Mantus Anchor on Test

[JonJo]

And I do not think Noelex has passed any educated comment on the bolts (and used the anchor without checking and has professed to knowing nothing about them) and to me those bolts seem quite important. The anchor might, or might not, work a treat - its not been tested yet in 50 knots, but if the bolts are a weak link (and fail unpredictably after 12 months) it does not matter how well it works, if, when on the beach, your rode only holds a shank.

Maybe my post was misleading - when I said I would not use the anchor without independent comment I was referring specifically to the bolts - I am quite capable of judging the performance of the anchor but not the integrity of the bolts. Noelex images and comments are excellent and great marketing for Mantus, and really support the advert below this post - but anchors are not only about how they work, but the integrity of manufacture. To gloss over the construction (given the cock-ups in the past) looks - well superficial(?) and possibly downright misleading. Reviews should be warts and all.

Cotemar, I recall you bought a Mantus - you must have checked the bolts (as they are a critical and unusual method of attaching shank to fluke) - you must have checked the bolts - what do you think?

Jonathan

[pbiJim]

For me, the bolt together design of the Mantus is a desirable selling feature. I like the idea of being able to disassemble the anchor for long term storage.

Bolts are fine with me as long as they are big & strong enough. Off the top of my head, I think that A 5/8" G5 bolt has a tensile rating somewhere in the range of 20-30 thousand pounds. If we were talking about a single bolt that had more than 10:1 leverage working against it, I would be concerned, but several of those bolts, in a normal flange pattern, would leave me to sleep just fine.

If anybody is concerned about the bolts, then get some higher grade bolts. If G8 isn't enough for you, then get traceable alloy socket head cap screws from Camcar, Holo-chrome or my personal favorite, Unbrako. Unbrako's Durlok cap screws might be a nice choice for this application if you're really concerned about a fastener failure. Unbrako Engineered Industrial Fasteners Of course, unplated fasteners would need to be changed periodically.

Bottom line for me, if I've got a piece of 3/8" chain, yanking on a set of four 5/8" bolts, unless there is some serious leverage involved, I'm not going to be worrying too much about the bolts.

[Jim Cate]

Originally Posted by pbiJim

...

Bottom line for me, if I've got a piece of 3/8" chain, yanking on a set of four 5/8" bolts, unless there is some serious leverage involved, I'm not going to be worrying too much about the bolts.

Roger that!

Jim

[JonJo]

Is you 3/8th chain a galvanised high tensile steel chain from China? Maybe the shank is a lever? And if its a good anchor, the fluke fixed? Are you, would you, use a Mantus anchor without question?

Recommendations here filter through everywhere, possibly the idea of using better bolts will get missed in the euphoria - it has happened before and I'm sure it will happen again. I'd recommend changing the bolts, American or European gal HT bolts (they are hardly expensive and easily available) have some history of success - these might be American gal HT bolts?

And as on the topic, welding and galvanising A514 HT steel needs care and considerable skill.

Jonathan

[noelex 77]

Jonathan, what size and type of bolts secure your anchor cleats to the deck?

[JonJo]

We do not have anchor cleats. We have mooring cleats but they are not designed to take the loads that an anchor can take, if we use them they take a basically stationary load of the yacht in a marina and we would ensure that load is taken on 6 cleats, each with 4 bolts.

But all the bolts on our yacht are Australian made, it says so, all are tested to Australian standards and none of them are gal HT bolts.

I have to ask - how many (imported, ie Asian) gal HT bolts are on your yacht?


It is not simply the use of gal bolts, or the use of 4 gal boats its the use of 4 gal HT bolts, 2 of which are going to be stressed more than the other 2, and which, if they are imported, have a poor reputation. Additionally these bolts are subject to constant cycling with snatch loads, which none of the bolts on our yacht are subject to. Construction bolts are not tested for cyclical loads.

My fears are not focussed at this community but any endorsement of a product here will migrate and people might be aware of one part of any endorsement and not realise there are inherent risks, that could be overcome by simply changing the bolts or using a snubber. But snubber use, overall, is notable by its absence.

The only anchors I have heard of, purely apocryphal, to have failed (actually broken) are failure of CQRs (or their clones) at the hinge and failure of Deltas, or their clones, at the weld. These failures might not have been original, genuine models but simply poor copies. The only chain I have heard of that has broken, again apocryphal, are Chinese chain and if anyone suggested they were to buy Chinese chain there would be a deluge of posts warning against it.

If you are happy that's fine - but I suspect its based on gut feel - as you, nor anyone else, have not offered anything more substantive. I would agree that my fears are based on gut feel (same, same) and a lot of second hand stories (though gal HT bolt failures are well documented).

Jonathan

[Factor]

Originally Posted by noelex 77

Jonathan, what size and type of bolts secure your anchor cleats to the deck?

No anchor cleats here either. Anchor attaches to Bridle which is shackled to forebeam, same spot they lift the boat by in the factory.

[cheoah]

The bolts are huge for the loads that could be expected on a reasonably sized system. Other aspects of the system will surely give way before the bolts do. One could size them up to 8's if they were concerned, but I would bet my life on their sufficiency.

Checking them regularly for tightness and replacing them periodically is smart money.

It is a great design. I just had back surgery and being able to break up the weight is helpful. Having one stowed for long distance voyaging is a killer benefit for a small boat.

Thanks Noelex for posting this info - great stuff, and I'll not get to see my anchor like you're able to.

The point about bolts holding attachment points on most boats is very good. Just because the concept is new, does not mean it is anything less than brilliant. Having a stowed Fortress is pretty standard best practice for cruising yachts. Having a backup bower disassembled and stowed neatly will become standard, especially at the Mantus price point.

Great thread, hopefully all kinds of Mantus owners will report their results using this new design.

[noelex 77]

Another boat joined me in the anchorage today. They dropped a Rocna and set the anchor well with a lot of reverse on a similar scope (4:1) in slightly deeper water (the Mantus in 9m the Rocna 10.5m). The Rocna was a smaller size. I think a 33kg verses the Mantus 57kg.

Both these anchors are doing just what they should do. They have set well, first time, in less than a shank length and have rotated completely level.
This is sort of excellent performance I see time and time again from quality anchors that are dropped in a competent fashion. From this setting position the anchor is an ideal position to resist stronger wind and dig in deeper if necessary. The results from inferior anchors are noticeably worse. I hope to show the difference in future photographs.

These two anchors have set almost identically with perhaps the Mantus has set just slightly deeper than the Rocna. Don't read too much into these minor differences, especially with just one comparison, the substrate, or the setting force may have been slightly different.The Rocna had been just dropped when the photo was taken. The Mantus shows the shows the swing of the chain and shank as it has been in place longer.

[noelex 77]

Rocna.

[downunder]

Originally Posted by noelex 77

Another boat joined me in the anchorage today. They dropped a Rocna and set the anchor well with a lot of reverse on a similar scope (4:1) in slightly deeper water (the Mantus in 9m the Rocna 10.5m). The Rocna was a smaller size. I think a 33kg verses the Mantus 57kg.

Both these anchors are doing just what they should do. They have set well, first time, in less than a shank length and have rotated completely level.
This is sort of excellent performance I see time and time again from quality anchors that are dropped in a competent fashion. From this setting position the anchor is an ideal position to resist stronger wind and dig in deeper if necessary. The results from inferior anchors are noticeably worse. I hope to show the difference in future photographs.

These two anchors have set almost identically with perhaps the Mantus has set just slightly deeper than the Rocna. Don't read too much into these minor differences, especially with just one comparison, the substrate, or the setting force may have been slightly different.The Rocna had been just dropped when the photo was taken. The Mantus shows the shows the swing of the chain and shank as it has been in place longer.

Good sharp photo.

[sailorboy1]

Hard to believe people are making a weak point claim about the fluke/shank bolts. 1 of those bolts is going to be stronger than the chain attached to it.

In real life I expect my chain to break (almost unheard of) or my cleat to rip out before an anchor to break.

[Tayana42]

Noelex, thank you for the info and the photos. Making me rethink my choice of anchor and anchor size.


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[Mantus Anchors]

Originally Posted by JonJo

Bolts in this application, anchors, take all the load and the load is applied as a snatch load on a regular basis. I'm not sure that construction bolts are tested for repeated cyclic snatch loads - but as has been pointed out, I'm no engineer. I am sure this method of assembly is all fine (but I would not use one until convinced by someone, independent, who knows what they are talking about).

Jonathan

The Anchor Bolts -
Guys check out this link, Deneen took some time to do this write up. I think and hope it explains how bolts could be good enough for a wheel of the car, or a propeller of an airplane.... or many other applications that are much more demanding than an all important anchor.

"RESULTS: The Margins are huge. For Yield Strength they vary from 500% to 800% (depending on anchor size) and for Ultimate Strength, MS varies from 700% to 1000%. (Remember this INCLUDES a Factor of Safety of 3!) In fact, these numbers are so big they are probably meaningless. (For comparison, the airplanes you fly in carry margins in the range of 1%-5%.)"

Except that, we are way more conservative than the guys designing airplanes.....

cheers,
greg

[xeon_tsd]

I used my Mantus for the 1st time last weekend. We do have pretty sticky mud round here. I only had out a 3:1 ratio, and the wind was about 20knts. By the time I made it back to the cockpit to put it in hard revers, we where already set. No significant wind changes, and the swell wasn't too bad. We stayed the night (with the short scope due to other boats) and where rock steady. When we pulled up anchor i found a few old oyster shells and a bungee chord entrap ed in the mud-ball. The anchor has already earned 50 cents back! Seriously though I know this was not a hardcore test, but compared to the CQR I had replaced, it definitely set faster.

65lb Mantus on a 44 foot, 28,000 lb sailboat.