Should You Bend or Spread Your Cotter Pin | Sailing Wisdom 

Many who have had a leg break off a cotter pin probably tried to straighten and re-use it. What I have more commonly seen on aircraft, is cotter pins that have gotten repeatedly snagged and bent (on clothing or rags from pilots and mechanics inspecting the aircraft), and then pushed back into place; eventually one of the legs fatigues and breaks off. Which is why the industry standard is for the legs to be bent as tightly against the fastener as possible, and then trimmed short to minimize the possibility of snags. In the comments to your post asking for input on the thumbnail for this video, you asked that everybody keep in mind that you are talking about sailboats and not aircraft, which is a point well made. But also consider that a lot of the same factors apply... You still need to be concerned with the cotter pins getting snagged on lines, sails, clothing, etc and damaging those things, as well as having the pins get bent and eventually fail from repeated bending cycles. One thing that occurred to me is it would be a real pisser to be launching or retrieving an inflatable dinghy in the wind, and have it punctured from coming into contact with a protruding cotter pin leg. Also I wouldn't place too much faith in a pin withstanding hundreds of cycles of being slightly bent with pliers. In actual practice, you're going to have thousands upon thousands of cycles of vibration and other motion in the standing rigging over the life of each cotter pin. If the legs are bent tightly against the fastener such that no relative motion is happening between the two, no big deal. But if they are only slightly bent to 15 or 20 or however many degrees, they are going to be constantly moving in the hole, all day, every day that the boat is sailed, or there is wind. It may not be a lot of motion, but the constant nature of it can have a big effect.

For the love of Pete. It's a one time use. It does't matter if bending them around stresses them more initially. That's not the load they will take once in position. The only force the pin will take once installed will be in shear. I feel like someone took 1/2 of a science class and thinks having a youtube channel makes him Mr. Wizzard.

My understanding was that the reason behind the small bend (15 degrees) was to allow you to pull it quickly in an emergency situation (like the rig fails in a storm and you need to get the mast off the boat so you can survive). I had never heard any discussion of metal fatigue. However, I don't think your test is applicable unless you are constantly bending and unbending (reusing) the cotter pins. In the wild, you bend it once, and it is only bent back just before you discard it and replace it with a new one. Also, if you do a small bend, and the bent leg breaks, the pin will fall out. If you do a wrap around, and one leg breaks, the pin won't fall out. In truth, I use a small bend.

Small engines and motorcycles is where I have the most experience with. Both the standard is to wrap them back, 1 breaks and it still holds and less likely to catch on something or some one. Never had one fail

I love how you get into all the small details of sailing. Thanks for all your hard work doing these videos.

This was quite entertaining, Herby! You had me in stitches. I loved your explanation of the logic you came up with. I won't get into a long explanation or debate here on the pros and cons of the different methods. A few commenters below have provided sufficient reasoning based on their experience. I personally go with wrapping the legs around the clevis pin. This way is in fact a requirement in some areas such as motorcycle road racing competition. If the legs are not wrapped around the clevis, you won't pass tech inspection. There are many reasons why it is preferable to use this method over simply putting a slight bend to the cotter pin legs and allowing them to stick out. In the end though, it's your boat, your clevis pin, your cotter pin, so you get to decide what's best for you. "May the Force be with you."😁

I don't know which is worse, that you spent all that time and effort testing out the carter pins, or that I spent half an hour watching you do it???????? Another question to answer!!!

Was trained at American Honda and yes, you trim real long tails, but the cotter pin is bent back and kept close to the bolt (usually threaded with castle nuts). Its designed for this. If you look close, its a bend around, not at a 90 degree. When you remove them, you replace them. I don't think auto and motorcycle manufacturers and engineers would all be doing this wrong. Look at an axle bolt on a motorcycle and see how its done. By the way, depending on its use, I use hairpin cotters on a lot of my clevis pins! :-)

Depends on the specifics of the fitting. If the clevice fits into a fitting that allows a clean wrap of rig tape with the legs of the cotter pin slightly spread and not a snag problem, that's good. I never leave bare cotter pins if possible. Rig wrap em, even when bent around the clevice. Too easy to snag on something, especially sails, usually spinnakers when dousing because they are flapping around all over the place. On boats where rig tune is important, and is adjusted between races on a race day with multiple races, the cotter pin head in the turnbuckles is stitched onto a wrap of velcro. The legs of the cotter pin are trimmed to stick out of the turnbuckle about 1/8". You stick the pin in and wrap the velcro around the turnbuckle to hold it in place. Very quick and secure, easy to remove and replace for adjusting shroud tension.

SO , let me get this right , bend one leg 15° & one leg brakes off.....pin falls out Bend BOTH legs all the way around & one leg brakes off....pin STAYS IN.... HUMMMMM....RUN THAT BY ME AGAIN

I’ve always wrapped them round, no problem in 30 years of sailing, last time I had the rig tuned I was recommended to do the 30 degree split, I’ve lost three cotter pins since then, twice I only noticed after the downwind shroud broke free. They turn head down and wriggle out, the last time was in heavy seas off the Shetlands. I immediately went round and wrapped every pin. Sorry but your tests bear no relevance in the real world.

If you take needle nose pliers at the end of the cotter pin and roll it up to where it’s in a roll and not a 90° bend they last forever. They will look like Swiss rolls It takes the stress out of the 90° bend.

After forty five years of being involved in aircraft maintenance I have never seen a wrap around cotter pin work it’s way out! On your Atlantic crossing, the pin holding your boom to the mast dislodged itself and separated at the gooseneck. Obviously, the cotter pin worked its way out. Often a washer is placed under the cotter pin which is secured using the wrap around method. This helps to prevent the holding pin sliding through. In most installations where a holding pin is used, there is a top side flange to prevent it from sliding through the fitting, As a mater of good practice all critical connections should be inspected on a regular basis. It is mandatory that prior to any flight aircraft have a thorough walk around inspection, It seems reasonable, a boat should have a similar inspection as often as practical.

I have nearly zero sailing experience... but a good bit of aircraft. With them they use few if any clevis pins, but do use clevis bolts and a few castle nuts. One of the main concerns of cotter pin installations is technician safety. Aircraft have many tight confined areas that often require reach throughs, and haphazard installation of cotter pins (safety wire, tie wraps and/or anything sharp) can & do result in lacerations. I'd suspect boaters would have similar concerns... like if someone were to accidentally stumble across a pin and get cut/punctured days from port; would you want to deal with that? How bout if forced to climb a flailing mast some dark night... same risk. Also, I suspect corrosion is your biggest enemy... salt spray, bird droppings[1] and the like. Cool videos, thanks, been subscribed for a while now! [1] I remember reading ages ago about a bridge failure attributed to birds... it seems it's design included many areas favorable for nesting, and their droppings & whatnot greatly accelerated rust. With aircraft, water entrapment areas are always avoided in the design phase... not only for corrosion mitigation, but ice expansion. Regular inspections of forging/casting drain holes are a common thing for some aircraft.

A cotter pin is subjected to shear and it is therefore important that it fits the diameter of the hole and does not move in the hole. Therefore, it must be placed tightly around the bolt to prevent it from moving up and down. In the video you can see that the split pin is too thin and therefore represents a risk. Just bending up the cotter pin brings also an enormous risk of injury for the people who move on deck!

You keep saying 10x but there are a few factors you didn't take into account. One is rate the bends are cycled. The faster you bend it the more it heats up the metal & snaps quicker. Also once it is bent around the pin & doesn't get unbent 90 degrees & rebent. It would get the same or perhaps less movement after that then the one bent 15 degrees. That would mean less or at the most the same distortion in subsequent cycles as the one bent 15 degrees. Additionally it is less likely to snag & then perhaps less cyclical movement.

press against the end of the bent 15* leg, it pushes back in to the clevis hole very easy, or a soft bump on the 15* and its straight again with nothing holding it in the clevis, both a no go in my book. Also the end sticks out and cuts anything close to it like a sail or your hide. To avoid a stress riser at the bend dont go past 15* grab the very end with a stout pair of needle nose and curl like a handlebar moustache putting most of the stress at the last few MM not at the edge of the clevis. and no sharp ends exposed. A good pair of safety wire pliers are a great tool for this.

I am fairly certain that someone bet Herbie a beer that he couldn't make a cotter pin bending video longer than half of an hour. Challenge accepted. I hope the beer tasted sweet.

I'd go with fully bent because then both of the legs have to break off before it fails! With the 15° bend, the pin can fall out as soon as the first leg breaks and there's even a second failure mode of pushing it out from the legs side without breaking anything off. And if you never ever reuse those things anyway, I don't think it's relevant how often you can bend it.

In my 55 years of bending cotter pins fully around the clevis pin both on sail boats and racing vehicles, I have never had one or both of the legs break. I always replace used cotter pins of course. My practice used however, is to bend based upon potential snagging or catching. If no possibility of snag... I bend 15 degrees. If snag or catch is inevitable..., I wrap the legs around the pin. I have found certain applications in race vehicles have produced opportunities to snag due to tight places.

Another view would be that the head of the cotter pin has already been stressed at manufacture. Spreading the legs would only require a single fracture before falling out. bending them back on themselves would require a fracture in two locations for the pin to come out.

Very late comment. But I just watched this. Your approach is interesting and informative. I offer a few thoughts. 15 degree bent legs usually stress one leg more than the other. They leave more exposed sharp points to tear sails, catch lines, and rip your skin. You commented on the difficulty of fully wrapping the legs. Use longer cotter pins, vise grips to hold the clevis pin, and diagonal cutters to tightly wrap the legs. Then cut the legs off near the head with the dikes in your hand. Finally, wrap the entire clevis pin and cotter pin with electrical tape to prevent any tears or skin rips. Now to the other part. If a leg breaks off a 15 degree bend, the cotter pin can fall out. The fully wrapped cotter pin requires both legs to break before it can fall out. As a mechanic, I was taught to fully wrap the legs and cut off the extra. As a sailor, I was taught to fully tape any cotter pins. An alternative is to throw all the cotter pins in the garbage and use wire rings or split rings that don't have sharp edges.

great video but unfortunately your test was irrelevant to the life of a cotter pin, it may have been fun and the maths may have been fun but the fact remains that the cotter pin is a single use item, so the only bending cycles it receives after installation is via snagging on things under load. If you wrap the legs right around and tuck the ends as close to the head as possible the chances of snagging are almost zero, not true with your 15 degrees, as for using up its life on installation the pin is designed to be installed any work hardening occurring on installation has been taken into account in it's design. So in short I believe you are giving poor advise with the 15 degree thing, and as for it being a little harder most things done correctly are a little harder.

thanks nice job Hiram

When on my apprenticeship my journeyman tolled me that there was a special place in Hell for a man that bent both legs of a cotter pin. We were working 1/4" steel pin. To remove a pin like the one you have with both legs rolled back is a real tough job. So just bend one.

Test the shear load strength at both ends simultaneously like how they are meant to work. As designed it is supposed to shear the entire pin diameter at both ends of its hole with side loading. Fatigue and work hardening are two very real things and two very different relations to designs. Guess which one you were testing.

Firstly, here in the UK we call them "split pins", cotter pins are very different and not found on boats (unless you have a bike). I would NEVER open the legs a small degree. I always wrap them using taper nose pliers.

Interesting angle, however 1. There is a special tool to lock secure the pin, and they are fabricated for one time use. 2. The property of the pins are such that actually before using they should be heated up to 200° C . Which will alline the molecules of the pins. 3. this information is from Vitters one of the big ship yards Netherlands. 4. Same kind of process you find in Aerospace and Automotive industry.

I tried to reuse a cotter pin, it broke on the THIRD time while removing it ~ I think there are more variables involved to simply conclude that the 487 times in your test has any relevance to real world applications... I would HIGHLY suggest using a new one EVERY TIME unless it's on a one time use project/disposable item.

Either way works for me. I say do what works best for you, it your boat and your the captain. 8-) As long as the cotter pin doesn't fall out of the hole, it does it's job.

Oh my gosh! I was stuck in the bath unable to skip the last 20 minutes but had the greatest pleasure of watching your dancing to music pliers! I'm sure you had great fun making that video!! Keep up the good work guys!!

In my humble opinion - only if you reuse the split pins would it be an issue with work hardening. Fold them over but never reuse a cheap it's a one use item!

ALWAYS BEND THEM AROUND. END OF STORY.

It is a better job bent right round out of the way. Thay have no stress once installed Plus it's a split pin acting as a cotter pin

Yes, Math is fun. However, you have made some base assumptions that I think are false. You are assuming that each bend puts in the same amount of stress. However I'm thinking that each bend makes the material less ductile and thus each successive bend puts in more stress than the previous one. That means it is not a straight line and the first bend puts in MUCH less stress than the last. Don't know if that would result in a log scale or not but it would make things a lot different. Also, we are looking at one of the "pins" of the cotter pin failing. Which solution would be best if one does fail? I'm thinking the 15 degree bend, with only 1 pin, would pull through pretty easily while the wrap around wouldn't be able to pull through. And, then there's how you bend it. The sharper the angle of the actual start of the bend could make a big difference as well. Using heavy pliers and making that a sharp 90 degree bend and then bending the rest of the pin around the clevis would be worse then doing a more gentle rounded bend! Oh, and there is the quality of the cotter pin. You can purchase different quality ones. Finally, another option I've seen is to use pliers, grab the longer pin and and bend it "around" with the pliers, leave the other one alone! Anyway, thanks for making me think!

Problem is the legs are way more likely to get caught on things that might stress those legs if they are sticking out if they are bent out of the way and back they are bent ONCE and very unlikely anything will bend it at all until you go to remove that cotter pin and then you use a new one when you reinstall. Also it’s not JUST how many times you bend the leg but how many times in a SHORT period of time. HEAT is generated when metal is repeatedly flexed the frequency of that bending had far more to do with fatigue. Bend it faster it will fail in less bends BUT each bend if it is a further Bend is in the bending process longer so it breaks in fewer bends. But it’s is still the rearranging of molecules and the heat that creates that causes the failure. Bending a cotter pin once so the legs won’t get caught and possibly unbend or push the pin out is by far the safer bend. And Yes the Bend caused some fatigue BUT not enough to cause failure and the legs being less likely to get caught far out ways the number of times you can bend it before it fails as your never supposed to bend it again without replacing it.

The comments from the other industries and from those that have lost pins strongly suggest the full wrap. My biggest concern is snags from lines or clothing, as I have both distorted and lost ring dings/cotter rings on stays, once while racing. I'm a fanatic about taping them, same with pins if possible. As someone hoping to sail solo around the lower part of the world my concern would be jettissing a downed mast quickly which suggests small bend, but would also increase the chance of a collapse in the first place. Typically I thought the idea was to cut the wire and usually sail with tools for this purpose. Great video got me thinking, got me laughing.

I think your theory is wrong. The metal is stressed more yes, but the work hardening from bending it further makes it hold in place. The Cotter pin does not see those loads when installed. The real test is how hard it is to pull out of the hole and what pressure it would take to shear it. The slightly bent Cotter pin could be potentially knocked out if a line or something were to strike it just right.

1. Always use a new pin (unless temporary until you can replace with new , emergency) 2. Bend both, opposite directions around. 3. Clip excess. Done Shortcuts can kill someone.

Good info, less bend when protection and interference is not critical. Get the ends out of the way when they are potential snags. YO... big dang hoo in nice background picture (data?) great tunes, thanks

For some reason and in certain instances prefer to change cutter more frequently than risk damaging a sail because it's sliding and catching on a 15 deg cotter.....my two cents worth.

Work hardening your test. Each time you said was one is two. Time 1st bend is not work hardening the pin. Repeated bending does work harden steel yes. If you look at the engineering studys done at the Edison institute on work hardening of fasteners and the transverse strength. If you worked on my plane or boat and did that to save time. You would have plenty of time to do what ever you want your fired.

this is why i use wrap pins with velcro......never bend cotter pins and for spreaders, split rings...never cotter pins

Great info and important tips about rig maintenance. keep up the great work!

Yeah…I have to go with bending both back. That one slightly bent leg gets snagged or breaks it’s over. They would twice as unlikely if they’re both bent.

So its weaker but if the other one can be knocked through how much easier? The risk would be which is going to fail more the knock through or the shorter stress life. Kind of missing the other half of the test. also if been banged how likly is it to bend back that 15 degrees. I would imagine the little bent one would be easier to bend back and like you said they turn around in the pin... Its almost like you focused on only the failure method How much force was required to bend back the slightly spread cotter.

Interesting test, but I think it can be expanded on. First off; automotive uses may not be as applicable to rigging, less vibration ( in my opinion). I think what last of the comments are referring to are the pins coming out. Extra security. I feel the next step is friction. Understanding that the cotter pins are not under any load, but falling out being the issue. Does the weakened pin ( according to your test) pull out with less force than the pin bent at 15 degrees?

Never leave straight, always fit new and bend tight as possible to reduce snagging. Tape if possible to reduce snagging further......don't use the key ring type.

The probability of a 'bend cycle' taking place is much higher if the pin is mostly open and repeatedly hits something or the other. If its bent out of the way, yes the initial fatigue is higher but in the daily usage no more 'bend cycles' should take place. isn't it?

Good stuff. Thank you. It is just what I wanted to know.

I am missing something here, what is the conclusion … bend slightly, or bend all the way back ?

I love your perseverance, great video! I looked this up for putting on dirt bike foot pegs, and ended up wrapping them. I did notice stainless was much harder to bend compared to regular steel... Were your tests stainless?

i also dont think your taking int account the radius. i think folding them back on themselves is cleaner. and for a bazzilion cycle they will hold up until my next trip up the mast. but im on a small boat witha simple rig

I just cant believe theres 32min video about how you set a cotter pin.

Who is cycling the legs of these pins back and forth? I might put a pin back where I got it from in a pinch, and if it looks in really good condition.

I'll keep bending around...but trimming them shorter first.

Well, you do mention fatique. AFAIK, fatique comes from repeated bending - as in thousands or million times of repeated bending. Not from once bending a pin around. Please hold that in mind. And put in a fresh pin every time you need to assemble the things. And consider what the pros are writing.

Please... A cotter pin is to be used one time not to be bent repeatedly 50 times... I can think of no use of a cotter pin where it would even accidentally be bent 50 times... But one hit on the end of a spread cotter pin can drive it out of the hole it's in, which I've done with a hammer, no breaking necessary... Whereas a bent cotter pin has to be unbent before it can be removed... Which is kind of the whole point of a cotter pin... to remain where it was placed until forcibly removed...

In American aviation you bend one down the pin / bolt and the other over the top. Safe, smooth, but not quick to remove.

Never mind just cease then with monel wire its way more eliable!

I dare you to wrap a cotter pin with tape that is not wrapped around the clevis. And if you don't wrap it with tape have plenty of band aids and sail tape on board!

It's the gremlins who turn them upside down :-)

CAN YOU EMPLOY OTHER DEVICES TO ACT AS "PREVENTERS" ? DESIGN WHAT WORKS OUTSIDE THE BOX ?

Bent around the pin is not 90*. It's an arc. Definitely tighter than 15*.

You have done the general public a disservice. Your non-scientific reasoning is flawed and unsafe. To use the fatigue method as reason for saying one method is safer than an another is like saying all metal objects that are bent over 30 degrees is weaker and therefore should not be used. Of course that is not true. Yes, there are times in certain situations where you may not want to full wrap a cotter pin, but those are specific individual situations and NOT to be use in general installations. That includes sail boat rigging. Cotter pins are by design meant to be bent. The fact they are stressed is taken into account by design. They know this and that is part of why they are a one time use only item. You come off as if the engineers who have spent literally decades of research and design of cotter pins have not done this testing. They have... as an experimental flight test mechanic myself, I know they have because I have done it... A LOT. What you did here today is my job, to run testing like this and find out if those designs are good or bad. I can say that NO, your methods of testing and reasoning are incorrect and dangerous. Trust in the aviation methods... as they have all been written in blood. Literally. Everything in the aviation maintenance methods regulations are there because someone has died because of it.

Foremost THEY ARE SPLIT PINS and NOT cotter pins and they are not the correct pins for that purpose. Split pins should have one leg longer than the other, be of the correct diameter to fit the hole and not protrude through more than 1 cm or 1/2". Then the shorter leg is lifted enough to stop the pin from falling out of the hole, around 30-45 degrees and that is all that is required. No bending the pins double or wrapped around nuts.

Stop. 32 minutes for a cotter pin video? So which is it? All the way around or 15 degrees?

just bend it at 45 and call it a day, this is OCD at it's finest but good to know.

I just clicked to see how someone could talk 32 minutes about bending a cotter pin. Thank God you don't teach safety courses at my job...

Interesting

This is wrong... Bend the cotter pin all the way around, both sides. If one side fails, then the other side will keep it from falling out and keep your mast from falling down. Leaving them unbent on one side and bent a few degrees is not the safest solution. There should be no additional forces applied to the cotter or split pin once cold formed into the fully bent position, and doing both sides is what you want. You want those ends out of the way from getting snagged where they can bend back. You want the cotter pin to be free floating in the hole also. And you don't want the ends out where they can get snagged.

I love your channel but I am sorry buddy. You got this one wrong. Rolling the cotter locks it in place and does not allow rotation or chatter. As the locked in cotters only load is in shear there is less movement of said cotter pin and thus less chance of rub wear on the cotter from the clevis or castle nut. Not to mention that a cotter pin is ROLLED. They are designed to take the metal stretch and ARE A ONE TIME use item.... I can not emphasize enough NEVER USE THEM TWICE!

hahaha hahahahaha i love your videos but this one was wild HAHAHAH i watched it tho!

i think bend back and for heats the metal that cause the break !!!

I’m sorry, but, I have never seen a broken cotter pin. Have you tried to break one? C’mon. Bend it and forget it. Why be worrying if you have it bent enough to stay in. And if bending them the whole entire way until they wrap around the pin, or removing them is too time consuming that it’s causing overtime and $$, you need to find another career because, I guarantee you have bigger problems, and you are charging way too much in $$ or time to do the work. I a. Terribly sorry for the run-on sentence.

As a former aircraft tech. Cotter pins are used only once! They should be bent properly. Yes, they can be a pain. But they are essential for keep your riggning to stay up! Tape them to protect sails, clothes ect.. This is a non issue, as they are very cheap! Clickbait ranting...

Friend: Hey Ben what did you do last night? Ben: Oh I watched Herbie bend cotter pins until they broke while counting how many times it took them to break. Friend: Ben you need to get a life! AND so should Herbie!

his experiment shows the bending of a cotter pin at a single point on the pin at either 15 degrees or 90 degrees. but what if the bend is spread over a longer length of the pin. instead of bending the pin 90 degrees at a single point, the 90 degree bend is spread out over several millimeters of the length of the cotter pin. would't that reduce the point stress on the pin?

Have you ever heard Tuck Cotter Pin Pliers?

8x8

Jfc 32 minutes? What’s the answer

Many mistakes on this video - for one, your test introduced heat from bending the pin leg back and forth full angle multiple times, which isn't representative of the real mechanical stress such a pin would experience (if anything - such repeated bending is more likely to occur if you leave the tails long AND not bent around the clevis pin). Second - you didn't consider the speed of turning the pin tails around, which also would have significant impact on the heating and consequently - strength of the metal - doing it slowly allows the metal to bend with less stress (work hardening) and heat than of you do it fast. Another factor is how you bend the tail - I use needle nose pliers with round jaws, and wrap the tail around slowly - that way I avoid creating a sharp angle in the tail, avoid heating it, and as long as I don't try to cheap out by reusing what is only meant to be used once - never had one break. You're comparing one method allowing for 487 or so cycles while the other allows for only 44, for a pin that is only intended to have one cycle before you replace it with a new one - not really relevant... One last point against leaving the tails straight instead of wrapping them around the clevis pin is that wrapping them around usually puts them neatly inside the bottlescrew, whereas leaving them straight like you showed is almost always going to give the sails and/sheets and halyards something to rub against or get cut by and from that - rip.

Herbie, you have no idea. Cotter pins? How about lockwire inside a turbojet engine? Not for the faint of heart: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-hcxHQXYU-Os.html

I don't see my response from when you posted 1st time.

Nope! Sorry Bro.

interesting but way too long for the information provided.

I'm really sorry I had to unsubscribe, but your questions completely blocked my access to RU-vid and it's the only way I could find to get past them. Definitely a RU-vid bug, but it drove me away.

You can't bend the legs of a cotter pin because they are not split, these are SPLIT PINS, not cotter pins. Learn the difference

Cotter pins are cheap....bend one leg, or both, replace often...problem solved.

I subscribed to this channel today and I'm now seriously contemplating unsubscribing after watching this video...

i dont belive you

Some of your most ridiculous work. Others have covered its ridiculousness in the comments, suffice to say, just because you have a hypothesis doesn’t make it so.

Ridiculous test.