Holy Carp! That must be an expensive system.

Price aside, can you tell me why you went with the Karver blocks instead of, say, a floating Harken 2651 40mm Ti-Lite Single, a Ronstan 20151A or 30151A cheek block forward, and a smaller diameter secondary line? That's what I've been thinking of using.

Of course, we all wonder what blocks you use in the aft end.

Are you using a boom-external outhaul with this setup?

Thanks for the pics!

Harken carbo blocks and all Ronstan blocks are [censored].... they simply explode in the sort of application.

I will take pics of the rear end of the system today and post shortly.

Karver blocks are awesome and never stuff up.

We use Harken Wire Sheaves in the small rope sections, 980kg working load means they hold together pretty good.

Yeah, it's definitely 10:1 and 13:1 system. :-P

The funny thing is: some people told me that the "8:1" cascaded systems are easier to sheet than the 8:1 conventional systems. Well, of course they are, since they are actually 9:1.

When I floated this same design some time ago on catsailor, I was told that cascades had fallen out of favor, as too unreliable, having limitted travel, and requiring lots of line. Has this changed due to the stiffer carbon mast? Have the downhauls also changed? On my old T, I kinda like my 7:1 downwind. I can't imagine what 13:1 would be like!

At Nationals last year, I did notice John and Charlie with a 8:1 + untapered salsa line + carbon mast on their boat. But as I get older, I do start dreaming about 13:1.

You could still use the 8:1 and be fine but we like the ability to trap flat on the wire and play sheet without using back and shoulders (sit up a bit to sheet) We use the 9: mode when its windy as the sheet loads are actually a little lower then compared to 8-14kts when you have heaps of sheet load.

The downhauls are tending towards 16:1 but some still have 8:1

Since I have a boom in my garage awaiting conversion (Thanks Dan!) I would like to pick your brain a bit. If you have the time, please tell me if I'm making sense here.



I've heard people curse Ronstan blocks on this forum before, though I've never seen a failure first hand. Do these blocks really not live up to their SWL ratings? Or do people just not understand that the SWL rating needs to be 2x the line load for a 180 degree turn?

I don't understand why the Harkens would have any trouble in the primary section, where the sheeting forces should be slightly less than in a conventional 8:1 setup. However, they obviously cannot carry the loads in the secondary.

Since the strongest Harken small boat ball bearing traveller car is rated at 1250lbs MWL, I've been assuming main sheet total load does not exceed that. Based on this assumption, the configuration with a cascaded 3:1 primary with 3:1 secondary sees the highest loads: the secondary line has 375lbs of tension, meaning you need a block rated at 750lbs at the front of the boom to carry the 180 degree turn. This is above the SWL of Ronstan and Harken ball bearing blocks, but not above the Karver's.
However, the floating block needs only a 375lb SWL rating, which is well within the 485lb SWL of the economical Harken 2651.

Cascades with a 4:1 secondary see maximum line loads of 300lbs in the secondary, requiring blocks with ratings of at most 600lbs SWL. This falls withing the rating of most of the Ronstan 30mm ball bearing series, so I would expect them to work with a 4:1 secondary. Harken ball bearing blocks cannot handle the loads.



Thanks! Thanks a lot!



That's good to know. Thanks. They are still ball bearing blocks though, which makes we wonder:

What about the Marstrom boom-internal system with needle bearings. Why have I never seen that system actually used (except I have seen the similar system on the Marstrom 20)? It is an option on the Tornado order form.



Aren't these plain bearings (not ball bears and not needle bearings)? Don't they turn less freely? Does this seem to be an issue?

Wow: there are lots of questions in my mind. Thanks in advance if you can answer any of them.

You make perfect sense explaining the advantage of purchase upwind.

Do you do the Boyer thing and set the traveller and play the sheet downwind to moderate hull flight (in addition to steering)? Or do you play the traveller and steer? Or do you just steer?

I ask because I do the Boyer thing, and 13:1 would make this sheeting much less effective. (And 'cause I want to know what technique you use!) Then again, since you fall back to 10:1 when the wind (and puffs) pick up, I guess it's not all that big of a difference in the rough stuff.

Thanks once again,

If you exceed the SWL of the Karver blocks, they break. Which is OK, as long as you know it. Only heard good things about them.

The Ronstan stuff does fail in an internal boom, we have used the friedrecksen wire blocks and they blow up after a few days sailing, they are rated high enough (cant remember exactly) but they just dont last. The Harken carbo blocks blow up as well even when used on the big rope section.

The Harken wire blocks are very well made and have not failed us yet, most guys use them for internal booms.

The Marstrom (playskool) blocks are good when you first get them but they require a lot of maintenance and they are also prone to breaking the side of the block surface off.... we had this at the europeans and it really screwed our day. I am now running the 51mm Harken wire sheaves and they have less friction than the Marstrom blocks and are indestructable.

attached is a pic of the rear of my boom, more pics to follow.

the end of the boom showing outhaul etc

shot shows the whole of the rear part of the boom and sheet system

Macca, while we have your attention..
How do much faster do you think/feel the Tornado is with the carbo mast? I notice that the rating has not changed under our Scandinavian handicap system, but the boat must be faster now.

I personally did blow one Ronstan block in my 10 years of sailing. It was one of the first series ratchet blocks. It had an issue that was recognized by Ronstan and they redesigned their ratchet blocks. They replaced my old block (broken) with a new one.

All the other harken blocks seem just fine to me. Same for Harken. I do have some misgivings about the way Ronstan designs their mainsheet systems but that is about it.

I'm using small Ronstan blocks in my cascading downhaul system and they have held up perfectly over the last three years of sailing. It is a 12:1 systems and blocks are loaded up passed their SWL.

Having said all this I think that my boats do tend to see lower loads then Tornado's or Andrew's (Macca) Super Taipan 5.7. Maybe that is the reason Ronstan fittings are just fine from my perspective.

Wouter

Then maybe it is the non-ideal alignment of the lines/blocks in the internal boom setup that is damaging the Ronstan and Harken blocks. I did find that the "plastic" blocks of both makes really do not like skewed loading or skewed line entries/exists. That tends to eat away at the plastic sides and eventually break the block. Is that what happened with the blocks Macca ?

Personally I'm interested to have a cascading mainsheet setup inside my boot like you, but I don't have big bucks for blocks like you have. So that is why I'm asking, I need to build it using cheap blocks.

Wouter

Macca why is that a line through the side of the boom wall and the orange block ?

Wouter

Macca,

What is that small diameter grey line in front of the mainsheet that is still attached to the bottom mainsheet block ? The one with its own 2:1 purchase. Is that linked up to your mastrotation setup or possible the downhaul ?

Wouter

It is a 13:1 system.



Well the claim is still true when both are true 8:1 systems. There is just less friction in the system. A similar effect can be had by tapering the sheet. And that is what many are using now over cascaded systems. Cascades are still often used as downhaul systems as tapering is less practical here.


Wouter

There is some torsion on the rear block system, the loads are skewed to one side of the blocks a little more than the other. but its pretty minimal and is no more than you would expect from a system that has these loads and hence these blocks.

The blue line through the orange block is there to stop the mainsheet ever popping off the sheave and to stop the block spinning in the boom. it is only held in place by a bolt passing right through the centre of the Karver block.

The small diameter line on its own 2:1 system is a sheeting gauge, it has a shock chord attached to the line and then to the front of the boom, there is a scale marked on the boom about a foot from the font, so you can see how tight the sheet is without looking to the back of the boat. Euan (my crew) wanted it and it doesn't bother me so we did it.

I think the T with the carbon mast is quicker but it is very marginal in most conditions. I think it would be impossible to give it a hard number in terms of increased performance. Certainly in big wind and waves it is much nicer to sail and is for sure quicker. The change to the carbon mast was never for performance, more for consistency in rigs. in this regard it is perfect.

Thanks for the pics. I admire your handiwork. Very nice.

That looks like an outhaul set with stopper knots? Yes, I have wondered about the value of messing with the outhaul at mark roundings with spinnaker. I see you've made up your mind!

Again, thanks for the pics.

Since you're talking F16 loads, you might want to try a cheap and elegant 9:1 setup I devised. I have a detailed sketch somewhere. I will try to find it. It's pretty easy to describe, though, and works with narrow extrusions:

* A harken sheave for 3/8 line at the aft boom end, supported by a through bolt and spacers. (Build-your-own Karver.)
* A harken 2651 airblock floating block.
* A hole near the aft bottom of the boom, to act as a becket for the end of the primary sheet.
* A Ronstan 30151 cheek block at the front inside the mast.
* A pair of Ronstan 30151 cheek blocks mounted on the outside of the boom, to act as the upper blocks of the 4:1.
* A small hole mid-boom for the secondary line to pass from the inside of the boom to the outside. The hole should be placed in-line with the tensioned line to prevent wear.
* An eye secured to the end of the through bolt to act as a becket to terminate the 4:1.

If you place the blocks intelligently, this system reaves beautifully, and there is *zero* torque on the boom arounds its length, nor any significant block side loading when sheeted tight. The trick is to put the internal cheek block, pass-through, and eye/becket all on the same side of the boom.

You can *eliminate* out-of-line loads on the Ronstan blocks by using a pair of singles at the bottom, so they align themselves with the loads, and by sizing the blocks for the bottom of the 4:1 that have diameters matching the width of the blocks at the top, so the top blocks are not side-loaded. Finally, note that the cheek block on the hole/becket side of the boom must be mounted at 45 degrees (to suport the 90 degree line wrap) and should be mounted forward of the opposite block.

Finally, Do not use a long pigtail below the 4:1 to "save weight". If you sized the secondary line properly, you won't save weight by doing so, and lengthening the secondary 4:1 will minimize block side loads and extend the life of the system.

It's the simple, cheap, culmination of all my thoughts on what I wanted to do on my boat up until last week.

I would be very interested in your diagram

Wouter