Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 23-07-2010, 21:52   #16
Senior Cruiser
 
osirissail's Avatar

Cruisers Forum Supporter

Join Date: Feb 2009
Location: A real life Zombie from FL
Boat: Gulfstar 53 - Osiris
Posts: 5,416
Images: 2
The tensioner in Post 10 is elegant except for a few small details. You have to find a block that will work with the psi loads on that backstay and it has to accept the size wire you are using and has to have a radius that will work with the wire without kinking/damaging the wire due to perpendicular loading on the wire instead of axial loading. Rigging wire is not all that flexible and doesn't like side loads.
- - And an additional question is - Is your mast designed to be bent? Ketch boats are not really racing boats and standing rigging is normally permanently fixed with periodic "tuning" needed as the wire ages and stretches. If the mast is not designed to be bent and unbent you could get into more troubles than you want with a mast failure.
__________________

__________________
osirissail is offline   Reply With Quote
Old 23-07-2010, 21:53   #17
Registered User

Join Date: Jan 2010
Location: Port Ludlow Wa
Boat: Makela,Ingrid38,Idora
Posts: 1,973
Just a question

If you put a sheave that far above deck, how are you going to grease it? It's going to be a high load item and will require attention. Two sheaves mounted on the deck would be accessed more easily. All the working parts would be at deck level. In the DC9 and the MD80 the slats are controlled by multiple cables wound on the a common drum. Works good lasts a long time.

Hurry up and finish that boat and go sailing!!!!
Todd
__________________

__________________
IdoraKeeper is offline   Reply With Quote
Old 23-07-2010, 22:13   #18
Registered User
 
Stillraining's Avatar

Join Date: Oct 2008
Location: Puget Sound
Boat: Irwin 41 CC Ketch
Posts: 2,876
Idora...Draw me a picture please ..I cant visualize it.

How often would it need lubed...Im thinking self lubricating delrin bearings myself...no?
__________________
"Go simple, go large!".

Relationships are everything to me...everything else in life is just a tool to enhance them.
Stillraining is offline   Reply With Quote
Old 23-07-2010, 22:46   #19
Registered User

Join Date: Jan 2010
Location: Port Ludlow Wa
Boat: Makela,Ingrid38,Idora
Posts: 1,973
split backstay

Sorry, I am on the road and don't have all the tools I need. I will try words instead.
Imagine the current attach points on the deck as sheaves which lead the wire to a winch drum mounted vertical on the centerline of the boat. One wire winds across the top on one end and the other across the bottom on opposite sides of the drum. (Like a windlass) When the drum rotates both are tensioned equally. Come to think of it you could use a vertical windless and brake and it would be safe.

Can Delrin take the shock loads? Just trying to keep the parts down where you can get at them.

Sorry if I am unclear (that's what I am told at home)

Todd
__________________
IdoraKeeper is offline   Reply With Quote
Old 23-07-2010, 23:12   #20
Registered User
 
Stillraining's Avatar

Join Date: Oct 2008
Location: Puget Sound
Boat: Irwin 41 CC Ketch
Posts: 2,876
Ah!...I get it now....too much deck clutter.

Was just researching the derlin thing...cant find a wire shived one any way so its a moot point probably.

Realistically how often would that shiv need attention anyway...Its not like it will get but a couple 180 to 360 degree revolutions per sail.
__________________
"Go simple, go large!".

Relationships are everything to me...everything else in life is just a tool to enhance them.
Stillraining is offline   Reply With Quote
Old 24-07-2010, 06:52   #21
Registered User

Join Date: Dec 2009
Posts: 3,016
Images: 4
The sheave is not a problem. The sheave will not need grease as it runs very little, maybe 4 inches. And it probably has a plain bearing anyway.

If I recall, marine wire comes in 1x19 (19 single strands) which is seen in standing rigging, and 7x7 (seven strands of 7 wires each) which is for running around blocks. Your block will be for "wire". It will have a solid, large diameter, probably metal, sheave and steel cheeks. You will probably need to get the block from a serious rig shop rather than the usual retail sources.

This is a common way to set it up. As some poster said you can also use synthetic line for this but it's mainly a weight saving technique which I'd guess you're not too keen on. And a pro rigger should be consulted for designing that trick.
__________________
daddle is offline   Reply With Quote
Old 24-07-2010, 07:27   #22
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Baltic (Summer) (the boat!); somewhere in the air (me!)
Boat: Cutter-Rigged Moody 54
Posts: 19,745
Quote:
Originally Posted by Stillraining View Post
I would like a way to adjust my back-stay tension on the main mast of my Ketch .

Is this accomplished the same way as a split back-stay on a sloop?...with some sort of car and block and tackle?

I dont see how this would not be a real mess to contain, as the split in my back-stay is at least 1/3 the way up the leach of my Main sail...it has to be to clear the mizzen shrouds.

Red circle shows split location
Entirely off topic, but that's a pretty boat.
__________________
Dockhead is online now   Reply With Quote
Old 24-07-2010, 09:39   #23
Registered User
 
Stillraining's Avatar

Join Date: Oct 2008
Location: Puget Sound
Boat: Irwin 41 CC Ketch
Posts: 2,876
Quote:
Originally Posted by osirissail View Post
The tensioner in Post 10 is elegant except for a few small details. You have to find a block that will work with the psi loads on that backstay and it has to accept the size wire you are using and has to have a radius that will work with the wire without kinking/damaging the wire due to perpendicular loading on the wire instead of axial loading. Rigging wire is not all that flexible and doesn't like side loads.
- - And an additional question is - Is your mast designed to be bent? Ketch boats are not really racing boats and standing rigging is normally permanently fixed with periodic "tuning" needed as the wire ages and stretches. If the mast is not designed to be bent and unbent you could get into more troubles than you want with a mast failure.
Orisssail:

Somehow I missed this post...all very good points...

1) I am going to consult a rigger for the block issues..and have thought of all this wire bending tight radius already...Im still considering twin hydraulic application due to that as it would leave everything the same except shorting the two legs to accommodate the cylinder...Its just expensive is all. Am-steal is still an option but I have stated my concerns with that already.

2) Im not fractionally rigged as you already know so its not like Im bending the mast so much as tightening the forestay...I love wind...If it isint a SC waring or greater its not a very good day for sailing IMHO......so I need a way to consistently increase and decrease my forestay tension for proper sail trim yet relieve it at the dock...its just to hard on the boat IMO ...at least an old one like mine to leave everything that tight all the time.

Quote:
Originally Posted by daddle View Post
The sheave is not a problem. The sheave will not need grease as it runs very little, maybe 4 inches. And it probably has a plain bearing anyway.

If I recall, marine wire comes in 1x19 (19 single strands) which is seen in standing rigging, and 7x7 (seven strands of 7 wires each) which is for running around blocks. Your block will be for "wire". It will have a solid, large diameter, probably metal, sheave and steel cheeks. You will probably need to get the block from a serious rig shop rather than the usual retail sources.

This is a common way to set it up. As some poster said you can also use synthetic line for this but it's mainly a weight saving technique which I'd guess you're not too keen on. And a pro rigger should be consulted for designing that trick.

Agreed...I don't see a lube issue myself either but always open to others experience and will listen...This old dog learns new tricks pretty easily.....so Im not closing the door on synthetics or other ideas either but am very Leary of errant knifes, sharp things of any kind around them..especially in this aplication...Also the UV thing has its own issues..

If I used twin hydraulics the rigging would be 10 to 12 years like every other piece on the boat...start to bend that around shivs or switch to synthetics and you through that out the window.


Quote:
Originally Posted by Dockhead View Post
Entirely off topic, but that's a pretty boat.
Thanks!...After almost two years in the yard... she isnt quite as charming but will be again...................................someday... .I want to go sailing....
__________________
"Go simple, go large!".

Relationships are everything to me...everything else in life is just a tool to enhance them.
Stillraining is offline   Reply With Quote
Old 26-07-2010, 10:47   #24
Senior Cruiser
 
Sailmonkey's Avatar

Cruisers Forum Supporter

Join Date: Sep 2009
Location: Houston
Boat: '76 Allied Seawind II, 32'
Posts: 5,774
I've never greased the blocks on the runners........they have plain bearings, and they don't move quickly.
As for the block, they're already made off the shelf items. Harken can match a tensioner with a block for you, all you need to do is add the 7X19 wire (done with mechanical terminals like hayn hi-mods), shake and add water.

on a side. Have you already played around with pre-tensioning the backstay for beating in heavy air?
__________________
Sailmonkey is online now   Reply With Quote
Old 26-07-2010, 10:57   #25
Senior Cruiser

Cruisers Forum Supporter

Join Date: Aug 2009
Location: between the devil and the deep blue sea
Boat: a sailing boat
Posts: 17,314
Dyneema's good. Then again why so much hassle tensioning. Why not pre-tension properly and let it be?

Racing? A lot of heavy weather upwind work?

I found it that on a cutter rig it is much easier to fly the inner sail (staysail I think) than to tension the furled, or shortened genoa. Sort of like the shorter the string the less curve in the jib given the same tension of the stay.

We have a tensioner but do not really remember ever needing it badly. It is there so I will use it, but I could do just as well without it (top rigged sloop, double backs).

b.
__________________
barnakiel is offline   Reply With Quote
Old 26-07-2010, 11:03   #26
Senior Cruiser
 
Sailmonkey's Avatar

Cruisers Forum Supporter

Join Date: Sep 2009
Location: Houston
Boat: '76 Allied Seawind II, 32'
Posts: 5,774
Quote:
Originally Posted by barnakiel View Post
We have a tensioner but do not really remember ever needing it badly. It is there so I will use it, but I could do just as well without it (top rigged sloop, double backs).

b.
I added a tensioner to my pearson vanguard. While it was nice to be able to tune like the boats I crewed on with other peoples money, it was nothing really other than cosmetic shape for the headsail(the boat would only go so fast or point so high anyway).
__________________
Sailmonkey is online now   Reply With Quote
Old 26-07-2010, 20:03   #27
Registered User
 
Stillraining's Avatar

Join Date: Oct 2008
Location: Puget Sound
Boat: Irwin 41 CC Ketch
Posts: 2,876
Quote:
Originally Posted by Sailmonkey View Post
I've never greased the blocks on the runners........they have plain bearings, and they don't move quickly.
As for the block, they're already made off the shelf items. Harken can match a tensioner with a block for you, all you need to do is add the 7X19 wire (done with mechanical terminals like hayn hi-mods), shake and add water.

on a side. Have you already played around with pre-tensioning the backstay for beating in heavy air?
Im thinking the same way about the lube issue.

Yes I put some pre bend in the mast last time but it wasn't enough in the snot....so if I crank more on I want to be able to releave it when done playing.

Quote:
Originally Posted by barnakiel View Post
Racing? A lot of heavy weather upwind work?

I found it that on a cutter rig it is much easier to fly the inner sail (staysail I think) than to tension the furled, or shortened genoa. Sort of like the shorter the string the less curve in the jib given the same tension of the stay.

b.
The latter.

I have an inter forestay as well but I sill want the adjustment...Hydrolics with a guage is also a way to actually see what kind of tension is on it.

Quote:
Originally Posted by Sailmonkey View Post
I added a tensioner to my pearson vanguard. While it was nice to be able to tune like the boats I crewed on with other peoples money, it was nothing really other than cosmetic shape for the headsail(the boat would only go so fast or point so high anyway).
Probably true...see previous answer.
__________________
"Go simple, go large!".

Relationships are everything to me...everything else in life is just a tool to enhance them.
Stillraining is offline   Reply With Quote
Old 26-07-2010, 21:23   #28
Registered User
 
Portobello's Avatar

Join Date: Mar 2009
Location: Hobart
Boat: Portobello - a Walter Knoop designed "DOVEN 30"
Posts: 231
Images: 5
Quote:
Originally Posted by Stillraining View Post
So you just keep adjusting your turnbuckles all the time?....or just set it and forget it?

My understanding is normal turn buckles do not have the thread design
for constant adjustment all the time....that's not their purpose.
Mine is similar to the one here:


http://www.harken.com/images/back3.gif

Cheers
__________________

__________________
Love the journey!
Portobello is offline   Reply With Quote
Reply

Tags
backstay tensioner

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
Hello from Croatia (Split) lovor_vukovac Meets & Greets 12 06-02-2010 22:11
SSB and Split Backstay denverd0n Marine Electronics 6 15-10-2009 15:17
Split Bareboat BVI - May'ish ? Moonchaser2304 Atlantic & the Caribbean 0 30-01-2008 20:42
Anyone split their time between an RV and boat? CSG Liveaboard's Forum 24 29-08-2007 08:35
Air to Air Single split AC Octopus Plumbing Systems and Fixtures 4 15-07-2007 08:19



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 08:32.


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.