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Catalina/Capri 25/250 Sailor's Forums

Catalina 250 Specific Forum

Adjustable Backstay

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John Russell
Master Marine Consultant

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USA
3444 Posts

Initially Posted - 05/02/2009 : 18:35:07

If I could get the hardware cheaply for an adjustable backstay for my boat, why would I want it? I don't race.

John Russell
1999 C250 SR/WK #410
Bay Village, Ohio
Sailing Lake Erie
Don't Postpone Joy!

Edited by - on

delliottg
Former Mainsheet C250 Tech Editor

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USA
4479 Posts

Response Posted - 05/02/2009 : 18:37:42

John,
Take a look at Arlyn's site, or search for posts on this. He explains quite well why an adjustable backstay isn't needed on our boats.

Edited by - on

Nautiduck
Master Marine Consultant

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USA
3704 Posts

Response Posted - 05/02/2009 : 19:18:48

Skip it. Our boats have a modified B&R rig and hardly need a backstay to begin with. Adjusting the backstay will just screw up the settings on your shrouds.

Edited by - on

Steve Blackburn
Master Marine Consultant

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Canada
1091 Posts

Response Posted - 05/02/2009 : 23:56:48

I agree. I`ve removed mine to go with a single non-adjustable backstay. I race.

Edited by - on

Arlyn Stewart
Master Marine Consultant

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USA
2980 Posts

Response Posted - 05/03/2009 : 03:26:43

Hey John... Randy and the others have it right. A backstay tensioner will harden the foresail but not the mainsail on the 250 and in fact will make the mainsail fuller.

The racer however can do the same thing that we beach cat'rs did and tune the rig for the existing conditions prior to racing. If the air is light on race day, loosen the forestay about six turns to power up the sails. Don't forget to replace the cotter pin and to retension for heavier air as a loose rig on a 250 causes significant over heeling in heavier air.

One may not think this is that big of an issue but in the world of one design racing, a tight rig on a light air day or a loose rig on a breezy day are seriously handicapped.

Edited by - on

John Russell
Master Marine Consultant

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USA
3444 Posts

Response Posted - 05/03/2009 : 06:26:46

Thanks, guys. I guess I'll pass.

Edited by - on

Seadog
Deckhand

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USA
13 Posts

Response Posted - 05/18/2009 : 16:09:01

I would like to chime in on the use of an adjustable backstay. I keep hearing that on this rig tension on the backstay only hardens the forstay and bags the main. This is true for all masthead rigs. To flatten the main after applying tension to the backstay; harden up the outhaul and cunningham.
If your boat does not have a cunningham installation is simple.

Edited by - on

Nautiduck
Master Marine Consultant

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USA
3704 Posts

Response Posted - 05/18/2009 : 19:21:57

Seadog, you are correct. Bending the mast is most effective on fractional rigs.

Edited by - on

Seadog
Deckhand

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USA
13 Posts

Response Posted - 05/18/2009 : 19:51:08

Nautiduck,
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Bending the mast is most effective on fractional rigs.
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

I can completey get onboard with that comment.

Edited by - on

Arlyn Stewart
Master Marine Consultant

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USA
2980 Posts

Response Posted - 05/19/2009 : 11:45:51

Ryan... Comparing the C25 and C250... a backstay tensioner causes a very different set of trim changes. On the C25 when the mast head is pulled aft it does have some effect in producing forward bend and flattening the main because the forward lowers do not allow the center of the mast to move aft.

On the 250, if the masthead is tensioned aft, spreader tension holding the center of the mast forward is relaxed and the mast suffers reverse bend actually making the main fuller rather than flatter.

So, I'd respectfully disagree with you that it is true (backstay makes main fuller) for all mast head rigs.

Regarding the fractional rig... a great advantage is that no forward lowers are needed for a tensioner to flatten the main.

Edited by - on

Seadog
Deckhand

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USA
13 Posts

Response Posted - 05/19/2009 : 16:31:49

Arlyn,

I miss took the effects of draft moving aft (increase weatherhelm and heeling) as increasing the depth of the sail. This happens as sail cloth stretches overtime or wind increases. My error.

You are correct when you said for C25 tension on the backtstay opens the leach and flattens the top 2/3 of the sail, but moves the draft aft decreasing the sails efficiency. Tension on the cunningham moves the draft forward of 50% regaining an efficient entry and further reducing weatherhelm. The outhaul and/or flattening reef flattens the bottom 1/3.

I do have question about the swept spreaders. What angle are they swept?

I don't have a 250 yet but have been thinking of the rig, please help me understand what is happening for this boat. The B&R rig has a diagonal or diamond stay which strengthens the mast eliminating the need for a backstay. The 250 does not have the diagonal stay and requires the backstay to add strength to the mast. Is this why it is called a modified BR rig?

Looking at the rig it would seem the swept spreaders induces prebend into the spar and the lower stay limits the amount of bend in the mast as well as providing lateral support, a similar set up is found on small boat with fractional rigs. Tension on the upper stay acts like pulling the string on a bow, bending the mast.

Does the mast actually loose the prebend? Could the sail become fuller do to the lower stay not allowing the mast to bend forward pulling the sail tighter/flatter. Would readjusting the stays bring the mast back into proper mastbend alignment.

On my fractional rigged dighny to induce prebend you tighten the stay (single stay swepted spreader) on shore. When you increased tension the bend in the mast increased. Then using a caliper on the water I could adjust for wind conditions by tacking and adjusting the leward stay. I had the settings dialed by measureing the distance between the studs in the turnbuckle.

Is the main on the 250 cut for mastbend?

Thank you

Edited by - Seadog on 05/19/2009 17:55:12

Arlyn Stewart
Master Marine Consultant

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USA
2980 Posts

Response Posted - 05/19/2009 : 22:04:08

Ryan, Quite a bit to cover. I don't recall the spreader angle but the spreaders are considered radically raked so that the aft stay tension forces the mast forward at the spreaders.

The 250 is basically designed for firm tensioning and if it is run loose it will suffer pretty bad heeling in a breeze. Of course it can be made to go faster in lighter air with a detuned rig (looser) but the boat does fairly well in light air with a normal firm setup.

Yes, if the 250 is run loose, it will suffer reverse bend and a very full and powered up main and of course a lot of heeling and leeway if run that way in a breeze.

There are a couple of ways to rig the boat to use a backstay tensioner. By running what I have called a running baby stay, a backstay tensioner will work and the boat can be set up for a loose rig and then tuned firm on the fly by first hardening up the baby stay and then the backstay tensioner. Such a system will firm up both sails but it requires releasing the running baby stay prior to tacking and resetting after the tack so its not something that most sailors would rig. I've rigged mine with it but only because I'm almost a 100% cruiser on the Great Lakes so am not doing that much tacking as a small laker sailor would.

The other way is to use what you suggested, a set of diamond shrouds and fitting those shrouds with a tensioner.

The creators of the B&R rig never envisioned a backstay with such a rig and if a tensioner were used, it would be at the forestay but those kind of systems are complicated. I really think the backstay is there because I doubt Frank Butler could sleep at night without it as he likely didn't want to appear as cheap as Roger McGregor.

Edited by - Arlyn Stewart on 05/20/2009 15:05:53

Seadog
Deckhand

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USA
13 Posts

Response Posted - 05/20/2009 : 08:55:40

Arlyn,

Thank you for the response.

Edited by - on

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