SJ23 Tech Tip F18, (Reissued 2007-05-20, Bob Schimmel)

Step the Mast With an A-Frame.
INDEX - poles, foot hinge, apex hinge, mast stepping procedure, hinge pin.
Stepping a heavy mast on a sail boat can be a dangerous job.  It can also be expensive to replace a dropped mast, not to mention replacing what you've hit.  For these reasons it is important to control it as much as possible.  Don't take any chances.
In a trucker's world an A-frame secured to the back of a flat deck is usually called a "gin pole" and is used to easily and safely lift or manoeuvre heavy objects on or off the deck.  An A-frame can also be found mounted on the edge of a work barge as a very robust yet simple crane.  You don't see them much anymore because it is quicker to rotate a hydraulic crane than rotate the entire barge.  In the outdoor sporting world, an A-frame can be used to move material or people across a creek.  Either one of these methods is simply a convenient way of moving a heavy object through a short distance.  Years ago sail driven commercial canal boats in Holland were equipped with an A-frame as a permanent deck fixture to lower the mast to slide under a bridge.  The boat's momentum carried it past the bridge and the mast was raised on the other side to resume sailing.  This procedure had to operate very smooth and quick so the vessel would not loose way.  Blocking the canal to other commercial traffic is considered a major blunder.
In the trailerable sailboat world, an A-frame comes into its own for stepping a mast.  The advantage of using an A-frame is that you have lots of mechanical advantage to reduce the lifting effort and lots of control to minimize sideways movement.  The longer/taller the A-frame the greater the mechanical advantage.  The huge control that you achieve with an A-frame leads to the single biggest advantage, safety.  Mostly because you don't have to stand under the unsupported mast.  If you step the mast hand over hand, with the aid of a block and tackle connected to the forestay, then you must steady the mast sideways to protect the deck plate.  The most difficult part during the lift is the transition from standing in the cockpit to standing on the cabin roof.  It is during this CRITICAL TRANSITION that the deck plate is usually twisted loose or you increase your odds of dropping the mast with you under it.   I have stepped the mast in a side breeze with my A frame, there is that much control, but I don't recommend it.  If the wind is quite strong, it much safer to align the hull to the wind and step the mast quickly.  I have done this quite a few times.  The less time you spend in the transition zone with an unsupported mast the better.  If the wind is really strong, park the boat somewhere and go find a coffee shop to wait it out!

CONSTRUCTION - Make your A-frame in the order that the components are described here.  It reduces your chances of making an error relative to the effort required to make each component.  Cut the poles, attach the hinge plates to the poles, bolt them to the T extrusion on the foot pads, screw the T extrusions to the wood pads and finally, cross the poles to form the apex and drill the hole through the two poles for the apex hinge.  By following this procedure you eliminate a bunch of complex measuring that will likely be off by several degrees making for misaligned hinges that can't pivot.  The chances of you measuring it correct are minimal!  Remember, Murphy! 

A-FRAME POLES - The aluminum poles of my A-frame are 2" OD with 1/4" thick wall.  This size and thickness is overkill to the Nth degree but the price was right; 1/8" thick wall is sufficient, even down to a 1" OD tube.  See NOTE below.  Each pole measures 101" long.  The distance from the pivot bolt in the foot to the hinge bolt in the apex is 99" with 1" of pole beyond the apex.  The apex fits just short of the forestay fitting, leaving room to easily transfer the forestay from the A-frame to the deck.  It is prudent to attach the forestay to the deck quickly to ensure safety for the mast and the people standing around it.  It is also convenient to leave the A-frame on deck for trailering or winter storage, as seen in these two  photos.

NOTE:  When I designed this A frame I had no idea how much force I was dealing with so I erred on the side of safety by using heavy material.  After using this A-frame for several years, on other boats as long as 30', I realize I overbuilt the assembly.  I now know that lighter poles are quite OK since the load is all compression.  In fact I have seen poles made from 3/4" conduit (1" would be better as they won't vibrate under the load with the danger of buckling).  I have also seen poles made from 1.5" spruce trunks, gnarled up 2" poplar trees and fir (2x4)"s.   If you intend to use wood then choose clear straight grained wood.  It would be relatively simple to cut a notch in the end of the wood pole to insert the hinge plate and slip a metal collar over the end to reinforce the grain.  I recommend saturating the ends with epoxy for strength and coating the wood with Cetol to protect it from the elements.  Another simple method is to use 1/8" thick metal tubing slipped over the end leaving 6" of metal protruding beyond the wood.  Flatten the 6" protruding tube and bend it to align with the T extrusion to form the hinge.  Light gauge aluminum poles would make it easier to carry the assembly.  Be your own judge in this design.  I have this habit of building everything to withstand WWIII.  I hate flimsy Mickey Mouse stuff.  No offence Walt!  TOP

A-FRAME FOOT HINGE & DECK PAD - The hinge at the foot of each pole consists of a 1/4" thick aluminum plate fitted inside the bottom of each pole and is fastened with a 3/8" bolt with two centering spacers.  The spacers are short sections of tube cut from an old aluminum ski pole.  Click here for a cross profile of the hinge assembly.  Notice the two notches cut into the pole to fit plate into.  The spacers and notches hold the plate firmly inline with the tube.  The plate is bent sideways 250 to align it with the aluminum T extrusion on the deck pad so the frame can tilt.  The T extrusions must lie parallel to the center line of the hull or the turning axis of the hinge so the frame can pivot.  (If you used a full articulating ball joint here, all of this critical alignment can be dispensed with as the joint would pivot freely regardless of the angle.  These ball joints are not cheap but they work very well.  The aircraft industry uses them extensively for perfect alignment of control arms).  The hole in the hinge plate is drilled slightly forward of center so the A-frame can lay flat on the deck.  The two deck pads are made of (2x8)" soft spruce to protect the gel-coat and are coated with tung oil to prevent rot.  The 3" long aluminum T extrusions are screwed to each pad.  Thus the hinge operates freely through the full 1350 arc that the frame must operate through.  With the deck pad wedged against the toe rail and the stanchion, it doesn't move.  All of this may sound complicated, as it takes a bit of finagling to bend the plate just right, but both hinges must turn freely.  Take your time with this part of the job. TOP

A-FRAME APEX HINGE - The simplest way to create a strong hinge at the apex is to overlap the ends of the poles.  It may look unsophisticated but it works, it is easy to make and stores well.  I was well on the way to making a fancy hinge when common sense prevailed!   Assemble the feet, bolt the poles to the feet, cross lap the poles, lock them together and drill a 1/2" hole through the middle of both poles.  Insert a 1/2" bolt using a large nut as a spacer between the poles to create room for the eye bolt nuts.  The two eye bolts (use cast type for strength) are through bolted, one in each pole, just below the apex hinge bolt.  If you can find a long enough eye bolt to go through both poles so it also makes the hinge, all the better. 
The forestay attaches to the aft facing eye bolt and the 4x1 block and tackle attaches to the forward eye bolt.  Be very careful in drilling the two holes.  Alignment of the moving parts is critical.  If you are off by a little bit, the hinge will bind.  I suggest making the foot hinges first, assembling them on deck, then drill the holes for the apex hinge.  Finally, test your frame by swinging it through the full arc of the required travel; about 1350.  At right you see the apex of the A-frame hanging below the mast with the block and tackle in place.  I tow my boat regularly with the A-frame hanging just below the mast, unless somebody has borrowed my A-frame!  TOP

RIGGING - If you use a 4x1 block and tackle you will require 80' of 3/8" line.  This length creates a long tail section which allows the tailing person to stand well out of the mast's drop zone.  Some jam tarts are squeamish about sticks falling on them!  

ASSEMBLY - Having assembled the frame on deck, mark the starboard and port poles with a felt pen for easy reference when laying it on the deck the next time.  It may not be obvious now but you'll thank me for this tid bit of advice later!  

A-FRAME MAST STEPPING PROCEDURE - Inspect the standing rigging where it attaches to the mast.  All cotter pins must be rolled over and show no sign of fatigue.  All nuts must be screwed down to full depth and secure.  There must be no "meat hooks" (broken strands) sticking out of the wire and there can be no kinks in the wire.  The continual changing tension of the wire, between strained and released, will eventually fatigue it, resulting in breakage at the kink.  If any clevis on a turnbuckle is kinked, replace it.  Resist the temptation to straighten it.  Oscillating bending will induce rapid fatigue and ultimate breakage.  This is exactly the same process as flexing a piece of metal in your hands to break it.  While this A-frame makes it is possible to step the mast by yourself, the job is still easier with two people. 

  1. If you intend to step the mast on land, block the rear end of the trailer so it can't fall down and/or make sure it is securely hitched to the tow vehicle to prevent tipping.  (An alternative is to float the boat in calm water, pointed into the wind to eliminate side forces on the mast).  Also, ensure you are on the shore side of any overhead electrical power lines or other obstructions. 
  2. Lay the A-frame on the fore deck with the apex at the bow and the deck pads wedged against the forward side of each stanchion.  Secure each deck pad with a short line tied around the stanchion and to the toe rail to prevent movement.  This extra bit of security is worth it.
  3. Tie all other loose mast lines to the butt of the mast to eliminate clutter on deck. 
  4. Loosen the shroud turnbuckles 3/8" up from the tuned sailing position.  This prevents the shroud tension from increasing which puts excessive load on the rigging and the chain plate.  (Ensure there is at least 1/2" of thread screwed in).  Tape the bottom swivel of each turnbuckle in the upright position.  (This is important as it prevents them from bending over, binding and breaking). It is assumed that the standing rigging is attached to the chain plates and never removed.
  5. Close the companionway sliding hatch. (Don't step on it).  Carry the mast aft until the foot rests in the deck hinge plate or tabernacle.  Rest the middle of the mast on the transom support bar.  With the foot of the mast resting in the deck hinge plate, insert the hinge pin and insert a cotter pin in EACH end of the mast hinge pin.
    NOTE: The condition of the fasteners that hold the foot casting to the bottom of the mast extrusion MUST be very secure as they undergo a tremendous amount of torque when the mast is stepped.  If the rivets are worn loose, replace them with 1/4" NF stainless steel bolts.  Drill out the rivet holes and tap a thread through the foot casting.  Snug the screws in and secure them with sealant to prevent movement and corrosion.
  6. Tip the A-frame up to vertical and attach the forestay to the aft apex eye bolt and secure two jib halyards around the A-frame bars close to the apex.  While the halyards will provide extra security in case the forestay breaks, their primary purpose will be to hold the mast forward against the taut backstay once the mast is up.  Then attach the top end of the block and tackle to the forward apex eye bolt and the bottom end to the forestay fitting.  (DO NOT attach to the rams horns as they may slip off or may NOT be strong enough).  Take up the slack line of the block and tackle and wind the free end around a winch or to a cleat to secure the line.  Take a last look around the deck to ensure all rigging and turnbuckles are free to stand up.
  7. Pull on the free end of the block and tackle to raise the mast, watching for jammed turnbuckles, snagged lines, etc. If you feel resistance stop to investigate the problem.  You can do serious damage to a turnbuckle by bending it, there is that much mechanical advantage to this A-frame.  
    HINT - If you tape the bottom swivels of the shroud turnbuckles together it keeps them upright to prevent buckling and breaking while stepping the mast.  Similarly tape the bottom swivel of the backstay in the upright position.
  8. Once the mast is vertical, hold the A-frame down on the deck with your body weight, pulling the forestay taut.  Transfer one of the halyards to the pulpit, pulling the mast fully forward till the back stay is taut.  Similarly transfer the other halyard to the opposite side of the pulpit.  The taut halyards will keep the mast standing while you transfer the forestay from the A-frame to the stem fitting.  Take your time so you don't drop the pin or split ring.  In lieu of the halyards and to speed things up I sometimes have an assistant push the mast forward.  But with the halyards you should be able to step the mast on your own.
  9. Snug up all turnbuckles.  Ensure the mast is perpendicular to the deck, tension the rigging and lock the turnbuckles.
  10. Remove the A-frame and store all pertinent lines together in a bag for the mast take down in the Fall.
  11. Reverse the procedure to lower the mast. 

If you have never stepped a mast before, rehearse this procedure in your mind so you know it cold.  Go through the motion, doing several dry runs if you have to.  Nobody will pass judgment on such an important job as this.  Practice, practice, practice till everybody understands.  The astronauts do it all the time.  Whenever I have a "green horn" help me, I always go through at least two dry runs with them till I know they understand.  You know they understand when that squirrelly look on their face changes to a "light bulb" smile.  If this doesn't happen change your description of the process!  Go slowly so no steps are missed. 
I once helped a guy to lower his mast and quickly discovered he knew very little about the procedure when the mast was not quite at the bottom.  The combination of short over tightened lines nearly ripped deck fittings out and prevented the mast from being lowered to the bottom.  It was scary how quickly he was willing to release a crucial line to lower the mast to the bottom.  Had he done so, the mast would have dropped.  As it was, the dock watchers supported the mast while the too short deck lines were released and then lowered it to the bottom.  After discussing the problem, he still didn't realize the complications of a mast base that pivots on the cabin roof, well above the deck where the A frame feet pivot.  Sometimes the obvious isn't obvious to all!  But it does demonstrate the need to fully understand the problems at hand.   TOP

 

1 - This is my first time using the A-frame and my buddy Ron was curious about the latest gadget I built so he came along to help.  The road tie down lines were  released, shrouds freed of deck fittings & deck is cleared of gear.

2 - Mast has been carried aft and the foot aligned to the tabernacle. Here I'm twisting the mast into alignment so Ron can insert the hinge pin.  Note that the mast is supported by the

3 - Hinge pin inserted. I made this custom hinge pin because every helper had a very difficult time inserting the factory pin through the tabernacle and mast base.  The end of the pin is slightly tapered to facilitate easy insertion.  The loop on the end makes it real easy to manipulate the pin.

3a - Hinge pin - The pin shown is made from 1/4" stainless steel rod.  I bent one end back on itself to create a loop for easy operation and the other end has a hole drilled through the rod for a cotter pin.

4 - Final check of A-frame, forestay is attached to the apex of the A-frame, block & tackle line is attached between the apex and the bow.  Halyards not yet attached to the A-frame.

5 - Windex and VHF antenna attached to mast head. Loosened turnbuckles standing up. All lines clear. Mast ready to be raised.

6 - Mast half way up. I steady it sideways during the bottom portion of the lift to protect the mast step when the boat is floating or in a side wind. Its a bit wiggly on a floating boat.

7 - Mast is almost vertical with the A-frame pulled down on the deck.  It is important to push the mast forward while transferring the halyards to the pulpit so you can comfortably attach the forestay to the bow fitting.

NOTE - I am considering modifying the above process to facilitate single man mast stepping by using the halyards with the forestay. 
If it works I will post the modified procedure here. TOP

 

MAST HINGE PIN - The factory hinge pin is difficult to insert through the four misalignment mast base holes or to remove since there is no hand hold.  I made a replacement pin from 1/4" stainless steel rod.  One end is bent back on itself to create a 1" diameter loop for easy handling.  The other end is slightly tapered for easy insertion through the four holes and has a hole drilled through the rod to fit a hair pin through.  You could drill a second hold near the ring for a second hair pin.

COMMENT - "Using an A-frame to step the mast is so effortless that it takes all the worry and frustration out of the job.  There is minimal sideways movement of the mast.  We stopped several times during the lift to check on things and to take these photos.  I wouldn't dare stop in the middle of a lift using the hand over hand method.  The deck pads stayed in place and the hinges worked perfectly.  I've used this A-frame to step the mast of several other SJ23s and an SJ7.7M and only tied the deck pads with a short length of line.  This poses no problem as they stay in place.  There is only a slight force to push them aft towards the stanchions.
Despite the ease with which I describe stepping the mast I still recommend that this is a two man job.  Steadying a 27' mast in a side breeze can be a daunting load.  Better to align the hull to the wind.  If it is too windy, better to find a coffee shop!"  TOP

Replacement SJ23 Mast - If you intend to break your mast or want other replacement rigging parts, phone Gene Adams at PORT GARDENER SAILBOATS.  He has lots of parts and can get just about anything else that isn't in stock.

Replacement SJ24, 26, 28 or 30 Mast - If you want replacement rigging parts for these models, phone SPAR TECH - 15230 NE, 92 St. Redmond, Washington. 1-206-883-2126.

NOTE 1 - If you wish to leave the A-frame in place while towing, suspend the apex of the frame from the mast with a line.  This prevents the frame from pounding on the deck, punching a hole through the gel-coat.  In addition, you could use a tie down line to prevent the frame from bouncing up to the mast.  To date I know of eight A-frames that have been built using these plans.  Mine has stepped dozens of boat masts.  Hmmm, I should say this qualifies for free grog!  

 

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