Specs for Adjusting Shrouds on 34'
- Thread starter Richardwm
- Start date
As a rule of thumb shrouds should be tensioned to 15% of their breaking strength, which is dictated by the size of the wire. There’s usually not much model specific guidance beyond that.
More in depth guidance for tuning rigs is at https://www.riggingandsails.com/pdf/selden-tuning.pdf
More in depth guidance for tuning rigs is at https://www.riggingandsails.com/pdf/selden-tuning.pdf
For me a very timely post. I've got to adjust my rigging after my O'Day 34's deck recore project. Karma is 1981 O'Day 34.
Here it is;
I found this .... er somewhere, and OCRed it. Sharing it here, because this does come up occasionally.
As with anything that you find on the internet, take ALL OF THE ABOVE with a grain of salt.
Finally, if someone on FaceBook is looking for this, PLEASE POINT THEM HERE, and don't post it to FaceBook. Here it is searchable/discoverable.
O'DAY YACHTS WITH ISOMAT SPARS
Mast Wedge and Pin Instructions
These instructions are for installation of the mast boot, wedges,
and deck pin on O‘Day Yachts equipped with Isomat spars.
l. Before stepping mast, slip neoprene collar over the mast and up to the gooseneck. The smaller end goes on first.
2. After stepping mast, and before final tuning of the shrouds, install the rubber wedges between the collar and mast.
3. After final tuning, and a short sail in light-to—moderate winds, drill a l/2" hole through the mast, just above the
collar. Install the l/2" stainless steel pin through the spar and fix in position with cotter pin. This pin will hold the deck from flexing. It is important that it be installed. The pin should be fust forward (approximately l/2") at the extruded niche in the side of the mast.
[NOTE - I have done this to my boat. I DO NOT RECOMMEND THIS! There is a far better system, using turnbuckles and "T" fittings that clip into the deck plate (my Isomat deck plate casting has cutouts for these!) which beats using a ½" stainless steel pin through the mast to hold the deck down. If you use the pin it needs to be held in place with cotterpins and washers... It is a mickey-mouse solution]
4. Silicone (or Butyl) sealant must be placed around the mast and mast collar where the clamp will tighten. Be sure to fill the spinnaker track and mainsail track grooves well with silicone (or Butyl) sealant. The rubber boot is clamped around the collar and the mast. For the top clamp, leave enough boot to roll it back over the clamp.
Illustration 1:
STEPPING AND TUNING THE MAST
Before stepping the mast, be sure all running and standing rigging is properly installed, cotter pins are spread, and halyard sheaves are free to rotate. The upper shroud is run through the slot in the outboard end of the spreader. After the shroud is in place, tape over the end of the spreader to protect the sails. Check the spar lights to be sure they are operational.
Open all turnbuckles to their full extension.
Refer to separate sheet for mast-collar instructions.
Step the spar through the deck and table (if applicable), and then onto the mast step. Be careful not to pinch the mast wires during the stepping. The mast step was set at the factory to provide an aft rake. If you wish to adjust this, loosen the mast—step bolts and slide the step fore or aft.
The mast—ground wire should be attached to the mast at this time.
Attach all the shrouds, tighten the headstay, backstay, and upper shrouds to a taut condition. Refer to the mast-collar drawings to install the rubber wedges, mast pin, and boot.
Installation of the pin is essential to prevent the deck from lifting, when full rigging forces are applied. Do not sail until this pin is properly installed. For now, leave the lower shrouds slack. Attach a weight to the main halyard and allow it to hang freely. Adjust the headstay and backstay to achieve a straight spar, when sighting up the trailing edge.
- O'Day 37 - 12"
- O'Day 34/35 - 8"
- O'Day 30 - 9"
- O'Day 28 - 7"
aft of the spar, when measured at the gooseneck. Next, with the boat level athwartships, tighten the upper shrouds to get the mast straight. Finally, tighten the lowers no more than hand tight.
Final tuning must be accomplished while sailing. In a light breeze (6 - 8 knots), adjust the shrouds to achieve a straight spar on either tack. In heavier winds, any curvature should be gradual and constant from the deck to the mast head.
The rig will need adjustment after a few sails to compensate for the stretch in the wire. Be sure to install cotter pins in all turnbuckles and clevispins, and tape over them to prevent injury to crew or damage to sails.
Fine tuning for the best performance will depend upon your local conditions and your sails. Consult your dealer or local sailmaker for their suggestions.
DANGER: WHEN you ARE HAULING, LAUNCHING, AND SAILING NEAR LOW OVERHEAD WIRES, YOU MUST BE VERY CAREFUL THAT THE MAST DOES NOT TOUCR THE WIRES. THE MAST COULD CONTACT HIGH VOLTAGE ELECTRICITY TO THE PEOPLE ON BOARD AND CAUSE SEVERE BURNS OR DEATH. THE BOAT’S LIGHTNING GROUND SYSTEM WILL NOT PROTECT YOU FROM THE HIGH VOLTAGE POWER FROM POWER LINES.
CHAINPLATE RODS
O'DAY 28, 30, 34/35, 39
The chainplate rod system used on the shrouds of your boat is designed to carry rigging loads to the structural floor pan. IT IS IMPORTANT THAT THE INSTALLATION BE CHECKED FOR PROPER ROD TENSION. The system is designed to carry rigging loads to the pan, rather than the deck.
After the boat is launched and the spars installed, but before the rigging is tightened, the rods should be taut. Pulling on the rod, at mid—height from pan to deck, you should notice a very slight deflection. If the rod is loose, it should be tightened. After final rigging and a few early sailings, recheck the rod tension. If the deck is deflecting at the chainplates, the rod needs further adjustment.
To tighten the rod, remove the cap on the pan at the base of the rod and get a wrench on the nut. Above the pan is a flat spot on the rod. Use another wrench or locking pliers to turn the rod. DO NOT OVERTIGHTEN. If the rods are too tight, with the rigging slack, the deck could be pulled down, creating a depression on deck and damage to the gelcoat surface.
The U-bolt, to which the turnbuckle attaches, is bolted through the deck to an aluminum plate that holds the top of the rod. Annually, the U-bolt should be disassembled and rebedded. When reinstalling, tighten the U-bolt nuts to a snug condition. Again,do not overtighten, or you will damage the deck finish. After reinstalling the U-bolt, be sure to check the chainplate rod tension.
I found this .... er somewhere, and OCRed it. Sharing it here, because this does come up occasionally.
As with anything that you find on the internet, take ALL OF THE ABOVE with a grain of salt.
Finally, if someone on FaceBook is looking for this, PLEASE POINT THEM HERE, and don't post it to FaceBook. Here it is searchable/discoverable.