do you think the melges 14 will catch on?

When the halyard cleat is at the top the mast there is hardly any halyard to stretch so the Cunningham works more effectively. Also, the mast is only under half compression compared to a base cleat when the Cunningham is yanked on. Don't know how important that is in boats like the Aero though.
There is less halyard stretch, although most dinghy sail designs have a softer luff than the stretch in a typical modern line used as a halyard so I expect it is imperceptible in a dinghy of this size with a dacron sail.

The mast compression is the same whether you locate the halyard cleat at the bottom of the mast, half way up the mast or at the top of the mast. As one naval architect explained to us......."Hold up a broomstick in your left hand with a 40lb weight tied to a line going through a sheeve at the top of the broom stick.....if you tie the line off by the sheeve or at the bottom of the broomstick, the compression is still 40lbs.......compression is affected by the tension on the main and the equal and opposing force provided by the mast, not where you tie off the halyard"

Another trick to prove this......apply max luff tension with the halyard and the mast lock off.....so the mast is pre-bent under compression. Lock the mast lock so the halyard is locked... release the halyard. The mast will not spring back up to vertical under less compression.

Old wives/Etchell sailors lore.
The definition of mast compression decides whether you think the compression changes. I agree that halyard cleat location does not effect compression at the bast of the mast - that is provided by mainsail forces, standing rigging (not applicable here) etc. However, the mast will be compressed between the head of the sail and the location of the cleat by the halyard tension and any cunningham tension applied to the sail. Having a halyard lock, or cleat at the top, ensures that this compression is only experienced by the very top of the mast, which is the definition being applied here.

With an Aero, the halyard cleat is external to the mast, so with the amount that the rig bends it must cleat at the top. Otherwise, the distance between mast tip and where a mast base cleat would be would shorten too much as the rig bends, reducing halyard tension and allowing the sail to sag. If the halyard tension is kept high enough to ensure a tight luff when the rig bends with a mast base cleat, you would, as Amati states, simply create a bow.
Yup .....this is the most valid reason for mast head lock on a carbon rig. Its not the mast compression, it is because the distance between head of the sail and the cleat can change and so halyard tension can change. Merely adding vang on a bendy rig (good in big breeze) also eases the halyard (bad in big breeze) so mast head lock will effectively eliminate this stretch.

 
When the halyard cleat is at the top the mast there is hardly any halyard to stretch so the Cunningham works more effectively. Also, the mast is only under half compression compared to a base cleat when the Cunningham is yanked on. Don't know how important that is in boats like the Aero though.
There is less halyard stretch, although most dinghy sail designs have a softer luff than the stretch in a typical modern line used as a halyard so I expect it is imperceptible in a dinghy of this size with a dacron sail.

The mast compression is the same whether you locate the halyard cleat at the bottom of the mast, half way up the mast or at the top of the mast. As one naval architect explained to us......."Hold up a broomstick in your left hand with a 40lb weight tied to a line going through a sheeve at the top of the broom stick.....if you tie the line off by the sheeve or at the bottom of the broomstick, the compression is still 40lbs.......compression is affected by the tension on the main and the equal and opposing force provided by the mast, not where you tie off the halyard"

Another trick to prove this......apply max luff tension with the halyard and the mast lock off.....so the mast is pre-bent under compression. Lock the mast lock so the halyard is locked... release the halyard. The mast will not spring back up to vertical under less compression.

Old wives/Etchell sailors lore.
The definition of mast compression decides whether you think the compression changes. I agree that halyard cleat location does not effect compression at the bast of the mast - that is provided by mainsail forces, standing rigging (not applicable here) etc. However, the mast will be compressed between the head of the sail and the location of the cleat by the halyard tension and any cunningham tension applied to the sail. Having a halyard lock, or cleat at the top, ensures that this compression is only experienced by the very top of the mast, which is the definition being applied here.

With an Aero, the halyard cleat is external to the mast, so with the amount that the rig bends it must cleat at the top. Otherwise, the distance between mast tip and where a mast base cleat would be would shorten too much as the rig bends, reducing halyard tension and allowing the sail to sag. If the halyard tension is kept high enough to ensure a tight luff when the rig bends with a mast base cleat, you would, as Amati states, simply create a bow.
The definition of mast compression is the down force being applied through the walls of the mast which is equal and opposing to the up force exerted through the halyard (lifting against the sail) and shrouds (lifting against the deck).

When you tighten your shrouds, you will create a similar "bow" effect , even though the shrouds are effectively "locked" at the top of the mast. Next time you are going out on your Aero, apply aggressive halyard tension with the halyard lock off ...sufficient to apply prebend to the rig.....then lock the halyard...et voila, the prebend is unchanged.

Now agreed that if you stand at transom and pull halyard, you are creating an additional force which is not compression , which will bend the mast.

There are a variety of forces that the controls of a sail boat can apply to the mast. Some create compression. Some do not. Its all fun to figure out.

Force can turn a corner. The outhaul on a boom is similar. The compression along the boom is the same whether you cleat at aft of boom or at front of boom.
Not quite... Due to the sheave at the top, the force the sail pulls downward with is doubled on the top of the rig. With the cleat at the very top of the rig, as on an Aero, this doubling in force is only acting on the top 1 or 2 inches of rig. If the halyard was cleated at the bottom of the rig, as in many other dinghies, this 2:1 action acts over almost the entirety of the rig - from the sheave to the cleat point. Any bit of rig below the cleat point is unaffected by this, and only affected by shroud tension, rig forces etc. This is the reason big boats spend thousands on 2:1 halyards (halving compression between the top of the rig and the cleat point) and halyard locks (eliminating halyard-caused compression forces). This enables them to use lighter rigs, lighter halyards, less hull structure...

11514.gif


 
now that's what I call a comprehensive answer!

I had one similar to that prepared but

- without the drawings

- more words like "idiot", "stupid Naval Architect", etc init

when my pc crashed - so I never sent it.

But thanks JR, now everyone should finally understand this.

I have one comment to add (for those who still haven't got it).

As long as you don't attach the halyard to the boat but to the mast (somewhere), the force that pushes the mast into the boat is not affected by the type of halyard, position, or reeving. Thats probably what the f***ing Naval architect meant but some i***t didn't understand it.

It "only" affects the compression force (and therefore the compression stress) within the mast.

If you however tiey down the halyard somewhere in the boat (e.g. with a pulley and a cleat), then the force is transmitted to the boat and the mast is pushed down harder into the boat.

 

JimC

Not actually an anarchist.
8,171
1,064
South East England
JR has it right. The difference in mast bend between using a halyard lock and using a cleat at the base of the mast on my flexible IC mast is very significant.

I would be very interested to know who Mambo Kings Naval architect friend was. If you consider a sail which is secured to the mast at the tack, and has a halyard cleated off then whilst the compression in the mast from halyard/luff tension is considerable, the amount of that compression that comes through the mast foot is zero. The weight hanging analogy is distinctly misleading.

 

jeffers

Member
280
0
UK
My main experience with this sort of thing are OK's and Finns- we used halyard locks up top. Is that Aero practice?
The halyard is spliced onto a short piece of thicker line and that engages in a cleat at the top of the mast. There's then a boss on the side of the mast that you route the halyard around to another cleat on the front of the mast. If you get it tight it does not flap that I've ever noticed. The remaining tail then tucks into a sail pocket by the tack. All rather neat and simpler than I'm making it sound.
Anybody figured out how to modify mast bend with this setup? Or is the mast layup designed to take this into account? Does what sounds like a wraparound halyard chafe against the mast as it flexes?
Is the mast top cleat a halyard lock?

On the Aero is it a v-cleat I believe. A halyard lock would work better IMO. That is what we have on the D-Zero and no chance of it popping out as long as you make sure the ferrule goes in to the lock properly when you hoist.

 

jeffers

Member
280
0
UK
Jeffers can be relied on to pop in to tell us how the D-Zero is superior in every way.
No a question was asked and I answered it as I believe to be the truth (with regards to the way the Aero halyard cleats). Feel free to correct it if you think it is wrong.

Anyway it is true about the D-Zero (but then again being an apparent paid troll I would say that wouldn't I, still waiting to be paid though)

 

DTA

Anarchist
746
12
San Antonio
My main experience with this sort of thing are OK's and Finns- we used halyard locks up top. Is that Aero practice?
The halyard is spliced onto a short piece of thicker line and that engages in a cleat at the top of the mast. There's then a boss on the side of the mast that you route the halyard around to another cleat on the front of the mast. If you get it tight it does not flap that I've ever noticed. The remaining tail then tucks into a sail pocket by the tack. All rather neat and simpler than I'm making it sound.
Anybody figured out how to modify mast bend with this setup? Or is the mast layup designed to take this into account? Does what sounds like a wraparound halyard chafe against the mast as it flexes?
Is the mast top cleat a halyard lock?

On the Aero is it a v-cleat I believe. A halyard lock would work better IMO. That is what we have on the D-Zero and no chance of it popping out as long as you make sure the ferrule goes in to the lock properly when you hoist.
I'm not sure what a "halyard lock" is, but it sounds like a some kind of mystery-shackle connecting the head of the sail to a "lock" at the top of the mast, but with the added benefit that it can somehow be opened and closed by virtue of the sailor manipulating the halyard in some manner while standing at the base of the mast. If that is indeed accurate, then it's hard to see how anyone could argue that it's not a superior solution (unless the cost is prohibitive).

 

Port Wine

Member
92
7
Here
I sailed a Melges 14 yesterday. They were demo at Gulfport Yacht Club. I also sailed an Aero last year. I must say that for the $, the Melges seems to be a better deal. It seemed more predictable. I can see nice evening sails with a cocktail (must add cupholders) or of course racing. Could add a kid to train. I am 185 lb and sailed the large rig (9.8m?) in about 10knt. Very relaxing. It was almost sunset after regatta. I liked the Aero a lot. Fleets of both seem to be building. The Aero seemed more "windsurfer" and the Melges seemed more "boat" if that makes sense. Just my $0.03

 

Mystique

New member
10
0
I sailed a Melges 14 yesterday. They were demo at Gulfport Yacht Club. I also sailed an Aero last year. I must say that for the $, the Melges seems to be a better deal. It seemed more predictable. I can see nice evening sails with a cocktail (must add cupholders) or of course racing. Could add a kid to train. I am 185 lb and sailed the large rig (9.8m?) in about 10knt. Very relaxing. It was almost sunset after regatta. I liked the Aero a lot. Fleets of both seem to be building. The Aero seemed more "windsurfer" and the Melges seemed more "boat" if that makes sense. Just my $0.03
very cool! what do you mean by 'more predictable' ?

 

Port Wine

Member
92
7
Here
Predictable is a subjective term. For me, the extra momentum of the Melges made it more predictable. Not ment to put down the Aero's "instant on" and "instant off" nature. 

 

tillerman

Super Anarchist
5,445
2,685
Rhode Island
Sounds like the Melges 14 and the RS Aero are different enough - perhaps mostly because of the difference in weight - that they do appeal to different audiences, and that they are both having some success. Look forward to seeing some joint RS Aero and Melges 14 regattas in the near future.

 
Clearwater Sailing Center in Florida is sponsoring a Performance Dinghy Open Regatta October 21-22. Plans are to make it an annual event to be the southern states HPDO (High Performance Dinghy Open at American YC, Rye,NY) Melges 14 and aeros are invited, along with FD, 505, Contender, Windmill, Fireball. Oh, and great RC, ahem. More info later on the CCSC web site.

Dave Ellis Tampa Bay, Florida

 

Dex Sawash

Demi Anarchrist
2,571
798
NC USA
How about UFO and the Weta?  They would be good additions to that fleet.


Clearwater Sailing Center in Florida is sponsoring a Performance Dinghy Open Regatta October 21-22. Plans are to make it an annual event to be the southern states HPDO (High Performance Dinghy Open at American YC, Rye,NY) Melges 14 and aeros are invited, along with FD, 505, Contender, Windmill, Fireball. Oh, and great RC, ahem. More info later on the CCSC web site.

Dave Ellis Tampa Bay, Florida
Would be a good idea to offer portsmouth with a new event. Could have a rating cutoff so a Dolphin Sr doesn't show up and fuck the sequences. If the date falls well in class calendars, future years can build boat counts. 

 
Toyed with the Portsmouth fleet idea. Frankly, I know pretty much all the boats in the area and only Raiders and E-scows come to mind. E-Scows are already at CCSC, so maybe. WETA? Enough in the Tampa Bay area that travel? UFO? Let's get a fleet of boats in the SE first.                                                                                First year we want to just do a very good job with a few classes. Then, in future years, we'll see.                                                                                                       Dave Ellis, PRO, Performance Dinghy Open

 

Latest posts




Top