Spade Anchor Unsafe - Remedy ?

[Talbot]

IMHO this unit should have a castellated nut with a split pin passed through it as used on car suspension. This is the safest form of fastening. However I dont recall ever seeing a stainless or galvanised castellated nut.

[Vasco]

Talbot,

They must make stainless ones, I've got one on the bottom of my gooseneck on an Isomat rig.

[Jon D]

In essance that's what's being delivered

The spade I bought this spring has a longer bolt that is drilled to accept a locking pin which is included.

They also include several nylock nuts with instructions to only use once so the self locking works.

[NeilR]

... Alain Poiraud, the Spade designer, is a long time liveaboard sailor of many, many years experience. He's currently on his boat in Uruguay.

Cheers

Neil

[Richhh]

Quite an interesting set of comments on the use of nylok nuts to hold the pin on the Spade anchor. I have a 44# spade anchor and love its performance (for other than soft mud). Its probably the best damn anchor Ive ever owned.

The FIRST thing I did when I got my Spade several years ago was IMMEDIATELY remove the Nylok .... as nylon usage is totally contraindicated for immersed long term applications because it very quickly hydrolyzes (polymer long chains break down) when continuously immersed in WATER. Hydrolysis of nylon is a well known issue in the chemical process industry; and thus, nylon is rarely if ever used in water wetted applications.

[Alain d'HYLAS]

Originally Posted by Richhh

nylon usage is totally contraindicated for immersed long term applications because it very quickly hydrolyzes (polymer long chains break down) when continuously immersed in WATER. Hydrolysis of nylon is a well known issue in the chemical process industry; and thus, nylon is rarely if ever used in water wetted applications.

Hi Richhh,

Interesting to see this old story coming out again. Since the post of Dieterick Meenken, more than two years ago.. no one single occurrence, no one similar accident!!.. therefore, in 10 years of experience, and thousands anchors all over the world, with this type of anchor, the grounding of SV"Deep Blue" is absolutely UNIQUE..

Now talking about the Nylock nut?
You are talking about " immersed long term applications" Do you have any idea of the % of time your anchor is "immersed" and, following your answer, can you consider it as a "long term immersion"? ?

I've been using my own Spade anchor for about 10 years now.. and as a living aboard sailor, I can tell you that my anchor was quite often in the water.. and I can't see any evidence of "quickly hydrolyzese".
If the outside of the Nylon ring, would be from time to time in the water, I can assure you that there is absolutely NO water coming into the nut..

Do you have any personal knowledge of a Nylstop nut being destroyed in a Marine environment..

Alain

[GMac]

Originally Posted by Richhh

Quite an interesting set of comments on the use of nylok nuts to hold the pin on the Spade anchor. I have a 44# spade anchor and love its performance (for other than soft mud). Its probably the best damn anchor Ive ever owned.

The FIRST thing I did when I got my Spade several years ago was IMMEDIATELY remove the Nylok .... as nylon usage is totally contraindicated for immersed long term applications because it very quickly hydrolyzes (polymer long chains break down) when continuously immersed in WATER. Hydrolysis of nylon is a well known issue in the chemical process industry; and thus, nylon is rarely if ever used in water wetted applications.

How to make Alain happy and sad in the same post
I'm guessing you use a Polyester on your rode and/or snubber. How do you find it?

[Talbot]

I guess if you really wanted to be safe then the nyloc nut would need to be changed for a castellated nut, but you would then have the problem of finding a stainless castellated nut.

[GordMay]

Stainless Steel Castellated Nuts are common in aircraft applications, and are available:
http://www.sirius-aviation.com/nuts.html#310

Recommended reading:

”Fastener Design Manual” ~ by Rich Barrett (Barrett Engineering Consulting)
Barrett is the author of NASA's Fastener Design Manual, and his free online manual is fairly complete, yet concise.
Part 1: http://www.tcnj.edu/~rgraham/barrett/manual1-A.html
Part 2: http://www.tcnj.edu/~rgraham/barrett/manual1-B.html

[Talbot]

Are aviation nuts A2 or A4 stainless? I suspect that they would only be A2.

[GordMay]

Good question.
I'm not familiar A2 & A4 designations, but I suspect (not certain) the aircraft nuts are type 304 SS, not 316.

[Talbot]

A4 = 316

A2 = not so good in sea water

[GMac]

A Nylock would not break down 'that' fast would it??
The Spades are pined as well so they have the extra back-up anyway.

I never realised Nylock were a one-shot item until the Deep Blue hiccup. Most I have spoken too did not either.

[Alain d'HYLAS]

I think the GOOD question has to be asked??

IS the Spade Anchor Unsafe ?? - and if YES , which Remedy ?

and to answer the first part of the question, ask the several thousands of poeple who have uused it , + those who have used it in very difficult situations: Storms, Huricanes, event tsunamis and earthquake??

If the answer is yes.. then it would be interesting to try to find a solution! but, please, why trying to find a solution.. if there is NO problem??

[GMac]

I'm using one and not at all worried about it. You are right saying one hiccup in many thousands does not make it a problem.

Just wondering why all these years I did not hear about the nylock one use bit. I've a great fan of them and still are.