Last Update: March 08, 2012

EC12 Building Home Page
Special Presentation Home

Some Help in Building an EC-12 Boat or Rig
by Scott Vernon (all photos by author unless noted)

  Want to keep the cost of building your boat and rigs down?  Save a lot of money plus get the enjoyment of building your own rigs and gear and tinkering.  You can buy an EC-12 ready to sail, or in various stages of completion, but it is a boat that you can build yourself once you have the class approved hull. You can do everything from building a rudder to pouring lead for the keel to making sails yourself.  Many of us do. All of the many many parts can be fabricated or bought from suppliers and of course many RC airplane parts are used. I will hold myself back from talking about every single part that goes on an EC-12. There are excellent sources of information available to you online and in books about EC-12 building, setting up and racing. If there is a local EC-12 fleet then you can go and meet the people and look at boats and see the things that you might build. Regardless you might want to buy one or both Ragged Symmetry books which have patterns for many of the specialty parts such as mast crane, stay and jib racks and typical lengths for things like jumpers and spreaders. They are packed with great and applicable info for you and I. Now there are parts like foam glass decks and foam cored glass rudders available if we choose to spend some money in order to make our job quicker and easier. The Manual has an extensive list of suggested basic construction tools. If I were to recommend just one of the books it would be Optimizing, but I am glad I bought both and refer to them often. The books are available from the EC-12 class website, under the Class Store button in the Clubhouse area.

You can make a rudder and pour your own lead ballast. Be very careful pouring lead; especially to not overheat it, do not breath the fumes and do not let hot lead contact water or moisture due to the danger of injury from exploding hot lead. Pouring ballasts is interesting because you can read the words and see the pictures in Optimizing and decide that you are going to pour the best ballast shape ever. And you might just do it. Shaping and glassing a rudder is kind of an art form and good therapy.

Suppliers sell rigs for up to $300.00 or more.  Do it yourself and you can buy a mast for about $30.00, make booms from a second mast blank or use aluminum arrow shafts for $5.00 or less each and add the odds and ends to make a rig (less sails) for around $130 or less in your home shop.  Minimal tools are required.

The EC-12 building site offers a great deal of help in building your own boat. Rick West, our current class secretary, has created and maintained an amazing website that is geared toward the home builder of EC-12s. It is . It is a very large site with page after page of great information. It is fairly easy to navigate by subject/specific area being built. The site assumes that the builder will buy a lot of the basic small parts like spreaders and jumpers and stay racks from EC-12 specialty suppliers. I am going to tell you here what to look for if you want to make those parts yourself. The words and pictures on that site are still invaluable to you. Some listed suppliers might be out of business, but current suppliers of similar parts to those shown can be found on the EC-12 class website.

Let me tell you some of what the Ragged Symmetry books contain:

The EC-12 Manual: (a lot of the following parts are shown with sizes or dimensioned drawings in the pages following page 81) fixed mast top crane, brass tube spreaders, jumper strut length, hounds and rigging of bowsies at the top of the jib, stay racks, jib rack, mast step plate, locations of parts on the deck, sliding hatch, rig tension meter, sailbox. Two well-built boats are shown in detail, but many of the rig connections and adjustment parts are not per current east coast racer practice.

Optimizing the EC-12: Information on parts is brass spreaders, jumper struts, jib rack, stay racks, mast step plate, locations of parts on the deck, ballast shapes, rig tension meter, cradle pattern and building instructions, the useless weight of paint, etc, etc.. One of the strengths of this book is telling you to worry about making the best boat you can and how to do that. Also there is excellent information on how to tune the boat. There is a lot of information that might be considered over the top/too scientific, which is why some people have made the mistake of putting these books in a box in the attic. I can email the lists I have put together of great pages if you ask for it by email or on the discussion group at the class website. The book talks about such things as weight and waterline, hull trim angle (bow up or down), and optimizing the moment of inertia through good boat building. Then after you launch, the boat it tells you backstay tension, twist, mast bend and lateral mast bend, sail shape/fullness, mast bend, jibstay sag, and sheeting angles for various wind and water conditions. It talks about boom deflection and self-steering by the boat. Two more well-built boats are shown in detail, and again many of the boom to sail connections and rig adjustment parts are not per current east coast racer practice.

Here is my perception of the current state of EC-12 race boats on the east coast from a complexity standpoint versus some of the information in the book Optimizing. Moving the rig forward or aft from the standard 25.5 inch mast location is done to balance the helm, but I do not believe the computerized CE (center of effort) program has very many supporters among east coast racers. Moment of Inertia is an important consideration and most people use what is considered a short high ballast. That might be between 12 and 15 inches in length. Most people buy a ballast and many cut an inch or more off the aft end and perhaps a little or a lot off of the forward end depending on the ballast design. That allows the builder to add (some of) that ballast back onto the boat to give the desired hull trim angle (and also to ensure that the boat meets the waterline measurement rule of between 42 and 43 inches) when the boat gets floated. Some people still do pour their own ballast. One of the ballast shapes in the back pages of Optimizing has a peaked top shape and that is a very good idea, either peaked or curved top. Flat top ballasts also are big winners.

If you want to build a boat or even a rig, start by looking at and/or running a copy of “the construction guide” at . Click on “documentation” and then “EC12 plans”. The PDF is a pop-up and it will take a bit of time to open. It has pretty much every dimension you need to locate the parts and build a competitive boat. That website is sometimes referred to as EC12web. It is mentioned in the construction article in Model Yachting Issue 145, but with an incorrect address. There really are a lot of information and good pictures on that site if you keep looking.

To start building a boat contact a class authorized supplier of hulls and buy a hull by going online to which is the EC-12 class website. You should become familiar with a lot of the pages such as rules and the discussion group, but for building you want to go to “Resources” “Class Suppliers” and see where you can buy major parts such as hull, rudder, ballast, mast, another mast to use for making a couple of booms, etc. There is a large amount of good build information in the Discussion Group (under Clubhouse) on that site. It is a good idea to join in and ask (and answer) questions when you are building and later when you are racing. Read the class rules before and during construction. Understand them and take care to build a legal boat.

You have to buy a hull (from a class authorized supplier), and electronics, and it is advisable to buy a mast and sails from an EC-12 specialty supplier, but everything else can be bought from a specialty supplier, hobby shop, online hobby supplier or home built. If you can afford it I would recommend buying a ballast and rudder and perhaps a foam glass deck, but it is up to each person based on his or her finances, abilities and ambition. Tom Germer tells in this issue how to fabricate a beautiful and light wood deck, but I am sure there are some people who feel it is enough of a challenge to install a supplier deck. For construction of a structured balsa/glass deck the construction guide shows patterns for deck beams and the build site shows procedure.

Here are pictures and descriptions of building techniques for many of the systems and parts that can be fabricated by the home builder. The design of the parts that you build might be limited by your level of skill and/or your tools, but that is why I am showing a few different ways to make a good gooseneck and a good vang. Those are two major parts of an EC-12 rig and each of them can be simple or more difficult to construct. It should be noted that these two mechanisms take a lot of strain and some abuse in EC-12 sailing and racing. All parts of a racing EC-12 need to be fabricated strong enough and maintained in such a way that they do not fail in high winds and minor collisions. Some of the assemblies are not very sophisticated and others look like they were made by skilled craftsmen.

When I say glue, I mean epoxy or CA. Be sure to heed all warning labels and cautionary information..

I will show how to make goosenecks and vangs in the first part of this article, then rigging the outhaul and other parts on the boom, jumpers and spreaders on the mast, rigging the jib at the boom and the hounds, radio systems boards, words about the rudder installation and long tiller fabrication.

Gooseneck using CB2212 butt hinges

This shows the making a gooseneck using a set of CB2212 butt hinges available online from They seem to be a reliable supplier. This is past national champion Danny Thomas’s boat and rig and this gooseneck is known to be reliable. The CB2212 is plastic with a brass tube axis. Some people run one brass tube full length thru both hinges instead of the two short axis tubes. I am not a fan of the plastic clevises shown on the stays, but prefer brass Sullivan. It is tricky to find the CB2212 on that website. Here is one convoluted path to follow. Hit/left click on Tatone insignia bottom right on the home page. Hit “Welcomc to www.Tatone…” Hit “Click here for control horns and hinges.” Hit the yellow writing for the CB2213 hinge. Now you finally can see and order the CB2212 hinge. Put it together and you might see that it will need a little massaging to make it turn freely 180 degrees as it is made of plastic parts molded in two piece molds. The way that Danny has built his gooseneck with the barrel of the hinge right up against the mast does not put a lot of stress on the hinge.

Simple and effective vang and detail

This seems like an obvious design for a very simple and effective vang. This particular one looks like the design got changed after the first few years of use. Maybe this vang is not pretty enough for the pages of Model Yachting, but to me it represents what someone who values function and simplicity can easily do and redo on the kitchen table of their condo. The gooseneck parts are from a former supplier, but the (top and) bottom part could be whatever you choose as long as there is a RH threaded swivel ball link or Sullivan clevis on the forward end for the rod to screw into. There is a brass L bracket wrapped (or screwed) to the bottom of the boom. Chris Stater’s vang is 2-56 partially threaded rod, but it could be 4-40 for added stiffness to support the boom. One thing about this vang besides the fact that it is very simple to make is that it is pretty much bulletproof if care is taken in the design and building. Another change that I would make to it is to use short pieces of brass tube on the rod trapping the bracket rather than the wraps of glued white line shown in the picture. I like to put the little brass tube pieces as tight together against the bracket as possible to eliminate play. The forward piece is just glued in place, as its only job is to support the boom, and the aft piece is kept in place by (gluing and) squeezing or pounding a wide flat on the end of the rod thus trapping the not flattened piece of brass tube. It is vital to make it impossible for the brass piece to ever slide off the end and vital to not rely only on glue alone to withstand the high tension that an EC-12 vang is subjected to. One rule of thumb with these boats is to not rely on epoxy or CA as a bond in any small area on these boats that can be subject to high loading in tension. Pins and/or screws are recommended as reinforcement, but not at the expense of drilling though and weakening a small diameter part.

A more sophisticated gooseneck and vang

This is an excellent gooseneck and vang. It is on Reichard Kahle’s boat. I saw this same vang on Baron Bremer’s boat at the St. Augustine Nationals in 2009, but did not get a presentable picture. I will describe the parts that I would use to make it. Prepare the boom by cutting a slot in the bottom and a hole through the sides for a pin or threaded screw so the ball link can be installed there.

Use a couple of Dubro part number 2139 2-56 swivel ball links which take a 2-56 screw but have a 4-40 size hole in the plastic barrel end. Take a Dubro part number 2157 steel turnbuckle and cut away the center un-threaded part. Take a 3/16 OD x .049 wall Aluminum rod from a hobby shop or online supplier. Cut RH threads in the forward end of the tube and in the forward ball link and LH threads in the aft end of the tube and aft ball link.

Screw and glue the RH thread end of the cut turnbuckle into the ball link, leaving the good end of the turnbuckle (with unblemished threads) exposed. Do the same with the LH thread part of the turnbuckle and the other ball link. Put a nylon stop nut on the threaded rod at the gooseneck and assemble the vang as shown in the photo.

Of course qty 2 4-40 Dubro swivel ball links could be used instead of 2-56. And the Dubro ball link could be screwed to the bottom of the boom as shown on John B’s vang. The gooseneck parts are similar to what is shown in the next photo.

Gooseneck and Vee downhaul

This photo shows a gooseneck similar to Reichard’s using a couple of small blocks of aluminum shaped and tapped. It is a good strong way to make a gooseneck. In this picture also take note of the Vee downhaul, which is the best configuration for a main downhaul as it relaxes tension as the boom goes out due to geometry.

Removing mast luff groove using curved needle nose pliers

This shows the process of removing the luff groove from a teardrop mast to make it into a boom. At least two booms can be made from one mast. File the rough edge to be smooth. This makes a good stiff light boom and is the most popular with the class.

Lower lower stays

The short stays clipped to the aft end of the stay racks are called lower lowers and are generally only used in high wind. They were removed from his boat by Frank Vella as soon as this picture was taken since the wind was light. They have fallen out of fashion in the class due to the belief that they restrict fore and aft bending of the lower mast. That bending de-powers the mainsail in high wind and is a desirable thing. However, I am a fan of lower lowers. The benefit is that sailing downwind in high wind they stabilize the mast’s sideways bend and keep the boom end from rising which would add twist to the mainsail. Less mainsail twist is desirable downwind in high wind as it makes it much easier to keep the boat under control. This shows a very good way to attach them to the mast; a loop which slips over the existing gooseneck screw. One way to allow the mast to bend fore and aft, but not let it bend sideways is to rig the lower lowers so they pull directly to the side. Perhaps the stay racks would need to be swapped side to side. But the aft pull of the lower lowers is not necessarily a bad thing as it allows use of more backstay tension (creating more forestay tension) without the lower mast bending too much such that the lower mainsail develops diagonal creases.

Boom and sheet attachment

Booms on this boat are made from mast sections with the slot cut off. Notice the use of ring dings attached to the boom for the sheet to clip to. A word of caution is that those rings need to be at least one step up from the weak ones that we see in the stationary department. The weak ones will straighten out and fail in high wind. It is fairly easy to find the stronger ones, and I bought a big supply at a fishing tackle store. The sheet loop is attached to the ring using a fishing tackle clip. For the outhaul there is a small diameter aluminum or brass tube glued into the hole at the end of the boom. The ends of the tube are rounded off slightly to not chafe the outhaul.

Outhaul setup

Chris Stater’s main boom shows a way to rig up the outhaul. The angle cut is not common.

Homemade stay racks

Here is a detail from an earlier photo showing stay racks, They are easy to make. John B sometimes rigs up lower lower stays and has 2 holes for them to attach to. A stay rack like this one can be made from whatever suitable piece of aluminum extrusion you can find; maybe an aluminum front door sill which offers a lot of possibilities due to its complex cross sectional shape. That sill will have a tee which can be used to make a jib rack and a flat area for a mast step. John’s jib rack is shown in another photo. The photo of Reichard’s vang shows his stay racks which are homemade and are mounted through the deck. He puts a large flange outboard of the upright part of the stay rack under the deck and files the top surface so that it fits nicely under the fiberglass shear lip that is on all of our hulls. No screws; just epoxy, I would imagine, and super strong.

Attachment of jib stay to boom and jib tee

This picture shows one of the latest ways to attach the jib stay to the boom. John B gets credit. The jib stay just disappears into a hole in the top of boom. Drill a hole in the top of the boom and cut a thin slot aft of the hole with a Dremel. Take a little metal ball from a key chain/light pull and drill out one end of it oversized. Run the jib stay (out of the bottom of the jib) thru the ball (entering the ball thru the small hole/with the big hole in the ball facing away from the jib). Tie a knot in the jib stay wire - so the knot bottoms out inside the ball against the small hole. Glue the knot inside the ball. Slip the ball into the hole in the top of the boom. Pull it back into the slot and wrap a piece of electrical tape over the hole (which is forward of the jib). Note the hook at the jib tee. It is a good hook. I feel that the very popular 408 soft metal hook should never be used on EC-12s. It straightens out and lets the rig fall far too easily. The 408 hook can be identified with its reverse curve at the end of the hook mouth.

All of the stays on the mast can be rigged up similar this by drilling a tiny angled hole in the mast for each stay, feeding an overlength stay wire though the hole up to the top of the mast, putting a swage or ball on the end of the wire, pulling the stay wire until the swage or ball bottoms out at the hole inside the mast and then cutting the stay to length and adding the rigging pin and clevis at the bottom of the stay.

Sliding bowsie on the boom.

Shown here is the bowsie that slides on a Dacron line along the boom. The Dacron line runs through the front and rear hole of the bowsie and there is a separate small diameter Spectra line running thru the middle hole of the bowsie from the boom side. It goes around the Dacron line then back down through the middle hole back toward the boom and a knot gets tied making that a tight loop. That loop makes it so the bowsie will slide on the Dacron line but it takes a lot of pressure to make it slide. Both the outhaul and the sheet length might get adjusted this way. That bowsie setup is shown on the build site, Classic Rig, Main Boom Assembly page.

Jib topping lift

Shown here is a topping lift which generally incorporates an elastic which is shown. The topping lift maintains twist in the jib. It runs from the aft end of the jib boom up to the hounds. Most topping lifts have a bowsie loop near the bottom to control the amount of jib twist. The idea behind the elastic is that the aft jib boom will lift in a strong puff causing the topping lift to go slack. On end of the elastic is attached to the topping lift. The other end has a knot tied around the topping lift allowing the elastic to slide and always have tension. So when the topping lift goes slack the elastic takes up the slack and keeps the topping lift from hanging up on the spreaders. I am not a fan of the elastic and I use a 30# Spectra loop taped to each side of the jib luff and running around the topping lift, taped at such a height that it prevents the topping lift from hanging up on the spreaders and cut to a length allowing a proper jib twist without the jib hitting the loop. It is important to have the loop end at each side of the jib luff and not be threaded through the jib luff. I want the loop to break loose in an entanglement not rip my jib. The loop is seen on approximately one boat at any regatta that I enter.

Homemade brass tubing jumpers

The jumpers shown are misplaced as they should be about 3/8th inch below the hounds, but they are good homemade jumpers. The mast is drilled to take the spreaders at a 50 degree angle and the continuation of each hole is a smaller hole that comes out the side of the mast. The smaller hole is too small for the spreader to fit thru, but is the size of the rod inside the jumper tube. The holes must be at slightly different heights so that the jumpers can cross inside the mast. Jumper length is generally about 2 inches. They can be brass or aluminum, but I would recommend brass either 1/8 or 3/32 inch diameter. The outboard ends can be pinched and drilled to take the jumper wires or a short piece of wire can be bent double and inserted into the end of the jumper trapping the jumper wire. Some people, like the owner of the fast and famous pink boat, do install the jumpers about 6 inches below the hounds for some reason, so apparently location is not critical.

Easily copied jumpers

Here is a nice looking and simple set of jumpers from Sails ETC. It seems that it would not be too difficult to make a pattern inspired by this photo and to fabricate a set of similar jumpers.

Removable homemade spreaders

Removable homemade spreaders are simple. These are 3/32 diameter brass tube with a 1/16 diameter steel rod inside. The ends are squeezed flat and drilled. The rod is trapped in one spreader and runs through a hole in the mast that is just big enough for the rod. It is important to make a nice clean small square to the world hole in the mast. Some people, myself included, tend to favor 1/8 diameter brass spreaders with a 3/32 diameter (or 4-40 in a pinch) steel rod inside, in spite of the increased windage. They tend to survive entanglements on the water better than the ones shown here. Neither of these spreader sizes breaks; the rod just bends.

Masthead crane

This picture is from Rick West’s build site and shows a good shape for a crane. The mast gets slotted to accept the crane and the crane has a protrusion at the bottom that fits down in the mast. The size and outline of a typical crane is shown on page 61 of the EC-12 Manual. This photo shows a plastic hinge that will be attached to the head of the mainsail. Do not use that. For some reason this hinge became all the rage in the 1990’s, but it only was necessary for a “rocking crane” that never did catch on. Current best practice is a grommet in the head of the mainsail and Spectra loop tied through a small hole in the crane along with the upside down Vee downhaul. For the groove in the mast, one file that is thin enough to enlarge a cut made by a hacksaw blade (besides the flat bladed needle file) is a metal nail file. Material can be aluminum about .063 thick if it is without lightening holes. The length of this crane aft of the mast is 1 5/16 inch and thickness is about .08. I believe the crane shown is no longer available to buy. By the way, be sure to cut the mast length to no more than 71 7/8 inches if you have a 1/8 inch thick mast step. The rule says max mast length including the crane is 72 inches measured from the deck.

The U of a sliding cockpit hatch cover can be seen in various photos. There are detailed instructions on how to build one on the build site. . At the time this is being written you need to go to the “structured deck” page to find the link to the “install hardware” page which shows info and pictures of the sliding hatch fabrication. There is no link leading to it on the molded deck page. Rick promises to fix that soon, perhaps before publication.

Radio systems board

Tom Germer’s systems board/ballast/sheet line system as one unit is shown here. The systems board with arrow shaft sticking forward is permanently screwed to the ballast and at the end of the day he is able to easily remove it all for inspection and ease of carrying the boat.

There are a couple of websites that show good plans for a systems board.  Rick West’s site. Pick “the chassis” button and also the “board mount” button. Pick the “sheetline system” button and that will show you the current construction method which is to put the forward bow block on an “arrow shaft” that is attached to the systems board.

You can see that there is an arrow shaft running forward from the radio board on Tom Germer’s boat. There are a series of good pictures of this on Al Stall’s build page One thing to take note of on Al’s page is the bow block shaft retainer. Al used an arrow shaft running forward and it is necessary to kind of jam that in up forward to keep it from wanting to bend under sheeting loads. On the forward end of the shaft is a double block with the sheet loop and tensioning elastic running through it. This detail has become normal practice after an absence of a decade or more. What was old is new again. The benefit versus a block attached to the hull or bulkhead up forward is much improved access when the sheet loop breaks. The sheet line and elastic can be removed along with the radio board as one assembly for maintenance. The overall beauty of Al Stall’s build page is that you can see all of the parts that make up and EC-12 and somewhat how they all go together on one single web page of thumbnail images that can be clicked on and enlarged. Al shows the pattern for his systems board on his page.

Vertical radio systems board

This picture is of Dave Brawner’s vertical systems board. I will talk about rudders here because the shaft length might determine what sort of systems board you put in the boat. Most people seem to put a short rudder tube in their boat: one that ends below the waterline. They put grease seals in the rudder tube and grease on the rudder shaft to keep water out of the boat. The process is shown in the book Optimizing and also on the build site Hit “Rudder” in the hull section of the site. So those people install a systems board like Tom Germer’s or, Rick West, or Al Stall. Dave Brawner has a long shaft/long rudder tube which ends above the waterline in his boat. If the rudder servo is installed with the servo arm off to the side then it will be necessary to put a bend in the push pull long tiller arm or have the pull lines at a steep angle or to raise the rudder servo in the hull. Dave Brawner has done the more logical thing, which is to create a vertical systems board with the (winch and) servos attached to the sides. The arms of both the jib trim and rudder servos stick up in the air. This gives better geometry for the jib trim servo as it gets the turning block up high near the sheet line, and certainly better geometry for the rudder servo arm setup which allows the long tiller to be pretty much horizontal. You will have to make a paper pattern of what you think Dave’s system board looks like if you want to try to copy it. Since this is such a less than useful picture I was going to leave it out until I realized the benefit of a vertical systems board. The aft flange has a switch and also the connector where the battery pack plugs in. The rudder servo can be seen mounted on the left side of the board with its servo arm up high. The round cap and black block on the right is an RMG280 type winch mounted on the right side of the board. Above the winch is a jib trim servo mounted on the right side of the board with its arm/axis aft. The board is bolted to the mast support and perhaps there is a flange at the bottom so it is also screwed to the ballast up forward. Screwdriver axis must be given some thought when laying it all out beforehand. Dave’s 1990’s era boat does not have a sheeting loop arrow shaft running up toward the bow, but a modern build would probably include that.

Push-pull rudder system tiller tubes

This picture shows the long tiller for a push-pull rudder system. Dubro 2-56 or 4-40 partially threaded rods are used plus lock nuts. These are carbon fiber tube or arrow shaft. Many people use a pull-pull system.

A backstay eyebolt is needed but not shown. One possible choice is the Sullivan S549 threaded 4-40 eyebolt. With this eyebolt it is recommended to use a washer both above and below deck to keep it from wanting to enlarge the hole and wobble and rotate. I think a dab of glue in the deck hole would be good as well. It is best to orient it with the hole fore and aft and hook it from aft to prevent snagging lines on other boats. Most people use a model boat parts supplier piece.

I have not written about rigging up the sheetline system. It is not easy to take pictures of that on a completed boat. It is best to look at it on Rick West’s build site by clicking on the “sheetline” button. On your boat it is a good idea between regattas to sheet all the way out and also to relax the elastic. I like to clip a “remove before flight” clothespin with a blue masking tape flag on my deck at the hatch opening to remind me to tighten the elastic before launching. A loose elastic can lead to the sheets coming off the drum when sheeting all the way out.

I hope this helps a bit for anyone thinking of or trying to build an EC-12. I believe the question of why I never got a job as a technical writer has been answered.