Washing Spinnaker in the Potomac

[ROAD Soldier]

The weather man was wrong in a good way. Winds were suppose to be only 5-6mph today but got about double that. I flew my cruising spinnaker thinking that would be the only way I would be able to sail in the low winds. Instead of just coasting along got some real speed and came up with a good way of measuring heel. Spinnaker in the water means 30 degrees heel.

http://youtu.be/GxckxNJfiss

[Russ]

It's not supposed to be in the water.

[Catigale]

Nice video....close hauled with the spin ....LOL!,

[Obelix]

Watching the video closely it is interresting how slack the lee upper shroud is. My shrouds look similar in 20+ deg heel. Based on the parallel ongoing detailed discussion in this forum raises the question, is the tuning of this rig still considered OK

Obelix

[Catigale]

It is, because sailing wont produce consistent shock loading of the slack shroud they way it would be experienced on a mooring. You dont need 300# tension in the rigging at all times, in other words.

[ROAD Soldier]

Watching the video closely it is interresting how slack the lee upper shroud is. My shrouds look similar in 20+ deg heel. Based on the parallel ongoing detailed discussion in this forum raises the question, is the tuning of this rig still considered OK

Obelix

I never measured my tension on my shrouds until last year at Pirate Sail I borrowed C130's tension-meter. My lower shrouds were so tight at 500lbs plus that it scared me so when I got home I loosened both sides one notch, so what it reads now I don't know. The upper ones were reading almost 200lbs so I left them alone. Now another factor to consider is I am flying a cruising spinnaker in the video at close hauled. In order to do that you have to put some serious tension on the Spinnaker. I never used the winch handle but I am hovering around 250lbs and I grabbed that sheet with both hands and leg pressed back on it,that might have something to do with slack in the lee shrouds .

[Obelix]

I'm interrested what tensions my shrouds currently have; I never adjusted or measured them since we got the boat in 2008. It appears while heeling, as if the shrouds may have gotten a bit looser over the years.
Maybe some real stretching took place or maybe my imagination is just playing with me, anyhow I just ordered a tension gage at Amazon.

Thanks for the replies.

Obelix

[mastreb]

I never measured my tension on my shrouds until last year at Pirate Sail I borrowed C130's tension-meter. My lower shrouds were so tight at 500lbs plus that it scared me so when I got home I loosened both sides one notch, so what it reads now I don't know. The upper ones were reading almost 200lbs so I left them alone. Now another factor to consider is I am flying a cruising spinnaker in the video at close hauled. In order to do that you have to put some serious tension on the Spinnaker. I never used the winch handle but I am hovering around 250lbs and I grabbed that sheet with both hands and leg pressed back on it,that might have something to do with slack in the lee shrouds .

I would put 500 lbs. at an upper maximum but not overly worrisome. It's about 20% of rated load (off the top of my head) and should be within spec for the chainplates.

Correct me if I'm wrong?

[seahouse]

Hey Obelix!

My shrouds stretched over the first season’s use – they were looser when I pulled the boat at the end of the 4-5 month initial season. That’s expected.

This spring, I retensioned on the trailer before launching. But they did loosen somewhat over the summer. So next year (Loos gauge in hand) if I find they are again loose when I rig, I will retension and see what happens. Once the initial stretch takes place, the tension is supposed to remain fairly fixed, if the limits of stress are kept to.

I do expect that the (new) hull itself might play a small role initially in the relaxing of the tension (structural convergence of the three points; the two chain plates plus forestay deck fitting). Particularly given the 5 months on, 7 months off, cycling of the tension it got.

I would consider just over 2000 pounds as the breaking strength for 1/8” cable for the calculations, and apply percentage elongation to that. Looks like you’re using closer to 2500 pounds, Masteb. What number is everyone else here using?

The rigging manual I reference says 20%, but can safely go to 25% if necessary to reduce sag for top shrouds with aft-swept spreaders (the M, and not the X). These are industry averages, as I’ve stated elsewhere, but referencing the factory manual, Macgregor advises the low range on all rig tensions.

- Brian.

[Obelix]

Hi Seahouse,
Since I will adjust my 2008 rig for the first time, what actual tension on the LOOS Gage do you use for your upper and your lower shrouds I'd appreciate your actual numbers, to give me some starting points to compare.
Adjusting for 10% of breaking load and assuming 2000lb of breaking load that would indicate 200lb of tension for the upper shrouds.
Do you adjust the upper and lower shrouds at the same tension or are you applying a percentage for one being higher than the other
Thank you, again
Obelix

[Highlander]

I think Beene got ya beat hear Buddy
http://s844.photobucket.com/albums/ab1/ ... 010128.mp4

J

[ROAD Soldier]

I think Beene got ya beat hear Buddy
http://s844.photobucket.com/albums/ab1/ ... 010128.mp4

J

Typical Canadian cant control the wind blowing out his sails

[seahouse]

Hi Obelix -

I don’t have a Loos gauge yet, I have ordered one from Amazon.com. I mentioned this in a separate recent thread on the topic. So I don’t yet have experience with it, but to be fair, I would be lying to you if I said I was unfamiliar with its application. Maybe some of those who have a gauge can chime in with some more applicable numbers that they have used. I am really looking more forward to acquiring the knowledge that will accompany having and using it, than I am to actually putting it to use tensioning my rigging. (It's my Christmas present, actually) .

My initial tensioning (beyond dealer settings, which were way too loose) was done by measuring the physical increase in distance between 2 pieces of tape (elongation a function of tension) on a segment of the top shrouds. The method is exact, but the Mac manual (as I recall) suggests tensioning on what would be considered the low side of what is average for the industry, so the values I chose to use were not so exact. Plus the tensioning has to be done in steps anyway because it's the nature of the incremental vernier tensioners at the chainplates on the Mac.

I have a (CDI) jib furler, so my forestay tension is not as easy to access and measure as the top shroud or the lower shrouds. The function of the forestay turnbuckle is really to set the mast rake angle, but if you wanted to be fussy (and I’m relatively not in regard to this) I would suppose you could make small adjustments in the forestay turnbuckle that would allow tension settings in the top shrouds in between what you would get with the vernier adjusters alone, and still maintain your mast rake within the desired limits.

But the tension on the forestay is determined by the design of the rigging to be a certain constant ratio relative to the top shrouds. Because of this, and to offset the mechanical disadvantage that aft-swept spreaders stipulate, and the lack of a backstay, the tension in the shrouds needs to be greater than with inline spreaders (like the X has).

In my boat I plan to use no less than the numbers you said, no lower than 200 lbs for the top shrouds, unless I get too much slack / curvature when under sail, then I will retension higher. This is starting at the lower end so you might want to go on the higher side of this if it works out practically.

Note that the generic norm for this (aft-swept spreaders) is 15 to 20%, or up to 25% if shrouds are sagging, according to a tuning book I reference. (Illustrated Sail and Rig Tuning by Ivar Dudekam, which I highly recommend- I use Amazon.com). As easy reading as it gets, there are others.

When you tension the top shrouds the spreaders will pull the mast forward in the middle, causing it to bend. The lower shrouds are tensioned to what they need to be to straighten it to bring the mast bend back to the desired amount.

The amount of mast bend you want depends on a lot of things (sail shape and trim, desired weather helm with rake, everything else we just discussed, etc). Pull the halyard straight, taut and flush with the mast at the top and bottom and you can get an idea of the amount of bend by the gap at the middle of the mast. Maximum never to exceed 1.5 X mast diameter.

Expect that you will be dancing back and forth a bit between all these adjustments, because they are all interrelated, and of course you will want to watch port to starboard symmetry at every point too.

Hope this answers your question. When I launch again in the spring (it’s in my driveway, then into storage in a few weeks) I will get some experience – so maybe some feedback from you after you have a go at it would be helpful. Thanks.

Regards- Brian.

[Obelix]

Hi Brian,
Thank you for your extensive reply
I received my Loos PT1-Gage yesterday and will check/adjust my current tension within the month (Florida Suncoast). Loos is assuming 2100lb breaking strength for the 1/8” wire. So I will start with 220lb on the upper shrouds and 210lb on the lower ones, if my current tension-readings are lower. Since I also got a furler, I need to accept the forestay tension as a function of the the upper shroud tension.
If you interested, I can PM you with my findings after my first in-water trial and we could compare notes after you got your data.
Regards
Jurgen

[seahouse]

Sounds good Jurgen. I'm going to guess that you will need a higher lower shroud tension to end up with a mast that's not too bent, partly based on Roadsoldier's experience mentioned above. But it'll be interesting to find out where it ends up.

- Brian.