Standing Rigging Tension?

[Tomfoolery]

To use the same mounting hole on the mast, how much should the forestay be shortened, 8-9/16?

Sounds like a trick question.

Answer: Eight inches.

[Catigale]

7 1/2 according to this idiot, but this does not include the highly recommended toggle up top

http://www.macgregorsailors.com/modt/index.php?view=514

[BOAT]

Huh, the genoa they gave me from the factory goes all the way up - I only have one inch left at the top - the only way you could add that 7 inches to 'boat' would be to raise the mast hound too. And that would mess up all the other stuff (stays, etc) . . . .

If I cranck the mast raising winch real tight I can get the forestay pinned real easy so I really do not need this mod but after seeing it I can say that it would not fit on 'boat'. The genoa is too big.

[Tomfoolery]

Unless the forestay was laying flat against the face of the mast (where it wouldn't do any good), any increase in forestay length will require raising the hound by a greater amount than the increase in forestay length. If the forestay was at a very shallow angle to the deck (like 30 deg.), using a 300 in forestay, the increase in hound height up the mast when increasing the length of the forestay by 1 inch is about 2 inches. Making the angle 60 deg. off the deck (closer to reality), the increase in hound height with a 1 inch increase in forestay length is only about 1.15 inches, but it's still more than the increase in forestay length.

Using the I and J numbers I found (which are different depending on what site you look at ), the angle between the forestay and the deck is about 68 degrees, so the increase in hound height per additional length of forestay isn't going to be all that much, but it will still be greater than 1:1. Sketching it out (AutoCAD alert!), I get 8.66" increase in hound height with a forestay length of just under 300", including hardware (even the stem fitting sticking out of the deck). Changes in the I and J numbers don't make an appreciable difference in the change in hound height, as the various figures I found aren't terribly far off from each other.

One thing that will make a bit of difference is the angle of the hound to the mast, as it sort of sticks out from the mast, rather than aligning itself with the hole in the mast. If it's bent or the bolt is slackened a bit, it will lay down a bit more, and that can subtract some forestay length.

Since a picture is worth a thousand words . . .

[BOAT]

All well and nice but if you move the mast hound your also moving the side stays for the mast!
As you can see here that little bowline knot tail hanging down out of the top of my cover IS the Genoa head! There is NO room to go up 7 inches.

Here is a "picture" out my bedroom window:



(We are fogged in today - no sailing.)

[Tomfoolery]

The shrouds connect differently on the - there are bent tangs that are bolted directly to the mast, along with the hound (see Catigale's mod link). You can raise the hound without raising the shrouds. It's not ideal, as it puts a little bending moment into the mast, but the lever arm is so short in relation to the properties of the mast (and the forces encountered) that many, many folks here have done it with no ill effects.

I don't know the rig at all, but I'd guess you could extend the shrouds (at the top or at the bottom) along with the forestay (by adding a Johnson lever) if you moved the hound higher on the mast. But if you're happy with the way it pins, and the resulting rig tuning, then there's nothing to be gained by changing it.

Edit: Here's a pic of my mast. The hound on the right is the standard OEM unit, and the one to the left is the spinnaker hound I added last year. You can see the shrouds are attached at the mast with the same bolt that attaches the forestay and jib halyard block.

On a related subject, I don't actually need that jib halyard any more for mast raising, as there's a spinnaker halyard now. I may just terminate a length of dyneema on there for a MRS pendant and get rid of the block and halyard. Or just use the spinnaker halyard.



I know, I know - the aft side of that spinnaker halyard should be passing through the lower mast hound. I do that every time I take it all apart, raise the mast, find out I messed it up, and have to lower the mast to fix it. Some day I'll learn.

[BOAT]

I too have the spinnaker halyard up there a little above if only for the sole purpose of raising the genoa cover and as a secondary forestay in heavy winds because the M mast raising winch connects down low on the mast so you can remove it.

The M rig is a rotating mast - there is no room for modifications to that rig and the factory has filled the forstay with every possible square inch of sail they could cram in there. The genoa is HUGE. When the santa ana winds are blowing I need a winch to get the genoa trimmed.

[BOAT]

Okay you guys, I did what you told me to do - I got that guage thing that you said was for our boats. It says PROFESSIONAL TENSION GUAGE MODEL PT-1 on it. That's the one you said I need to use, right?

Okay, so I get that and I use it on 'boat' just like the instructions say and I put it on the outer side stays (the long ones) and the meter says 390 pounds.

Okay, then I put in on the inner side stays, (you know, the shorter ones) and they say 240 pounds. I do the other side and the readings are exactly the same.

So - do I need to do anything else?? Is that the right poundage for 'boat' ???

[Tomfoolery]

I couldn't say for sure. I think you should put it in a box and send it to me, and I'll give it a good test for you. Let you know the results.

I put that Loos gauge on my birthday list, but I think a deck brush with extendable handle is more likely to show up.

But to your point, I don't know what the values should be, but if the rig is behaving correctly when sailed hard, then you should strive to maintain those numbers over time. Now you have a benchmark.

[Sumner]

Okay you guys, I did what you told me to do - I got that guage thing that you said was for our boats. It says PROFESSIONAL TENSION GUAGE MODEL PT-1 on it. That's the one you said I need to use, right?..

That one looks nice. We bought the cheaper one...



http://www.defender.com/expanded.jsp?pa ... &id=180160

....and used it. It would be interesting to use them side by side,

Sum

===================================
Our MacGregor 26-S

Our Endeavour 37

Our Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links

[taime1]

Interesting readings BOAT - they seem to be similar to what others have posted in this thread. Did you check the forestay also? I'm not sure what it's supposed to be. I too ordered the PT-1, but it won't be here for a few more days. Besides, still too much freakin' snow on the ground for me to get at the boat properly.

[BOAT]

Hey Summer! You paid 97 dollars for that! MAN! YOU GUYS TOLD ME TO NOT BUY THAT ONE!! The guy at West Marine said the smaller one (the Model A) was more appropriate for our boats because the PT-1 was for big boats. AND YOU GUYS SAID HE WAS WRONG! So I did what you guys said and on my Amazon Prime I paid 91.00 dollars!!! See??!!:

1 "Loos Cableware PT-1 Tension Gauge for 3/32", 1/8" and 5/32" Cable Diameter, 800 Lbs. Maximum Measurement"
Unknown Binding; $91.10
In Stock
Sold by: Amazon.com LLC

http://www.amazon.com/Loos-Cableware-Te ... urement%22


I could have saved Summer 6 bucks if you guys would have told me that the Model A was okay – but as it is he bought it for 6 bucks more than the PT-1.

Hey tkanzler,

You can borrow my loos gauge thing if you want – it’s real easy to use. I know what the pounds are on the stays now, but I still don’t know if the pounds are the right amount or not. The factory did my boat, and I have sailed it in heavy wind and it points fine with one finger on the wheel – no problem. Does that mean the poundage is okay?

Taime1,

My forestay is filled from the very top to the very bottom with genoa sail. It goes all the way up. There is no place anywhere to put a gauge, but the instructions in the loose gauge box said:

“Fractional rigs with spreaders swept back: the forestay tension is balance by the upper shrouds.”

I guess that explains why they use a smaller wire on the front. The forestay does not really do anything but hold the genoa – I guess the major share of the mast pressure is supported by the side stays.
Anyways, if the instructions in the box mean anything I guess the forestay tension does not matter because it’s always going to ba a balance of the side stay tension. That sure makes things easy.
I’m sorry about the snow – it’s sunny and 71 degrees here now but will drop to 69 this afternoon, (just a bit chilly). It’s okay, I have a jacket.

[Tomfoolery]

“Fractional rigs with spreaders swept back: the forestay tension is balance by the upper shrouds.”

That is accurate. Looking straight down on the boat, the shrouds are swept out (side to side) and back, and balance each other side to side. Because they're also swept back, there's an aft component to their force that has to be balanced by the forestay. Whatever the shroud tension is, the forestay tension will be a function of that. Since the shrouds are mostly port-starboard, and only swept back a little, the resulting forestay force is relatively small, and also it's 'footprint' is much farther ahead than the spreaders are aft, so the 'leverage' comes into play. The end result is that the forestay force will be whatever it will be when the shroud forces are correct.

I guess that explains why they use a smaller wire on the front. The forestay does not really do anything but hold the genoa – I guess the major share of the mast pressure is supported by the side stays.

See above - the forestay balances the aft force component of the shrouds, and it holds the genoa.

Anyways, if the instructions in the box mean anything I guess the forestay tension does not matter because it’s always going to ba a balance of the side stay tension. That sure makes things easy.

That's it.

[Sumner]

Hey Summer! You paid 97 dollars for that! MAN! YOU GUYS TOLD ME TO NOT BUY THAT ONE!! ...

Not sure if I ever said which model to buy or not, but we paid a little over $70 a couple years ago....

http://www.defender.com/product.jsp?pat ... &id=180145

..... $77.00 now.

I hate to say what our tension is on our S as I didn't write it down, but as I remember the upper shrouds were around 320 and the 5/32nd forestay (took it with the furler foil off) was around 300. The lower ones were adjusted to get the mast in a straight line between the uppers and the deck.

The shrouds are working under a handicap leverage wise opposing the forestay so are higher than what you would think they might be,

Sum

===================================
Our MacGregor 26-S

Our Endeavour 37

Our Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links

[BOAT]

Okay, (I don't know what any of that means but I trust you). Anyways, 77 bucks is real good price.