Thanks for the info, Dirzhan.

@ blowpipe

I was wondering about that as well.

Technially, the "struts" of a catamaran is referred to as a sponson and the v bottom keel forms a portion of the overall hull.

I suppose you can call them a hull or whatever.

Given that the thread is about a RSN PV hitting an u/w object ... your clarification kinda sinks the proposal for "the concept of hydrofoil (or swath) would be useful in a future design to tackle littoral waters as the small draft will enable lower risk (not no risk) navigation"

Exceptions do not prove/disprove a rule. Must be quite an interesting navigation experience to hope for "navigation hazards" to pass between the "legs" so to speak. One could even claim that with 2 "hulls" in the water, you are twice as likely to hit something. Let's stick to draft shall we?

You can argue on the specific technical diff between a SWATCH and a Cat for all you want ... I don't quite see how it advances the cause for a shallow draft littoral craft.

You want shallow draft, go for a hovercraft or SES.

[edit: or the gee-whiz-bang-swoosh Susitina you linked to]

In layman's terms, what you're arguing is that a short, extremely fat man is less likely to hit something whilst walking than two tall, extremely skinny men.

Whilst "generally" SWATH has deeper drafts, which is what I said, SWATH designs can have shallow drafts too for littoral ops ie more like catamaran. That sacrifices buoyancy ie deep sea stability for littoral water operability.

The cross section of the struts for a SWATH can be far smaller than mono-hull ships thus reducing the likelihood of hitting rocks. In the case of a hydrofoil, the foils have a lower water plane. Feel free to ignore the impact of beam sizes.

So your view is that a hydrofoil or swath design won't cut it for reasons not stated. That's fine with me. Just reminds me why I should follow my original policy regarding your posts.

Come now, surely your purpose of posting is to seek debate? Or an exchange of views? Or you just want us to read and be in awe?

If you want to ignore someone, just ignore. No need to try and effect a high-horse stance and air to everyone that you are replying on sufferance.

I could have contradicted your post on an ASEAN Transport Pool or on Air v Land Logistics, but I didn't ... see I'm doing it too! ;)

No. What I'm saying is that your 2 tall men are more likely to hit their head on something than 1 short man would.
We are talking about crafts bottoming out or scraping an underwater object due to their draft ... not weaving their way past objects that just happen to fit into the space between 2 sponsons/struts
I think we're conjecturing on 2 different planes here.

No one is saying that a SWATH design does not have a smaller frontal cross section.

However, what you are now focussing on - the narrowness of the struts, does not relate to the issue of hitting a submerged navigation hazard. The narrowness of a SWATH strut is a waterline feature. This relates only to floating debris.

Last I checked, SWATH struts still connect to a submerged bulbous flotation sponson. How deep this thing goes helps determine whether you bottom out due to your draft.

If you wish to refine your original argument of "shallow draft vessel being good for littoral" into one of "narrow vessel being good for littoral", by all means. But don't act like this is what you have been saying all along.

Really? Which SWATH design has a shallow draft? The MV Susitna?

That is a "transformer" of a vessel. I had a read of your link - in shallow draft mode, it actually lowers the centre hull into the water ... effectively becoming a flat bottom barge. Or to continue your analogy, transforming from 2 tall skinny men into 1 short fat men.

I like the idea of the MV Susitna. But it's low draft capability is not related to it's SWATH design.

I'm actually referring to designs like this.

http://www.yachtboutique.com/Designers/SWA...luminations.htm

That is a nice vessel and compared to the Susitna, a cheaper way of achieving a variable draft design.

However, the Quad-VD illustrated is a 30m yacht with a quoted shallow draft of 1.2m. I can't find the displacement tonnage info for the vessel. I suspect it is in the 150ton vicinity.

By comparison, the Fearless class is a 55m, 500ton vessel with a draft of 2.7m. Not too shabby.

Which leads me to my question ... what is the draft of a similar 30m sized vessel of a non-SWATH design? Isn't it about the same? I'm sure someone can dig up a ~ 30m FAC with a draft of ~1.2m.

My suspicion is that the QUAD-VD has a minumum draft that is nothing exceptional for a vessel of it's size.

I'll grant you that a monohull with similar displacement and draft will have a smaller performance-stability envelope than the Susitna or Quad-VD.

BUT it doesn't prove the point that Quad-VD has a shallower draft that will make it more suitable for littoral patrol than other hull forms.

I know what happened.

But I don't want to preempt any official release. All I can say is, you guys are over imaginative.

Anyway, SWATH design or not, it will do nothing to stop this sort of thing from happening.

A 30m vessel with a flat bottom will have a small draft compared to a 30m vessel with a deep v hull. Might as well compare a LCT and say the LCT should have the best capability for shallow draft ie 18 inches.

Let's build LCTs for PVs. lol.

The advantage of the Quad-VD design is to allow it to move into a deep SWATH for deep sea stability whilst reducing draft and cross section for littorals. The quad only has 4 struts but supported by air ballast.

Like the LCT, its a question of design as to how much draft is needed. Increase the width and length of the pontoon = less draft. Standard physics.

The sea fighter which is 950 tons using the swath design has a draft of only 11.5 ft or 3.5m and that's not even using variable depth or air ballast. It should be half that draft for a vessel half its weight, assuming the same physics.

Nevertheless, the 3D idea which is what is being ignored is that where rocks are concerned, it is not just going over them cos some just can't be gone over but move to the left and right of them ie avoidance.

With mono-hull vessels like the fearless, that's 8.6m of beam potential x draft for whacking rocks. For SWATH designs, its the widthxdraft of the pontoons/struts.

floating rubbish? or swordfish attack? :lol:

Likely to be an underwater rock...Not sure will Mindef come clean about the incident ;)

No need to be facetious. No one is suggesting building LCTs for PVs - LCTs are plain not suitable for the role.

Neither is anyone saying that SWAFT boats are not suitable for Littoral Patrols either. That's certainly NOT my argument. In fact, I do think that SWAFT designs do have other advantages that make them good Littoral Patrol Crafts but shallow draft is not one of them.

I agree that draft is a function of design and balancing requirements into the design. If you weren't so quick to be sarcastic, you'd realise that one could design a shallow V-monohull (for low draft and planing high speeds) with a retractable keel and anti-roll fins for extra stability.

The point is, you've been trying to equate SWATH to shallow draft and I'm saying prove it.

You seem to think that the draft figures for the 3 SWAFT models you listed are pretty spectacular? Let's take a look at some contemporary designs ...

LCS-1 (Mono) - 115m, 3000t, 3.7m draft
Sea Fighter (SWAFT) - 80m, 950t, 3.5m draft
Visby Class (Mono) - 72m, 650t, 2.5m draft
MV Susitna (V-SWAFT) - 60m, 940t, 3.6m draft in SWATH mode
Fearless PV (Mono) - 55m, 500t, 2.7m draft
Skoljd FAC (SES) - 48m, 275t, 1.0m draft in air cushion mode.
Houbei FAC (Cat) - 42m, 220t, 1.5m draft
QUAD-VD (SWAFT) - 30m, ???t, 1.2m draft in SWATH mode
Super Dvora (Mono) - 28m, 60t, 1.1m draft

Still think the same?

I doubt either of us can speak with any authority on the nature and distribution of large vs small undersea obstacles.

Unless you can come up with something authoritative, I'll have to agree to disagree with you on the likelihood of the 2 thin men vs 1 fat man argument.

btw, just to correct your maths ... for the SWATH design, it's width x draft of the pontoon/struts x 2. ;)

It's time for a kopi session! B)

Alien invasion! from under the sea! :ph43r:

Hit the roof top of Sea Dragon Palace? or Sea Monster? :lol:

My naval friends told me that RSN do not need to do a major overhaul/repair to bring RSS Couragerous back online/service. Too much damage and anyway the duties can be given to the other sister ships.

Some naval guys/gals say the RSS Couragerous is hunted. Dounno if it is true or not..... <_<