Adjustable Diamonds

I'm trying to gather some information for setting up adjustable diamond wire tension on my A-cat. It has an applied composites mast (which I'm guessing is now FibreFoam) and the diamond wires go through the bottom mast plate to individual nuts on the underside...it's a real PIA to adjust tension. I want to go to the modern a-cat adjustable "from the wire" tensioning system with the lever arm and purchase and such...I'm pretty handy with composites and fabrication, but I don't want to jump into this without doing a little research (i.e. drilling holes in my carbon mast). Can anyone shed some light or point me to some resources?

contact Mischa Heemskerk... his dad was working on that, some years ago

Mischa just launched a new website, his contact details should be up there: www.mischaheemskerk.com

It's not THAT special...most new A-cats come with the system...surely someone state-side has had some experience retrofitting the system to an older mast.

http://www.fiberfoam.net/Default.aspx?tabid=94

Look for part A44, it's a whole kit to do the thing

I know Hans Klok (Catamaranparts.nl) sails with an adjustable wire tension and carbon mast.

Gill

Jake

First, try for details here
http://lists.topica.com/lists/usaca

To upgrade, you need to redo your mast base to accomodate the exit sheeves and the cleats for the diamond tensioner.

People also add some positve rotator ears if they want and certainly add a new deck sweeper rotation arm.

This is the prefered location for a veloctoek or compass.

You can get carbon plate from Hall spars or the link tami gave.

A cheaper solution is to take fiberglass G10 and vacumn bag carbon layers top and bottom to get the proper thickness, cut and finish to suit.

The hard piece to find or fabricate is the U shaped strap which wraps around the mast and attaches to the diamonds.

Mark

Manufacturing and composites are no problem. I've got two rolls of carbon, a great mechanical vacuum setup, and I work at a machine manufacturing facility with three steel cutting lasers, finishing, cnc, welding, milling, etc...

I guess I should have been more specific...I really want to know how much does the mast need to be reinforced where blocks enter and exit. What to people like or dislike about the system they have?...I probably need to start taking pictures and studying.

I don't know if this is the same system or not but Bim had a system where the diamonds and the cunningham were attached. Pull the line and the luff and diamonds were tensioned together. Might be an "easy" boat to get to see for an example.

I had the Bimm 2000 combi system when new..not precise--not so good. Eventually I turned the s.s. tubing "stirrup" around 180 degrees in front of the mast and used it for the diamond wire tensioner. Worked fine at 10:1 downhaul.

Later I got several aluminum or s.s. stirrups off old aluminum A-cat masts and used them on CF masts. These old designs work just fine, even better with tiny double bullet blocks and small line. But larger triples and quads are a nuisance in small spaces- do not use them.
9 inch long x 2 inch by 1/8 inch thick aluminum plate works fine- 2 pieces bent into a shallow Z, lightened by drilled holes. None of mine ever broke.... except the first one when I went out in a blow, when two very old, poorly-fastened rivets in the downhaul DID come off the aluminum mast..... Twang-CRUNCH... Splash.

Jake,
Most of the systems I've seen are home made, you should be able to do it easily. I'll look for pictures.

You might want to consider having a system that adjusts each side individually.

Bill

more pics

another view

Bill,

What do the lines that go in the mast do?

So part of your question is do you like them, do you use them. I dont, I have fixed diamonds that I rarely touch.

If I was going to do it, I would make each side adjust independantly, give you more flexibility in the adjustment.

I dont think you need to overly reinforce the mast, the point that the lever arm goes into the mast might need some reinforcement, but I'm not sure. The blocks need to be wire line blocks, not regular exit blocks.

All the attached pictures obviously have internal downhaul and diamond tension setups, not sure the purchase or how you fit all those blocks in the mast.

Bill

Yeah, I'm not so sure I want everything combined - rig tuning isn't that simple!

I saw one setup with a single line coming from the yoke into the base of the mast with a bunch of internal purchase - very clean but the innards were a bit mysterious. I'm most uneasy about how to attach things to the carbon mast and what kind of loading the attachment points can handle. Most fittings are riveted to the mast (and it's 7 years old) so I guess that's acceptable. 10:1 sounds like a lot of purchase if you had a lever-arm on the diamonds - did that include the leverage of the arm?

One set of exit blocks is for internal downhaul, probably 8 to 1 , the other set is for internal diamond tension setup, probably also 8 to 1 or more. These systems are set up so that you can pull on either line to adjust the tension, so depending on your tack, you can adjust both the downhaul and the diamond from the wire.

I just have one set of blocks for downhaul in my mast, so I only have one exit block on either side and one set of cleats. Check out the picture, the blue line goes into the mast and through an 8 to 1 block set up. The top of the 8 to 1 is tied off to a bolt that runs through the mast. The bottom of the 8 to 1 is ties to the yellow line which comes out the exit block and goes around the blocks in on the sail to make a 16 to 1 downhaul.

Its really not that complicated. PM me and we can talk on the phone. I had the same questions when I set up my mast and someone talked me through it.

those pictures are great Bill - PM coming.

I had a similar Applied Comp mast on a Boyer 4. I had the diamonds cut short and fitted with a toggle/swage turnbuckle at the bottom. With the toggle removed, the "T" that formerly held the toggle slides through the hole in the mast base. It's not adjustable from the wire, but is easier to adjust than the stock system, quick to implement, and cheap.

Nice. Thanks.

Jeez Jake,

You go and get something simple like an A cat and the first thing you want to do is complicate it with more stuff and lines to pull - Remeber you are by yourself and only have 2 hands.

I found the simpler solution was to run the diamonds into the mast and use a single bolt at the base for adjustment. Something that can be done easily on the water if the wind drastically changes.

If you really want to add all this [email]cr@p[/email], you should contact Rush Bird. Hed did up several and has all the dimensions and specs etc to make the change easy as possible, rather than inventing the wheel over.

Matt

That's why I posted here...didn't want to re-invent what already existed!

And I agree with you - too much complication is a bad thing. I don't intend to adjust them that frequently but what I have right now is impossible to adjust in under 15 minutes. I want to make it easier to adjust and figured that while I'm at it, I might as well put a control line on it...not that I'm known for over-doing stuff or anything. <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

Jake

I can tell you what Lars Guck told me...

"Don't change anything for three years.... Sail the boat!"

FYI.... Lars uses the fixed diamond adjuster as well. (It may be a single turnbuckle system though.) He flips the boat. unloads the tension at the spreaders... makes his adjustment and re attaches and tensions at the spreaders. Took him about 10 minutes at the NA's.

Yeah, well...Lars knows exactly where to put them...I don't. I've got great 10k and under speed but my moderate to heavy air tuning needs some work.

Welcome to the A cat. I had this same problem and after I heard the same thing from at least 5 five of those top guys I gave up and concetrated on my stearing (I still have not figured it out on the Uni like I can on sloop, but it was much faster as soon as I quit messing with stuff)

Isn't that the message we hear again and again. Get your trim into the ballpark and then concentrate on driving the boat. I suppose the problem when beginning in a new boat is to know when you are in the ballpark?

I found the A to be way overpowered to weather. It is so light and narrow with the very high aspect rig. I am light and no amount of adjustment made any difference what-so-ever as soon as it got to 12Knots. Just ask someone who has already been sailing and is near your own weight where they are at settings wise. Spreader rake and tension, and then mast rake (mast rake dependant on the boat type) Bingo - Your fully tuned. <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

In reality the ball park could be defined as the mast pointing up - The rudders and boards pointing down and the bow forward gets you in the ball park. <img src="http://www.catsailor.com/forums/images/graemlins/blush.gif" alt="" />

That is rich. Perhaps slightly oversimplified, but very good <img src="http://www.catsailor.com/forums/images/graemlins/laugh.gif" alt="" /> <img src="http://www.catsailor.com/forums/images/graemlins/laugh.gif" alt="" /> Message is very clear.

We've got three Boyer IV's here running against one of your BIM's and an A2. Both the BIM and A2 run deeper than all three of us Boyer IV's in the breeze. My main is pretty long and I'm already block to block with my light air setup (I'm very happy with my speed in the light air) so raking back more is going to be tricky. I've got to work on heavy air and find a way to foot off without losing control...hence time to work on the diamonds. The fastest way I know to figure out where the diamonds need to be set is by having something I can adjust easily and without flipping the boat each time.

I really thought I was going to be in for a deep learning curve on this boat but I've found it to be really intuitive with tons of feedback. It helps that the guys sailing around here are very similar in speed.

[quote
I really thought I was going to be in for a deep learning curve on this boat but I've found it to be really intuitive with tons of feedback. It helps that the guys sailing around here are very similar in speed. [/quote]

I could not agree more that the A provides instant feed back on adjustments. For me though at 12+ I am maxed out going to weather. Diamond adjustment adjusts draft in the lower/mid portion of your sail. The simplifed version is that more prebend is a flatter sail. My downhaul will pull my sail board flat, and do it with a pretty very wide range of diamond settings. It is impossible to get a sail flatter than flat, and the top of the thing is dependant on the mast/sail combo along with your rotation and sheet settings. The top of the thing is where you gain control (or not) in a blow. What we need is a good text book explaining the art of running the tiller and sheet, because that is where the good guys make the gains.


<img src="http://www.catsailor.com/forums/images/graemlins/blush.gif" alt="" />Sorry about this- All I started to do was give you some crap relative to complicating your life.

M

Matt,

I think you are contributing some great stuff, if not exactly to what Jake asked (sorry for helping in hijacking the thread Jake).



Exactly what I have thought many times as well. I have been looking a long time for a book or anything really which discusses that in details. "High Performance Sailing" digs into it somewhat, but not well enough for us. Like, how do you run your boat in weak winds with a chop offset from the wind..

I could not agree more that the A provides instant feed back on adjustments. For me though at 12+ I am maxed out going to weather. Diamond adjustment adjusts draft in the lower/mid portion of your sail. The simplifed version is that more prebend is a flatter sail. My downhaul will pull my sail board flat, and do it with a pretty very wide range of diamond settings. It is impossible to get a sail flatter than flat, and the top of the thing is dependant on the mast/sail combo along with your rotation and sheet settings. The top of the thing is where you gain control (or not) in a blow. What we need is a good text book explaining the art of running the tiller and sheet, because that is where the good guys make the gains.


<img src="http://www.catsailor.com/forums/images/graemlins/blush.gif" alt="" />Sorry about this- All I started to do was give you some crap relative to complicating your life.

M [/quote]

No offense taken on the hijack - this is the root of the problem I'm chasing.

thats not good, you need a sail cut higher in the clew.

yeah, I know...real pain to get under during tacks too. Budgeting for a new main in the spring.

There is a Florida senior sailor of A-cats notorious for never changing anything on the boat- runs it like it came from the factory...And has about 20 National Championships, mostly Hobies but no bugs on him about that.
I have been trying to figure out the tuning deal as Matt describes it on these pages---for 8 years now. As a trained scientist, I would have hoped to be better at figuring out the A-cat bits, (i.e: diamond wire downhaul management) but still do the same dumb things that are apparently now habitual. DOH! Rage Against The Stupidity! Tho maybe more Zen would help.....