Vang questions

Moderator: GreenLake

Re: Vang questions

Postby RobH912 » Thu Dec 26, 2019 5:22 pm

Gl & John - again thanks for the replies, and after re-reading the replies several times, playing around with the Harken Main Sheet calculator, I can understand the 900 - 1000 lb. working load calculation, and why you both have gone to 12:1 or 10:1 set up.

Also found great information on vang systems on the Ronstan site https://www.ronstan.com/marine/vang_systems.asp

GL - you mentioned that you were using the Ronstan RF20332 / RF20302 triples for your 6:1 so looking at the vang system examples, looks like a 12:1 would be their #8 example, but you have flipped it around so that the cleat is on the boom end rather than at the mast.

From an earlier post you made about my current set up with the 40C fiddle blocks
The cleat on the vang needs to open then other way, if you want to be able to release it.


Do you mean just switching the block with the cleat end to attach to the boom, rather than having block with cleat attached at the mast... or something else?

As I started to think about 6:1 option with a set of triples for the vang I was having some problems visualizing how to run the line, should the becket be on the cleat block or the other block, etc., etc. but found this useful link on the Harken site on how to reeve a 6:1 block. Thought I'd post it here for others. https://www.harken.com/article.aspx?id=42513

Then spent time looking closely at your 12:1 set up picture, blowing up the view as much as I could, but still have some questions on your set up.

For the triple block with the cleat that is attached to the boom, are you using a twisted shackle or the shackle that comes with the RF20332? The picture is not clear. As I re-read how to reeve a 6:1 set up, I still can't visualize how the lines between the two blocks will not cross / rub when the blocks are finally attached to the boom / mast. The harken article does say
Once the system is threaded correctly, you can cleat the rope and put some tension in the system. This causes the two blocks to sit at approximately 45 degrees to each other, but the ropes will sit squarely in the sheaves and the falls will not touch.
.

Your triple blocks do not look like they are sitting 45 degrees to each other but look to be in line with each other.

Looking at the red / yellow line in your picture for the 2:1 cascade, one end is attached to the triple block RF20302 but can not see where how it is attached to the boom (maybe line is tied to a snap shackle?), or is it somehow attached to the triple block at the boom?

Think I've learned more about blocks / pulleys / vangs over the last several days than I did in high school physics 50 years ago :lol:

Thanks!!
Rob


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Re: Vang questions

Postby GreenLake » Thu Dec 26, 2019 8:46 pm

RobH912 wrote:.... found great information on vang systems on the Ronstan site https://www.ronstan.com/marine/vang_systems.asp

GL - you mentioned that you were using the Ronstan RF20332 / RF20302 triples for your 6:1 so looking at the vang system examples, looks like a 12:1 would be their #8 example, but you have flipped it around so that the cleat is on the boom end rather than at the mast.

From an earlier post you made about my current set up with the 40C fiddle blocks
The cleat on the vang needs to open then other way, if you want to be able to release it.


Do you mean just switching the block with the cleat end to attach to the boom, rather than having block with cleat attached at the mast... or something else?


Rob,

Yes, the #8 configuration. Except, where it has the RF468 (a 990lbs wire block) for the cascade, I have something less sturdy, should probably be upgraded.

The problem with the DS is that the mast is in the middle of the cuddy, not at the edge as in many other dinghies. That means that it's difficult to pull down on the free end of the vang to release it. Some blocks can be adjusted to give different cleat angles, but didn't see that for mine and simply swapped the entire vang end-for-end. You can also just swap the 6:1 end for end. The way I have it, it's easier to adjust from further back in the boat (e.g. when single-handing), but also puts the tail a bit in the way of the crew. I leave the tip of the tail tucked into the other end of the purchase, to give a shallow loop with enough slack to allow the vang just about depowered.

Alternatively, you lose the cleat on the purchase, run the line through the deck and lead it aft (cleated on the side of the CB somewhere). Somebody had a nifty tube&cleat from Racelite for that. I personally tend to dislike long runs and I have the reach (and extreme hiking is not something we do constantly around here). Your conditions may differ.
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Re: Vang questions

Postby GreenLake » Thu Dec 26, 2019 8:59 pm

RobH912 wrote:...As I started to think about 6:1 option with a set of triples for the vang I was having some problems visualizing how to run the line, should the becket be on the cleat block or the other block, etc., etc. but found this useful link on the Harken site on how to reeve a 6:1 block. Thought I'd post it here for others. https://www.harken.com/article.aspx?id=42513

Then spent time looking closely at your 12:1 set up picture, blowing up the view as much as I could, but still have some questions on your set up.

For the triple block with the cleat that is attached to the boom, are you using a twisted shackle or the shackle that comes with the RF20332? The picture is not clear. As I re-read how to reeve a 6:1 set up, I still can't visualize how the lines between the two blocks will not cross / rub when the blocks are finally attached to the boom / mast. The harken article does say
Once the system is threaded correctly, you can cleat the rope and put some tension in the system. This causes the two blocks to sit at approximately 45 degrees to each other, but the ropes will sit squarely in the sheaves and the falls will not touch.
.

Your triple blocks do not look like they are sitting 45 degrees to each other but look to be in line with each other.

Looking at the red / yellow line in your picture for the 2:1 cascade, one end is attached to the triple block RF20302 but can not see where how it is attached to the boom (maybe line is tied to a snap shackle?), or is it somehow attached to the triple block at the boom?

I just rove the blocks the way they looked good to me. I'm sure that can be improved. Wasn't too worried about chafe. The rope is overdimensioned and the line force inside the purchase is less everywhere than what you pull (because of cumulative friction). But their suggested 45 degree setup is probably the optimal one.

I have one twisted shackle for the upper triple block. The yellow like is tied to the same becket as the blue line. (That may limit the acceptable working load of the setup, as that becket has to now hold the full (not half) amount of vang tension. The alternative would push the block out of alignment. The schematic diagrams tacitly assume that purchase and cascade are anchored next to each other; something that doesn't seem that workable, hence I did what I did.

However, if you have two straps on your boom, you can separate.

It's good to think these things through; I did mine a bit on the spur of the moment when I saw the set of triples on sale at my local store (and I had the single block lying around). The need for the twisted shackle was evident when I rigged this setup the first time, but my fellow sailors all have "magic buckets" full of stainless parts and this may have come from one of them.
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Re: Vang questions

Postby RobH912 » Fri Dec 27, 2019 10:29 am

GL - thanks for more detailed information, on the cascade line attachment and on switching the 6:1 setup around to have the cleated block near the boom.

I have one twisted shackle for the upper triple block. The yellow line is tied to the same becket as the blue line. (That may limit the acceptable working load of the setup, as that becket has to now hold the full (not half) amount of vang tension. The alternative would push the block out of alignment. The schematic diagrams tacitly assume that purchase and cascade are anchored next to each other; something that doesn't seem that workable, hence I did what I did.


The twisted shackle at the boom end must help align the set of triples to keep the line from rubbing between them.

Makes sense to rig the vang this way with the cleated block near the boom, allowing to pull down to release, based on the Ronstan hardware configuration. I have not moved to single handed sailing of the DS yet, but I could also see advantage of having the cleated block on the boom if I were single handed sailing.

Going to keep thinking about different set ups / equipment options... all good to do in the winter and then spread more time sailing when its warm.

Thanks!
Rob


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Re: Vang questions

Postby RobH912 » Fri Dec 27, 2019 11:04 am

John I was also interested in learning more about your 10:1 set up using the Harken 29 carbo triple blocks.

jalmeida51 wrote:My vang is 5 to 1 with a 2 to 1 cascade makes it 10 to 1. I use Harken 29 carbo blocks with 1/4 stay set line. I attach it to the boom with a vang plate. I don't worry about the blocks or line failing. If it is going to fail, I believe it will fail at the boom. The diameter of the boom is small in my way of thinking. But I believe it is the same diameter of the boom used on the Rhodes 19. I know there has been boom failures on the Rhodes for coming too hard on the vang. One solution was to slide a reinforcement sleeve down the inside of the boom. At 10 to 1 I have more than enough purchase. Of course I don't race. I had 4 to 1 on the Rhodes19 I used to own and that was useless. But being old could be part of the problem? Happy Holidays, John


Lately I've learned that there is always more info on the vendor's site on their products than appears on marine supply stores' web sites.

When I was revisiting the Harken site looking at the Harken 29 blocks I saw this feature in the description...
Cam reverses for either up or down cleating.
https://www.harken.com/productdetail.as ... &taxid=416

If this is the case it seems like it would be possible to set the cam for an "up release / down cleat" and mount the Vang's cleated block near the mast rather than at the boom end of the vang. I would like the crew position on the boat to manage the vang,

From the working load discussions in this thread it would seem like 10:1 would be sufficient but I need to get some paper and draw a schematic on how to do that with triple blocks.

I am curious on how you've set up the 5:1 purchase (using the triple blocks), location of the Vang's cleated block (boom or mast end), and reason for not setting up the triples as a 6:1?

Is your cascade set up similar to the Ronstan schematic #8 referenced above with the cascade line made fast at the mast end of the cascade?

Thanks!
Rob


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Re: Vang questions

Postby GreenLake » Fri Dec 27, 2019 6:40 pm

The difference between 12:1 and 10:1 is 20%. Not insignificant, but also not terribly significant. If 10:1 lacks power, the goto move would be a second cascade, so 20:1.

The purchase is defined by the number of parts between the blocks. With two triples that is six parts. As the blocks approach each other by 1", you pull out 6" of line. Now, if the free end exits the moving block and you pull in the direction away from that block, your hand moves another inch, or 7" in that example: you have rigged your purchase to advantage and it is now 7:1.

Including the cascade, mine could be 14:1 if I pulled in line with the vang (instead of simply pulling down). Depending on the exact angle, I could get between 0 and 15% better purchase than the nominal 12:1.

A true 5:1 would need a combo double w/becket +triple w/ cleat, whereas the 6:1 has two triples w/cleat and becket on the same triple.

If you can rotate the cleat (not possible on the Ronstan apparently) then that would be the way to go (and lead the line so it hangs down the cuddy edge). Not as convenient as skipping the cleat at the mast and leading the line to the CB trunk. Am told that I should be playing more with vang setting than I'm currently doing; will see.
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Re: Vang questions

Postby RobH912 » Sat Dec 28, 2019 11:16 am

GL - thanks for further clarification on 5:1 vs. 6:1.

Re-reading the post the John made I now realize that he does not say if the Harken 29 mm carbo blocks he is using are doubles or triples. I think that I had mistakenly assumed that he was using triples, which is why I asked my question on how he reeved the triples to be 5:1.

I'll wait to hear back from him.

A picture from the Harken download file on the 29 carbo blocks.

Thanks!
Attachments
Image 12-28-19 at 8.06 AM.jpeg
Image 12-28-19 at 8.06 AM.jpeg (60.12 KiB) Viewed 2965 times
Rob


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Re: Vang questions

Postby jalmeida51 » Sat Dec 28, 2019 4:33 pm

Hey Rob, My cascade is attached to the boon by a vang plate with a swaged ball on 1 end and a loop nicro pressed on the other end with a Ronstan 55 single block. It is made up of 1/8 inch stainless wire about 6 inches log. This way I can slide the ball out of the plate if I want to get rid of the vang. Cascade is made up of 5/16 stay set attached to the bottom of the mast and the bitter end is attached a Harken carbo block 29 with a becket P/N 342 . The vang line 1/4 stay set and to a Harken 29 carbo block triple P/N 345 attached to the bottom of the mast. It runs across the top of the cabin to Ronstan cam cleat P/N RF 5001.If you hike out this system will not work unless you route under the deck to a Racelite Rl860 swivel cam cleat attached to the c/b trunk. I stay in the boat and it works well for me. I don't race and I don't play with the vang. I set it and forget it. 10 to 1 is right for me but you might want more purchase? Another cascade? John
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Re: Vang questions

Postby GreenLake » Sat Dec 28, 2019 5:54 pm

John, the ball and plate is a good system, if your boom is set up for that or if you aren't scared by the hole to cut.

I opted for a SS strap, angled back, using rivets. Didn't get the angle close enough, so the vang bent the strap a bit, but the rivets look OK.Throughbolted U-bail might have been better.

Staying in the boat works for us most of the time as I often bring an extra person anyway. For example this "Barber elf" from the jib-trim thread.
2717
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Re: Vang questions

Postby jalmeida51 » Sun Dec 29, 2019 11:03 am

Rob, I use a 29 carbo block double with a becket P/N 343 not 342 attached to the bitter end of the cascade. John
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Re: Vang questions

Postby RobH912 » Sun Dec 29, 2019 12:57 pm

jalmeida51 wrote:Hey Rob, My cascade is attached to the boon by a vang plate with a swaged ball on 1 end and a loop nicro pressed on the other end with a Ronstan 55 single block. It is made up of 1/8 inch stainless wire about 6 inches log. This way I can slide the ball out of the plate if I want to get rid of the vang. Cascade is made up of 5/16 stay set attached to the bottom of the mast and the bitter end is attached a Harken carbo block 29 with a becket P/N 342 . The vang line 1/4 stay set and to a Harken 29 carbo block triple P/N 345 attached to the bottom of the mast. It runs across the top of the cabin to Ronstan cam cleat P/N RF 5001.If you hike out this system will not work unless you route under the deck to a Racelite Rl860 swivel cam cleat attached to the c/b trunk. I stay in the boat and it works well for me. I don't race and I don't play with the vang. I set it and forget it. 10 to 1 is right for me but you might want more purchase? Another cascade? John


John thanks for the detailed reply / including hardware part numbers and the Sta-set line sizes. I've been looking at Sta-set line for the vang since you mentioned that in an earlier post, looks good.

While I did race this past season in the SLI DS we were not hiking out, didn't play with the vang, nor did we sail the DS in very heavy winds... basically set it and forget it. Started down this vang upgrade path for #2444 which I bought this fall as I wasn't sure if my existing 4:1 vang was strong enough to handle the WL, nor had enough purchase.

Interesting idea on the vang plate, wire connected to the 55, allowing you to remove the vang easily.

How is the 5/16 sta-set line attached to the bottom of the mast? Tied to a bail or cleated? Also how is the the Harken 29 carbo block triple P/N 345 attached to the bottom of the mast? What I am really looking for is if these two attachment points the same, for example both the cascade line and the bottom triple are attached to the same bail or different attachment points?

After all of this great discussion / thinking I am going to go forward with two Harken 29 triples for a 6:1, p/n 347 (becket + with the cam that can be switched to an up release, attached at the mast) and p/n 345. Sta-set 1/4". Still looking at the cascade portion hardware.

GL and John - when you started talking about vang plates and SS bails / rivets I realized that I had not given any thought on attachment points, nor how strong they are. The SLI DS has SS bails on both the mast and the boom for the vang to attach to, but #2444 is set up differently.

Older Proctor mast and boom, there is a groove in the bottom of the boom, and there is some sort of "track eye slider" (for lack of the proper name) that slides inside the groove. There is a thumb screw and the eye can be moved / slid down the groove. Here is the only picture I have, hopefully enough so you can see what I am talking about.
vang IMG_1942.jpeg
vang IMG_1942.jpeg (112.39 KiB) Viewed 2948 times


What is this piece of hardware called? I have two others on the boom for the main sheet blocks, as well as one on the mast below the boom for the mast end of the vang. Not sure how strong the groove portion of the boom (or mast) is to handle the working loads we have been talking about for the vang. Should I be thinking of new bails for the vang?

Thanks!
Rob


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Re: Vang questions

Postby jalmeida51 » Mon Dec 30, 2019 12:09 am

Rob The cascade is attached to the bottom of the mast with a piece of 5/16 stay set. The 5/16 goes through a eye strap on the front of the mast. The eye strap prevents the 5/16 from riding up the mast.
The vang is attached the same way but it's on its own 5/16 loop and eye strap. If you use a mast bail you won't have to worry about the vang chaffing the loop. I added a Ronstan 55 block attached to the loop to prevent chaffing.
I'm not sure if you will damage the grooves in your mast & boom? Maybe Green Lake can shed some light on this? You will be increasing the purchase from 4 to 1 to 12to 1. I believe the part where your vang attaches to is called a sliding vang toggle but not sure?
I guess if you aren't sure about the grooves being damaged by using a 12 to 1 vang, you could call Selden Spars, I believe they took over Proctor Spars but not sure? John
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Re: Vang questions

Postby GreenLake » Mon Dec 30, 2019 1:23 am

I doubt the part in the boom can handle horizontal loads from a vang, and while the one in the mas would be loaded more perpendicular, I don't know where to verify safe working loads for these. It's easier to determine those for a U-bail.
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Re: Vang questions

Postby RobH912 » Mon Dec 30, 2019 11:45 am

John - thanks for the further explanation on your set up... think I understand it now.

GL & John - Would an "easy" solution to support a 12:1 vang be to use new SS bails riveted to the mast and boom, and remove the sliding track eyes from the mast & boom groove?

Sorry I need to ask one last "physics" question which I know I've been confused on throughout this whole thread.

From an earlier post my take away was that at 14 knots a vang would need to handle approximately 900 lbs. force. It seems like 900 lbs is the constant.

Regardless of the number of pulleys / purchase / mechanical advantage added to the system 4:1, 6:1, 10:1 are they not all holding 900 lbs force at their attachment points on the mast & boom?

Thanks!


"How much do you need?

You can actually estimate that. You'll need the maximum righting moment that you can achieve. Beyond that, you capsize, so that defines the max sail force (righting moment divided by the lever arm, given by location to center of effort). Now assume that force pulls at the boom and the vang needs to hold that. For a vang at 30° the total force is 4x the force pulling up.

At 14 knots there's about 1lb/sqft of force generated by the sails, or 100lbs by the main. we know you can easily hold her upright, so your vang will need to hold 100lbs. Comes to 900lbs easily, given the way the vang kind of attaches mid boom and at an angle.

There may be a worst case scenario here in assuming the vang needs to hold the entire sail force, so perhaps 500 would be enough, but this is the kind of reasoning behind sizing parts like that."
Rob


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Re: Vang questions

Postby GreenLake » Mon Dec 30, 2019 1:58 pm

For a 12:1 using one cascade.

If loaded to 900lbs, the line in the cascade will be at 445lbs, but the block will hold 900 lbs. That's what the bail will need to hold (on either end).

The purchase will be loaded at 445lbs, and the line in it will be at 445/6 lbs or around 74lbs. That's also the load the cleat has to hold.

However, at a pull of nearly 75lbs, you won't be playing your vang; that's why people use 20:1 if they plan to sail much in regimen where the actual load is close to those 900 lbs.

Some people use a rope loop insteadd of a bail for the mast; with an eye strap on the forward side, to hold it in position. Work because at the mast, the pull is nearly perpendicular and you have access all around (no sail in the way as it would be or the boom).
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