Rigging Tension - Cape Dory 25

[Andy Bazar]

I am seeking advice for "numerical pound tension" values for tuning the rigging on a Cape Dory 25. The owners manual gives general statements as follows:

Upper shrouds (3/16 inch diameter) about 1 inch give.
Head and back stay (3/16 inch diameter) about 1 inch give.
Foreward lower shrouds (5/32 inch diameter) about 1 to 2 inch give.
Aft lower shrouds (5/32 inch diameter) about 1 to 2 inch give.

I have used a Loos tension gauge and interpreted the owners manual as best as possible and have run 750 pounds on the upper shrouds and head and back stays to get the "1 inch give". I have run 350 pounds on the foreward lower shrouds and aft lower shrouds to get the "1 to 2 inch give". These values have seemed to work for me but I am uncertain how scientifically correct they may be. I have not encountered slackness in leeward shrouds on a close haul and have not observed any other adverse implications from these values so far after 5 years of applying these same ballpark tensions. I am concerned with over tension and potential damage to the boat. I am certainly not "bar tight" with these values but I don't know if they are "ideal".

If anyone has technical numerical values which apply, I would appreciate any direction that I might get in terms of what to apply.
Sincerely,
Andy Bazar, awbazar@yahoo.com



awbazar@yahoo.com

[Dennis Truett]

I just stepped my mast on my 26 d. I have access to a LOOSE gauge, but what are the specs? 1-2 inch give is too subjective for me. (You don't need a gauge for those specs.)

Dennis Truett
CD26D

I am seeking advice for "numerical pound tension" values for tuning the rigging on a Cape Dory 25. The owners manual gives general statements as follows:

Upper shrouds (3/16 inch diameter) about 1 inch give.
Head and back stay (3/16 inch diameter) about 1 inch give.
Foreward lower shrouds (5/32 inch diameter) about 1 to 2 inch give.
Aft lower shrouds (5/32 inch diameter) about 1 to 2 inch give.

I have used a Loos tension gauge and interpreted the owners manual as best as possible and have run 750 pounds on the upper shrouds and head and back stays to get the "1 inch give". I have run 350 pounds on the foreward lower shrouds and aft lower shrouds to get the "1 to 2 inch give". These values have seemed to work for me but I am uncertain how scientifically correct they may be. I have not encountered slackness in leeward shrouds on a close haul and have not observed any other adverse implications from these values so far after 5 years of applying these same ballpark tensions. I am concerned with over tension and potential damage to the boat. I am certainly not "bar tight" with these values but I don't know if they are "ideal".

If anyone has technical numerical values which apply, I would appreciate any direction that I might get in terms of what to apply.
Sincerely,
Andy Bazar, awbazar@yahoo.com

[Dennis Truett]

I just stepped my mast on my 26 d. I have access to a LOOSE gauge, but what are the specs? 1-2 inch give is too subjective for me. (You don't need a gauge for those specs.)

Dennis Truett
CD26D

I am seeking advice for "numerical pound tension" values for tuning the rigging on a Cape Dory 25. The owners manual gives general statements as follows:

Upper shrouds (3/16 inch diameter) about 1 inch give.
Head and back stay (3/16 inch diameter) about 1 inch give.
Foreward lower shrouds (5/32 inch diameter) about 1 to 2 inch give.
Aft lower shrouds (5/32 inch diameter) about 1 to 2 inch give.

I have used a Loos tension gauge and interpreted the owners manual as best as possible and have run 750 pounds on the upper shrouds and head and back stays to get the "1 inch give". I have run 350 pounds on the foreward lower shrouds and aft lower shrouds to get the "1 to 2 inch give". These values have seemed to work for me but I am uncertain how scientifically correct they may be. I have not encountered slackness in leeward shrouds on a close haul and have not observed any other adverse implications from these values so far after 5 years of applying these same ballpark tensions. I am concerned with over tension and potential damage to the boat. I am certainly not "bar tight" with these values but I don't know if they are "ideal".

If anyone has technical numerical values which apply, I would appreciate any direction that I might get in terms of what to apply.
Sincerely,
Andy Bazar, awbazar@yahoo.com

[John Vigor]

Andy, the rule of thumb for setting up the rigging (lacking any more specific advice) is as follows:

1. Give the upper shrouds and the backstay a tension of 10 percent of the boat's displacement. You will automatically induce a slightly higher tension in the forestay because it makes a narrower angle with the mast.

2. Tighten the lower forward shrouds (or babystay) so that the mast bows forward slightly, but noticeably, at the spreaders.

3. Tighten the aft lower shrouds to straighten the mast again fore and aft.

4. Sail for a few hours in moderate winds to take out any stretch and allow the rig to settle down.

5. Then, still in a moderate breeze, sight up the mast and adjust for athwartship straightness by letting out a little slack on one side, and taking it up on the other.

Certain boats may call for tighter rigging than this, but preloading with 10 percent of displacement is a good all-round figure and is not likely to send your mast through the deck or the keel.

John Vigor
CD25D "Jabula"



jvigor@qwest.net