EC-12 Tuning

 

Revised 4/2005

 

By Carl Olbrich

 

This is an open letter to the new members of the sailing club that have the urge to get their boat and themselves tuned so they can finish a race better than they currently are doing.

If there are at least 2 boats sailing it generally becomes a race.

Ok, so now you have a boat – new or old they all need a little (lot) of tuning. The builder may not be up to tuning or the older boat never was tuned so the skipper sold it.

For this tuning exercise we have to assume that all the electronics and equipment in the boat functions. The items listed have different impact on the speed of the boat and are not necessarily listed in order of importance.

I still get beat regularly but it is not the fault of the boat.

These items are what I have learned up to now.

Skipper training is another issue.

Just work on the items you feel comfortable with until you get to the level of satisfaction you desire.

Much of the information presented has been found on sites on the Internet and is not restricted for use by individuals.

 

1.      Hull – Balance

 

Boat without mast and sails.
The club has a tank (applies to the Triangle Model Yacht Club) that will help you make sure the hull floats on the designed waterline of between 42-43 inches. The longer water line in light air will help the boat sail faster. The hull should be balanced by moving equipment, relocating batteries or shifting lead. Lead can be removed with a dremel with a sheet rock side cutting drill. Balance the boat until the deck is level or almost level (bubble gauge) with 12-13 oz. of weight sitting on the mast base (simulates the weight of mast and sails). There is a theory that all the weight should be kept out of the ends of the hull and centered near the mast support. If you can keep all the weight centered and as low in the hull as possible you will have the most desired hull balance. Note: Some sailors add or subtract weight depending on the wind – but that comes later.

 

2.      Hull – Finish

 

You can paint the hull with krylon or other spray enamels or even automotive lacquer. You can also not put paint on the boat at all. A good smooth finish is desired and there are many articles available on how to do it. The articles include priming and block sanding to get a smooth surface. Generally you start with 120 grit sanding paper, 220-grit paper over a sponge, 320 wet and fill holes showing with putty, 400 grit before priming and work up to 1500 –2000 grit. If you are not happy with the final spray coat you can sand with 1500 –2000 grit and then polish the finish coat with a polishing compound. (ex. West marine polish with Teflon). Do not use any wax.

Most good skippers just sand with 1500-2000 grit a few times a year. The theory is micro-balloons created to act like roller bearings.

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. Hull – boom alignment lines

 

While you have the boat without the mast on etc. it is a good time to put boom indication setting marks on the deck. The rule for setting the main is 5 degrees off the centerline of the boat. Using trig (sine of 5 degrees) this is 0.87 inches at 10 inches from point of rotation of the main boom. Or 1.7 inches at 20 inches. The marks can be tape, or ink etc. The jib is set at 12 degrees, which is 2.1 inches at 10 inches from jib boom rotation point (point on boom not on rack). Or 4.2 at 20 inches.

 

   Blue lines on angles are 5 & 12 degrees off centerline.

 

4.      Mast Location    

 

The deck has a plate with holes or pins etc. to locate the butt of the mast. The question is which location to use? Experience will indicate that it is a trial and error to find the correct location. The location helps determine the center of effort of the total sail plan and will be effected by the location of the jib, mast rake and other variables. Start with the center location and as a general rule move the mast forward if the boat keeps heading up into the wind or back to the stern if the boat keeps falling off while close hauled. It’s easier to make this adjustment if the mast is square to the deck – both fore and aft (rake) and side to side.

You really want just a slight amount of heading into the wind (hunt for wind) so the boat will point better.

 

5.      Jib Location      

 

Like the mast butt location the jib rack hole that you use is a trial and error method.

Start with the backstay tight. Line the jib boom up with the mast and measure so that the clew of the jib is more than 2-2.25 inches away from the mast. The larger this dimension, the larger the slot will be. Experience will show that a larger slot in light air will work better. Too large a slot and the boat will not point.

   More than 2.25 inches clew to mast.

 

 

 

  1. Mast Install   

 

Set up the mast and install all the shrouds and backstay. Snug up the backstay.

The top shroud goes thru the spreader and is generally attached to the chain plate

in the hole directly adjacent to the mast. The middle shroud is normally attached (aft on the rack in 4 or 5 hole (depends on hole spacing) from the 1st connector. Adjust the top shroud so that a measurement from the chain plate to the top of the mast is equal on both sides, (or use a centering tool) and the shroud is tight. Adjust the middle shrouds to snug. Lay the boat over in the cradle and look down the mast from the top. Side to side the mast should be straight. Adjust the middle shroud until it is. Lay the boat on the opposite side and repeat the process until the mast is straight side to side.

 

      

 

     Centering Tool

 

 

 

  1. Mast Rake

 

Mast rake is the fore or aft measurement of the mast from a vertical relationship with the deck of the boat. The effect of mast rake is to move the sail plan either forward or aft to make minor corrections to either weather or lee helm. To change the rake the jib forestay (headstay) is generally changed in length. Various methods are used; a line and bowsie on the boom, adjustment of the length of the jib swivel to the rack and bowsie or kwik link assemblies at the jib attachment point to the mast. The picture in #16 shows a kwik link which permits adjustment. With this method you need a line between the link and the mast to permit the jib to turn in light wind.

Mast rake aft is the preferred setting.

  Mast rake setting tool – 16” or more vertical height.

 

 

8.      Jib Balance

 

Lay the boat on its side in the cradle.

The clew end of the jib boom without the jib sheet connected should just balance 1-2 inches below the left or right shroud rack.

Add or subtract weights to the front end of the jib boom (or inside the boom). Remember the jib boom should not extend past the bow when you are using some of the 1st holes in the jib rack.

 

  1. Luff sail settings

 

The main and jib sail should be tightened at the luff just enough to take out the wrinkles. The main is generally a downhaul (Cunningham) while the jib is pulled up with a bowsie arrangement (halyard). Tighten the luffs just snug.

Note: Remember to loosen the sails at the end of the day to prevent the sails from losing their shape.

 

  1. Backstay tension

 

Backstay tension is the method you use to set the tension on the jib forestay (headstay), the effectiveness of the jib topping lift and bend the mast to flatten the main at the luff.

There are gauges that can be made to indicate backstay tension. Normally the backstay tension is created by a bowsie and line. Some bowsie and lines can be routed (see picture) to make a ratio for finer adjustments. One end of the line is attached to a 3 hole clip and the other is attached to the bowsie. Tighten the bowsie until the clew end of the jib boom becomes hard to lift up with a finger under the boom. This is the initial setting and final settings will be discussed under wind conditions. A method to set backstay tension over a   wide range of adjustments is an absolute necessity.

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  1. Upper Jumper

 

The upper jumper is normally kept snug or under a little tension. This helps the mast        off–set the pull of the jib forestay and the backstay. As the wind increases and you increase backstay tension (to achieve sufficient jibstay tension) the mast will also bend more. When the amount of bend in the mast is more than the cut of the sail (wrinkles will show running up from the clew) the mast can be straightened by increasing the tension on the jumper by sliding the sleeve up (down) the wires. Tightening the jumper will start to put a bag back in the sail –by making a straighter mast.

 

 

  1. Main – Jib sheet travel

 

While the boat is over on its side in the cradle, turn on the transmitter and then the boat sail winch. Looking down from the top of the mast adjust the close hauled position of the Main and jib boom to the marks already on the deck. (main 5, jib 12 degrees). Recheck the mast to be sure it is straight side to side. This is only an initial setting for the jib. (see jib trim)

 

  1. Jib Trim

 

Jib trim is the ability to change the relationship of the jib to the main (12 vs 5 degrees).

Generally there is a servo that the jib sheet runs through that is designed to increase or decrease the length of the jib sheet. This action can open or close the slot which can have a large impact on your tuning on the water. In the initial set up the jib sheet servo should be set in the middle of the travel on the servo @ the normal 12 degrees with all the sheets set for close-haul. The adjustment for the servo is a designated rheostat on the transmitter. You then can let the jib out in light air, pull the jib in to point around a mark or in heavy air sheet the jib in while luffing the main. (See note in Other for another article on jib trim)

 

  1. Main/jib sail gap to boom

 

Both sails are mainly flat panels with some shape built into them mainly by the cut of the luff round and the front edge of the sail by the sail maker. You have to shape the rest of the air- foil by incorporating a gap in the sails at the boom. With the backstay tension set, the Jib gap should be about 2 fingers in the center of the boom. The main initial gap should be 3 fingers.  You set the gaps by adjusting the outhauls on each boom.

These are initial settings and are changed depending on wind conditions.

 

 

 

  1. Boom Vang setting

 

The boom vang sets the twist in the main sail. Too loose a vang will give a lot of twist and too tight a vang will take the twist out and stretch the leech of the sail.

A general guide to setting the initial twist is; with the boat upright in the cradle and wind filling the sails close hauled, stand 8-10 ft behind the boat and line up the back stay with the mast. Look at the leech (back edge) of the sail, you should see the windward side of the top batten, the ends of the 2 middle battens, the leeward side of the clew.

Adjust the vang until you get a view as described. It takes practice to see the settings.

Starting from this setting, wind conditions will require you to increase the twist as this is a minimum setting.

Another method is to look down from the top of the mast- looking for the top batten to be 15 degrees off of the boom (boom 5 degrees + 15 degrees = 20 degrees off centerline).

Even more than 20 degrees in light air.

The correct setting of twist in the top 2/3 of the main is where the other skipper will beat you sailing.

 

 

 

  1. Jib Boom Topping lift

 

To be competitive all EC-12s being raced should have a jib topping lift.

This adjustable line lets you control the twist in the jib just as the boom vang does for the main sail. The line runs from the jib attachment point at the eye or swivel where the jib attaches to the upper mast down to the clew end of the jib boom. This line should be adjustable in length (bowsie) and controlled from hanging up on the spreaders. People use elastic cords, keeper lines exc. to restrain the line when the jib boom lifts in a puff.  This line is adjusted so that viewed from the back of the boat most of the jib leech follows the curve of the main sail leech. The line (black in the picture) is really a very lightweight fishing line etc. 

 

              

Note: This is generally the last item to be set.

Check all adjustments – final.

 

  1. Sail telltales

 

You have read this far so you must be interested. Actually telltales on your sails are probably the most rewarding and easiest improvement to your sailing. It should be the first thing you do. Then learn to sail with them.

Find some very visible light silk and make your telltales. (3/8” x 5 strips of SIG Sik #LS007- Rose Pink) or up to Ύ” for visibility. Any light material large enough to be seen.

Main – outboard end of both upper mainsail battens.

Jib- 2 sets of telltale (starboard different color than port) 2 inches back from headstay.

Note: Boat #36 has main and jib telltales.

Visit this site for more information on how to use telltales.

www.onemetre.net/technical/telltales.htm

 

 

 

 

 

 

 

  1. Rudder

 

The rudder on an EC-12 is large and not only directs the boat but acts as a drag or brake when used. Other than slow easy turns around a mark, jybing, tacking, the rudder should not be used for more than a few degrees of adjustment of direction. The general approach to controlling use of the rudder is by practice. However, in a race the normal reaction is to forget and use the rudder. The rudder servo arm can be shortened to restrict travel and limit your ability to turn the rudder. Some transmitters can be adjusted for short travel or long travel. In heavy gusty winds you need a rudder with full travel to overcome the boats reaction to the gusts. Practice sailing the boat by sheeting in or out and with minor use of the rudder.

Sailing to windward you should only need to use the rudder every few boat lengths and just correct slightly, the boat should hunt for wind. If the rudder is needed more than that the mast should be moved and all the tuning redone.

 

  1. Wind Conditions  This section under review.

 

There is a lot of finesse to tuning the boat to various wind conditions. You first need to determine what the average wind is and learn to tune for that wind. It really takes a spreadsheet and recording of all the setting etc. to finally get your boat correct.

The following notes are what can be considered the basics:

Set so the - JIB LUFFS JUST BEFORE MAIN.

Note: This section may only apply to Carr sails. There are many different ways to make the sails. Carr sails are concave cut Jib and convex cut main with high twist design,

 

Light Wind  - less than 5 mph.

                  Mast straight – Carr Sails

                  Increase twist of main and jib.

                  Jib wider to main – (use jib trim)

                  Less tension on jib headstay – light air, more in heavy winds

                  Little tension on jumper

                  More than 2 fingers at the boom on the jib, 3 fingers on main.

Medium to High

                  Mast, controlled bend to match luff cut in sails.

Increase back stay tension,

More jib headstay tension

Slack lower shrouds to permit mast to bend forward (flatter sail)

                  Main sail twist- minimum twist from behind boat on centerline – you can see

Leeward side bottom batten

                              Windward side top batten

                              2 center battens ends straight toward you

                 

  1. Other Items

 

·        Sails – attachment of sails to the mast works well with 3 mm beads (AC Moore) and a light string (Dacron). Use a wire in the entire sail luff. Then use the  light line and run the line thru the sail and thru the bead. The line is then tied around a 3/32 tube to make a spacing from the sail to the mast. Glue the knot.

 

Another method is to use rods, tubes, heavy wire or weed wacker string cut about Ό inch long that will fit inside the mast track.. You then take a small piece of tape and wrap it around the rod and attach it to the sail.  The rod etc. must be able to slide in the track after assembly and you should have spacing of the sail to the mast. You can use reinforced packaging tape if you do not have any other sail tape.

 

·        Jib to Main Off Wind – The sail settings when sailing off wind are more effective when the jib and main are both parallel. The jib starts 12 degrees off centerline and the main starts 5 degrees off centerline. (This article is for drum winches only).This means that at 45 degrees the jib travel (sheeting out) must slow up to match the main. Without the use of a jib trim you can make this function automatic by increasing the length of the jib sheet attachment point on the boom. The rule is the jib sheet attachment point on the boom should be 10% longer than the main sheet attachment point on the boom. Ex. Main 13 inches, jib 14.3 inches.

 

21.  On the water tuning

 

·        After sails have been set on shore for wind conditions.

·        Closehauled – bear off without changing sheeting, Look at leeward jib telltales.

Note which telltale moves 1st. Upper need more twist, lower too much twist.

Reset twist until jib luffs evenly.

·        With a normal slot (12 vs 5 degree) reset the main twist to match the jib.