Mantus Anchor on Test

[noelex 77]

Mantus have sent me an anchor to test.
It will be interesting to see how it compares to my almost same sized existing Rocna anchor.

Here is the new anchor on dry land. We will soon be relaunched after antifouling so I will be assessing its performance and hope to soon get some underwater shots of it in action.

[JPA Cate]

Courageous concept, noelex,

Please keep it coming. Some of are interested and without any oxen to gore, either.

A.

[JonJo]

But what size, or weight, Noelex? You say 'same' sized - do you mean area or weight or both.

And Ann - you could not be 'holed up' in a nicer location, almost 2 weeks of gorgeous weather (one could almost call it a 'Royal Fortnight') sadly to break in the next 12 hours. Where are you sojourning?

Jonathan

[Prairie Chicken]

Yes, please let us know your opinions.

[noelex 77]

Originally Posted by JonJo

But what size, or weight, Noelex? You say 'same' sized - do you mean area or weight or both.

Both.

My Rocna is listed as 55kg with a fluke area of 2300cm2. The Mantus is listed as 56.8kg and 2500cm2.

In anchor tests where the anchors have been actually weighed there is often a slight discrepancy between the nominal weight and the actual weight. Likewise real fluke surface area is subject to some variation. (Projected or actual?)

The blade shape of the two anchors is slightly different. The Mantus blade is more pointed. Longer and slightly narrower, but overall the total fluke area of the two anchors looks close visually.

[evm1024]

Should be an interesting thread.

With those 2 anchors side by side I wold be interested in your thoughts of cutting off the Rocna shank, drilling some holes and mounting the Mantus shank in place.

Regards

[JonJo]

Its difficult to know how to measure area of a fluke, I favour projected but I suspect some anchor makers quote total. But the 2 flukes are so similar and the sizes/weights so similar I suspect differences in area and weight will have minimal impact on performance (it will be in nuances of design). The Mantus also differs in having no upturn at the rear of the fluke, compared to the Rocna, and the larger (wider) roll bar has an impact.

Before you grind the bolts smooth (in use) I wonder what specification of bolts you have with your model - they will be clearly marked on the bolt heads.

I'm sure you will be trying the Mantus without its roll bar (it will set more deeply).


evm 1024 - why swap the shanks?

Seems a risky move - if it does not work Noelex loses his Rocna. But it will be interesting to hear Noelex comments, as he can examine them both, side by side.


Jonathan

[evm1024]

Just wanted thoughts on the feasibility on using a Mantus shank on a different fluke. (and not wanting to hijack the thread)

If one had a bent anchor or if your Manson did not fit your roller very well how successful would using your spare Mantus shank work on the other anchors flukes?

I'm interested in the results of the testing he will do because I will likely buy a Mantus anchor to go alongside the Manson I currently use. I plan on buying a spare shank for the Mantus at the same time. Thus if the shank of an existing anchor I have got bend, the spare shank could be used. If the angles are not too different.

Just curious.

[JonJo]

Originally Posted by evm1024

Just wanted thoughts on the feasibility on using a Mantus shank on a different fluke. (and not wanting to hijack the thread)

If one had a bent anchor or if your Manson did not fit your roller very well how successful would using your spare Mantus shank work on the other anchors flukes?

I'm interested in the results of the testing he will do because I will likely buy a Mantus anchor to go alongside the Manson I currently use. I plan on buying a spare shank for the Mantus at the same time. Thus if the shank of an existing anchor I have got bend, the spare shank could be used. If the angles are not too different.

Just curious.

Fortunately evidence that Supreme shanks might bend are conspicuous by their absence. But I take your point having a spare shank might be advantageous as cutting a bent one off, relatively easy, drilling 4 holes (again) relatively easy - so an unbiased and independent opinion of the merits of the Mantus shank would be invaluable.

Jonathan

[evm1024]

Originally Posted by JonJo

Fortunately evidence that Supreme shanks might bend are conspicuous by their absence. But I take your point having a spare shank might be advantageous as cutting a bent one off, relatively easy, drilling 4 holes (again) relatively easy - so an unbiased and independent opinion of the merits of the Mantus shank would be invaluable.

Jonathan

Exactlly

Noelex, Let the testing begin (please, I'm holding my breath).

[Jim Cate]

Originally Posted by JonJo

Fortunately evidence that Supreme shanks might bend are conspicuous by their absence. But I take your point having a spare shank might be advantageous as cutting a bent one off, relatively easy, drilling 4 holes (again) relatively easy - so an unbiased and independent opinion of the merits of the Mantus shank would be invaluable.

Jonathan

Hmmm,

Doing this sort of "repair" in the field suggests that you would have to bolt the replacement shank to one side or the other of the stub of the old shank. This would make the force on the fluke asymmetrical, and I wonder if that would impact the anchor's performance?

Honestly, the incidence of bent shanks (on anchors other than the under spec Rocnas) is so low that this concept of carrying a spare shank becomes dubious to me. Far better to carry a spare main anchor for the much more likely event of total loss of the hook!

Jim

[JonJo]

If you have an angle grinder you could cut the old shank off and grind down the stub smooth - I do not see that as being an issue (though not having an angle grinder might be). Its easier to drill and bolt than weld, if you are sitting on a beach.

But the only fluke to which a Mantus shank would fit would be, Bugel, Supreme, Rocna - so your point is valid.

Jonathan

[noelex 77]

Originally Posted by JonJo

Before you grind the bolts smooth (in use) I wonder what specification of bolts you have with your model - they will be clearly marked on the bolt heads.

Sorry too late it has just gone into the water for the first time.

I will try to get a look at the markings when I pull the anchor up.

The bolts seem like overkill to my non engineering eyes. This is a photo of the bolt diameter in comparison to anchor shackle pin in my set up.

Of course there are 4 bolts holding on the anchor shank to the fluke, verses relying on only a single bolt (pin) in the shackle joining the chain to the anchor.

[jannw]

How, exactly, does one test an anchor?

And how does one test and compare two virtually identical anchors?

Not meaning to be difficult, but do you honestly think you will be able to make any meaningful objective comparison?

?

[JonJo]

Originally Posted by noelex 77

Sorry too late it has just gone into the water for the first time.

I will try to get a look at the markings when I pull the anchor up.

The bolts seem like overkill to my non engineering eyes. This is a photo of the bolt diameter in comparison to anchor shackle pin in my set up.

Of course there are 4 bolts holding on the anchor shank to the fluke, verses relying on only a single bolt (pin) in the shackle joining the chain to the anchor.

If the bolts are galvanised HT construction bolts then in theory there is not an issue, see comment at end. Though HDG HT construction bolts from nefarious sources are notorious for failure from hydrogen embrittlement. If the bolts are HDG mild steel, then there might be a different issue. The weld on your Rocna, which should be stronger than the steel, is huge compared to the size of those 4 bolts. Most of the load is on the front 2 bolts, they take most of the tensile load.

Anecdotal stories suggest Deltas are prone to failure, if and when they fail at all, at the weld, CQRs often fail at the hinge.

If you are using a Crosby HT shackle it is, individually, tested to 2 times its WLL limit.

The shackle is 'simply' under tension from the load on the chain. The bolts also under tension - subject to a lever action from the length of the shank, which if the anchor works (which I am sure it is) will be subject at times to snatch loads when you (or others who have the same anchor) lift it. HT construction bolts were never designed for snatch loads (or this is one of the arguments against HT chain - brittle, not good under snatch loads etc etc.)

But you know most of these arguments and stories (and I'm in your camp - but have not yet made your committment).

I'm not trying to gore the bull, or oxen. But if bolts sufficed it would be a much cheaper and acceptable mechanism (so much easier and cheaper to ship) to join the shank to the fluke - but no-one else has gone down that route (and I wonder why).

Jonathan