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Jim Young Sailing

© 2005-16 Jim Young


The Basic C420 Rigging Guide

by Jim Young

(UPDATED early 2018 - this guide was originally written for the Performance C420, built by Perfomance Catamarans (NACRA), in 2004. The mold for that boat was purchased by the then-new Zim Sailing in late 2009. Zim has made a few rigging updates and hardware changes over the years since, but all of the same basics apply. You should be able to use this guide to help rig a C420 of any vintage, regardless of builder.)

From out of the box to ready to go sailing, this is how to set up your new C420.

Lots of pictures here, study them carefully.

Start with the hull. Make sure all fittings are securely attached. Have a roll of tape handy, and use it to tape over any split rings or cotter pins that do not normally get adjusted. Then move on to getting the lines inside the hull organized, it will make life much easier to do it first rather than wait until after the mast is up.

The top of the Board Box (also called the centerboard trunk).

Take a close look at the top of the board box and all the cleats. The aft/starboard cleat is for the board uphaul, and the forward/port cleat is for the board downhaul. Make sure both are free and working. Notice in the photo how the board uphaul line is tied off for traveling.


Hiking Straps

Now take care of the hiking straps. The front ends actually go over the top of the thwart (yes, that is what that glass thing going from the board box to the inside of the cockpit is called). The ends slide over a bar that is bolted into place from underneath the front edge of the thwart. From there, tie the back ends of the straps to the eye at the aft end of the cockpit. Tie them tight, you don't want sag in the straps, and then tape the knots. Finally, tie the straps to the bar across the back of the board box (top board box photo).

New in 2006, a new hiking strap that lets you fix the length between the skipper and crew position, really great for a shorter crew to be sure the strap is longer. Use the eyes to tie to the crossbar with utility cord, not shock cord.

Next, attach the mainsheet ratchet block to the eye strap on the back end of the board box - not to the eye on the bar - on its stand-up spring.

Shock Cords

Now to the front end. There are two shock cords to organize, one runs across the back end of the spinnaker bag through a pair of holes on either end of the bag area - pull cord ends through the holes and use figure-8 knots. Next run the trapeze shock cord, it runs from the small eyes on either side near the side stays, up thru holes in the mast partner and around a block hidden up underneath the bow, to the eye on the other side. Use a bowline knot to leave about a 2-inch loop in the cord as it comes out of the eyes.


Next we need to get the mast organized. We want to get all the lines run and everything taped before the mast goes up. Lots of little details here; notice how the trapeze lines hang from the shackle loops and the shackle pin is used for the side stays. Likewise, the shackle pin for the jib halyard does double-duty, with the forestay.

Next item is to attach the spreaders, this is done with the clevis pins that are in the fitting on the mast. Just line up the holes. Now look at the ends of the spreaders and the small hook-eye and screws. The side stays go through here. This is a good place to start using tape, cover the ends of the bars well so that there is nothing to snag a sail or line.



Now attach and run all the lines; the main halyard up and through the top fitting on the mast, the spinnaker halyard through its block just above the hounds (where the stays all attach), the jib halyard line gets tied to the becket on the block on the end of the jib halyard wire, and the topping lift line gets run through its block closer to the middle of the mast. Make sure the metal hook that is attached to both the line and the shock cord is on the part of the line coming out of the FRONT of the block (photo below). Now get out the tape again and start covering everything that might snag a sail, and notice especially how we use tape to make the spin halyard and topping lift blocks stand away from the mast - if you don't do this, the block will fall against the mast and pinch the line so it will not run freely.

The mast is almost ready.... pull all the lines down and tie the ends together or tie them at the spinnaker pole ring so you don't lose them as the mast goes up.





Before you put the mast up, attach the side stay adjusters to the stay plates on each side of the boat. You don't need to attach the side stays until after the mast is up. Now put the mast base bolt in to the second hole from the front in the mast base fitting in the hull. This is a good starting point, and may change after experience, and skills, show the sailors how to balance the boat for optimum speed. You may want to check this by measuring inside the boat from the transom to the back edge of the mast after it is up; most C420 tuning guides recommend this distance be 9' 4 1/2".

Set the mast in the boat, align the mast base groove with the bolt, and raise the mast. Attach the forestay first, to the middle hole on the bow plate, the attach the sidestays so they are very slack, just enough to hold the mast up.

Once the mast is up, its time to organize the nest of lines. Start with all the ropes; run the main halyard tail through the clam cleat on the front of the mast that is about 1 1/2 ft above the deck, then run the tail through the center of the cleat on the PORT side of the mast below the deck. Tie a figure-8 in this end so its does not run back out of the cleat.

Main Halyard clam cleatThere is a reason for using the cleat like this, so you can raise the mainsail by pulling up on the halyard where it comes through the cleat standing in the cockpit - this makes it MUCH easier to raise the mainsail when the boat is in the water. Tie off the other end (the part of the aft side of the mast) of the main halyard any place convenient (like the spinnaker pole ring) so it doesn't run away. This is the end that gets tied to the mainsail to raise it when its time to go sailing.

Next, make sense out of the topping lift; the part below the hook runs through the hole in the deck in front of the mast, and down through the eye on the hull that is just to the left of the mast base.From there, this shock cord gets tied off to to a piece of utility line that ties to the hiking strap eye strap at the back of the cockpit. The other end of the topping lift comes down the startboard side of the mast to the block on the mast base that is mounted farthest from the mast, then up underneath the board box cap to the front cleat on the starboard side of the boardbox.

The spinnaker halyard is next; look up the mast, and take the end that comes over the top of the block and tie it off somewhere convenient - a good rigging habit to get into, is to tie this to the hook (called a twing or pole guy hook) on the PORT edge of the boat that is just in front of the stay plates - this is the end that will eventually get tied to the head of the spinnaker, and it gets tied so that the halyard pulls the spinnaker out of the bag on the PORT side of the jib. The end of the halyard that comes down the mast goes through to block on the lower port side of the mast base, then along underneath the boardbox cap and comes out the small hole on the back end of the boardbox, where there is also a cleat for it.

Finally the jib halyard; the rope tail that is tied to the halyard block comes down the starboard side of the mast, all the way to the block on the bottom that is closest to the mast. Don't tie any knots in this line - as the jib is raised, the end of the line first goes through that block that is on the end of the wire part of the halyard, then back down to the standard cleat on the starboard side of the mast that is opposite of the cleat that the main halyard uses. This is the line that controls mast rake and takes all of the load so its important that it works well. There is one other small line, about 4 ft long, it gets tied to he loop on the mast that is just below the gooseneck, and is the cunningham, it goes through the cunningham eye on the mainsail and to the cleat on the other side of the mast from the eye it is tied to.

Bridle and Mainsheet

Almost out of lines to worry about; next is the bridle. This is a small, 9-ft line that needs a loop tied in the middle, then the ends go through the large shackles on either end of the bar that runs across the cockpit at the back end of the board box. The mainsheet block that you thought went on the eye strap just in front of the ratchet block gets attached to the loop. If you are lucky, this line has 'slip loops' already spliced on the ends, if not, you will have to be creative with knots on either end that you can easily adjust. The idea here is that the height of this mainsheet block can be adjusted for different winds, higher for light wind and lower for stronger wind, so that the boom can stay closer to the centerline. The two photos left and below show the block with becket attached to the center of the bridle, and the complete assembly with its slip splices.

Notice on left photo, no shackle is used, to help keep it lighter.

And below, everything to make a bridle, a marking pen and a knife with a splicing fid. Look carefully and you will see double splices, this holds much better than a single splice. The big loops are where the line gets attached to the big shacles on the ends of the mainsheet tube.


Here is a photo of the bridle/mainsheet system on the boat. Look closely for the 'slip splices' in both ends of the bridle - you can see the ends hanging down out of the splices. This works only with a modern hi-tech line such as Amsteel 12, or what I use, Endura 12. The tail of the line is spliced about 4" into the body of the line; when there is no load, its easy to adjust the line length, and when its under load, the splices don't slip at all.

Now, attach the boom to the mast, and run the outhaul line from the cleat on the boom to the block on the end of the boom, and just put in a convenient knot that can be undone fast. It goes up through the clew eye on the mainsail, then tied to the eye on the opposite side of the boom end from the block. Then the mainsheet, it attaches first to the block on the bridle, then up to the forward boom block, then back around the block it started at, back up around to the aft boom block, and finally down to the ratchet block (see photo here).

Spinnaker and Jib Sheets

Next is the spinnaker sheet, its a one-piece continuous line. Start by tieing one end to the forestay, then take the other end and go around the outside of the boat to the sheet block that is on the rail of the boat just in front of where the helmsman sits. Pull all of the slack line through the block, and tie a figure-8 in it 12' from the end that is tied to the forestay; make sure the fig-8 knot is on the BACK side of the block, not on the spinnaker side!. When this knot is in the right place, it will prevent the end of the spinnaker pole from hitting the forestay if it is accidentally released. (Check this knot position after everything is set up by hoisting the spinnaker and pushing the pole forward, and retie as necessary to keep the pole off the forestay.) Then run all of the line across the boat, in FRONT of all of the mainsheet system, and thru the block on the other side, and up to the forestay. Mark or hold where it enters that block, pull the end back through, and put in a figure-8 here on this side, same as the other side, 12' from the end of the line - and remember to check the knot position on this side. These figure-8s may need to be adjusted after time, when the lines have stretched out a bit, if the pole can hit the forestay.

The jib sheet is another one-piece line, The center of it is normally tied to the clew of the jib and left there. When the boat is rigged for sailing, the ends of the sheet goe through the pad eyes on the deck across the cleats, and figure-8s are tied int he ends.

(Neat rigging trick ~ I set up my custom jib sheets with a small piece of Endura 12, a high-tech line, spliced through the center of the line with about 10" of it hanging out. This small line ties to the clew instead of a big knot in the sheet itself. With this system, there are no big, bulky knots to hang up on the mast when you tack and jibe.)

Trapeze Wires

Tie the trapeze adjuster line to the bottom of the cleat on the trapeze wires, then run it through the middle bar of the trapeze loop or ring (called a dogbone) then run the line back up and through the cleat, finishing off with a fingure-8. The small loop that you left in the trapeze shockcord a long time ago then comes up through the dogbone, and take the loop end back over the bottom of the bone to secure it. Do the same on the other side. Notice that I run everything around the middle of the dogbone; the small ring is now a 'high' trapeze position for waves or with spinnaker, and the long side of the 'bone is the 'low' position for normal upwind sailing. This quickly gives the two positions needed without having to adjust the line throught the cleat.

Mast Rake

This is the beginning point of all tuning in this boat. Get out your tuning guide and memorize the mast rake measurement for light winds (21' 6 1/2"), this is your set-up and starting point. Mast rake is measured by tieing a tape measure to the main halyard, and pulling the main halyard up the mast all the way. Then pull the tape to take the slack out of it, over the middle of the transom of the boat and down to the the bottom of the hull, and read the tape measure at the center of the bottom of the hull.. Adjust the jib halyard to get to the correct number - it helps a lot to have someone pushing back on the mast so the forestay is tight. Then put a mark on the mast at the top of the block that is on the end of the wire part of the jib halyard. Now ease off the jib halyard, and slowly tighten up the side stay adjusters, and retighten the jib halyard, to check on the stay tension (use a Loos Guage, or simply twang the wires, you should get a nice low note, not a wabble-wabble of the rig - and yes, to get to this point, the jib halyard gets pulled really tight). As the rig gets tight, you will probably see the rake measurement change, just put another new mark on the mast at the correct jib halyard position. In the photo right, the current setting, with the wire swedge on the bottom band, is for light wind (mast farther foreward). The middle tape is the setting for medium wind, and the top tape for heavy air.

Once you have a nice, tight rig with the rake set for light winds, you can mark the side stay adjusters so you remember the position (or better yet, write down the pin position in the new notebook that you have for your C420 sailing), and then tape the pins and rings. Then use your tuning guide and measure the mast rake for medium (21' 2") and strong (20' 9 1/2") winds, and make the marks on the mast at the top of the jib halyard block for those settings, so you can instantly set up your boat for different conditions without have to measure anything. Hint; make sure the forestay is tight when you measure the rake, by either pushing back on the mast or pulling hard on the side stays.

As you rake the mast further back for medium and strong winds, the side stays will get some slack. Take this slack out by tightening the side stay adjusters. Second Hint; let the forestay off just a bit so you can get the adjuster pins in a bit lower, then make sure you can pull the rig back to the correct mast rake. Experienced - and highly skilled - crews may want to set the rig much tighter in stronger winds. This is a SKILL adjustment, it will not make the boat 'faster' if the sailors don't have the knowledge and strong-wind skills to handle it.

My rigging numbers for mast rake come from North Sails, and like most magic numbers, should be considered as guides, not as firm rules. Mast rake should be rechecked during the season - and especially at big events. Lines, even the steel stay wires, change with time and load, and its normal for the measurments to change. For this reason, on new boats especially, use tape on the mast and mark the tape with the rake settings instead of putting marks on the mast that may change with time.


The head of the spinnaker gets tied to that line that you tied to the hook on the port rail a long time ago, and the other ends get tied to the sheet lines (hint; don't tie the sheets to the sail, take the line through the eyes in the sail and use figure-8 knots, its less bulky), and then the spinnaker gets stuffed into the spinnaker bag, just make sure you do it so that the halyard to the spinnaker head comes down on the port side of the forestay and BOTH sheet lines come out of the same side, with one of the sheet lines going around the front of the forestay. When the spinnaker is in the bag, take the slack out of the spinnaker sheet, and ease the spinnaker halyard so that you can hook the halyard back under that same hook on the port side that you had it tied to - the halyard stays there for normal sailing, part of the crew's job before hoisting the spinnaker is to get the halyard out of the hook, and after the spinnaker is down, the halyard should be pulled back under the hook again. This keeps it from flopping around and possibly twisting around the stays, which makes it really ugly when its time to get the spinnaker back up.

The dreaded Boom Vang

This is easy to leave to last. These cascading vangs can get messed up, so we don't want to have it in the way while rigging. The simple end, with no lines dangling (far right side of the photo), is the end that goes on the boom. The other ends (lower left side in the photo) get attached to the steel loop (called a bale) on the bottom of the mast. That should leave a line hanging lose with a block on the end of it laying on bottom of the boat. On the aft, port side of the board box is one final cleat with a line in it - fish around with your hand under the board box top and you should find that line is a loop, one end coming up throught the cleat, and the other end coming back up throught a hole aft of the cleat in the board box cap to a fingure-8 knot. Untie the 8, pull the end back down, run it through the block on the end of the vang, and bring it back to to the hole, run it up through and retie the figure-8. The vang may have to be adjusted to work correctly, you will only know after sailing. The only line to adjust is the end of the vang that ties to that last block, don't try to play with the cascade system.

Hot tips and other rigging things to know;

  • Make sure the rudder pull-down line is correct, over the top of the last pin on the front of the rudder head, so it can be cleated tightly to hold the rudder down. Check the spring clip on the back of the boat often, to be sure it is working or you may lose the rudder in a capsize. For safety, tie a short line from the top of the rudder to the hiking strap eye inside the boat.
  • Better lines make the boat sail better. My favorites; a high-tech bridle made of Spectra, Technora, Dyneema, Endura, etc, 1/8 inch, with slip splices.
  • Second line trick is a light-weight spinnnaker sheet that floats, that means it has some polypropylene in it.
  • Third trick is a higher-tech main halyard, so the line doesn't stretch in stronger winds. We want the sail cunningham to work, which means that a good to great main halyard is necessary. Go with a medium-high tech line with a core that does not stretch but a polyester cover, so its still easy to tie.
  • Same trick with the jib halyard, use a high-tech line with a no-stretch core, and go down a size from the standard so it fits on the side of the mast at the deck easier.
  • Line colors; I hate the boats that have all the same color lines close together ("Hey, crew, I said pull on THIS yellow line, not that one!"). Not only should you have different color lines for similar jobs, but in a team or group, the boats should all use the same color-code to make it easier to coach, and to switch boats for speed testing and tuning.
  • Remember the class requires an 8-meter long, 8mm diameter painter, use only polypropylene since it will not absorb water.

I used to have a full rig kit of lines - but everybody has personal preferences! If you want at least 3 "main" lines (sheets and/or halyards) contact us for options and pricing. Below are some recommendations.

  • Mainseet ~ 8 mm Bzzz line yellow (Great on the hands)
  • Jibsheet ~ 7 mm Bzzz line green(and Bzzz works really well in cleats)
  • Spinnaker sheet ~ lots of 5mm and 6mm options, from 3/16" Sta-Set to 6 mm Euro Endura with tapered ends
  • Main halyard ~ 4.8mm Spyder Line black (zero stretch, so the luff stretches when you pull on the cunningham, not the halyard)
  • Jib Halyard ~ 3.8 mm Spyder Line purple. (again, zero stretch, so that the rake stays where you set it, regardless of wind)
  • Class-legal painter, Marlow Marstron 8 mm yellow, and the magical bridle, 3 mm Endura 12 in red.

Check out my Gear pages on this web site for a complete list of lines and other goodies. Pricing is dirt-cheap - and even cheaper for teams/groups/clubs that have worked with me. If you don't see something you need or want, contact me to let me know what you need.

Everything here, photos and text, © 2005-18 Jim Young