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[email protected] February 26th 08 12:19 AM

Wire tensions in masthead sloop rigs
 
Which wires in a masthead sloop rigged boat are under the highest
load?

I'm re-rigging my center cockpit 50' sloop (after 19 years) and need
to replace some turnbuckles. I'm thinking the new turnbuckles should
be on the wires with the highest loads - but don't know which ones
they are.

The rig is alum mast and boom, keel stepped. The boat is 38000 pounds
displacement. Mast is 52 ft above the deck and boom is 19 ft long.
Forestay (with Profurl), backstay (with insulators), 4 lowers (2 aft,
2 fwd), 2 intermediates, 2 uppers. The wire is all 3/8" stainless.
We never fly a spinaker and the max headsail is a 130% genoa.

Which wires are the highest loaded and where should the newest
turnbuckles go?


Jere Lull February 26th 08 04:48 AM

Wire tensions in masthead sloop rigs
 
On 2008-02-25 19:19:59 -0500, said:

Which wires in a masthead sloop rigged boat are under the highest
load?


I set our fore and aft stays at a higher static load, but every boat is
different, and dynamic and shock loads complicate the calculations.

I worry about the forestay first since it not only has that static
load, but the strain from the sails and mainsheet.

The backstay probably has the lowest dynamic loading, particularly if
your side stays are swept back.

--
Jere Lull
Tanzer 28 #4 out of Tolchester, MD
Xan's pages:
http://web.mac.com/jerelull/iWeb/Xan/
Our BVI trips & tips: http://homepage.mac.com/jerelull/BVI/


Dennis Pogson February 26th 08 08:53 AM

Wire tensions in masthead sloop rigs
 
wrote:
Which wires in a masthead sloop rigged boat are under the highest
load?

I'm re-rigging my center cockpit 50' sloop (after 19 years) and need
to replace some turnbuckles. I'm thinking the new turnbuckles should
be on the wires with the highest loads - but don't know which ones
they are.

The rig is alum mast and boom, keel stepped. The boat is 38000 pounds
displacement. Mast is 52 ft above the deck and boom is 19 ft long.
Forestay (with Profurl), backstay (with insulators), 4 lowers (2 aft,
2 fwd), 2 intermediates, 2 uppers. The wire is all 3/8" stainless.
We never fly a spinaker and the max headsail is a 130% genoa.

Which wires are the highest loaded and where should the newest
turnbuckles go?


Speaking from long experience, the forestay and cap shrouds seem to cause
the most problems. The intermediates are used mostly for tuning and keeping
the mast straight (laterally) under load.

On our 1980's fractional rigged racer, the backstay was so thin you could
play a tune on it, but the runners were massive and had their own winches,
so again the three-quarter forestay was under constant load, and, being
hidden under twin foil aluminum, was always a worry.

DP



Edgar February 26th 08 09:42 AM

Wire tensions in masthead sloop rigs
 

wrote in message
...
Which wires in a masthead sloop rigged boat are under the highest
load?

I'm re-rigging my center cockpit 50' sloop (after 19 years) and need
to replace some turnbuckles. I'm thinking the new turnbuckles should
be on the wires with the highest loads - but don't know which ones
they are.

The rig is alum mast and boom, keel stepped. The boat is 38000 pounds
displacement. Mast is 52 ft above the deck and boom is 19 ft long.
Forestay (with Profurl), backstay (with insulators), 4 lowers (2 aft,
2 fwd), 2 intermediates, 2 uppers. The wire is all 3/8" stainless.
We never fly a spinaker and the max headsail is a 130% genoa.

Which wires are the highest loaded and where should the newest
turnbuckles go?


If you are changing all the rigging on a 50' yacht it makes good sense to
change all he turnbuckles as well, not just the ones that look a bit dicey.
When you are alone in the cockpit, offshore, in the dark and it comes on to
blow a gale you will think about the items you decided not to replace and
wish you had done so.



Brian Whatcott February 27th 08 03:49 AM

Wire tensions in masthead sloop rigs
 
On Mon, 25 Feb 2008 16:19:59 -0800 (PST), wrote:

Which wires in a masthead sloop rigged boat are under the highest
load?

I'm re-rigging my center cockpit 50' sloop (after 19 years) and need
to replace some turnbuckles. I'm thinking the new turnbuckles should
be on the wires with the highest loads - but don't know which ones
they are.

The rig is alum mast and boom, keel stepped. The boat is 38000 pounds
displacement. Mast is 52 ft above the deck and boom is 19 ft long.
Forestay (with Profurl), backstay (with insulators), 4 lowers (2 aft,
2 fwd), 2 intermediates, 2 uppers. The wire is all 3/8" stainless.
We never fly a spinaker and the max headsail is a 130% genoa.

Which wires are the highest loaded and where should the newest
turnbuckles go?


Good question, Insufficient info to be sure.
I might take a sporting bet on the lower after stay.

Brian W

Lew Hodgett February 27th 08 07:10 AM

Wire tensions in masthead sloop rigs
 
wrote:

Which wires in a masthead sloop rigged boat are under the highest
load?


If you want to keep the belly out of the genny, then the forestay will
have the highest load.

Merriman is long out of business but a company in Connecticut bought
the rights.

Merriman bronze buckles can't be beat.

Lew




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