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Tahoe Cruiser
1st Mate

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USA
72 Posts
Initially Posted - 07/21/2015 :  20:56:58  Show Profile
So I have looked at all the old threads on this topic. I did not see anyone attaching the single stay to the fuel locker starboard side. I was thinking of this area as it is more centered and I think will be out of the way for the outboard motor and the tiller. I need to do this in the next couple of weeks and was hoping someone has done it and it works well. We use the swim ladder for boarding from dinghy and swimming so it needs to go away from there (split backstay as of now).
1998 250 WK/TR #355 "Trail Break"
Lake Tahoe California

TakeFive
Master Marine Consultant

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2269 Posts
Response Posted - 07/21/2015 :  21:13:53  Show Profile
I have never done this modification. I still have the split backstay. But my fuel locker walls are so thin that I would be very reluctant to put that kind of tension on it. Even in shear, I would be afraid that one side of any U-bolt would pull though the thin fiberglass.
Rick S., Swarthmore, PA
PO of Take Five, 1998 Catalina 250WK #348 (relocated to Baltimore's Inner Harbor)
New owner of 2001 Catalina 34MkII #1535 Breakin' Away (at Rock Hall Landing Marina)
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Stinkpotter
Master Marine Consultant

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Djibouti
9014 Posts
Response Posted - 07/22/2015 :  07:06:17  Show Profile
quote:
Originally posted by TakeFive

...I would be afraid that one side of any U-bolt would pull though the thin fiberglass.
...which suggests installing a chainplate with a substantial backer. I'd try asking Catalina Yachts.

On the C-25, the backstay chainplate looks like this:
Dave Bristle
Association "Port Captain" for Mystic/Stonington CT
PO of 1985 C-25 SR/FK #5032 Passage, USCG "sixpack" (expired),
Now on Eastern 27 $+!nkp*+ Sarge
Edited by - Stinkpotter on 07/22/2015 07:10:34
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TakeFive
Master Marine Consultant

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2269 Posts
Response Posted - 07/22/2015 :  08:12:53  Show Profile
quote:
Originally posted by Stinkpotter

quote:
Originally posted by TakeFive

...I would be afraid that one side of any U-bolt would pull though the thin fiberglass.
...which suggests installing a chainplate with a substantial backer. I'd try asking Catalina Yachts.

On the C-25, the backstay chainplate looks like this:



The C250 is a different boat. No matter how beefy the metal, the underlying fiberglass is thin on the fuel locker. I would also question how strongly the fuel locker is attached to the cockpit sole. It just wasn't designed to bear that kind of stress. It might work fine, but then on the other hand...
Rick S., Swarthmore, PA
PO of Take Five, 1998 Catalina 250WK #348 (relocated to Baltimore's Inner Harbor)
New owner of 2001 Catalina 34MkII #1535 Breakin' Away (at Rock Hall Landing Marina)
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Tahoe Cruiser
1st Mate

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USA
72 Posts
Response Posted - 07/22/2015 :  08:47:49  Show Profile
Funny thing is the guy I bought the boat off of a few years back didn't know how to set up the tension device for the rear back stay and sailed it with a completly loose rear backstay. I don't think that much force is put on the rear. I have left it loose many times while working on things in the rear of the boat and the mast has stayed put. I have a tall rig so it has a lot of canvas and the previous owner only reefed once in the few years he owned the boat.
1998 250 WK/TR #355 "Trail Break"
Lake Tahoe California
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TakeFive
Master Marine Consultant

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2269 Posts
Response Posted - 07/22/2015 :  14:27:58  Show Profile
quote:
Originally posted by Tahoe Cruiser

Funny thing is the guy I bought the boat off of a few years back didn't know how to set up the tension device for the rear back stay and sailed it with a completly loose rear backstay. I don't think that much force is put on the rear. I have left it loose many times while working on things in the rear of the boat and the mast has stayed put. I have a tall rig so it has a lot of canvas and the previous owner only reefed once in the few years he owned the boat.

I don't want to come across as confrontational, but this is serious stuff you're talking about. If you want advice, I'll offer it here. If you want approval, I'm not giving it, for the reasons you'll see below.

Changing your rig is major surgery, and should only be done with Catalina-approved designs. There is a reason why Catalina puts their U-bolt where it is for the single backstay modification. (I'm not even sure I'd be comfortable retrofitting a split backstay boat at all, because I wonder if their later model boats had floor reinforcement to accommodate the single-backstay design.) Maybe others who have done it can explain better.

Until then, I want to mention a few things. Nothing is orthogonal on a sailing rig. That means that all the tensions are interrelated - change one and you change the others. This is especially true with a rig that has swept-back spreaders and no forward lower shrouds.

If you lower the tension of your backstay by 100 lbs., you'll lower the tension of your forestay by 165 lbs (I did the trigonometry for you). So if your backstay is too loose, your forestay will be loose and may sag under the weight of the furler. That could cause your furler to malfunction. That could also cause your genoa to have too much draft, which may make your boat heel more in strong winds. A strong wind with loose forestay could also cause mast pumping, which at its worst could lead to rig failure. I experienced mast pumping once, and it is scary - I increased the tension in my forestay and backstay as a result, and the pumping went away.

My split backstay is tensioned with 200 lb on port, 255 lb on starboard. (These values are needed to prevent mast pumping, as mentioned above.) The two sides aren't equal because the "Y" connecter is not perfectly centered (which I think Catalina did because the catbird seats are not perfectly symmetrical, and the slight off-center position keeps the backstays from contacting either of the seats). The angle between the two splits is about 30°, so the tension on the single part of the backstay (above the "Y") is about (200+255)*cos(15°)=440 lb. The calculated forestay tension is therefore about 725 lb, which explains why the forestay is 3/16" instead of 5/32". (All of these values are about 15% of breaking strength, which is the standard recommended benchmark for forestays and backstays that are at rest.)

So my question for you is, are you comfortable having 440 lb. of tension pulling up on one side of your fuel locker? I think you're at risk of seeing fiberglass starting to separate at the floor joint of your fuel locker. Maybe if you have wheel steering you and a buddy can sit on the locker, but you may not want to stand up for very long!
Rick S., Swarthmore, PA
PO of Take Five, 1998 Catalina 250WK #348 (relocated to Baltimore's Inner Harbor)
New owner of 2001 Catalina 34MkII #1535 Breakin' Away (at Rock Hall Landing Marina)
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Stinkpotter
Master Marine Consultant

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Djibouti
9014 Posts
Response Posted - 07/22/2015 :  18:10:38  Show Profile
...which is why I said I'd ask Catalina.
Dave Bristle
Association "Port Captain" for Mystic/Stonington CT
PO of 1985 C-25 SR/FK #5032 Passage, USCG "sixpack" (expired),
Now on Eastern 27 $+!nkp*+ Sarge
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Tahoe Cruiser
1st Mate

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USA
72 Posts
Response Posted - 07/23/2015 :  08:39:57  Show Profile
Thanks for the quick math figures. Not my strongest skill set to say the least. I will find a better place for the single back stay. The mast pump scenario has been scary in strong gust. The whole rig starts shaking when winds go from 10 to 25 in a few seconds. I find it difficult to get the ideal tension on the forestay as the furler seems to be so heavy and the sag so prevalent.
1998 250 WK/TR #355 "Trail Break"
Lake Tahoe California
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Steve Milby
Past Commodore

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USA
5851 Posts
Response Posted - 07/24/2015 :  11:14:07  Show Profile
quote:
Originally posted by Tahoe Cruiser

I find it difficult to get the ideal tension on the forestay as the furler seems to be so heavy and the sag so prevalent.
That's the situation when you should be using the backstay adjuster. Calling it a "backstay" adjuster might be a misnomer. It really adjusts the forestay tension. Pulling on the backstay adjuster takes the sag out of the forestay. Just be careful that you only tension it enough to remove forestay sag. Some people pull it with all their strength, thinking "more is better," but it isn't. When racing, I regularly tension the backstay adjuster when sailing to windward, and ease it when sailing off the wind. A little forestay sag when sailing downwind powers up the rig. Tensioning it when sailing to windward depowers it and keeps the boat on it's feet and pointing high.
Steve Milby J/24 "Captiva Wind"
previously C&C 35, Cal 25, C25 TR/FK, C22
Past Commodore
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Peregrine
Admiral

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830 Posts
Response Posted - 07/24/2015 :  12:36:48  Show Profile  Visit Peregrine's Homepage
quote:
Originally posted by Tahoe Cruiser

So I have looked at all the old threads on this topic. I did not see anyone attaching the single stay to the fuel locker starboard side. I was thinking of this area as it is more centered and I think will be out of the way for the outboard motor and the tiller. I need to do this in the next couple of weeks and was hoping someone has done it and it works well. We use the swim ladder for boarding from dinghy and swimming so it needs to go away from there (split backstay as of now).


Are thinking about moving your "single" backstay off to one side or adding a split backstay?
A single backstay off center would not be a good thing, split backstays are great, like Steve said, being able to adjust the sag (it is never gone) to the wind conditions makes sailing to weather better.
Either way IMO the rig needs to be symmetrical or you risk the the rig failing.

John Gisondi
Peregrine #4762

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TakeFive
Master Marine Consultant

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2269 Posts
Response Posted - 07/24/2015 :  13:33:19  Show Profile
Just to clarify for our C25 friends who are not familiar with the C250, Catalina has supplied the C250 with single and split backstays. In rough chronological order, they started with single (port asymmetrical), went to split (roughly symmetrical but sometimes a little off center), then introduced the catbird seats, started getting complaints of cockpit interference from people with catbird seats and/or steering wheels, so went back to single backstay (port asymmetrical).

So the vessels, as shipped from Catalina, had either single or split backstays.

The single off-center backstay is a safe rig, but must be tuned to a single tension. Adjusting tension of an off-center backstay will cause significant problems with uneven tension of the shrouds. You can search the archives for examples.

The split backstay appears like it would accommodate a tension adjuster, but it is very uncommon on the C250. I do not know why, but I believe that with swept back spreaders the changes in backstay tension can affect the tension of the shrouds in unexpected ways* (and thus affect pre-bend), so you basically have to re-tune the while rig every time you adjust the backstay.

This goes back to what I said before: Nothing is orthogonal, especially in the C250 rig.

I believe that the C250 was designed for a firm forestay and backstay at all times.

*"unexpected ways" = Tensioning the backstay in a conventional rig would increase pre-bend by pulling the masthead back. But pulling the masthead back with the C250 rig would de-tension the uppers, which puts less forward compression on the spreaders, which may DECREASE pre-bend. This would also decrease tension in the lowers. Loss of side-to-side rigidity of the rig could cause side-to-side pumping of the mast. You need to tune the whole rig as a single unit.
Rick S., Swarthmore, PA
PO of Take Five, 1998 Catalina 250WK #348 (relocated to Baltimore's Inner Harbor)
New owner of 2001 Catalina 34MkII #1535 Breakin' Away (at Rock Hall Landing Marina)
Edited by - TakeFive on 07/24/2015 13:37:54
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Tahoe Cruiser
1st Mate

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USA
72 Posts
Response Posted - 07/24/2015 :  14:30:06  Show Profile
Rick,

You hit it on the head. My boat was set up by PO with a split back stay adjustable tension device by way of fiddle block/cam. I want to have one back stay and tune it and leave it. I believe using the tensioner with rope in the equation doesn't let me tune it like this modified BR rig should be tuned.
1998 250 WK/TR #355 "Trail Break"
Lake Tahoe California
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Peregrine
Admiral

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830 Posts
Response Posted - 07/24/2015 :  15:06:35  Show Profile  Visit Peregrine's Homepage
quote:
Originally posted by TakeFive

Just to clarify for our C25 friends who are not familiar with the C250, Catalina has supplied the C250 with single and split backstays. In rough chronological order, they started with single (port asymmetrical), went to split (roughly symmetrical but sometimes a little off center), then introduced the catbird seats, started getting complaints of cockpit interference from people with catbird seats and/or steering wheels, so went back to single backstay (port asymmetrical).

So the vessels, as shipped from Catalina, had either single or split backstays.

The single off-center backstay is a safe rig, but must be tuned to a single tension. Adjusting tension of an off-center backstay will cause significant problems with uneven tension of the shrouds. You can search the archives for examples.

The split backstay appears like it would accommodate a tension adjuster, but it is very uncommon on the C250. I do not know why, but I believe that with swept back spreaders the changes in backstay tension can affect the tension of the shrouds in unexpected ways* (and thus affect pre-bend), so you basically have to re-tune the while rig every time you adjust the backstay.

This goes back to what I said before: Nothing is orthogonal, especially in the C250 rig.

I believe that the C250 was designed for a firm forestay and backstay at all times.

*"unexpected ways" = Tensioning the backstay in a conventional rig would increase pre-bend by pulling the masthead back. But pulling the masthead back with the C250 rig would de-tension the uppers, which puts less forward compression on the spreaders, which may DECREASE pre-bend. This would also decrease tension in the lowers. Loss of side-to-side rigidity of the rig could cause side-to-side pumping of the mast. You need to tune the whole rig as a single unit.


Wow. I knew there was a reason I didn't venture into the 250 forum too much.
Best of luck.

John Gisondi
Peregrine #4762

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Stinkpotter
Master Marine Consultant

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Djibouti
9014 Posts
Response Posted - 07/25/2015 :  13:28:21  Show Profile
quote:
Originally posted by TakeFive

... *"unexpected ways" = Tensioning the backstay in a conventional rig would increase pre-bend by pulling the masthead back. But pulling the masthead back with the C250 rig would de-tension the uppers, which puts less forward compression on the spreaders, which may DECREASE pre-bend. This would also decrease tension in the lowers. Loss of side-to-side rigidity of the rig could cause side-to-side pumping of the mast. You need to tune the whole rig as a single unit.
I was thinking exactly that when picturing an adjuster on the C-250, which I've never seen. And I've seen statements on other sites that a backstay adjuster is not appropriate on a rig with swept-back spreaders, including some other Catalina models.
Dave Bristle
Association "Port Captain" for Mystic/Stonington CT
PO of 1985 C-25 SR/FK #5032 Passage, USCG "sixpack" (expired),
Now on Eastern 27 $+!nkp*+ Sarge
Edited by - Stinkpotter on 07/25/2015 13:34:42
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Tahoe Cruiser
1st Mate

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USA
72 Posts
Response Posted - 07/25/2015 :  14:31:33  Show Profile
quote:
Originally posted by Tahoe Cruiser

This is what my setup looks like.
[URL=http://s916.photobucket.com/user/Salsarider/media/image.jpg1.jpg.html][/URL]
[URL=http://s916.photobucket.com/user/Salsarider/media/image.jpg2.jpg.html][/URL]
1998 250 WK/TR #355 "Trail Break"
Lake Tahoe California
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Stinkpotter
Master Marine Consultant

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Djibouti
9014 Posts
Response Posted - 07/26/2015 :  15:02:09  Show Profile
So, Tahoe... If you crank that adjuster down tight, what happens to your upper shrouds. Conventional wisdom is that their tension is reduced, maybe to the point that they go slack, which could be a problem. Just curious... But I'm guessing that adjuster is not a Catalina feature--rather something created by a previous owner.
Dave Bristle
Association "Port Captain" for Mystic/Stonington CT
PO of 1985 C-25 SR/FK #5032 Passage, USCG "sixpack" (expired),
Now on Eastern 27 $+!nkp*+ Sarge
Edited by - Stinkpotter on 07/26/2015 15:05:09
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Tahoe Cruiser
1st Mate

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USA
72 Posts
Response Posted - 09/14/2016 :  23:32:06  Show Profile
I know this is an old thread but I never gave my final results. I bought a custom made back stay and attached it to the starboard side as a single back stay set up. I have sailed it all summer and it works great. It is nice not having the port stay in the way. I tuned the whole rig so the mast is plumb sideways and a little angled back per Catalina's recommendations. I have been in 20+ knot winds regularly and the rig is solid.
1998 250 WK/TR #355 "Trail Break"
Lake Tahoe California
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kjk
1st Mate

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USA
91 Posts
Response Posted - 09/15/2016 :  08:09:19  Show Profile
Worth the later entry just so we can all read the word "orthogonal" again...
Kevin J. Kiely
Rockport, MA
1999WK
Hull # 407
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pharris7779
Deckhand

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USA
4 Posts
Response Posted - 09/19/2016 :  08:14:55  Show Profile  Visit pharris7779's Homepage
I spoke with rep from Catalina before about putting about a 5-6 foot spar/pole stainless close to center line of boat on transom & having a single backstay attached to that. You could even use some of the existing holes in the transom for mast rest when transporting. He said "you could do it but you'd have to build up that area of the transom & the pole would have to be stiff/strong enough to take the load. Maybe 1/4" walled anodized aluminum would do it?? The back stay would be over your head, out of the way & you could fly a flag off of that to look better cosmetically. Whoever designed this boat didn't do it with wheel steering in mind. Any thoughts?
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TakeFive
Master Marine Consultant

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2269 Posts
Response Posted - 09/19/2016 :  08:37:09  Show Profile
Make a vector diagram of the 5-6 foot pole that you're proposing. With its long lever arm, the forward torque on that thing from your backstay would be enormous. That torque would be transmitted to your attachment points, pulling out on the bottom bolt and pulling in on the top.

When discussing the "transom" you need to think of two elements: the real transom down below the cockpit sole which is about 1" marine plywood core, and the much thinner fuel locker on top of the cockpit sole. Your top rudder gudgeon goes through the fuel locker, and its backing plate can compress the laminate if you over-tighten the bolts there. It is not that strong - just put a good backward force on the back rail and watch the stresses on the nuts inside the fuel locker.

My concern is that the huge torque on your pole would crush your fuel locker with its forward torque, and compress your core with outward force below the cockpit sole - even with a backing plate. At worst, the torque on your transom could even cause hull failure.

There's usually a reason boat designers do things the way they do. Structural modifications to high stress areas need to be modeled carefully beforehand.
Rick S., Swarthmore, PA
PO of Take Five, 1998 Catalina 250WK #348 (relocated to Baltimore's Inner Harbor)
New owner of 2001 Catalina 34MkII #1535 Breakin' Away (at Rock Hall Landing Marina)
Edited by - TakeFive on 09/19/2016 09:35:56
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pharris7779
Deckhand

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USA
4 Posts
Response Posted - 09/19/2016 :  11:37:40  Show Profile  Visit pharris7779's Homepage
Thanks for the info Rick good to hear from someone who knows a lot more than me about the subject. No way I'd attach it to the fuel locker but if it was doable I'd look into putting 1/4 to 3/8" aluminum plate of proper size & maybe glassing it into the transom on the inside. Was thinking you could brace pole with stainless rail, fuel locker but when you mention flexing in fuel locker I guess that wouldn't help.
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528
Navigator

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USA
181 Posts
Response Posted - 09/20/2016 :  05:00:33  Show Profile
http://www.catalina-capri-25s.com/forum/topic.asp?ARCHIVE=true&TOPIC_ID=17959

Hi Guys, here is the original archived thread with all of our thoughts and pursuits.
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Dave Brown
Navigator

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USA
174 Posts
Response Posted - 09/22/2016 :  08:57:56  Show Profile
I have a tall rig, #411, and it as well came with a split back stay.
I as well had trouble with it getting in the way of the swim ladder.
I removed the "split" add a single block, rope from the port side, to the block and put a 4 to 1 on the STB side. now the boat is like factory. I can adjust it when sailing, and back it way off, and move out of the way when swimming.
It was a good fix for me, and works well with ONLY 250. (disclaimer).
that's my 2 cents worth.
Dave B.
Nebraska
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Notice: The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.