Why are mainsails not hank on?

[Rockinar]

Im new to sailing. The hank on jibs have me curious. Why are mainsails not hank on? Seems to me it would be better. Easier up/down, self serviceable, you have a stack pack on the boom so no "bag" on the deck like a jib.

Why am I not hearing about hank on mainsails?

[boatman61]

Because its a fat mast not a skinny wire..

[jmh2002]

Mast hoops - hanks for mainsails

[Rockinar]

Originally Posted by boatman61

Because its a fat mast not a skinny wire..

I'm trying to say, why can't there be a cable that runs in the back of the mast to hank on, instead a track?

[Simi 60]

Originally Posted by Rockinar

I'm trying to say, why can't there be a cable that runs in the back of the mast to hank on, instead a track?

More to the point, why would you when you have a perfectly good track.

[Chotu]

I mean they kind of are. They are just hank in instead of hank on.

[cal40john]

Originally Posted by Rockinar

I'm trying to say, why can't there be a cable that runs in the back of the mast to hank on, instead a track?

Sight up your jib next time you're sailing. Notice that under load it is not straight, but is a catenary. The higher the wind the deeper the curve of the forestay the deeper the draft of the sail and the further forward that the max draft goes. This is not the direction you want the sail shape to change going upwind.

The mast is much less prone to bending, adding a stay behind it gives you the same deficiencies as the jib.

Used to sail on a Cal 34 with a hydraulic backstay. We would pump it up to minimize forestay sag while sailing upwind. When we turned to go downwind and would want to put up the spinnaker we couldn't get the spinnaker pole out of the chocks it was in until we eased the backstay to unbend the boat.
Solid glass no core boats are bendy.

[JPA Cate]

Another reason is for smooth air flow. That is one reason race boats introduced foils, and sail with bolt ropes to go up the luff rope groove.

Ann

[RaymondR]

I have seen a hanked on main sail used on a boat with a tubular truss mast. The hanks were attached to a wire which ran from the deck up to the top of the mast on the aft side parallel with the mast.

[roland stockham]

On a traditional schooner rig the center sail (fishermans) was like an upside down jib. It was hanked to a wire that went to the top of the foremast then back to the mainmast and acted as both the luff wire and backstay. Sag in the wire was noticeable!

[Cpt Pat]

Originally Posted by cal40john

Sight up your jib next time you're sailing. Notice that under load it is not straight, but is a catenary. The higher the wind the deeper the curve of the forestay the deeper the draft of the sail and the further forward that the max draft goes. This is not the direction you want the sail shape to change going upwind.

The mast is much less prone to bending, adding a stay behind it gives you the same deficiencies as the jib.

Used to sail on a Cal 34 with a hydraulic backstay. We would pump it up to minimize forestay sag while sailing upwind. When we turned to go downwind and would want to put up the spinnaker we couldn't get the spinnaker pole out of the chocks it was in until we eased the backstay to unbend the boat.
Solid glass no core boats are bendy.

Side question: would using rod instead of wire rope for the forestay reduce sag and improve jib performance?

[psk125]

Some boats do use hanks for their storm trysail. They rig a wire between two padeyes in the mast to avoid the complications of multiple tracks or luff grooves. People using storm trysails are not usually overly worried about smooth airflow and efficient aerodynamic shape.

[skipmac]

Originally Posted by Cpt Pat

Side question: would using rod instead of wire rope for the forestay reduce sag and improve jib performance?

Slightly but enough for the racy guys to do it.

[Greg K]

Here's a related question that I asked on another thread but haven't yet received an answer to: Why was the foot of the mainsail on most boats for as long as I can remember attached with slides to the groove in the top of the boom for the full length of the sail? In other words, what was the function of that arrangement? The ubiquitous use of stack-pack like systems these days has, by necessity, ended this practice, so what was the benefit that has been lost by gong to loose footed mainsails?

[jmh2002]

Originally Posted by Greg K

Here's a related question that I asked on another thread but haven't yet received an answer to: Why was the foot of the mainsail on most boats for as long as I can remember attached with slides to the groove in the top of the boom for the full length of the sail? In other words, what was the function of that arrangement? The ubiquitous use of stack-pack like systems these days has, by necessity, ended this practice, so what was the benefit that has been lost by gong to loose footed mainsails?

Loose footed mainsails came about way before and nothing to do with stack packs.

It's performance related. It's easier to adjust the outhaul and the foot of the mainsail if it's loose footed, and a better sail shape can be achieved.

So much so that on race boats whose rules forbid this a very light piece of sail cloth was used at the foot to attach it to the boom, just to meet the rules, but otherwise the structural attachment was at the clew.

This is really about modern sail development. Originally the load needed to be spread along the edges of the sail, but technical developments in sail coth and sail construction enabled highly loaded heads, tacks, and clews to be possible.

These days there is no need to the foot to be attached to the boom.