Hobie Cat Forums

It is currently Thu Aug 28, 2014 7:47 pm

All times are UTC - 8 hours [ DST ]




Post new topic Reply to topic  [ 11 posts ] 
Author Message
PostPosted: Mon Jun 11, 2012 2:11 pm 
Offline
Site Rank - Admiral

Joined: Tue Jul 19, 2011 7:15 am
Posts: 227
Location: Indialantic, FL
My 7:1 Harken setup for the main sheet has a standard non-captive D-shackle to attach the upper block to the boom. I'd like to replace that shackle with a snap shackle to make it quicker/easier to quickly attach and remove. Looking at the options, I am seeing that there are different strengths available. What "Maximum Working Load" do I need for this snap shackle? Any specific recommendations for Ronstan, Wichard, Suncor?

Thanks,

Mark

_________________
2007 Hobie Tiger


Top
 Profile  
 
PostPosted: Thu Jun 14, 2012 10:10 am 
Offline
Site Rank - Captain

Joined: Mon Oct 18, 2010 11:25 am
Posts: 26
Location: Glen Lake, MI
Not quite answering your question, but offering the solution that I use. My upper blocks are hung with a homemade variation of a soft shackle made with 3/16" dyneema. Can't speak to it's longevity, but so far it's performed well in a variety of wind over about 10 days on the water. And it's easy to install and remove. Plus the line only cost $2 and I spliced it with my coat hanger fid in about 10 minutes.

Here's a picture:
Image

And a video of how it works. (It's much faster with the use of two hands.)
[youtube]http://www.youtube.com/watch?v=BXw7queyZ-0&feature=plcp[/youtube]

This spring I upgraded to a the low profile 7:1 Harken setup from an old set of big blocks, which gave me a lot more space, but also was going to add to the length of the sheet I needed by a couple feet. By hanging the upper blocks down the length of the soft shackle (10") I figured I could I save about 7' of line on the main sheet, which keeps the tramp a little cleaner and at about $1.50/ft saves a few dollars. I also avoided the expense of a $25 snap shackle. We'll see if I'm still using it at the end of the summer.

By the way, I have a snap shackle on the bottom block. Don't remember the brand, but it's made in France. Probably 20 years old and works just fine.


Top
 Profile  
 
PostPosted: Thu Jun 14, 2012 1:16 pm 
Offline
Site Rank - Admiral

Joined: Tue Jul 19, 2011 7:15 am
Posts: 227
Location: Indialantic, FL
Thanks for the great suggestion....wish I would have seen it sooner. I like the idea that your solution reduces the amount of line on-board. I ended up buying a Lewmar snap shackle from West Marine, part# 3734415.

_________________
2007 Hobie Tiger


Top
 Profile  
 
PostPosted: Thu Jun 14, 2012 8:10 pm 
Offline
Site Rank - Captain

Joined: Sun Apr 17, 2011 6:31 am
Posts: 71
Location: Johannesburg, South Africa
Adding my sixpence worth;

There are 3 connections on the boom and that is to spread the load when cranking down on the boom.

As this load is substantial with the current purchase, you risk the possibility of snapping / deforming the boom when the wind really blows.

I don't say it will happen but you run the risk of it potentially happening.

cheers

_________________
Richard Stephens
Image


Top
 Profile  
 
PostPosted: Fri Jun 15, 2012 6:34 am 
Offline
Site Rank - Admiral

Joined: Tue Jul 19, 2011 7:15 am
Posts: 227
Location: Indialantic, FL
Hi Richard,

I was a little concerned about the single connection to the boom as well, but have seen several examples of people doing it without any issues. I've been in 20mph winds (and a big "knock-down") with my setup and no problems so far. I think a good enhancement to the picture shown above would be to have the dyneema line loop through the aft hanger, up and over the boom, down to the upper block, then up through the center hanger and over the boom, back to the upper block. It spreads the load across two points, takes it off of the hangers themselves, and puts it further back towards the outhaul connection. Maybe it's overkill, but I think I'll give it shot just for fun.

Mark

_________________
2007 Hobie Tiger


Top
 Profile  
 
PostPosted: Fri Jun 15, 2012 8:48 am 
Offline
Site Rank - Old Salt

Joined: Mon May 09, 2005 10:25 am
Posts: 2553
Location: Jersey Shore
A couple comments-

Adding a pigtail to the main blocks will not eliminate any mainsheet from the tramp- you will have the same amount of sheet on the tramp (actually, if you don't shorten the mainsheet, you'll have more line on the tramp). The pigtail just eliminates excess sheet between the blocks on the boom.

As far as breaking the boom from using only one block hanger, I think it's HIGHLY unlikely that this will happen. I've raced the 18 for over 20 years, seen lot's of booms set up like this, and never recall seeing one break from using a single hanger. However, the center block hanger really doesn't align well to the mainsheet load when used as the sole hanger. It's better to remove it, move it back about an inch, and angle it slightly forward so the rivet holes line up more closely with the mainsheet load. I did crack the center block hanger once a while back when using it as the only mainsheet connection point. I suspect the crack was probably at least partially caused by the angle of the hanger not being aligned with the angle of the main blocks. I have also seen the hanger bend forward at the bottom rivet holes because of the mainsheet load. I now have a backup loop of line that passes through the upper mainsheet shackle and goes over the boom. If the hanger breaks, the loop should at least get me through the race.

The other thing you can do is take off the aft block hanger and move it forward on the boom. Put it about an inch behind the middle hanger and angle it forward so the hoop partially sits inside the hoop of the middle hanger. Then you pass your mainsheet shackle over both hangers for double the strength. This is the strongest setup.

The spectra pigtail is cool, but I would keep a close eye on that line for wear. I'd be more than a little concerned that the edge of the stainless block hanger will eventually cut into the pigtail as it's not a very smooth/rounded edge- it was designed to be in contact with a stainless steel shackle, not a piece of line. I think the pigtail will be even more likely to get cut by the block hanger if you don't re-align the hanger.

sm


Top
 Profile  
 
PostPosted: Fri Jun 15, 2012 10:17 am 
Offline
Site Rank - Captain

Joined: Mon Oct 18, 2010 11:25 am
Posts: 26
Location: Glen Lake, MI
Thanks for the suggestions on the re-positioning the block hanger on the boom. Might be a good project for the next rainy day. Between the PO and I it's been hung like that for quite a few seasons and still looks good, though there is a slight bend forward now.

No wear on the pigtail so far, but expecting some I made a second one just in case. And if it were ever to break while I'm out, I can still hang the blocks directly from the D shackle.

Thinking through it now, you're correct that the pigtail doesn't eliminate any sheet on the tramp, just allows for a shorter overall length. I went down in diameter from 7/16" to 5/16" so it just felt like there was less on the tramp.


Top
 Profile  
 
PostPosted: Fri Jun 15, 2012 10:52 am 
Offline
Site Rank - Admiral

Joined: Tue Jul 19, 2011 7:15 am
Posts: 227
Location: Indialantic, FL
Hi SRM,

Thanks for the thoughts. I had to draw pictures and do the math to arrive at the same conclusion about the "line on the tramp". You have to pull in the same amount of sheet to get to a fully sheeted situation, so there is no less line on the tramp. You Do save line overall, and therefore some money and weight (not much). If you move the upper block 1 foot closer to the lower block using a pigtail or some equivalent, you remove 7 feet of line out of the system in a 7:1 system. Maybe the best pigtail solution is to tie one end to the upper block and a snap shackle on the other end, which attaches to the hanger.

Mark

_________________
2007 Hobie Tiger


Top
 Profile  
 
PostPosted: Tue Jun 19, 2012 2:44 pm 
Offline
Site Rank - Admiral

Joined: Sat Jul 23, 2005 10:04 am
Posts: 153
Location: Bowie, MD
Having a long pigtail on your mainsheet blocks also limits how far you can rake your mast back before you would be "block to block" on your mainsheet.


Top
 Profile  
 
PostPosted: Tue Jun 19, 2012 3:46 pm 
Offline
Site Rank - Admiral

Joined: Thu Sep 23, 2010 1:58 pm
Posts: 176
Location: SE Michigan / NE Indiana
Wouldn't it be better to just use the quick-disconnect pin that attaches the main clew to the boom? What's the advantage of disconnecting the blocks? Perhaps easier access from the tramp I guess.

Having the boom flapping about (or at least weather-vaning) in the wind might give someone a headache...

Perhaps I'm missing something?

_________________
Jeff R
'88 H18 Jolly Mon
'10 F18 Closely Called
Sail Michigan's Great Lakes in 2014
cramsailing.com


Top
 Profile  
 
PostPosted: Wed Jun 20, 2012 9:25 am 
Offline
Site Rank - Captain

Joined: Mon Oct 18, 2010 11:25 am
Posts: 26
Location: Glen Lake, MI
I store the mainsheet blocks inside for the 98% of the time I'm not sailing it during the summer. I figure it only takes a minute to install each time out, and it saves them from a great deal of UV exposure and weather. Boom is unpinned and stored on the tramp. Perhaps a little anal, but it works for me.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 11 posts ] 

All times are UTC - 8 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group