Tuning the Forward Lowers

Now that you have tuned your headstay, backstay, and cap shrouds, it is time to move on to the Forward Lowers.

These stays are not found on all boats, so if you don't have them, you can skip this section and move onto tuning the aft lowers (which in your case would be the "Lowers"). The purpose they serve is to help induce bend into the mast. They pull the middle of the mast forward while the backstay pulls the top of the mast back. This causes the mast to bend slightly, which is a good thing!

The sailmaker will want this bend, as it is important and calculated into the design of the mainsail. If the mast were straight, the sail would not fly as well. 

The tension on these stays will be less than the Cap Shrouds but more than your lowers. It is important to tension both sides at the same time and by the same amount to ensure that you don't pull the mast to one side or another.

If you are using turnbuckles, this will go very quickly and easily. If you are using dead eyes, then you will need to set up the tensioning line system.

As you go tightening, you want to sight up the mast to make sure it remains in column (which means straight). There are different ways to sight the mast, which we will go over at a later point as well. You will continue to tighten the stays while watching for the forward bend to happen and making sure that it doesn't begin to bow to the sides. This is why you want to do them at the same time.

For turnbuckles, you will start off

2 turns on port, 2 turns on starboard, sight the mast,
2 turns on port, 2 turns on starboard, sight the mast, ...

Once they begin to have some resistance, you will switch to

1 turn on port, 1 turn on starboard, sight the mast.
Proceed as needed until it is perfect

For deadeyes, crank the

port winch 1 full turn on high speed, starboard winch 1 full turn on high speed,
port winch 1 full turn on high speed, starboard winch 1 full turn on high speed, ...

Until the slack has been removed from the system. Then

port winch 1/2 turn on low speed, starboard winch 1/2 turn on low speed, sight the mast.
Proceed as needed until it is perfect

If the mast bows to one side, either tighten the side it bows from a bit more and sight the mast to make sure it corrected, or loosen the side it bows to a bit and sight the mast again to make sure it corrected.

If the forward lowers are tighter than the cap shrouds, you want to stop and reassess the situation. This is usually caused by a loose backstay. Since the mast is tipped too far forward, you need to crank down on the forward lowers to achieve proper mast bend. If this happens to you: 

Release the forward lowers
Tighten the backstay and possibly loosen the headstay to move the masthead aft.
Moving the masthead aft can make the cap shrouds slightly looser, so they will need to be readdressed. 
Then tighten the forward lowers again.

At this point, the forward lowers should be able to achieve the proper mast bend without becoming tighter than the cap shrouds. 

The next stay to set are the aft lowers