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artic warrior · 27-10-2015, 02:49

Hi, Thank you for getting back to me,
ah ok similar to mine then,, but they suggest 29kg but I would go up one size to the 38kg. I livaboard full time too and like to sleep at night,,,

I will look at the dimensions of the larger sizes, I use 12mm chain, so that's no problem...

Can you tell me the thickness of the fluke at the rear of your anchor, I believe its the same flat part where the shank bolts through.

Thank you,

Colin

Quote:

Originally Posted by noelex 77

Our yacht is a custom designed aluminium vessel. It is 14.6m long (about 48 feet). It is stoutly built. The designed displacement is 14.5T, but we cruise full time and the boat is our home so we have a heap of ~~junk~~ useful gear on board, as well as large capacities such as 1000L diesel.

We started using a Rocna 55 kg 7 years ago and over the last 18 months have been using a 57 kg Mantus.

The concave roll bar anchors such as the Mantus, Rocna and Manson Supreme are all excellent performers and all are a great choice providing they fit. The concave roll bar anchors share a lot of similar characteristics, as you would expect, but overall in my opinion the Mantus is (slightly) the best of the designs. As you say, I think a large part of this is the wider base to the back of the fluke. This presents the tip at a very aggressive angle and helps with the initial penetration in tough substrates. I think the longer more tapered fluke Mantus has is also a help in weed. Finally the slightly less deep shank helps with the weight distribution. The drawback is the wider base of the Mantus and longer more tapered fluke make it a slightly bigger anchor overall.

Good luck with your home made project Colin. Post some pictures when it completed. There is a thread and whole user group devoted to homemade anchors here:

http://www.cruisersforum.com/forums/...ct-113732.html

Simonsays · 27-10-2015, 09:14

Quote:

Originally Posted by Jim Cate

Well said, mate! I hope that we can indeed agree on those stipulations, and get back to empirical, verifiable information about real anchors in real bottoms, set by real cruisers/charterers/stuffups.

Jim

you forgot the "photographed by real mermaids" part...

**noelex 77** · 27-10-2015, 10:29

Quote:

Originally Posted by artic warrior

Can you tell me the thickness of the fluke at the rear of your anchor, I believe its the same flat part where the shank bolts through.

I don't think there is anything wrong with using ideas from other anchors when producing your own version. This is how anchor development has generally progressed. Hopefully you might come up with something even better. Many of our modern anchors have been produced, often by a single individual, in this way.

I am a little uncomfortable supplying a lot of details that may be used by someone else to produce an identical copy, but in the spirit of getting some idea of suitable sized steels for this general style of anchor, I have measured my 55kg Rocna for you. The Mantus is on the bottom at the moment and it is not going to easy to measure accurately leaning over the bowsprit, even when it is up.

The back of the Rocna fluke is 8.5mm, which includes galvanising. I hope this helps.

**noelex 77** · 27-10-2015, 10:30

This was a new anchorage.

Once again the Mantus has done a great job, setting within a shank length with minimal heaping up, although there is a little more list than normal, but still an excellent result.. The photos were taken just after the drop, so some are still a little cloudy.

artic warrior · 27-10-2015, 11:35

Im sorry you feel uncomfortable, as only one measurement was asked,
And how you surmise it to be a copy when the shank I have is totally different, but thank you anyway.
I was asking for the thickness of the fluke so I could separate it from the shank in weight so I could then know roughly how heavy the shank was to relay info to another forum im following,

Regards

Colin

Quote:

Originally Posted by noelex 77

I don't think there is anything wrong with using ideas from other anchors when producing your own version. This is how anchor development has generally progressed. Hopefully you might come up with something even better. Many of our modern anchors have been produced, often by a single individual, in this way.

I am a little uncomfortable supplying a lot of details that may be used by someone else to produce an identical copy, but in the spirit of getting some idea of suitable sized steels for this general style of anchor, I have measured my 55kg Rocna for you. The Mantus is on the bottom at the moment and it is not going to easy to measure accurately leaning over the bowsprit, even when it is up.

The back of the Rocna fluke is 8.5mm, which includes galvanising. I hope this helps.

**noelex 77** · 28-10-2015, 06:56

In my view this was a rather dismal performance by a Delta.

The anchor was dropped in good sand near the stern of our boat. The scope was plenty (7:1), but in the only light/moderate wind (20-25 knots) the anchor was slowly dragging.

On the plus side the anchor never broke out, but moved back perhaps 30m in 5-6 hours. Fortunately the boat eventually realised they were slowly dragging and left, hopefully for the security of a marina.

Here you can see the puffs of sand as the anchor gradually moved backwards. That is our keel in the top left:

It is impossible to photograph the long drag mark in a single frame, but this will give you some idea:

hoppy · 29-10-2015, 03:50

That's a pretty poor effort by the Delta. With 7:1 and the way the bottom looks that it should have dug in.

kas_1611 · 29-10-2015, 03:56

It's pictures like that Delta that make me glad I retired it to the locker as a spare and stuck the Vulcan on the bow.

Keiron

**noelex 77** · 01-11-2015, 00:31

This was a Claw (Bruce copy) anchor.

It was set up by a local to hold their boat while they holidayed in the area so it is a cross between mooring and anchoring.

Interestingly, they were using a tandem anchoring system. There has been a lot of debate and controversy surrounding the effectiveness of this system.

I would not recomend this set up in the manner it is used here. The attachment point on top of the crown has the potential to flatten the fluke angle in the substrate. In addition, there are other problems such as the extra chain limiting the diving ability of the anchor.

Nevertheless, this Claw was actually doing reasonably well. It was nice and level and the fluke was completely buried.

Tandem anchoring is really something that needs studying more. Unfortunately, there are so many different combinations of anchors with different ways to attach the anchors together, that it is not an anchoring technique that is easy to evaluate.

I will show the other anchor in the next post.

**noelex 77** · 01-11-2015, 00:51

In case you have missed it, Panope has some great videos in this thread showing anchors setting:

http://www.cruisersforum.com/forums/...ng-155412.html

I think the more we can see anchors working underwater the more we can understand how different anchor models perform. So take a look.

**noelex 77** · 04-11-2015, 00:47

This was the other anchor that was attached to the crown of the Claw. It is a grapnel.

These anchors are popular with local fisherman. The often preferentially drop in weed/rock as the fluke area in insufficient to hold in anything else, especially this sort of design with just prongs.

This one has come up against a rock, which was supplying all the holding power.

**noelex 77** · 04-11-2015, 05:30

Hallelujah! A convex plow anchor that is doing well. 7m @ 7:1.

This was (I think) a Delta. The less good results that I have typically photographed are normal for this part of the world with a hard sand below the softer surface sand, but if you have a substrate without this harder layer, the Delta and most other anchors will start to do well. There are isolated patches of sand like this in the area.

This anchor has set in a reasonable distance . It is nice and level with most of the fluke and shank buried. My only criticism is that some of this bury is from heaping up, but even this is minor.

The sand here looked different, it was a coarser grained, gravely type of sand.

**JPA Cate** · 04-11-2015, 13:14

Quote:

Originally Posted by kas_1611

It's pictures like that Delta that make me glad I retired it to the locker as a spare and stuck the Vulcan on the bow.

Keiron

It'd probably work okay for your dinghy!

Ann

Prairie Chicken · 04-11-2015, 13:28

Our Rocna at Cala d'Egos, Mallorca in sand @ 8.2 m with 20 m out, no px used to set. These two images have been processed differently to show the 'trail' better.

This was a lunch stop in fairly tight quarters with a light breeze. I found the trail in the sand quite instructive. As the wind didn't shift during the stop, I suspect the boat had some forward way when the anchor landed.