Drilling Holes in Anchor Shanks

[noelex 77]

Wandering around marinas I see a lot of anchors with holes drilled in their shanks.
None of these anchors were bent, despite signs of reasonable use, but I don't think this Is a good idea.
As well as the hole weakening the shank any metal retaining pin through the shank runs the risk of bending adding jamming the anchor in place.
























This aluminium Spade seems to have a bet each way with a metal pin, but a large reinforcement plate welded to the top of the shank. This is a bad idea. The plate will inhibit penetration.

[4arch]

I haven't noticed that one walking around marinas but maybe I'm not looking hard enough. What I've noticed is that about 80% of anchors are just too darned small - many of them almost laughably so. About 10% are noticeably bent but still in use. I agree drilling holes is probably not the best way to go. You also compromise the galvanizing. When I upgraded to a "next gen" anchor I modified my roller to work with my anchor instead of modifying my anchor to work with my roller.

[Vasco]

Lightening holes. Quite common on cats.

[barnakiel]

These are a- holes.

;-)
b

[DRS]

A few of them are far enough up the shank that they are probably for attaching a trip line to.

[delmarrey]

It must be a Euro thing. I don't think, in my whole life, I've seen that many anchors with nonfactory holes. Where are you finding these, a scrap yard?

[noelex 77]

Originally Posted by delmarrey

It must be a Euro thing. I don't think, in my whole life, I've seen that many anchors with nonfactory holes. Where are you finding these, a scrap yard?

Most boats in the Mediterranean are propped on shore over winter to avoid damage from the storms that occur in the colder months. The anchors are normally lowered to the ground.

It is a great way to get a look at a lot of different anchor designs in detail.

All the anchors (except the CQR) were connected to the main rode so they were presumably the primary anchor.

[markpierce]

Haven't noticed any strange holes in anchors around here. Regardless, aren't most anchorings for lunch or to stop to fish, so who needs more than a lunch hook? Also, in relation to mass, aren't recreational boat's anchors equal or greater than on ships?

Here's on older boat used for research. Compare the ship's anchor to the relative size of a typical recreational boat.

[markpierce]

Originally Posted by noelex 77

Most boats in the Mediterranean are propped on shore over winter to avoid damage from the storms that occur in the colder months. ...

That's strange. The Mediterranean climate here doesn't require boats to exit the water over winter. Between occasional storms/rains, winter boating is delightful. But then, Mediterranean docking (rare here) has serious weaknesses.

[noelex 77]

Originally Posted by markpierce

Haven't noticed any strange holes in anchors around here. Regardless, aren't most anchorings for lunch or to stop to fish, so who needs more than a lunch hook? Also, in relation to mass, aren't recreational boat's anchors equal or greater than on ships?

In Greece, where the anchor photos were taken, many boats will be using their own anchor to Med-moor in the smaller marinas or on town quays, even if they don't want to take advantage of the fantastic anchorages overnight. So a "lunch hook" anchor is not very suitable here.

As you point out, many boats in the more developed parts of world travel from marina to marina. In some areas it is because no suitable overnight anchorages exist, but often it is a lack of confidence in their anchoring gear. A great pity.

Large ships anchor in a different way. Unfortunately, the equipment and techniques do not scale down to "our" sized vessels.

[noelex 77]

Originally Posted by markpierce

Between occasional storms/rains, winter boating is delightful.

+1

With modern anchoring gear and some common sense, I think sailing can be done year round here. It does not suit everyone, but it is surprising how few boats enjoy winter as we do anchoring as usual.

Many owners use winter to return home. Some boats need shore power during the colder months so retire to marinas, but better equipment does give more options.

[Terra Nova]

A small hole, drilled near the center of the shank, will have virtually no affect on the strength of the anchor.

[HappyMdRSailor]

Originally Posted by Terra Nova

A small hole, drilled near the center of the shank, will have virtually no affect on the strength of the anchor.

(below is only applicable to rectangular cross section i.e. flat bar shanks)

Except laterally with the axis of the hole... The reduction is the ratio of missing material along the tensile side of the bending moment....

Take a 1/4" hole out of a 1" shank, and you have a 25% reduction in force required to take the material to the yield point...

[motion30]

UO TE=Terra Nova;1667728]A small hole, drilled near the center of the shank, will have virtually no affect on the strength of the anchor.[/QUOTE]

maybe. but it still definitely a spot where Rust will start

[noelex 77]

Originally Posted by Terra Nova

A small hole, drilled near the center of the shank, will have virtually no affect on the strength of the anchor.

None of these anchors were bent despite what looks like considerable use in some cases, so obviously the strength has been sufficient.

Most anchor shanks bend in lateral (horizontal) direction and your comments assume the failure mode is from a vertical force. As HappyMdRSailor points out, the reduction in strength in the horizontal plane is proportional to the overall depth reduction (apart from the CQR).

Despite the lack of problems with these anchors I still don't think it is a good idea, but it does suggest there is is a lot of reserve. Rather than these isolated holes an overall lighter shank would significantly improve anchor performance and reduce the risk of dragging, but then someone would probably drill a hole in it.