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alifish

J/29 Cascading Backstay

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So I've always run all my purchase internal for my backstay (6:1 under the deck, coming out up and over a turning block under the original split backstay. Back down through deck and to another 6:1 on other side) , want to change to cascading. When I was younger it wasn't so hard to use, but at 66 I don't have the muscle to play it like I used to. When boat owners post pictures of a MH with a cascading system it appears they have shortened the wire from the top of mast to the initial purchase. I'd be going with a synethic backstay and doing the same thing as shown in the class tips on the website.

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The typical cascading backstay shown on class site is a 48:1 purchase. My boat initially came with this purchase and it was OK, but have since changed to the 72:1 system that Hustler and other top 29's use. Much easier to use in my opinion and much more tolerant if you are constantly changing headstay lenght for different conditions.

 

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What Squalamax said. Also consider a hydraulic system...seriously not a bad option if you are not racing one design. 

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One Design, ya sure! There never has been any one design racing in J/29s in the PNW, always been a mix of frac and MH. Then some of the fracs had 150% some had 163%, Mixes that with combinations of double and triple oversize chutes. When I got my MH it had 218% spins, in Seattle there was Slick with a 8" taller mast. My MH has all stock measurements. The only Seattle J/29 that beat me consistently was Dynamo Hum, I always felt good about beating them, and we partied hard together!

NO HYDRAULICS, want to be able to play the backstay in puffs along with sheet tension and traveler.

Will be about the same as 72:1 system, Going to continue to use the under deck 6:1 on each side, with some of the same stuff like Husler. One big block up top, cascading down to another.  which cascades down to a double or triple under it and down through the deck which will lead to the each side 6:1 under the deck on each side. With the double it should be about 72, with a triple it would be more.

However the purchase amount wasn't my question, How much did you shorten the backstay itself to top block attachment? To accommodate for forestay on or off!

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I have a dyneema backstay so I could make it any lenght I wanted. Replace every 3 years or so for safety. I do all my own rigging work so no big deal. 

The 72:1 system is configured the following. Dyneema bridle from port side transom chainplate up through heavy duty runner block spliced on shortened backstay. This leads down to a 6:1 purchase connected to starboard transom chainplate. This is your gross tune, which has a cam cleat mounted on bottom block in system and provides 12:1 purchase.(6:1 cascaded with bridle = 12:1)

The upper block end of the 6:1 purchase leads to another smaller 6:1 purchase(bottom end mounted on pad eye just to starboard of tiller) which is double ended and leads to both sides of the cockpit for control by helmsmen. 

Typically, you set your gross tune before racing and play your fine tune upwind. Downwind, you blow off the gross tune for fraculating. 

Headstay lenght doesn't matter as your gross tune purchase can be tightened more or less depending on mast rake. 

If I think of it, I will take a picture of mine tommorow before racing. The above description might be a bit convaluted......I apalogize! 

I've always wanted to mount all the purchase below decks except for the bridle from either side of transom. This would reduce the windage of the two tackle purchases substantially which would be nice. Much cleaner appearance as well. Maybe someday..........

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Tried to upload pics here of backstay but its not letting me for some reason. Sorry. 

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Got how it works, I too am going to go with a bridle off Starboard side over a big block, and down to a smaller dead-ended block that doubles it. then down to double to align it through some deck holes, then it will go to the 6:1 on each side under the deck.

So it starts with the 6:1 under the deck, comes up through the deck and will go to a 4:1  under the bridle, which would make it 24:1, then up to the intermediate block which would again double it - - to 48:1 and double again at the big block that is directly under the bridle top ending up at aprox 96:1. Like your thoughts on a major gross adjustment independent of the fine, guess it could on the dead end of the intermediate block under the bridle. I don't really want to drag in like 20' of line prior to fine adjustments

BUT again I ask how much did you shorten the Dyneema backstay from the original length of wire rope termination prior to the split on the wire yoke.

Does the length make any difference, like if it's higher or lower to the ratios?

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Do not use Dynema for the standing part of the backstay for a masthead rig!  There will always be some sort of stretch / creep. A mate did it on his MORC 30’, he winds on backstay and a minute later the headstay is soft again. 

 

Ping ctutmark!

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You are starting at the wrong end, plus you need to account for friction with your setup. 48:1 is plenty, assuming a man can pull 50 kg pretty easily, thats over 2 tons allowing for some friction loss.

How much travel do you want, lets assume 150mm, 

1st cascade 2:1   300mm

2nd cascade 4:1  600mm

3rd cascade 8:1 1200 mm

to triple block 48:1

Allow a minimum of 1.5m between the top block and the deck for the above setup

 

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Isn't purchase, purchase didn't think it was dependent on which end ya start at? But I will bow to your apparent knowledge. Guess I'll just get a piece that's as long as the stock BS and tie it off to double check where every thing ends up, and then put my splices in : )

No on the dynema, didn't think would be an issue??

 

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On 8/2/2018 at 4:09 PM, silent bob said:

Do not use Dynema for the standing part of the backstay for a masthead rig!  There will always be some sort of stretch / creep. A mate did it on his MORC 30’, he winds on backstay and a minute later the headstay is soft again. 

 

Ping ctutmark!

Must have been low end dyneema or theres other issues with the boat. I have used vectran in the past for the backstay and the bridle. Have since switched to dyneema and there is no difference I can ascertain in creep. The dyneema lasts alot longer in the sun! As long as you use sk78 or better you will be fine. 

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On 8/5/2018 at 7:13 PM, alifish said:

Isn't purchase, purchase didn't think it was dependent on which end ya start at? But I will bow to your apparent knowledge. Guess I'll just get a piece that's as long as the stock BS and tie it off to double check where every thing ends up, and then put my splices in : )

No on the dynema, didn't think would be an issue??

 

My backstay block is about 6' 2" off the deck. Sorry I didn't measure the backstay. Hustlers is lower to the deck than mine. The exact lenght can vary quite a bit and still work. 

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What about a Wheel?  The IMX38 and 45 had these Wheels below deck.  Cleaner with a playable line?

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We had the wheel in an X35 worked great except the couple of times it was released too fast and the damn thing spun out and there was a rats nest wrapped around the wheel. Cost us the race each time it happened. Went to a cascade shortly after.

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On 8/7/2018 at 1:00 PM, Squalamax said:

My backstay block is about 6' 2" off the deck. Sorry I didn't measure the backstay. Hustlers is lower to the deck than mine. The exact lenght can vary quite a bit and still work. 

Yep sure thing but its about the design, cascades rapidly use a lot of real estate which is why they are usually only used on the first few purchases. 74" less 6" travel gives 68" so you run out of cascades at 8:1

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7 hours ago, Kevlar Edge said:

We had the wheel in an X35 worked great except the couple of times it was released too fast and the damn thing spun out and there was a rats nest wrapped around the wheel. Cost us the race each time it happened. Went to a cascade shortly after.

doh-homer-simpson-jpg.80925

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22 hours ago, Gutterblack said:

Yep sure thing but its about the design, cascades rapidly use a lot of real estate which is why they are usually only used on the first few purchases. 74" less 6" travel gives 68" so you run out of cascades at 8:1

I'm not using a cascading system in the usual sense. When I bought my boat, it was set up with the usual multiple cascade 48:1 system found on most J29 MH's. It was OK and worked, but the 72:1 system described above is much better. Easier to play the BS in breeze, easier to ease large amounts to fraculate down hill. 

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