Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 19-04-2008, 18:07   #16
Registered User
 
Dudeman's Avatar

Join Date: Jun 2007
Location: Gunnison, CO
Boat: Wharram Pahi 31, Oh Be Joyful, ohbejoyfuljourney.blogspot.com
Posts: 42
climbers use a dynamic rope that they climb on. All other slings, chordage etc. is static.
__________________

__________________
Dudeman is offline   Reply With Quote
Old 19-04-2008, 19:45   #17
Certifiable Refitter/Senior Wannbe
 
Wotname's Avatar

Cruisers Forum Supporter

Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: Van DeStat Super Dogger 31'
Posts: 7,334
Quote:
Originally Posted by GMac View Post
......

PS. Spectra and Dyneema do have slight differences but none that 99% of people would see in real life.
OK, I am normally (always?) in the 99% group but like to take any opportunity to try to get partway into the 1%ers.

If you are willing, could you detail some of the differences (either here or elsewhere - don't want to hijack the OP thread).
__________________

__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
Wotname is offline   Reply With Quote
Old 19-04-2008, 20:36   #18
Registered User

Join Date: Feb 2007
Posts: 51
In a gross divergence from internet forum norms I'll not only give my opinion, but also provide an actual reference! The Waterlines column in this month's SAIL magazine touches on this issue. The slab reefing system of a test boat was rendered useless by polyester reefing lines. The resulting stretch rendered the boat unsailable in just 35 knots of wind.

Reefing lines must be extremely low stretch to be of use when they're needed most.
__________________
Hubec is offline   Reply With Quote
Old 20-04-2008, 00:36   #19
Marine Service Provider
 
GMac's Avatar

Join Date: Oct 2005
Location: North of the Bridge, thankfully
Boat: R930
Posts: 1,659
Quote:
Originally Posted by Hubec View Post
The Waterlines column in this month's SAIL magazine touches on this issue. The slab reefing system of a test boat was rendered useless by polyester reefing lines. The resulting stretch rendered the boat unsailable in just 35 knots of wind.
After using polyester for many miles on many differing boats I do struggle to see how they got to 'unsailable', that's a pretty big call. Even way way back in the day when it was 3 strand it still worked even if it did need tweaking up often.

Actually just remembered, I brought a 60fter back from Brisbane just before Xmas and it had 3 strand 'something' reefing lines. That old and mouldy I couldn't tell what it was. They had to work for 24hrs odd but sadly only made 18hrs odd before wearing through, which I put down to age more than anything. Quick swap out and good to go again but as usual, I would have preferred if it wasn't at 2am. Why do things like that always happen in the early hours???, most annoying.

Maybe SAIL were using some of the dodgy polyester that is creeping out there lately. Real sharp price but still bloody expensive as some has alsorts of crap as a core. Looks just like real stuff from the outside but look inside and I've seen a paper like substance rolled up and one had stuff that looked like shredded carpet, both would have massive stretch and strength issues. It's trapped many people.

I think those with decent polyester shouldn't panic.

Wotname - I'll dig out a bit I did for someone on the differences for you. I'll even try to update it with info on the new SK90 that is arriving. SK90 is a 'grade' I suppose you'd call it of the raw material. Started at SK60/62 which has pretty much been phased out in favour of SK75. Mostly just a strength thing.
__________________
GMac is offline   Reply With Quote
Old 20-04-2008, 01:11   #20
Certifiable Refitter/Senior Wannbe
 
Wotname's Avatar

Cruisers Forum Supporter

Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: Van DeStat Super Dogger 31'
Posts: 7,334
Quote:
Originally Posted by Hubec View Post
...The slab reefing system of a test boat was rendered useless by polyester reefing lines. The resulting stretch rendered the boat unsailable in just 35 knots of wind.

Reefing lines must be extremely low stretch to be of use when they're needed most.
Gee that must explain why I have not been able to sail very well everytime I put a reef it over the last 25 years - I was using the wrong reefing line.

Referenced opinions are OK but the argument fails the commonsense test.

In this case, the reefing lines under test stretched too much, the reefing lines were polyester, polyester is known to stretch, therefore the polyester is not suitable for reefing lines. This is not the only possible deduction from the facts. What else do we know - well, polyester has been used for decades for reefing lines, sailors have reefing and sailing satisfactory for decades, therefore polyester is OK for reefing lines. So we have a discrepancy, therfore logic has failed or at least one "fact" is wrong or the conclusion is flawed. Experience tells me that logic doesn't fail, the facts (in this case) seem to be OK so perhaps the one conclusion is wrong.

Commonsense should kick in about here and tell us to look deeper into the conclusions.

Gmac went straight to the heart of it and his version seems to fit the known facts. As well as that, it makes sense (commonsense?).

Of course new technology will make older technology redundant, but can't turn older products into unusable items.

Look forward to the info Gmac - thanks
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
Wotname is offline   Reply With Quote
Old 20-04-2008, 03:18   #21
Senior Cruiser
 
Alan Wheeler's Avatar

Cruisers Forum Supporter

Join Date: Dec 2003
Location: Marlborough Sounds. New Zealand
Boat: Hartley Tahitian 45ft. Leisure Lady
Posts: 8,038
Images: 102
I can't tell you what the differences in use are, but I can tell you the chemistry differences.
Vectran and Spectra is made from a Liquid Crystal Polymer or "Aromatic Polyester". It has really good UV resistance, starts to lose strength from 220degC (which is really impressive) and melts at 330DegC.
Dyneema is quite different. It is made from Ultra High Weight Polyethylene. Or for short...UHMWP. This material has the highest impact strength of any plastic. It is virtually self lubricating and thus, has very low friction and thus very low heat generation.
__________________
Wheels

For God so loved the world..........He didn't send a committee.
Alan Wheeler is offline   Reply With Quote
Old 20-04-2008, 06:39   #22
Certifiable Refitter/Senior Wannbe
 
Wotname's Avatar

Cruisers Forum Supporter

Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: Van DeStat Super Dogger 31'
Posts: 7,334
OK, I had it a little different: that Dyneema and Spectra are both high-moduls polyethylene. Dyneema is trademark of DSM (European company) while Sprectra is the trademark of Allied Signal (USA).
Vectran is the liquid crystal polymer, invented by Celanese Acetate and now owned by Kuraray Co.

Perhaps I have it wrong (again.......)

Gmac???
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
Wotname is offline   Reply With Quote
Old 20-04-2008, 08:21   #23
Registered User
 
Oceansandmts's Avatar

Join Date: Feb 2007
Location: Northern Vermont
Boat: "Piscator"
Posts: 87
And the winner is: Wotname.
__________________
John
Chuck Paine Sarah 32 under construction
Oceansandmts is offline   Reply With Quote
Old 20-04-2008, 08:37   #24
Certifiable Refitter/Senior Wannbe
 
Wotname's Avatar

Cruisers Forum Supporter

Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: Van DeStat Super Dogger 31'
Posts: 7,334
Do I get a Star Reefer stamp?
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
Wotname is offline   Reply With Quote
Old 20-04-2008, 10:42   #25
Senior Cruiser
 
roverhi's Avatar

Cruisers Forum Supporter

Join Date: Aug 2005
Location: Kona, Hawaii, Carlsbad, CA
Boat: 1969 Pearson 35 #108 & 1976 Sabre 28
Posts: 6,006
Send a message via Yahoo to roverhi
FWIW, just spent a day sailing in windy SF Bay. Winds over 30 mph. My 7/16" Sta-Set clew reefing lines did just fine. If they stretched, I couldn't tell it. Sail was flat even when overpowered at the second reef. BTW, went with 7/16" over 3/8" for chafe reasons. Plan on doing some long distance cruising and you do get chafe when reefed for long periods. 3/8" probably would have done just fine. 3/8" tack reefing lines didn't stretch noticably, either.

If you like to waste money, by all means use hi-tech lines. I suppose if you are a weight nut, going with too small to handle hi-tech would have a place.

Aloha
Peter O.
__________________
roverhi is offline   Reply With Quote
Old 20-04-2008, 13:29   #26
Senior Cruiser
 
Alan Wheeler's Avatar

Cruisers Forum Supporter

Join Date: Dec 2003
Location: Marlborough Sounds. New Zealand
Boat: Hartley Tahitian 45ft. Leisure Lady
Posts: 8,038
Images: 102
Ooops, your right Wotname. I was supposed to say Spectra and Dyneema. My Brain just ain't what it used to be.
__________________
Wheels

For God so loved the world..........He didn't send a committee.
Alan Wheeler is offline   Reply With Quote
Old 20-04-2008, 19:04   #27
Certifiable Refitter/Senior Wannbe
 
Wotname's Avatar

Cruisers Forum Supporter

Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: Van DeStat Super Dogger 31'
Posts: 7,334
No problem Mr Wheels and I am also very familiar with the "brain" issue!!!!
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
Wotname is offline   Reply With Quote
Old 21-04-2008, 07:42   #28
Registered User

Join Date: May 2007
Location: Currently East Coast USA/Caribbean
Boat: Stevens 47
Posts: 223
Images: 2
GMac - Unless Vectran has changed, it has terrible UV propeties. I'm surprise to see it used in the cover.

A great way to improve a reefing system is to attach a block at the leech reef points. Use webbing and handsewing to attach the block to the pressed in ring. The block significantly reduces the friction at the high load end: 1) making the last 2' of setting the leech reef easier 2) reduces (maybe eliminates?) the chaffe on the leech reef line.
__________________
svTOTEM is offline   Reply With Quote
Old 21-04-2008, 07:49   #29
Certifiable Refitter/Senior Wannbe
 
Wotname's Avatar

Cruisers Forum Supporter

Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: Van DeStat Super Dogger 31'
Posts: 7,334
Again I understood Vectran to have an very high resistance to UV which is one of the reasons NASA uses so much of it in space missions????

I have wondering about using blocks as you describe - does the block cause any noticable chafe to the sail especially when flogging or is this not a problem?
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
Wotname is offline   Reply With Quote
Old 21-04-2008, 08:16   #30
Registered User

Join Date: May 2007
Location: Currently East Coast USA/Caribbean
Boat: Stevens 47
Posts: 223
Images: 2
I've never seen a chaffe issue on the sail, and minor chaffe on the webbing that attaches it. The block should be up close to the ring. The handsewing should be such that the webbing connecting the 2 should be rigid. If you reef often, you should inspect, and probably replace the webbing yearly - much cheaper then replacing your reefing lines.

As for Vectran, if I remember right, it was first developed for the shipping industry. The UV characteristics are worse then araimid fibers (kevlar). This is why it was never a viable sailcloth. Of course it is expensive, but in the grand prix racing world, money is not the limiting factor. If found the following graphs from the Vectran website -
http://www.vectranfiber.com/pdf/24Pa...al61206-16.pdf
__________________

__________________
svTOTEM is offline   Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
furler-reefing Amgine Construction, Maintenance & Refit 19 21-06-2007 13:30
recommendation for headsail furling/reefing eldiente Deck hardware: Rigging, Sails & Hoisting 6 28-05-2007 23:00
Single line reefing harryvee Deck hardware: Rigging, Sails & Hoisting 13 07-07-2006 19:22
Reefing Systems sjs General Sailing Forum 4 26-08-2004 10:14
Roller reefing / furling sails BBWolf General Sailing Forum 1 12-11-2003 21:10



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 11:02.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.