Backstays?

[AKCoastie]

This is probably a stupid question but here goes. Being that the Mac's mast does not go through the cabin, what keeps the mast from falling forward when sailing downwind. It would seem to me that backstays would be an important safety modification for any boat planning on sailing in anything stronger than light winds.

[Hamin' X]

The geometry of the shrouds and swept back spreaders, maintains the proper rearward forces.

~Rich

[Gerry the fish]

The shrouds attach further aft than the mast - providing enough suport to hold the mast from going forward. Dont know what the stainless cable is rated for - several hundred pounds I would guess. The mainsheet (when the sail is up) also provides some aft tension.

Many dinghy sailboats use the same principle - shrouds attached a short distance behind the mast with no backstay.

Some people are concened when running down wind without mainsail in an M (no backstay) that the shrouds are not enough to hold a genoa and you should rig something to the mainsheet up to the top of the mast. Its not a bad idea but I havent seen actual numbers to say whether its necessary. Has anyone actually had their mast fold forward in this condition?

Gerry

[March]

The X's mast attaches to a bracket mounted on top of the cabin--the foot of the mast makes a "hinge" with one bolt as a pivot. There is no way that hinge would go past the dead point that keeps the mast vertical, short of ripping it off. Nor can one conceivably imagine the Mac with all sails up, flying in a wind that might bend the aluminum mast forward. Still, the X has a backstay and I feel all right about it--we fly the flag attached to it.

[Hardcrab]

Gerry,
Think about it this way.
You are running directly down wind while wing on wing with a genny on your backstay-less M.
The boom is extended as far as you can to the stbd, the genny is winged over on the port.

The mechanics of the "main sail/boom/mainsheet" acting like a backstay during this time is almost non-existent.
(Very unlike the condition when/if the boom is centered).
If the mainstays were to fail, the mast would fall forward some distance until the main/boom/sheet got centered before acting like a backstay.
Almost, if not all, of the forward acting force on the mast is on the aft swept spreaders and stays in this example.

Now throw in a "winged" genny adding it's power felt by and restrained by the stays.
More force on the aft swept spreaders, but still nothing contributed by the main/mainsheet/boom "backstay" over on it's "wing"

M's sail like this all the time with no worries or concern.

Next, take away the main sail "half" of the wing to wing loads and just fly a genny.
In my mind, the stays "load" being felt has been cut somewhere in half.

Why will just the genny flown cause nasty loads to the aft swept stays and the mast to crash?

[Divecoz]

I dont have a degree in Geometry or in Nautical Engineering, Sooooo allow me to voice my opinion from a practical /common sense point of view. BTW this doesnt always hold true... common sense sometimes equates to common mistake.
Someone at the MacGregor Factory has a degree in both those expertise I would assume ... and a PHD as well in Frugal haahaha
But Roger expounds upon the Ms ability to be sailed with just its main sail in light wind. Big selling point BTW and not a lot of boats sail well in light wind with only the main flying. But Our Dear Friend and supplier Never once mentions or shows the M flying just the fore sail. Its a nice point about the M you can single hand it in light wind without the need of expense of a Roller Furler.
In 6 years of the M's production has anyone had or heard about a mast failing under sail?
Wing on Wing. Is this not a light air condition ? I have sailed WoW in light air and I feel if I was foolish enough to try it in heavy wind my bow would plow ... or so it seemed to me during a few short wicked gust.. So for me ... I dont find it a to be good sailing sense to WoW in Heavy wind .
Where the heck is Leon ? Leon has dealt with this as I recall... Doesn't he have some sort of Custom back stay installed?

[Hardcrab]

Dive,
I'm no Mech engineer either, just a conclusion on my part while looking at the issue.
Sure, a backstayed rig should be stronger.
But the backstay-less rig of the M is "strong enough so as not to matter", if nothing else.

I'm not saying sailing WoW is the best way to sail. Slow and hot. Gybe if you need to make a course.
But, I'd never consider it to be a "light wind only" point of sail.

How do you jive with the extra power of an Assym Spin flying downwind with the boom way over, and no backstay or mast crashes?

I'm saying that loads on the mast/stays are higher with two sails up versus either one, and there is no "backstay" action in my boom winged out example, so we can take the "main acting as a backstay" off the table for any extra "strain" relief, at least when sailing WoW/DDW.

So my uneducated conclusion (IMHO and YMMV) is:
If the rig is strong enough to take the power created by two sails, then it follows that either just a genny or just the main is creating less power and therefore less strain will be applied on the rig.
If it doesn't crash with two sails, then it doesn't crash with one sail.

If this is not correct, then what is it that I'm missing?

I'm not sure where the idea came from that the Mac M is somehow unsafe with flying just a genny because of no real "backstay" installed.
I've flown just a genny many times, but I'll agree, that means nothing to anyone else's experience.
With equal conditions, I'm thinking my genny alone is faster than my main alone. It's a bigger Sq Ft sail, I think.
Balance didn't seem to be to far out of whack.
I just need more speed than usual to make a tack.

I seem to remember Leon stopped using his running backstays. Not much gain for the hassle, as I recall his post.

[Highlander]

Here's what I'm working on Back stay on a traveler to accomadate the rotating mast

http://i235.photobucket.com/albums/ee20 ... 010006.jpg

http://i235.photobucket.com/albums/ee20 ... 010016.jpg

But it's turning out to be APITA to get done with the constant rain & thunderstorms this is only stage 1 of three stages of this project as it will have three functions !!!
Finnaly getting some nice weather

J

[RocketsCrew]

Here's a little experience I had with my M. I live at the end of Howe Sound and every afternoon we get a wicked inflow... 25-30knots. when I was new to the boat I did the silly thing of flying wing on wing home one day and have since a couple of times with a 150 genny. Ya Hoo. At one point I was surfing along at 9.5 knots, dagger board half way up. I'm pretty sure the M was planing(which should actually reduce the loading?). I've since inspected all the rigging whenever I drop the mast and see no damage or wear. I've also had conversations with very knowledgeable racing sailors of conventional boats who load their rigs to the max all of the time. The consensus is that the tri pod rigging on the Mac should be just fine, the limiting factor being how far you can wing out your main.Since the boat is on its least resistance point of sail, is there really that much more loading? I think the loading could be much more evident on a reach in heavy wind. I'm considering some running backs for this point of sail. I saw a simple set up in the mods section here, and was on a conventional race boat that had them the other day. They do work well. Cheers

[violaman]

I would like to add my experience sailing my 2007 M wing on wing.
June 2007. Lake Chelan, WA. Sailing from Stehekin to Safety Harbor (located approximately in the middle of the lake), distance - about 27 n miles, covered in less than four hours. The speed average 7.4 knt, max 8.2 never dropped to less than 6 knt.
Conditions: Water (sea) 2-4 ft wind waves with extensive white caps. Wind estimated using Beaufort Scale 15-20 knt with gusts over 25 knots.
Sails: Full factory main, 150 genova. Dagger board all the way down. (mistake; should have been no more than 1ft down.)
Sailing down wind wing on wing. Boom pressed against shrouds. Wang pulled very tight.
As the wind strength increased, the boat attempted to round up in to the wind several times resulting in a couple of accidental jibes. Counter steering did not help much since no water flow occurred around the rudders. ( Water slides down the crest of the wave with about the same speed as most boats sail resulting in no flow around the rudders and no steering.)
After one nearly serious broach and feeling no control of the boat, I decided to take sails down. In a process I lost two battens.
Conclusion: M's Fractional rig has enough strength to withstand any winds up to the point when we cannot control our boat's behavior and have to reduce sail area or take down sails altogether. I assume that rigging has no damaged shrouds, or BENT SPREADERS. Since in such conditions they are under tremendous compressive pressure. The backstay is needed only for headstay tension adjustments for going up wind.

[Ivan Awfulitch]

Sailing down wind wing on wing. Boom pressed against shrouds. Wang pulled very tight.

Hey, watch it, this is a family friendly site.

[bscott]

Roger explained in his video that the backstay was necessary for down wind sailing.

When I converted my to a rotating mast I kept the shroud geometery the same and installed dual 4:1 backstays. I found that I had to ease both stays off when tacking to let the mast rotate. After the tack I found that the leeward stay had stress applied to it on its own due to mast forward pressure. A broad reach had even more pressure. After the tack I then manually harden the stay to banjo like stress.

When on a beam reach or run I ease both stays which lets the mast move forward giving the foresail more fullness. I also ease the jib halyard for even more fullness. I found that the stiff mast doesn't bend enough to flatten the main very much but it does have some effect on the forestay. Hardening up the main halyard has more effect on flattening the main. Since I rely on my backstays to support the mast I only tension my upper shrouds to a Loos 260 and inners to 220.

Bob

[bubba]

Hay Rocketscrew We have sailed directly down wind in our M in 35 mph breezes with only the 3rd reef up and surfed the wind waves at 9.5. We don't need to overpower our Mac M mast to get speed, just pull up your daggerboard. We also have the Mac A-spinnaker and have reached speeds in the 9's mph with full main and 2 feet of daggerboard down in 15 mph breezes running down wind, make sure you have a spinnaker sock to control it.

As far as running back stays I trust the Mac M computer engineered rigging and use our 3 reef main and 110 roller jib. Also check the rigging for wear regularly. I have seen the running back stays on the Black Pearl that had a 550 sq ft A-spinnaker with 6 ft bow sprit and other modfications to add more stress than stock rigging.

[mtc]

AKC;

Having kids on board with the potential of rigging failure not likely but possible, I too pondered the no backstay feeling and modified my M. It's listed in the mods to give you some more ideas on yours. Works well and takes no time to rig. The main purpose of the mod was to tighten the forestay and give me a little more pointing ability, but the other gain was a little more comfort that when running the mast wouldn't at least come down forward. As for falling aft, I also use a secondary forestay.

mtc

[delevi]

Thousands of these boats are on the water and work fine with the tripod design without backstay. Hunter's B&R Rig is essentially the same thing and there are many of them out there.. no backstay. This is not a statement about performance, since I installed an adjustable backstay on my to help control forestay tension and flatten the main, but from a safety standpoint, I wouldn't sweat it. BTW The 5/32" cables have 3200 lbs breaking strength.

Enjoy the boat.
L.