Mainsheet block hanger off boom

[Street Cafe - 9239]

HI,

I am new to the Heron class.

Could someone explain please the logic in having the mainsheet block at the boom on a string hanger? 

Thank you, Susan

[Ian L Cole]

Susan

It appears no one has replied as yet,

So to my mind the block mounting position at the end of the boom is to assist in leverage, and the tethering

(I use multiple loops of spectra) is to allow for the different entry and exit angles occasioned by the huge movement of the boom,

particularly when running off the wind (notice the twist) and thus allows ‘virtually no rubbing on the block side  (friction)”

the mounting position is discussed in Don’s book and the measurement section.

If the block were mounted to a fixed saddle you wouldn’t get the same twist (but whilst mine moves “it is not so loose as to occasion tangling!)

 

There are probably more views, reasons and  opinions.

Trust this helps

 

Ian L Cole  "After FX"  10156

on behalf of

SA Heron Sailing Association Inc.

c/- 1 Day Ave

Daw Park         Sth. Australia  5041

Phone / Fax     08 8357 4202

Mobile          0438 844 974

 

http://www.facebook.com/SouthAustralianHeronSailingAssociation

 

www.heronsa.asn.au

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[Brien Hennessy]

I have one on my boom Susan. When I have asked the general Heron population, they mostly reiterated something about mechanical advantage being improved. I disagree with this explanation because I think that is incorrect. In fact, I think it reduces power. I have one, however, for two reasons. But I'm uncertain if it is logical.

1. It sheets the boom wider (further from midline) than without one. The wide jib sheeting angle and the fat round hull forward of the centre-case mandated by the class rules / design mean that the sheeting angles that are efficient in driving the hull are wider than more modern classes. The skiff that I sail has a seven degree sheeting angle for the jib, and the main a five degree sheeting angle in non-planing setup. The heron jib sheets twice as wide as that because of the carlin width rules. Therefore, if the main sheets at ten degrees off midline (which it does with full sheet tension in ten knots without a strop), the leeward aft third of the bottom third of the main stalls and power falls. This results in the boat going slower to windward. When the main is sheeted wider, all of it sets and the boat feels livlier. Of course this can be achieved by using less main sheet tension and adjusting the vang more, but I find it easier to adjust the main sheet tension for gusts and waves rather than the vang.

2. Slightly less rope length is required for the mainsheet and smaller sheet movements are needed to adjust the main (hence my reduced power comment above). 

Is it critical? Absolutely not.

Is it curious? Absolutely.

Brien

O For Awesome

10272

[Street Cafe - 9239]

Thank you for your thought provoking replies - I now have some things to look at and explore with that part of the rigging.

Susan

[Better Than Ballet - 9940]

Susan,

Jack Holt originally designed the heron as a multipurpose dinghy (Sail / Row / Motor).
'
As a legacy of the Motor function the mainsheet attachment on the transom is split to allow for an outboard.

I am unsure why the (sailing) heron association has not permitted this to be changed to allow for single CL transom attachment.

This would enable the boom to be centered and also reduce the amount of vang tension required.

This change could be made on all herons easily.

The Brits (whom you would be more traditionalist than us) have adopted some modern approaches (see attachment).

[davisonhome]

Hi again Susan, there is a small mechanical advantage created to do with leverage, but as with all gearing there is an equal decrease in effect for identical effort.

Any competent skipper will have no problem using either the conventional block mounted directly to the boom or a strop type system - it is not a big issue in the scheme of things, more a small performance tuning aid as competence and knowledge grows. 

happy sailing,

Richard.

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[Don Jamieson]

Re soft hanger off boom.  The main reason I went to one forty years ago was that if you have a hard scratchy piece of hardware (hanger and bolt) on the end of your boom, then when the boom is stored inside the boat for transport, the fitting scratches up the top of the side tank.  It also allows the block to take up different angles more easily as the boom is eased out on a run, as others have pointed out.  Any mechanical advantage effect is I believe immaterial.

Don Jamieson

[James Gough]

Hi Susan, my understanding is that it allows one to carry more leech tension for the same sheeting angle, or conversely to carry the same leech tension at a wider sheeting angle, as the strop allows the boom to sit outside the triangle formed by the mainsheet. For my massively heavyweight butt this means I can use less vang, which means less mastbend, which means more power. And I can never get enough power.....

 

Cheers, Goughy

 

From: heron-...@googlegroups.com [mailto:heron-...@googlegroups.com] On Behalf Of Street Cafe - 9239

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