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Catalina/Capri 25/250 Sailor's Forums

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Mast Tuning (shrouds)

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Tray
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Namibia
224 Posts

Initially Posted - 05/14/2002 : 19:55:52

I know this has been covered before, but I need clarification.

How loose should the upper and lower shrouds be under load on the leeward side? I've noticed that mine are really loose, almost dangling. Should I tighten them up?

Thanks,

Tray
C-250WB #554
"Weeny Bean"

Edited by - on

MarkTM
Navigator

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USA
178 Posts

Response Posted - 05/15/2002 : 10:20:52

What does your mast look like when under load? If it is not staying "in column", you might be running the risk of a snapped mast. My uppers are tight enough so that no slack can be seen on the leeward upper regardless of the point of sail. My lowers are loose enough so that the leeward lower has just the slightest amount of slack under a good load. The mast remains in column. If I were to tighten the lowers further, I get reverse bend on the mast which adds power to the main in strong winds . . . not what I want.

Mark Melchior
C250wb "Lorelei" #384
[url="http://www.texassailor.com/"]<img src="http://www.texassailor.com/texas.gif " border=0>[/url]
(click flag to visit Central Texas Sailor)

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ssteakley
Captain

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USA
467 Posts

Response Posted - 05/17/2002 : 00:06:26

I agree with Mark unless you are a racer that plans to win every race like Derek Crawford. Die Hard racers are willing to pay for the extra cost of running a loose rig. For those of us who are more interested in cruise type sailing and lower maintence cost then the shrouds should be always relatively tight to prevent the shock of suddenly shifting loads in the case of loose shrouds. The mast must be balanced on port and starboard tachs. Sight up the mast while under sail, the upper shrouds should be tighter than the lowers. West Marine sells a guage to determine the initial load on the shrouds, then find a friend to take the helm amd do final adjustments under sail in a 10-15 knot wind....remember that the mast should be balenced and in line from deck to the top.
Steve steakley
Moon Chaser
#385 WK

Edited by - ssteakley on 05/17/2002 00:07:46

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Derek Crawford
Master Marine Consultant

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USA
3323 Posts

Response Posted - 05/17/2002 : 10:57:00

Steve - thx for the comment!<img src=icon_smile_blush.gif border=0 align=middle>
So far either "dei gratia" or just dumb luck, running a loose rig hasn't cost me an extra dime. We were out yesterday in 20K+ winds running a 110 and a reefed main and we had a blast...and we were well over hull speed when off the wind.
Derek on "This Side Up"

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Steve Milby
Past Commodore

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USA
5909 Posts

Response Posted - 05/17/2002 : 14:32:24

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>I agree with Mark unless you are a racer that plans to win
every race like Derek Crawford. Die Hard racers are willing to pay for the extra cost of running a loose rig.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

I agree with Derek. I've seen people do far more damage to their
boats by over tightening their rigs than by running them loose. I see no reason to tune a rig differently for racing than for cruising. If it is adjusted correctly, the mast is free to flex within limits, but it cannot flex far enough to cause damage.

Stainless steel stays have a certain amount of stretch in them. If they are adjusted so tightly that there is no slack in the leeward upper stay, even when beating to windward in a strong wind, then excessive stress is put on the chainplates. When the stays are tightened so much that all the stretch is taken out of them, then any further tightening begins to flex the fiberglass and structural members of the boat in ways that were not intended by the designer.

If they are not tightened so much that all the stretch is taken out of them, then, when you are beating in strong winds, the windward stay will naturally stretch, and the leeward stay will naturally become slightly slack. When beating to windward in strong winds, a lot of slack in the leeward upper stay is a bad thing, but a little slack is normal.

People make a distinction between racing and cruising that I do not think is valid. The right of way rules for racing are the same as for general sailing. The physical principles that make a boat sail fast and efficiently are the same for racers as for cruisers. When I'm cruising, I make all the same adjustments to my sails, and use all the same sailing techniques that I use when I race, because boatspeed, pointing ability and efficient boat handling are just as valuable to cruisers as they are to racers. Speed gets you to your destination faster, which means you are not exposed to nautical hazards as much. Pointing ability enables you to claw off a lee shore, and to find shelter more quickly. Efficient boat handling enables you to make sail and rig adjustments quickly, and to retain control of your boat in difficult conditions. A cruiser who can maneuver his/her boat and who understands the niceties of the right of way rules as well as a racer, is a safer sailor.

In most places that I have raced, three or four of the racers are the most likely to win most of the time. The other racers are out there mainly because they know it's a great way to improve their sailing knowledge and skills, they enjoy the camaraderie, and they enjoy the excitement and variety in their sailing activities. If you can only enjoy racing when you win, you might not like it, because nobody wins all the time, but if you race for the right reasons, you will love it, no matter who wins the little etched goblet or plaque.

Steve Milby "Captiva Wind" C-25 T/FK #2554

Edited by - on

Tray
Navigator

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Namibia
224 Posts

Response Posted - 05/17/2002 : 14:41:18

...so the general consensus is no, they should not loose and dangling? I'll tighten them a little at a time, and see how they look under load.

Thanks.

Tray
C-250WB #554
"Weeny Bean"

Edited by - on

MarkTM
Navigator

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USA
178 Posts

Response Posted - 05/17/2002 : 15:47:33

Steve,

I guess everything is relative. When I compare my C250 to the C25s in my marina, I am running a loose rig. Their (C25) shrouds are like banjo strings. I say my uppers are tight . . . but not that tight. Since the C250 only has one set of lowers, any tightening in them will cause reverse bend to the mast.

While I'm relatively new to sailing (four years), I have yet to be on a sailboat that had any discernable slack in the leeward uppers (including a friend's Sabre 34 and Catalina 320, and charter boats including a Morgan 46, Catalina 34, Catalina 36, Islander 36 and C&C 36). Maybe there was some slack and I didn't see it. But, then again, I wasn't in heavy air on all of these boats. Some, yes.

Mark Melchior
C250wb "Lorelei" #384
[url="http://www.texassailor.com/"]<img src="http://www.texassailor.com/texas.gif " border=0>[/url]
(click flag to visit Central Texas Sailor)

Edited by - marktm on 05/17/2002 15:50:51

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MattL
Admiral

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990 Posts

Response Posted - 05/18/2002 : 09:52:44

Generally I am a sort of lazy person. I race on Thrusday nights, but just because I like seeing all the boats out together. I have been on or about sailboats since grade school. I didn't learn anything from racing, no other sail boats at our lake, but everything came from reading books and magazines.
From what I have gleaned I set up the boat on the trailer getting everything as tight as I can by hand. Next tighten 6 or so turns and go sailing. If the leeward shrouds are slack I take up a little when I get back to the dock. Then I forget about it. For the rest of the season If I take down the mast for a trip on the hard I loosen a set number of turns to releive tension and then when raising tighten the same number of turns. Oh remember to hold the upper part with a wrench or you will turn the shrouds not the turnbuckle <img src=icon_smile.gif border=0 align=middle>

Matt Loeffler
E.C. Rider
Cat 25 86'
FK/SR _/)

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Arlyn Stewart
Master Marine Consultant

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USA
2980 Posts

Response Posted - 05/18/2002 : 19:28:39

This discussion needs to take account of the very large difference in the c250 and c25, as the c25 has forward lowers. This is actually a big difference and bears heavily upon the rigging design.

Doing away with the forward lowers, means that the center of the mast has to be held in its forward position by the use of radical raked spreaders. To accomplish this, the uppers must be fairly tight but as Mark points out... the lowers only snug enough to hold the mast laterally in column on a reach.

This design also elimnates the use of a backstay tensioner which would allow rig tuning on the fly as the c25 enjoys. The C25 can enjoy a loose rig for power up...and in a breeze, harden the backstay which pulls pocket out of both the main and jib. The c250 must therefor be tuned for a single setting, and if power were chosen... it would find itself in trouble in a breeze especially because of the higher canvas to ballast ration.

If a backstay tensioner should be employed on a c250... it could firm up the headstay and reduce its pocket, but at the same time, allowing a greater pocket in the main (again, because the spreader pressure forward would be slackened allowing reverse bend. Actually this does work fairly well under double reefed main as employing the backstay tensioner then offers little pocket to the remaining mainsail but firms up the headstay quite well reducing heeling by 5-10 deg. Of course the leeward shrouds will flop in the breeze.

I sent Mark a tape of a 10 min segment of a 90 mile crossing of Lake Huron. I took the video because its the fastest that I've had my c250 going. It was making a 7.4 knots with full main, two turns of furl on the 110 and the backstay tensioner hardened. This setup firmed up the headsail and powered up the main and drove the boat hard and carried it through the swell with little loss of speed but lots of swoosh which can be heard. The leeward shrouds are really loose but the mast was in column laterally with only a slight bit of reverse bend (the main was sheeted hard minimizing reverse bend. Interesting also, was that we sailed for a two hour stretch at this speed with not a single adjustment of sail or helm which was locked.

I found the combination of a fast (flat) jib and power main (pocket) to be interesting and best as can be figured... was the right stuff to drive the boat beyond its hull speed more than one knot.

However, I'm not reccomending the backstay tensioner... but rather a fairly firm rig. Not tight enough to play a tune however. The lowers will be consdierably looser.

Quite frankly... I don't think the open cabin without bulkheads or side decks will support a tight rig...

Arlyn C-250 W/B #224

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Steve Milby
Past Commodore

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Response Posted - 05/20/2002 : 13:57:09

Tray,

Your original question was:

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>How loose should the upper and lower shrouds be under load on the leeward side? I've noticed that mine are really loose, almost dangling. Should I tighten them up?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

The answer to the question should be, "Yes, tighten them, but don't overdo it."

It's difficult to communicate precisely over the net, but I think we're all saying the same thing. A lot of people think their shrouds and stays should be taut, "like banjo strings," but overtightening them creates a risk of structural damage to the boat.

Mark said:

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>When I compare my C250 to the C25s in my marina, I am running a loose rig. Their (C25) shrouds are like banjo strings. I say my uppers are tight . . . but not that tight.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Arlyn said:

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>To accomplish this, the uppers must be fairly tight but as Mark points out...the lowers only snug enough to hold the mast laterally in column on a reach. <hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

None of us is advocating adjusting the shrouds and stays until they are bar-tight.

Imagine that you are using a socket wrench to tighten a bolt. If you tighten it all the way, and then continue turning the wrench, something has to give, and the head of the bolt will twist off. The same is true with your stainless steel shrouds and stays. Because of the way they are manufactured, they will stretch a little when put under tension. But, there is a limit to how much they will stretch. Turnbuckles are capable of putting enormous tension on your cables. If you stretch them to their limit, and then continue putting more tension on them, something has to give. What will give is the chainplate, where the cables are attached to the structure of the boat.

As Arlen observed:

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>I don't think the open cabin without bulkheads or side decks will support a tight rig...<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

I don't know any way of determining, accurately, whether you are overtensioning your cables, except by adjusting them so that the leeward cables are slightly relaxed when the boat is beating to windward in strong winds. When you see them relax very slightly, that is a visible indication that tells you that you have not adjusted them so tightly that they are putting excessive stress on the chainplates. If the leeward cables do not relax at all, then you really have no way of knowing whether they are slightly too tight or way too tight. The other side of the coin, however, is that you don't want the leeward cables so loose that they allow the whole rig to move significantly when you change tacks.

Steve Milby "Captiva Wind" C-25 T/FK #2554

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ssteakley
Captain

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USA
467 Posts

Response Posted - 05/21/2002 : 00:03:23

OK, once again I have learned a bit from you guys. One note ,however, is that the catalina owners manual suggust that the shrouds should be tight enought so that there is no slack on either tach. Obviously the comments of overtighening are very important. I have no desire to shorten the life of the chainplates by overtight shrouds, but I can't help but to expect the same to be true of to loose shrouds where the mast snaps the windward shrouds a little as you come about to the opposite tach. I once witnessed a situation where a car towing another with a chain allowed a little slack in the tow chain and when he accelerated he pulled the bumper off the car being towed. If the shrouds are just snug you prevent the problem of pulling the chainplated through the deck and you prevent putting sudden loads on them as well. Difference in maintainence cost surely will not be apparent in the short run but I expect they may be evident after several years depending on the use of the boat. And yes I want to say one more time that the 250 and the Cat 25 are completely different animals.
Steve Steakley
250WK "Moon Chaser"

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Steve Milby
Past Commodore

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USA
5909 Posts

Response Posted - 05/21/2002 : 20:04:27

Steve,

When the chain pulled the bumper off the car, the chain was so slack that it allowed the tow vehicle to accelerate until there was a significant speed differential between the tow vehicle and the towed vehicle. When the chain became suddenly taut, something had to give, and the "weakest link" was the bumper.

You indicated that the C-250 Manual says “…the shrouds should be tight enough so that there is no slack on either tack.” I might have overlooked it, but I could not find that language in the C-250 Manual. However, there is a section that describes the way in which you should tune the rig under load. It says, "Observe carefully the behavior of the leeward shrouds. They should never be loose." To me, that statement does not mean that they should be tight. It means just what it says. They should not be loose. There is a point at which the tension is substantially released from the leeward shroud, but it is by no means loose. There is still enough tension on it to straighten out the little kinks in it, but it is not under a significant amount of tension.

I am not suggesting that the cables supporting the mast be so slack that they allow the mast to accelerate before it gets stopped short by the cables. Nor am I suggesting that the leeward cables sway visibly. I am suggesting that the leeward cables should be adjusted so that they are "slightly relaxed when the boat is beating to windward in strong winds." In other words, when the boat is at the docks, the cables on both sides of the boat will be tensioned equally. When the boat is beating to windward in strong winds, the leeward cables will not be loose and swaying, but if you look at them, you will see that they are not quite as rigid as the windward cables, and if you tug on them, you will feel that they are not under much tension. They should not be tight, and they should not be loose. They should be slightly relaxed.

Although there are significant differences between the C-25 and the C-250, stainless steel cable behaves the same way on both boats, and what I am talking about is how to take into consideration the inherent behavior of stainless steel cable when tuning any boat. I'll leave it to the C-250 sailors to suggest how best to tune them for speed.

When it comes to mast tuning, sailors tend to fall into one of two categories. Some are "tight tuners," and some are "loose tuners." But, if you really think about what they are saying, there isn’t as much difference between them as it seems. Most tight tuners really don’t mean that the rig should be bar tight, and most loose tuners really don’t mean that the cables should be waving in the breezes. To a very great extent, the difference between them is more rhetorical than real, but they sure can get animated in arguing about it. That’s what makes the forum interesting!

Steve Milby "Captiva Wind" C-25 T/FK #2554

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ssteakley
Captain

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USA
467 Posts

Response Posted - 05/22/2002 : 23:50:14

Steve Milby,
excellant post! Something always gives on a sailboat, the question is how much is to much.....time and money will tell. I plan to fall somewhere between the tight and the loose tuners which means at least monthly attention to tuning. And for each of us our sailing conditions are quite different, some in hot, some in windy, some in cold, some in fresh water, some in saltwater. What is perfect for me at Canyon Lake Texas is not the best for the Kettering,Ohio.....perhaps when posting we should identify our neighborhood?
Steve Steakley
Moon Chaser

Edited by - ssteakley on 05/22/2002 23:53:08

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Tupelo Honey
1st Mate

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USA
45 Posts

Response Posted - 06/03/2002 : 12:57:27

my two cents . . .

on my 250wb, using a loos tensioner, i have the forestay at 28, the lowers at 14, the uppers at 17, the backstay at about 22. this seems to be about perfect. the only thing i notice is that in stronger winds--15-20, the mast takes a slight bend backwards from the spreaders up. i think this is okay, though i'm now awaiting feedback from someone who knows better!

d

"...and that wake better be arrow-straight, or i'll lash ye to the mast!"

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Ben - FL
Admiral

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880 Posts

Response Posted - 06/04/2002 : 22:04:43

Last week I dropped my mast for the first time to install a swivel block for the topping lift. When I bought the boat the topping lift was tied to the mast head. BTW, I'm going to fabricate one of those A-frames for lowering the mast. Just running a bridle through a block at the bow and then around the jib sheet winch works great until the mast angle and the bridle angle get so close that the line just streches and down she comes. Fortunately mine landed in the crutch.

Anyway, after stepping the mast again I ran into the same problem Tray had when I went up to help him. That is that without lower forward shrouds, how do you get the prebend in the mast? Mine was bending the opposite way it should.

I finally opted to just leave everything just snug. This way the mast was mostly straight and centered. I can't rake the mast without lengthening the luffspar.

Safe voyages,
Ben, FL s/v Chick-a-pea C250wk

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