S - hook for upper mainsheet block to boom

hi all,
winter project on my nacra 5.2 is to try swapping my old 6:1 harken mainsheet system with an equally old ronstan 7:1 system from a tiger shark (18" paper tiger)

i see that many use "S" hooks to hang the top block from the boom hanger and was wondering what loads i should be calculating for buying an S hook and also for making a pigtail to bring the blocks closer together (so i can use the same mainsheet length), 100kg/220lbs? enough?

100kg? How hard do you pull on the mainsheet? 40 - 50 kgs at least, multiply by 7 and then multiply with Pi as a safety factor

5mm or 6mm.

Now why do you want to go for an S hook? If you sail/race a lot and rigging time is very important it makes sense. If you are not stressed while rigging, a shackle is better in my opinion.

IMHO these are really the best for attaching the main:

I use the same.

this where i get confused, which is why i asked

50kg x 7 = 350kg plus safety factor 50kg so i need an S hook rated to 400kg, close to a 1000lbs.....

the only S hooks i can see are rated to about 100kg and the snap shackle people post pics of seems identical to the 1 in the shops i see rated at 120kg.....

the shackles that are doing the job now are probably only rated to 120-150kg, divide by 5 - means either i am pulling less than 30kg, possible, or the shackles are very conservatively rated and are working very near their rated values...

edit....i see the muurays snap shackles on pg31 are rated to 1000lbs

http://www.murrays.com/archive/31.pdf

I use the same snap shackle as Tony, but to be clear I use it between the main and the boom. My sheet blocks are attached to the boom with a regular shackle (the one you need a screwdriver to open) as I almost never remove them.

I've had an s-hook straighten out on me and I've seen one other do the same. I feel like the snap shackles are too heavy (unless you can afford the titanium versions) and I just go with a regular shackle now. Keep it simple (and reliable).

i asked a similar question (or responded to one) a while back. i had many people tell me the s hooks can bend under stress... i said i have never seen that and i have used mine for years...

Guess what.. they were right.. when i upgraded to an 8-1 i bend the hook. BUT there was a larger hook that i was using and it never bent.

I used a snap on the bottom blocks and the s-hook to the boom. I have removed it and now just use a shackle (i spliced a pigtail)

I have a couple of little fitting that use dyneema line instead of a shackle. They have proved very reliable, easy to use and are very light.

I have also used a short line with a ball on one end and an eye spliced in other just barely big enough to push the ball through.

I use as well a loop of 3mm double braided dynemma with a plastic ball at the end. It certainly holds more than 500kg and you can open it with gloves.

Cheers,

Klaus

I had 4mm dynemma (single braid) spliced around the boom bail (where the upper blocks attach) and it lasted 3 sails before it broke from the rubbing. Next time i will have to use a shackle on the bail.. but i felt that kind defeated the puropose... granted the bail is not smooth.. its a flat piece of stainless...

Watch out with the little plastic balls. I don't trust them anymore since I used one at the spinnaker tack (pass a loop through the tack and slide the ball through): I saw it explode in pieces under load.

I now use a small dyneema loop I spliced. It took me while to get the damn thing right. It has a sliding eye on one side which is closing up under load, and a turk knot variation on the other side to get through the eye. Like the attached image (sourced on the net, mine is not that neat!)

All the rope manufacturer sell you those loops for a small fortune but explanations on how to do them properly are non-existent...

Correct, I did an experiment with an oversize suitcase scale to see how much I cna actually pull, 30kgs is good, at 38kgs I tore the skin off my hands ( dam forgot about the gloves ), using legs as well I could get low 40's but and this is a big but, it was in ideal conditions and I'm sure on a boat would be less.

Good fun experiment to do though.

When I sailed the new Viper in July it came with the Dyneema hank to attach the upper block to boom. It worked very nice and is light weight. I do like that setup.

Alec and I had an S-Hook straighten out on us on the 6.0 at the beginning of a C-100 in a blow. Sheet in, get on the wire, BANG! Hook straightened. Don't recall it being a wimpy hook either. In that blow, not much left to do but limp into a cove while things flogged. I tend to use snap shackles a lot, but in most cases I use regular shackles now. Crew gives me crap for making sure they're tight, too.

they are easy to make.. the biggest issue is making sure the knot doesn't come undone... which is unlikely.
I made some myself and tested with a 32:1 block set up and damn near broke my deck and the blocks and the "softie" was fine. There is no way that the force would exceed this on one of our boats. Abrasion can be an issue but provided there are no sharp edges then there shouldnt be an issue

Very cool... the one in the image doesn't appear to have a lock stitch.. i take it you add a lock stitch?

For a straight bury (which that looks like), I'd add a lock-stitch. A self-secured eye (such as a brummel splice) wouldn't need it. I'd also taper and bury the end of the button knot.

Regards,
Eric

which part are you saying to lock stitch?
can't do a brummell splice or lock stitch on the splice because because you need to loosen the splice when it goes over the knot and to be able to undo it

Yeah, but what Pepin said was --

There is no lock stitch. You need the eye to slide. When pressure is applied on the loop the eye closes locking the knot in place. To open or close the loop you just slide the eye open and push the knot through, and you can only do that when there is no tension on the loop.

It's a simple bury, the outside is bunched up a little so when pressure is applied the inside slides and close the eye. The knot is done with the two end of the line still inside each other. At the center of the turk knot there is a stopper knot made at the end of the lines. There is no need for a lock stitch anywhere, the turk knot acts as the lock stich.

Now that I know how it's done I need to take measurements to make it right everytime: judging how much line you need to do a turk knot is hard!

I will trade you a couple 4 packs of Tennent's Super Lager for a set

I make those the lazy way.
-Make the eye just like a normal splice by pulling the end back into the core.
-Then cut both the inner and outer core at the same time at the desired length.
-Burn the ends together so that it kind of forms a little stub.
-Then just put a single of figure eight knot in and you are done.

IMHO the Turk knot in the expensive version is just for show.

Sorry man, I only drink real ale or champagne. Not super lager!

sounds like my technique, except I torch the end after tying the knot with what I call a "flame thrower" type lighter that gets to high enough temp to melt the dyneema a little.

I just tried Tony's method. Duh. Doesn't look as good as a turk knot, but works just fine and it's way way way quicker to make. I don't think I'm going to do a turk knot again! Thanks!

Well, I went ahead and made a couple.

In my first attempt, I tied a chinese button knot first, and buried the end. Then I put an eye in the other end. Unfortunately, I tested opening and closing the eye before putting in a lockstitch and I inadvertently pulled the eye out. At that point, I decided that the bury wasn't long enough anyway, and I should splice the eye first.

On the second try, I did an extra-long bury on the eye, and put a lockstitch in (near the tail of the bury) just to keep the loop in place while I tied the button knot. Then I tied a knife-lanyard-knot and cut off the end flush under the knot. I don't think the lockstitch is structurally necessary, as the stop-knot binds the core in place.

It wasn't that difficult. The hardest part was burying the tail of the eye, and only because I was using too large a fid. It was an interesting exercise, and I'm glad I did it even though I use a snap shackle and don't plan to change it out.

Regards,
Eric

I no longer use a fid for burying, I use stainless wire. Starting with around 1m50 of wire bend it over onto itself, crimp the free ends toguether and then slide a plastic ball with the small hole toward the crimp. To do a bury slide the wire inside the cover from far back, exit where you want to finish the eye, put the free end in between the two wires, pull it back using the plastic ball to bunch up the cover.

A wire is the only way to deal with a 3mm dynnema line anyway as the smallest fid only works to 4mm.

Anything wrong with just using a normal pin type shackle like this other than it take a bit longer...?

Nothing wrong with shakles except that using HM line can save miniscule amounts of weight (that can add up), probably costs a little less, requires skills and most importantly (as Tami used to say) and it sure looks cool!

I am simply looking for excuses to use splices as i have now purchased 3 different sets (or types) of fids... (for the cost of about 50 shackles)

PS the Brion Toss Fid (about $75) works almost the same exact way as Pepin's wire except it has a 1mm loop of dyneema to "grab" the tail and pull it through (instead of pushing like a Sampson/Selma fid does) for the bury

All that is well and good but don't you still need a shackle to go through the "swivel/button" at the top of the block? So your actually adding weight and an extra failure point unless your running the line through the little hole in the swivel,in which case it would seem to cut it alot faster.

I agree.. i think the thread got off track a bit and we were no longer talking just about connecting the blocks but how to make dyneema loops (to be used in other places)

In 7 years I never had one of these fail. Boom connection to mast did. But not this. And easy to connect when the wind to blowing good.

Doug

I went ahead and made another dyneema loop. This one is intended to replace the wire loop that connects my mainsail tack to the downhaul blocks (around the boom gooseneck). I did a simple bury for the eye, exited the line, put in a locking brummel, and then reburied the tail. At the other end, I tied a chinese-button-knot and buried it's tail as well. The entire loop (except for cutting off the button tail and burying it) was tied from the "spool-end", so I only wasted a few inches of line.

I'm going to have to do something to keep the line from snagging on the gooseneck (I think wrapping with tape may suffice). My hope is that this will be a little easier to connect than getting the pin in the small shackle.

Again, it was fun to do. I hope it works.

looks good.

Eric - I am doing something very similar on my boat with Dynema, I have that same cable for the downhaul but it was too long. I am just using a doubled over loop of dynema and it works like a champ, I can get more adjustment out of the downhaul now as its not block to block right away like it was with the cable.

I like the fast pin solution of my Cap very much. Absolutely reliable and easy to release in difficult situations.

where is the fast pin? i only see shackles

My preference. Just attach to top of the upper block.

The bolt of the twisted shackle has no screw thread. It keeps in place due to the tension of the sail and is secured by the loop of (in this case) black shock cord.