Boom vang and topping lift;noob questions

[Hermit Scott]

Is the topping lift a sail trim adjsutment? or is it's only purpose to hold the boom up when the sail is down?
Some boom vangs have a 'prop stick' that telescopes and blocks and rope to pull the boom down. Is the telescoping prop stick's only function to hold the boom up while the sail is down like the topping lift does when the sail is down?

The leech on the main sail looks abraded for a few feet above the clew. I take it this is from the wire topping lift? Should I change to an all rope topping lift because of this? or did someone jsut slack the topping lift too much while sailing?

 

[jibes138]

Topping lift

The topping lift just lifts the boom when the sail is down otherwise it would be down on the deck. Some boats use a cradle for the boom to sit in. On some larger yachts with higher tech vangs they can also be used to hold the boom up versus just pulling it down. These are rigid vangs and usually are hydraulic but at the least act like a piston and cylinder.
Chafe on sails can happen from a lot of causes but rest assured the leach can be repaired. Sails are made with a tape to cover the rough edges, this is a piece of dacron folded in half and then sewn to the sail, You can rip out the chafed tape and replace it easily. You may also have a leech line so you might need to replace a few fittings for cleating the leech line. Or maybe add a grommet or two. If he sailcloth is damaged the repairs are a little more complicated depending on the extent of damage. You could replace the whole panel but it will likely mess up the shape if the sail is stretched in the old section and nice and stiff in the new section. As you get some experience search some sites for used sails, Lots of catalina 30's out there so lots of used sails that will fit for bargain prices.

 

[Ray T]

The topping lift is also used to support the boom for off wind sailing in light air. This will allow a more powerful rounded shape in your main.

 

[jibes138]

Interesting comment Mr. T

I never thought of using the topping lift for that purpose. A few questions...wouldn't this allow the top of the main to twist further forward and spill more air and thus lose efficiency? It is really an aerodynamic discussion, is a flat surface going to provide more force from the wind versus a surface with less frontal area but a curvature to it. I don't know the answer, but am interested in it. The air has to flow somewhere so there is flow going transverse to the sail surface but it would be interesting to see some water tunnel testing of various shapes in a downwind scenario for comparison. Thanks for the input.

 

[Joseph Shirley]

jibes138, Twisting off the main with a topping lift or a spring loaded rigid vang is common usage to racing sailors. As mentioned in extreme light air either on or off the wind it allows you to compensate for the weight of the boom and the downward pull of the main sheet and with the crew to leeward you can get some shape in the sail. In waves as you go over and up and down your mast continuously is rocking back and forth. A straight sail would be properly trimmed for only one instant of that motion, and be luffing or stalled the rest of the time. A little twist allows some varying part of the sail to be properly trimmed all the time. and twisting it off in heavy air luffs the head as you have already mentioned and that lowers the center of effort so you don't heel so much. This is often done instead of early reefing when you don't have too far to go to get to a weather mark on a race course.

The topping lift also holds the boom when you are reefing

Joe S

 

[sand sailor]

that explains the 4th sheeve at the mast head see i learnt something new today