Back stay adjuster

[Peter Griffin]

I am considering upgrading my back stay adjuster . I have a split back stay with the original block and tackle set up. I am interested in a cascading system using Dyneema line and low friction blocks.
Thoughts?
Thanks
Peter
Sent from my iPhone

[Ben Sutton]

Hi Peter,
Here is my two cents worth on that idea. I am not convinced you would gain much. The original system where the two backstay are squeezed together along with the mechanical advantage of the block and tackle, represents a huge amount of leverage already.
Perhaps I am not clear on what you are suggesting. Would you keep with split backstay system and simple add more blocks or go to a single backstay?
Ben Sutton
SV Evangeline
1990 C&C 34+
> On Feb 16, 2026, at 1:27 PM, Peter Griffin <petejg...@gmail.com> wrote:
>
> I am considering upgrading my back stay adjuster . I have a split back stay with the original block and tackle set up. I am interested in a cascading system using Dyneema line and low friction blocks.

> --
> You received this message because you are subscribed to the Google Groups "C&C 34/36 Owners" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to cc-3436+u...@googlegroups.com.
> To view this discussion visit https://groups.google.com/d/msgid/cc-3436/84FA6DDF-41AF-4A2E-9DF8-FC849CE12613%40gmail.com.

[Peter Griffin]

I would keep the existing configuration. From what I have read the cascading system would give more purchase with less friction and the Dyneema line has very little stretch.
Sent from my iPhone

> On Feb 16, 2026, at 5:33 PM, Ben Sutton <sutt...@gmail.com> wrote:
>
> Hi Peter,

> To view this discussion visit https://groups.google.com/d/msgid/cc-3436/3056E9E6-7ABE-4DF7-9280-88A28953BDD2%40gmail.com.

[Ben Sutton]

Yes that is true. I wonder if there is a maximum tension one would have to worry about. It would be interesting to see what others think.

> On Feb 16, 2026, at 2:39 PM, Peter Griffin <petejg...@gmail.com> wrote:
>
> I would keep the existing configuration. From what I have read the cascading system would give more purchase with less friction and the Dyneema line has very little stretch.

> To view this discussion visit https://groups.google.com/d/msgid/cc-3436/C04280C5-AD22-406F-BDDA-6AF4F1620A2F%40gmail.com.

[David Knecht]

Hi Ben- I think you misunderstood my question.  I have the same split backstay system for adjusting the backstay which has a block and tackle to pull the car that tensions the split arms to adjust tension.  My question was about getting the split backstay arms attached to the eyes on the transom after they are detached to pull the mast.  You can't simply attach them on my boat.  There is not enough reach to get to the eyes.  You have to use a block and tackle attached to the non-split part of the backstay or to the turnbuckle upper to get enough tension on it to reach the eyes.  Once both arms are attached you can adjust the turnbuckles and car to achieve the desired backstay tension.  

BTW- I am not sure Dyneema and low friction blocks on the adjustment block and tackle would help the function.  I suspect the movement of the car is hindered by the pinching tension on the car's blocks.  I have to pull slack in the adjustment line and then move the arms of the backstay back and forth (pinching and expanding) to get the car to go up (less backstay).  When it is really tight, it will go up some by itself, but to get it looser, I have to work it (PITA when racing).  If someone has a solution to that problem, I would love to hear it.  Dave

David Knecht

S/V Aries

1990 C&C 34+

New London, CT

To view this discussion visit https://groups.google.com/d/msgid/cc-3436/3056E9E6-7ABE-4DF7-9280-88A28953BDD2%40gmail.com.

[Chuck Scheaffer]

Backstay maximum tension:  

I seem to remember someone stating that rod rigging should not be tensioned beyond a certain percentage of breaking strength as it will stretch permanently and that weakens the rod.  The owner's manual has a Table 5 that lists the -10 Backstay having a breaking strength of 10300#, Preload Limits are 25% to 33% or 3399# and Absolute Preload Limit is 40% or 4120#.

We keep our hydraulic backstay ram around 600# at the dock and pump it between 1000# to 2500# maximum backstay and there is a 3500# relief valve to protect the system from overdoing it.  But bear in mind, that's the pressure in the cylinder.  I'm not sure what the actual tension translates to on the backstay rod itself.

Chuck Scheaffer, Resolute 1989 C&C 34R, Pasadena, Md

To view this discussion visit https://groups.google.com/d/msgid/cc-3436/B7FB3FFC-6A66-483C-85B6-506DFA667AB3%40gmail.com.

[Clark Trow]

Peter,

I'm considering adding a backstay system and am also wondering about how much purchase will be required.  My initial thought was to install a double block to the backstay car and a double block with fiddle on the port backstay padeye, and then add a cascade to the starboard side, but I'm not sure how much purchase I'd need on the starboard side.

My backstay splits about 10 feet above the backstay mounts on the transom.  There's another 34+ in the yard my boat is in and his backstay splits about 30 feet above the transom backstay mounts (that boat has 2 hydraulic backstay adjusters).  C.S. Johnson, the company that makes the only backstay car I've been able to find online, recommends a 1:1.5 ratio (distance between mounting points to height).  It seems the reason is that with the split higher up, a boat hook or other device might be required to push the car up to a neutral point.  

How high up does your backstay split?

Clark

[Clark Trow]

David,

How high up does  your backstay split?  The problem you explain seems to be the reason C.S. Johnson recommends a 1:1.5 ratio (width at transom attachment points to height).  If your backstay splits higher up (say 20 or 25 feet), that would seem to be the issue).

Clark

On Mon, Feb 16, 2026 at 6:36 PM David Knecht <davida...@gmail.com> wrote:

To view this discussion visit https://groups.google.com/d/msgid/cc-3436/B7FB3FFC-6A66-483C-85B6-506DFA667AB3%40gmail.com.

[Peter Griffin]

Hi Clark

   Mine splits about 9 feet off the deck. I did an inquiry on chat GTP. Putting all the information on my boat model , year and existing set up. It came back with very detailed information. It designed a cascade system. I am going to bring the information to a rigger for review. 

Sent from my iPhone

On Feb 18, 2026, at 5:32 PM, Clark Trow <clar...@gmail.com> wrote:



David,

How high up does  your backstay split?  The problem you explain seems to be the reason C.S. Johnson recommends a 1:1.5 ratio (width at transom attachment points to height).  If your backstay splits higher up (say 20 or 25 feet), that would seem to be the issue).

Clark

On Mon, Feb 16, 2026 at 6:36 PM David Knecht <davida...@gmail.com> wrote:

Hi Ben- I think you misunderstood my question.  I have the same split backstay system for adjusting the backstay which has a block and tackle to pull the car that tensions the split arms to adjust tension.  My question was about getting the split backstay arms attached to the eyes on the transom after they are detached to pull the mast.  You can't simply attach them on my boat.  There is not enough reach to get to the eyes.  You have to use a block and tackle attached to the non-split part of the backstay or to the turnbuckle upper to get enough tension on it to reach the eyes.  Once both arms are attached you can adjust the turnbuckles and car to achieve the desired backstay tension.  

BTW- I am not sure Dyneema and low friction blocks on the adjustment block and tackle would help the function.  I suspect the movement of the car is hindered by the pinching tension on the car's blocks.  I have to pull slack in the adjustment line and then move the arms of the backstay back and forth (pinching and expanding) to get the car to go up (less backstay).  When it is really tight, it will go up some by itself, but to get it looser, I have to work it (PITA when racing).  If someone has a solution to that problem, I would love to hear it.  Dave

David Knecht

S/V Aries

1990 C&C 34+

New London, CT

<pastedGraphic.tiff>

To view this discussion visit https://groups.google.com/d/msgid/cc-3436/CACU%3DxUz3MT0CxouuLeiajkzNAsBLq80Pmi5mA1BtjD62rkEA5w%40mail.gmail.com.

[Clark Trow]

Peter, 

I’d be very interested in seeing the cascade system that Chat GPT came up with and your rigger’s thoughts. 

Clark

On Feb 18, 2026, at 6:53 PM, Peter Griffin <petejg...@gmail.com> wrote:

Hi Clark

To view this discussion visit https://groups.google.com/d/msgid/cc-3436/76061389-112B-4044-B690-EDC3BBBF5A3D%40gmail.com.

[Francois Rivard]

I have split backstay adjuster and it works just fine,  we race Wednesday nights (spring, summer,  and fall around here) plus weekend regattas. Effective enough to bring the top of the mast 6 inches and allows easy access to the rear swim ladder. 

Money is better spent on bottom, running rigging, electronics, and other upgrades IMO

My 2 cents.  

François 

1990 34+ Take Five 

Laka Lanier GA 

[Clark Trow]

Francois, 

I appreciate your thoughts. My boat’s bottom is fair and stays pretty free of scum in Lake Erie. I’ve replaced all running rigging, purchased a Vakaros Atlas 2 last year (I highly recommend it), purchased new spinnakers 2 years ago (long story) and new main and jib last fall. Adjustable backstay and baby stay are next on the list. 

Clark

On Feb 18, 2026, at 8:26 PM, Francois Rivard <jeanfranc...@gmail.com> wrote:



To view this discussion visit https://groups.google.com/d/msgid/cc-3436/CAOcd1yfS9%3DH4Usdd6275S9yYAkfG4sLeLpaf9G0yLfLiuv%2BGsw%40mail.gmail.com.

[Peter Griffin]

I will keep you informed. There is an interesting video on you tube. Search  “ Schock 35 project boat. Triple cascade backstay”

Sent from my iPhone

On Feb 18, 2026, at 8:58 PM, Clark Trow <clar...@gmail.com> wrote:

Francois, 

To view this discussion visit https://groups.google.com/d/msgid/cc-3436/B6702642-C0C2-4C80-9FD6-61FDEB344AE9%40gmail.com.