It's True! The Mantus 65-lb. hooks first time, everytime.

[JonJo]

Originally Posted by scoobert

i will do a ronca copy. and will most likely buy a danforth as well.

Speaking from memory 302 stainless has a high tensile strength, much higher than mild steel, but again from memory it has an appallingly low yield strength - which means it will bend (and more easily than most mild steels). But my memory has failed me frequently - so I'd welcome being corrected.

Jonathan

[scoobert]

i will be beefing up the shaft, i see no good reason for such a narrow shaft.

[noelex 77]

Originally Posted by scoobert

i will be beefing up the shaft, i see no good reason for such a narrow shaft.

Anchor balance is important. Extra weight in the shank degrades the performance of many designs.
If you are planing a Rocna, Spade Delta or Boss (and many others) like design keep the shaft as light as possible.

[JonJo]

Originally Posted by scoobert

i will be beefing up the shaft, i see no good reason for such a narrow shaft.

This goes back to Mantus claim - that the removal of the roll bar improves the ability to dive and develop better holding power. I can confirm this is correct.

The reason anchor manufacturers have gone to thinner shanks is very simple - a thin shank allows the anchor to dive - thick shanks offer resistance to diving. There has been lots of work on the issue - look at the Vryhof website. But if you go to a thin shank you need better steel - which is why Manson and Anchor Right have gone for a typically 750 MPa yield steel (vs, from memory, the 200 MPa stainless you are proposing to use)

Once you start to increase the thickness of the 302 to compensate for its appalling yield strength you will alter the balance of the anchor, it will be much more difficult for it to 'self right' when lying on its side (the shank will be heavier).

Its an expensive material to experiment with, I'd build from mild steel to start with (with the thicker shank) see how it works and then build from stainless.

There was a really erudite and learned article on shank strength in Practical Sailor not long ago

Jonathan

[SailFastTri]

Originally Posted by scoobert

i will be beefing up the shaft, i see no good reason for such a narrow shaft.

Scoobert you may be unwise to try to "reinvent the wheel". If your anchor fails to hold you might lose the boat and more.

Unless you have a successful innovation or aspirations to be in the anchor business, your cheapest and safest bet is to buy an off the shelf solution.

BTW I agree with others that a galvanized anchor is better than stainless, unless your boat is intended as a dock trophy.

Another opinion; I own a Manson Supreme and a Rocna, and the Manson sets and holds slightly better in my limited experience, of 4 years using each mostly in mud and sand, with some grassy/weed patches.

No experience with the Mantus but looking at it I'd expect similar performance. A question though, is whether the bolts are as strong as welds?

[JonJo]

Originally Posted by SailFastTri

No experience with the Mantus but looking at it I'd expect similar performance. A question though, is whether the bolts are as strong as welds?

I think the shank will bend long before the bolts fail

Jonathan

[scoobert]

grade 8 bolts are great, but a weld is stronger, and if done properly, the weld is the strongest part of the anchor.

[Celestialsailor]

Originally Posted by scoobert

stainless has twice the yield strength of A36....
this is not the first time i have heard this misconception.

As usual, you're wrong and misrepresenting. A36 yield and tensile strength is higher than Stainless. And unless the stainless is in the 400 series, cannot be hardened.

[IdoraKeeper]

Oh my god! Here we go again. All the CQR bashing can now commence...?. More pix of bent Rocnas? Save me,,,where is my grinder...

[JonJo]

Originally Posted by scoobert

grade 8 bolts are great, but a weld is stronger, and if done properly, the weld is the strongest part of the anchor.

From memory Mantus bolts are Grade 5.

I am sure Mantus will confirm bolt specifications at the same time that they answer the query as to whether one can dispense with the roll bar completely.

Jonathan

[ternmarine]

For what its worth we only use 2205 stainless for our shanks

[malbert73]

Bought a mantus at the Annapolis boat show. Really liked their laid back customer service and information. The folks at the booth wouldn't take the bait when I mentioned the prior Rocna metal issue. They refused to say their anchor was necessarily better than others, just different and design specific. I like the look better and can see the tip digging in better in firm bottoms. For the price I got for the 35 lb for my 33 foot low freeboard 13,500 lb boat, I really can't go wrong value wise.

First impressions- robust. Feel very comfortable in bolted construction. I like the hollow roll bar, as it is very light. I like not wasting weight on the roll bar. Assembly was easy. Fit great on my bow roller.

I went out sailing on Sunday in the brisk NE wind. Decided to try anchoring for the heck of it. 15 feet, muddy/sandy bottom. I did a shoddy job since I was only stopping for lunch. Dumped out 70 feet of chain. Backed down. WOW what a jerk when the anchor set. Haven't ever felt that.

My prior anchor was a danforth 20H which is fine for chesapeake, but I don't trust with windshifts. dragged it this summer in a blow in a bottom that had some soft mud and leaf mix. Other anchor that came with the boat was a bruce 33 which is useless on chesapeake bay. Slow drag in anything over 20 knots typically.

I will post with more experience this fall and next year. So far impressed with very small sample size. Like that if it works well I can buy a spare and stow easily. If I ever bend a shank, I can easily have the shank mailed in to wherever I am at- less need to worry about entirely new anchor shipping costs. I like that I can experiment with taking off the roll bar if I want without using a grinder. Like the lifetime warranty.

[Stevens 47]

Originally Posted by malbert73

Bought a mantus at the Annapolis boat show. Really liked their laid back customer service and information. The folks at the booth wouldn't take the bait when I mentioned the prior Rocna metal issue. They refused to say their anchor was necessarily better than others, just different and design specific. I like the look better and can see the tip digging in better in firm bottoms. For the price I got for the 35 lb for my 33 foot low freeboard 13,500 lb boat, I really can't go wrong value wise.

First impressions- robust. Feel very comfortable in bolted construction. I like the hollow roll bar, as it is very light. I like not wasting weight on the roll bar. Assembly was easy. Fit great on my bow roller.

I went out sailing on Sunday in the brisk NE wind. Decided to try anchoring for the heck of it. 15 feet, muddy/sandy bottom. I did a shoddy job since I was only stopping for lunch. Dumped out 70 feet of chain. Backed down. WOW what a jerk when the anchor set. Haven't ever felt that.

My prior anchor was a danforth 20H which is fine for chesapeake, but I don't trust with windshifts. dragged it this summer in a blow in a bottom that had some soft mud and leaf mix. Other anchor that came with the boat was a bruce 33 which is useless on chesapeake bay. Slow drag in anything over 20 knots typically.

I will post with more experience this fall and next year. So far impressed with very small sample size. Like that if it works well I can buy a spare and stow easily. If I ever bend a shank, I can easily have the shank mailed in to wherever I am at- less need to worry about entirely new anchor shipping costs. I like that I can experiment with taking off the roll bar if I want without using a grinder. Like the lifetime warranty.

Great feed back thanks for posting. I like the same features that you mentioned.

Jack

[JonJo]

Originally Posted by malbert73

Bought a mantus at the Annapolis boat show. Really liked their laid back customer service and information. The folks at the booth wouldn't take the bait when I mentioned the prior Rocna metal issue. They refused to say their anchor was necessarily better than others, just different and design specific. I like the look better and can see the tip digging in better in firm bottoms. For the price I got for the 35 lb for my 33 foot low freeboard 13,500 lb boat, I really can't go wrong value wise.

First impressions- robust. Feel very comfortable in bolted construction. I like the hollow roll bar, as it is very light. I like not wasting weight on the roll bar. Assembly was easy. Fit great on my bow roller.

I went out sailing on Sunday in the brisk NE wind. Decided to try anchoring for the heck of it. 15 feet, muddy/sandy bottom. I did a shoddy job since I was only stopping for lunch. Dumped out 70 feet of chain. Backed down. WOW what a jerk when the anchor set. Haven't ever felt that.

My prior anchor was a danforth 20H which is fine for chesapeake, but I don't trust with windshifts. dragged it this summer in a blow in a bottom that had some soft mud and leaf mix. Other anchor that came with the boat was a bruce 33 which is useless on chesapeake bay. Slow drag in anything over 20 knots typically.

I will post with more experience this fall and next year. So far impressed with very small sample size. Like that if it works well I can buy a spare and stow easily. If I ever bend a shank, I can easily have the shank mailed in to wherever I am at- less need to worry about entirely new anchor shipping costs. I like that I can experiment with taking off the roll bar if I want without using a grinder. Like the lifetime warranty.

I like the Mantus design, its simple, it is demountable and the design works. It is a pity the same thought that went into the design was not employed in the choice of materials. It is also a pity that Mantus may be misrepresenting their product by apparently suggesting that the roll bar can be removed and the anchor safely used.

One hates be something of a killjoy but:

The Mantus shank is based on an approximate 550 MPa steel, this compares with Rocna's 620 MPa, the Supreme and Excel's 750 Mpa. This strength, of the Mantus, is not accurately devined - its the simply ball bearing test - but its in the right ball park. There was talk that the shank might be modified - but if it has then the modification has been kept very quiet.

Weight for weight, of anchor, the Mantus shank is made from the same thickness of plate as the Rocna, Supreme and Excel. Everything else being equal the Mantus shank would be about 15% weaker than the Rocna and around 25% weaker than the Supreme or Excel. Except that the Mantus shank is about 50% of the width of the equivalent weight Rocna, Supreme or Excel. Weight for weight, of anchor, the shanks are a similar length (the Mantus is slightly longer - but its not that significant)

This sadly means that the Mantus shank has less than half the strength of the current Rocna and is around 35% of the strength of the shank of the Supreme and Excel. Of course when it bends I suspect it will be, just as, easy to bend it straight again.


The removal of the Mantus roll bar is, another, accident waiting to happen. It may, as the really excellent video demonstrates, land the right way up when thrown off the foredeck. But if you are not in need of such exercise and lower your anchor with a windlass then the anchor may land on its back, equally the tide may change and the anchor pull free and land on its back. Without the roll bar the anchor is not self righting, the anchor will not set. Basically the anchor will drag, and forever.


There are people, some of whom are moderators (and should know better) who have both a Mantus and a Rocna - it does not take much to look at the shank and identify that the Mantus shank lacks the width of the Rocna.


I am sure Mantus will be anxious to correct my error of measurement of both shank steel quality and dimension and will be equally anxious to dispel the doubts I might raise about roll bar removal.

In the meantime, take care.

Jonathan

[malbert73]

It will be interesting to see how much the difference in shank width makes a difference, since it looks like the shank is plenty strong in the vertical direction. In the horizontal (side to side) direction in which these anchors bend shanks, you still only have 3/8 inch (or whatever it is) in steel thickness, so I wonder if the difference is as great as you suggest.
Time will tell, and I am happy trying the relatively unproven product with lifetime warranty, which cost me less than $300. If I find it bends easily at some point, I can replace shank and relegate the anchor to be a spare.
I think the design of the mantus with wider and lighter rollbar translates into deeper diving capacity and more blade surface area (as more metal is in blade) per weight as compared to rocna. Certainly more than manson which puts much more weight in rollbar and shank. That said, time and other experiences will tell. Probably we are all splitting hairs, and manson/rocna/mantus will all likely set and fail within similar condition ranges.

But your points are well taken. For less than $300, I am happy to experiment with an anchor which, if proves worthy, is easy to store- ie get a second huge one as a hurricane anchor and store under floorboards in cabin...