Backstay on the M

[Highlander]

Leon

The arch would be more than 6' high if it were mounted on the gunnells , anyway I'm working on some thing simular to your set up but I will make my own masthead swivel top out of Alum plating with ss bearing and the back stay will run off a 4ft traveller so enough said I had originaly made this set up for my mac19 but abandoned it so as I could cutter rig my Mac26M , I have to remove my mast swivel base to finnish off my rigid vang installation so thats when I'll make my mast head swivel brkt it was a fixed set-up for my mac19 but for the M it would have to be movable, everything else is made just have to redesign the base ! but I'll wait to hear your results first

J

[delevi]

OK, some final tweaks today which I am hoping will turn out to be the ultimate rig.
1. Took some load off the shrouds. Uppers now 320 lbs, lowers 200 lbs. and added a very modest amount of mast rake.
2. Installed mast rotation limiters. Actually took 5 minutes since I already had the block & tackles from my running backstays (bit of irony) And all mounts were already in place. One end shackles to an eye on the side of the mast. The other end to a large track eye which I have at the front hole of the jib tracks. These eyes are for preventers, but still plenty of room. Of course, the same setup on the other side of the mast. I'll keep the adjustment set at approximately 1/3 rotation. This angle will lign up the mast and boom on a close reach and have the mast a bit to leeward close hauled. With 4:1 tackle on either side, I can later adjust this but will likely keep the setting right there.
3. Replaced shackle on the backstay with one of those chain link shackles (like for trailer chains) though it will stay open. Will never release on its own when lightly loaded and makes for quick release and re-attachment on the other side.

I decided to use the backstay as a runner of sorts. When rotating the mast with the new rig settings and no backstay load, the mast remains straight until it is about 1/2 rotated. This is why I chose the 1/3 setting because it is still straight in this position. It is also aligned with the backstay in this position (the swivel top is straight on the masthead.) The backstay will be shackled to the leeward side, thus causing the mast to bend directly aft, eliminating any sideways force, which would cause the masthead to hook to windward. The huge benefit here vs. conventional runners is if you forget to release the backstay before tacking, it's ok. The mainsail will still pass underneath. It takes just a few seconds to swap sides and you're using the same backstay, so you don't have to slack one off and let it dangle to leeward.

Rotated the mast to the 1/3 setting, put load on the backstay of 300 lbs (per loose gauge) Nice bend in the top of the mast. Forestay went from slack to tight. Mast remains straight (no sideways bend/curve.) Good stuff

Of course, sea trials will reveal the real Macoy. Will post updates when the rain stops and I can get out there.

LD TRIPPLE REEFED!

[Highlander]

Hello Leon ,

What happened ! are you fogged -in ! The suspense is killing me

J

[bubba]

I think that I prefer these backstays one on each side http://i293.photobucket.com/albums/mm42 ... 8013-1.jpg they work for a 650 A-spinnaker and work without removing the rotating mast.

[delevi]

Bubba, that was my exact setup (which I removed a while ago.) There are two problems with it. 1. Sideways pull on the rortated mast, which curves the mast and limits the very effectiveness of the stay. 2. The need to release with each tack and not just release, provide ample slack so the mainsail doesn't hang on the runner. I found the process messy and annoying, not to mention dangerous when I forgot to release the runner a few times. Plus the runner does very little when the mast is rotated. My current setup is safe... I can tack without releasing the stay, then reattach to the other side after the tack for optimum performance. Single stay, interchangeable port & starboard versus two so no lazy (limp) stay to worry about. Plus it is a direct aft pull on the mast, so it is much more effective in straightening the forestay and not curving the mast to one side. The rotation limiters are icing on the cake. I have them dialed in to what I believe is the best angle of rotation (a small angle,) However, I can adjust that angle any time, up to maximum (standard) rotation.

John,

It has been raining here for a while. Forecast for the next 10 days is rain I guess we need it. I did catch a dry window on Saturday and got out with Srdjan. We had an awesome time. Light winds 7-11 kts. Never needed to load up the backstay, in fact had both sails at max draft. Rotation limiters felt nice, even in light air. Close reaching in 10 kts apparent, we were consistantly in the 6-6.5 kt range. When we hit the wake of the ferry boats, lost only about 1/2 knot boat speed, which as I recall is less than typical. Main & jib (genny will live n the bag for the next 7 months.) What made the sail really exciting is the race (which was moving int he opposite direction.) We had to maneuver through oncoming boats for a while until we could fall off for the return trip. As murphy would have it, the wind died to almost nothing just after we hoisted the spinnaker. Time to burn some fuel to get back before the showers start again.

Cheers,
Leon

[delevi]

Had her out in various conditions, as high as 30 knots wind, and the backstay has been a fabulous adddition for sailing upwind. The backstay loads up between 200-300 lbs (on the 1/8" cable) using moderate muscle on the 6:1 tackle. This causes a very noticeable bend in the top part of the mast. When this happens, the forestay gets tight and most of the sag is eliminated when sailing upwind in a strong breeze. The mainsail also goes flatter, as does the jib. It's neat to watch. Arena Yachts' claim was dead on. Heel decreases, boat speed increases, pointing higher. All good stuff. I had to alter the setup slightly, however. Arena told me to keep it shackled on the starboard side all the time but I was nervous about the mast bend (not straigt aft but hooking to starboard.) I installed mast rotation limiters, which I wanted to do anyway. They are adjustable, but I generally keep them at approximate 1/4 to 1/3 of the full rotation span. This aligns the masthead with the backstay swivel and the tension is directly aft on the partially rotated mast. When tacking, I let off the tension, tack, then change the backstay to the new leeward side and put tension back on. Basically using it like a masthead running backstay, but much easier since there is only one stay and the change can be done before or after the tack without worrying about the main getting fouled on the stay. With runners, the load is on the windward stay which pulls the mast sideways (on the rotating mast.) Keeping the masthead-mounted swiveling backsgtay on the leeward side allows for the aft loads without sideways pull which distorts the mast straightness and looses much of what it is designed to do (tighten the forestay.)

Leon

[Highlander]

Thanks Leon

Now I will copy your mod masthead swivel brkt now that I know your satisfied with it , I've been waiting to hear your results I will make an alum, masthead swivel brkt with a SS bearing , so I'll remove my swivel mast base brkt this wk-end & proceed to make the masthead brkt , its the stern mount that will be hard to figure out with my full enclosure so I will have to wait until I pull the mac outa storage & go from their , in the mean time thx for the updates , When Beene comes down to see you later he can give me more info on how you's two will be putting this mod through the race course !

Thx again & nice work

J

[delevi]

John,

I don't see a practical way to use the backstay with the enclosure or even the bimini for that matter. When I use either of those, I disconnect the backstay and get it out of the way. Of course, I rarely sail with the bimini... like to see the mainsail and haven't sailed with the enclosure. I have these items for motoring and camping. You might build an arch as you mentioned, but that's more than I care to take on.

Leon

[beene]

I have been thinking long and hard about this.

I think that the tightening of the forestay and flatening out of the leading edge of the headsail is crucial to up wind performance, as Leon has found.

However, I don't agree with the masthead as being the place to attach a backstay to with our Mac M boats to accomplish this goal.

Due to the uniqueness of our rig design, I think the best place to mount backstays would the the same hound the forestay is attached to.

Why?

Well, from my less than engineered point of view, I figure mounting a backstay at that point will interfere less with mast rotation, not bend the mast as much as mounting it at the top, and still have the desired affect on the headsail.

This mod would require having kind of a running backstay config, perhaps as Leon once had, needing the skipper to change the setup with every tack. Which, from my point of view, would be worth it when holding one tack for extended periods of time, of racing, or just being Leon who is well, looking for maximum performance from his Mac, (not that there is anything wrong with that....LOL)

Just my thoughts on the subject.

Ciao

G

[delevi]

Geoff,
Your comments make sense in theory. However, for some reason the Mac sometimes defies theory. As you know, I tried both setups and the masthead backstay is MUCH more effective at flattening the forestay. As a bonus, it also flattens the mainsial, and the whole system is significantly easier to use than the runners you describe which I once had. Safer too i.e. in case you forget to loosen during a tack, no biggie, vs. runners, could be a major problem. The biggest problem with the previous runners is the rotated mast. Although it's pulling right at the forestay attachment, the mast resists the pull since you're essentially trying to bend it sideways. Net affect on the forestay... marginal. But seeing is believing. You'll get to play with the system firsthand come May.

Cheers,
L.

[Highlander]

Ah Yes Mr Beene
But your M does not have a Masthead Cutter Rig so now your theory just went right out the window or is that out to sea Laddie !

J

[beene]

Hi Leon

Can't see how the mod you have helps to flatten out the main also. I get the head sail, no doubts there, just can't get my head around how it affects the main. If you take any right angle triangle and move the vertical line back so that it is 89 deg instead of 90, to avoid slacking up the roach, one must tighten up the main sheets. It should not matter, again in theory, where the vertical line is in that triangle. Move the mast fwd, you would have to slack off the mainsheets to allow for that, move it back, you would have to tighten them up to keep the sail flat. Guess seeing will be believing this May. Looking fwd to that as always.

Your points are all very valid.

I am not too excited about 2 things:
1. Bending the mast towards its weaker more vulnerable point, ie she bends far easier side to side then fore and aft.
2. Anything that affects mast rotation, as I love that part of the design.

But, being as how you have far more experience with both of these configs, I quite willingly bow to your expertise in the matter.

John....

Your rig defies any concept I could ever get my head around. LOL
She's 1 of a kind my friend. Probably always will be. Good on ya I say. Whatever floats your boat LOL.
Can't wait to see if she'll out run me this summer in some hands on sea trials.
With all that square footage advantage, you should just walk away from my wee M.

Cheers

G

[Currie]

Will let Leon answer the specifics of his rig but in general, bending the mast back puts a curve into the luff of the mainsail and flattens it by pulling the "belly" out of it.

Cheers,

~Bob

[Hamin' X]

Bob is correct, but this only works on fractional rigged boats. When the forestay is located below the top of the mast, pulling back on the top of the mast will induce the bend that he is referring to.

~Rich

[Currie]

Bob is correct, but this only works on fractional rigged boats. When the forestay is located below the top of the mast, pulling back on the top of the mast will induce the bend that he is referring to.

~Rich

+1