Recommended Standing Rigging tensions for Cape Dory 30C

[Javier2020]

Hi,

I have to tune the standing rigging of our Cape Dory 30C, Peace, hull 261, based in Lake Superior, and I was unable to find the recommended tensions.

Thanks for your help !

Javier

[moctrams]

Try this.
TUNING A CAPE DORY 30 CUTTER RIG
Start with centering the mast side to side (fore and aft is a mostly fixed setting due to the roller furler covering
the forestay turnbuckle allowing the only adjustment to be the back stay turnbuckle).
Take the main halyard, and bring it to the base of a stanchion behind the mast slightly. Hold the main halyard at the base of the mast, and tie off the halyard at the winch to lock it's length in place. Next move the halyard to the opposite side of the boat, and measure to the same point on the stanchion..exactly. Apply the exact same amount of tension to the halyard as you make this measurement. The halyard should be the exact same distance away from the stanchion point of reference, as it was on the first measurement. Take any differences out with the upper port and starb'd. shroud turnbuckles.

Ok, next, you need to set the fore/aft alignment. Pull the main halyard tight, aligned straight down the main sail slide track. The distance of the halyard from the mast should be equal at all points on the halyard. Make the fore and aft adjustments as needed to get this result.

Next is tensioning the rig. I use a Loos tension gage. Anything else is pure guesswork, and is prone to big, possibly damaging errors. I tension the uppers to about mid-scale on the
gage, in three steps. Work each side by hand until either turnbuckle is equally hand tight (same number of turns added or subtracted on each side_. Measure the tension and adjust as appropriate, equally on both sides. Next sight up the mast.
Put your eyeball right up close as possible to the track, and sight right up that track.
You will see even the slightest undulation. Adjust the aft lower stays by hand until tight, then add in some tension on the side that needs to be tightened to remove the s-curve. Eyeball the sailtrack again and verify that the mast is straight.

Now move back to the uppers, and adjust them to the same tension by using the gauge. Next adjust the back stay to that same value. You might want to recheck that the mast is still centered with the halyard trick mentioned earlier. This is a double check and usually there will be no adj. necessary.

Recheck the sailtrack for that old S-Curve and take it out with the aft lowers, but let off the opposite side that needs tightening first, then tighten the same number of turns on the side needing tensioning. Check the tension with the gauge again, and equalize all shroud pairs (i.e.: make each opposing pair the same tension while maintaining the mast center position, and keeping the tension in the lower to mid range of the Loos Tension Gauge for that size wire.

The uppers should be pretty close to their final values of tension by now, while the lowers are about 1/2 the way there.

Hand tighten the 2 forward lowers equally, then tighten with a wrench and screwdriver equally until all lowers (fore and aft) reach the same values. This should be about 80% of the final settings. Hand tighten the staysail shroud, then use tools to crank it to the value of the aft lowers.

Have a beer, then sight up the mast again to check for the mast being in-column. Check fore and aft column also at this point. If all is well here, then all that is left is to crank in the final numbers. If there is either an S bend or a bending of the mast fore and aft, loosen the lower shroud on the opposite side of the bend a little, and tighten the appropriate side an equal amount. Check the sail
track again.





Whew..by now, you are about 45 minutes into this thing, and almost done. Ok, lastly, equally tighten the uppers to a value that is mid range on the Loos gauge for that wire size
(the gauge has a diagram on the back side that tells you the tension that it is reading). This is for a CD30. You may want to experiment with differing end values
depending on the boat size. Verify that there is no S-bend again. Then tension the lower shrouds in pairs and equally. The aft lowers should be close to the same tension as the staysail stay. The fore and aft lowers should all have the same tension value.

Last time now..verify that the mast is straight and in column in both axis. Put in cotter pins/split rings to lock the turnbuckles in place (they definitely will and do unscrew if you sail without doing this).

Uppers: 9/32" @ 12% = 1,240#
Lowers, Fwd & Aft: 7/32" @12% = 760#
Aft intermediate: 3/16" @ 12% = 560#
Inner Forestay: 3/16" @ 12% = 560#
Backstay: 1/

[Javier2020]

Thank you ! that is amazing information, I will come back to you with some questions after I have time to reread it again and understand well all the steps.

Your email was cut at the bottom and I didn't get the number for the tension in the backstay, would you also recommend 12%?

Thanks so much !

Javier

[moctrams]

Sorry about that.

Backstay: 1/4" @ 13% = 1,100#

You need a proper Loos gauge:

https://loosnaples.com/tension-gauges

[Maine_Buzzard]

Counterargument-

Throw the Loos overboard. Focusing on numbers does not make the boat sail well.

Center the uppers using the halyard to measure tilt. The shackle should be evenly off the deck when the main halyard is held near the cap shroud turnbuckle. Go from side to side and adjust uppers oppositely until the mast is centered left to right.

Tighten cap shrouds evenly until they have a low “tunngg” vibration when hit. No slop in either. This is only one or two turns.

Tighten lowers so they are just snug. Add one turn on forward lowers.

Cut 3” pieces of stainless wire for temporary use in the cotter holes. Don’t waste pins. Ring dings are OK, but get lost using this technique.

Learn how to adjust your roller furler. Usually you loosen and slide up the torque tube between the drum and foil, and loosen lock nuts top and bottom. Furling line usually needs to be temporarily removed. The fixed drum of the furler is essentially just a turnbuckle body. Holding the forestay with a wrench and turning the drum adjusts the forestay tension/length.

(On this item, I must disagree with prior instructions. Know how to adjust your forestay, it is necessary.)

Set forestay and backstay to no slop when shaking.

Go out sailing in light air. 8-10. Tack often. If the leeward upper goes slack, tighten it up 1 turn, tack and tighten the other the same. Same for lowers.

Go to the bow, look at the curve of the headstay when hard on the wind with a genoa. CD30 should have 6-8” of bow when in a stiff wind, so 3-4” would be present in light.

Heave to. (Gotta practice!). Increase backstay tension if curve is large.

Tack out, go hard on the wind again. Feel the tiller. 2” pulled to windward, 5# of pressure to hold course? Mast tilt effects this. You can spend a day playing with this alone. Let go of the tiller, the nose should round up in a few seconds.

You can adjust this live by sailing upwind and downwind with the roller furler disassembled as above. Buy some 1/2 and 5/8” wrenches at garage sales and tie retaining lines to the pulpit. Know the limits of the furler threads, most have a red dot warning on the threads!

Sail in a 12-14 and repeat the process. Cap shrouds should never go slack, and lower rears might just start to loosen. Sight up the mast and adjust lowers so it stays straight.

Tack and check compass headings. Did she sail evenly to true wind? If not, back at the dock, check mast tilt.

Repeat on a firm wind day. Adjust as needed.

Do not:

Sail and tack hard with loose shrouds. Banging the mast in a blow will hurt the rig. The shock is what pulls the boat apart. Light air, adjust, medium air, rinse, repeat...

Adjust shrouds unevenly. Do one side, tack, do the other.

Drop expensive parts overboard.

You will not wreck your rig. It is state of the art for 1957, and does not need a Nuclear Engineering degree. Listen to the boat, walk around and feel the tensions.

Mark with grey electrical tape at the end of the season, next year start two turns below. I usually tuned my rig in the first two-three weeks of sailing.

[mgphl52]

Well done As usual...

[moctrams]

Well Maine_Buzzard. You have scared the Dickens out of the original post writer..

[Maine_Buzzard]

Check out Jonathan Haidt’s “The Righteous Mind”.

Understanding that differences in risk aversion lead to many of our philosophical differences is important.

I honestly believe that Loos markets to a segment of boaters that need scientific evidence that things are “right”. The gauges are useful for rod rigs, or for racing where repeating settings is critical.

I prefer to allow others to decide how they feel.

Learning why mast adjustment changes boat performance is best done hands on. Move the masthead fore and aft, and feel the tiller pressure change. Gauges and charts do nothing to help fundamental understanding.

FWIW, the USDA has an extensive list of requirements about tomatoes.

https://www.ams.usda.gov/sites/default/ ... 5B1%5D.pdf

Nowhere does it discuss what a tomato should taste like. Relying solely on a Loos gets you a grocery store tomato.

[moctrams]

Ketchup

[Steve Laume]

I had heard all sorts of information on how tight rigging wire should be. There are those that must have an amazing ear to be able to tell the difference in pitch between different wire sizes at different tensions. I would need the proper tuning fork to compare the proper sound. Then there are those that like to push or pull the wires to see how far they move. No one ever says exactly how hard you are supposed to push them or seems to have an accurate way of measuring the deflection. This is pretty basic and will give you a rough idea of how tight a wire is as long as you know what it should feel like. I think this works for experienced riggers who are tuning rigs every day. Then there are those that seam to be able to measure the stretch in a wire of any given length and calculate the tension in that manner as a percentage of the overall wire length. I just don't want to have to do that much math to get my rig right.

I am a firm believer in the Loos gauge. Yes it still takes a lot of time to fuss around with the rig to get it right. To keep the mast in column, the lowers might not even all be at the exact same tension but they will be close and you will know that because you can measure it. I can set the percentage of breaking strength and set it to whatever seems appropriate for each wire size. Once I have the proper percentage, it is easy to recheck it through out the season or before any major trip. This is a great way to know if anything has changed and it shouldn't.

Lots of good advise about rig tuning in the above posts. In my opinion, tossing out the Loos gauge is not a part of that, Steve.

[mgphl52]

Check out Jonathan Haidt’s “The Righteous Mind”.

or Robert M. Pirsig's "Zen and the Art of Motorcycle Maintenance"...

[Maine_Buzzard]

Ditto on ZMM.

Lyla is also superb, and less dated.

He died in Maine last summer.

[Jim Walsh]

I had heard all sorts of information on how tight rigging wire should be. There are those that must have an amazing ear to be able to tell the difference in pitch between different wire sizes at different tensions. I would need the proper tuning fork to compare the proper sound. Then there are those that like to push or pull the wires to see how far they move. No one ever says exactly how hard you are supposed to push them or seems to have an accurate way of measuring the deflection. This is pretty basic and will give you a rough idea of how tight a wire is as long as you know what it should feel like. I think this works for experienced riggers who are tuning rigs every day. Then there are those that seam to be able to measure the stretch in a wire of any given length and calculate the tension in that manner as a percentage of the overall wire length. I just don't want to have to do that much math to get my rig right.

I am a firm believer in the Loos gauge. Yes it still takes a lot of time to fuss around with the rig to get it right. To keep the mast in column, the lowers might not even all be at the exact same tension but they will be close and you will know that because you can measure it. I can set the percentage of breaking strength and set it to whatever seems appropriate for each wire size. Once I have the proper percentage, it is easy to recheck it through out the season or before any major trip. This is a great way to know if anything has changed and it shouldn't.

Lots of good advise about rig tuning in the above posts. In my opinion, tossing out the Loos gauge is not a part of that, Steve.

Excellent advice. Don't lose the Loos......