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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

Forestay adjustment

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hewebb
Admiral

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USA
761 Posts

Initially Posted - 02/09/2015 : 05:41:07

Saturday while racing I had a long time experienced person on board and His input was that my forestay was to loose because the foil was bowing. (He is a hank-on sailor who does not like furlers) Winds were 18 to 24 with gust to 30+. We had the 150 genoa reefed some. It is mounted on a Harken furler. I have a, non-adjustable, aft stay set to max tension with Loose gage in an effort to rake the mast aft some as the result of conversations last year. I am struggling with the idea of shortening the forestay because it will rake the mast forward. Being fairly new to the boat I am not sure what to do. My thoughts are that I can only control the tension on the forestay by the tension on the back stay and the length of the forestay will determine the rake. Currently the mast is pencil straight.

Any of you have words of wisdom or thoughts for me?

1988 WK/SR w/inboard diesel Joe Pool Lake
Hobie 18 Lake Worth

Life is not a dress rehearsal. You will not get another chance.

dasreboot
Admiral

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803 Posts

Response Posted - 02/09/2015 : 06:37:48

you dont have a turnbuckle on the forestay? I do under my drum.

Todd Lewis
Eowyn 87 TR/WK C25 #5656
ARWEN 84 TR/SK C25 #4031
www.mainsailsailingschool.com

Steve Milby
Past Commodore

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USA
5851 Posts

Response Posted - 02/09/2015 : 07:15:25

What you're describing is generally typical of a roller furled jib in blustery winds. The dilemma that you have is that, if you increase tension on the forestay enough to reduce forestay sag, the roller furler usually becomes difficult to operate. That's one of the reasons why racers don't like roller furlers.

I think the best thing you could do would be to install a backstay adjuster. If you could adjust the tension on the backstay, you could increase tension when beating to windward, taking some of the sag out of the forestay, and ease tension whenever necessary to roll the jib in or out.

The forestay on all C25s should be the exact same length, as specified by the designer. The length of the forestay can be adjusted by using the turnbuckle. By adjusting the turnbuckle out, you will tilt the mast aft a little, and the effect will be to increase weather helm. By adjusting the turnbuckle in, you will tilt the mast forward a little, and the effect will be to reduce weather helm. When you tune the rig, the objective is to reduce weather helm as much as possible, while retaining enough weather helm to be safe and fast. Too much weather helm causes drag, and excessive drag slows the boat and reduces it's ability to point to weather.

If you either lengthen or shorten the forestay, you will change the range of adjustability beyond what the boat's designer intended, and shortening the forestay won't solve the problem that you want to solve. The likely result will be that it will be difficult to get the rake of the rig adjusted correctly. It's always possible that a previous owner replaced the forestay with one that is too long. You should measure it's length, and only shorten it if it was replaced with one that is longer than factory stock.

Steve Milby J/24 "Captiva Wind"
previously C&C 35, Cal 25, C25 TR/FK, C22
Past Commodore

Lee Panza
Captain

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USA
465 Posts

Response Posted - 02/09/2015 : 08:30:49

As Steve pointed out, the best thing you could do would be to add an adjustable backstay, Howard. In addition to controlling forestay tension it gives you the opportunity to bow the mast to flatten the main a little.

One of the advantages the Cat25 has over most other boats our size is the double lower shrouds. By over-tightening the forwards it's possible to induce a significant degree of curvature in the mast. This prospect may seem frightening at first (you mentioned your "pencil straight mast) but it's common practice in small racing craft. I'm still flying the bagged-out main that came with this boat, and it's distressingly over-powered in conditions like you described, Howard (which would be a typical summer day here on San Francisco Bay), so I've bowed my mast around 4" or so forward at the middle. The cross-section of our mast extrusion is more than stout enough to handle this, and the aft lowers prevent it from buckling forward. The double lowers is one of the features that sold me on the Cat25 when I was researching which boat to buy.

With an adjustable backstay you can furl the genny to where the boat is comfortable, and crank the backstay down to straighten the forestay and flatten the main, and you'll find the rig to be a lot more manageable in stronger winds.

Nevertheless, a 150 is far too much foresail in conditions like that. Once you've put a few turns on the furler you've seriously compromised the shape of what's left. The maximum camber is shifted much farther forward, especially since each rotation of the foil takes in the same amount of cloth at the middle as at the top and bottom, but there's more cloth at the mid-section so you're not taking it in proportionally. This results in an exaggerated curve up front. Not only does this degrade its angle of attack, it also shifts the center of force forward putting a greater lateral force on the forestay and causing more sag. You've also introduced a substantial disturbance at the leading edge, which disrupts the boundary layer for a substantial distance aft.

If you encounter that kind of wind with any kind of frequency you'd be well-advised to invest in a second genoa. A smaller genny will make a much greater difference than a tighter forestay if you're interested in improving your upwind performance in stronger winds.

The trouble with a destination - any destination, really - is that it interrupts The Journey.

Lee Panza
SR/SK #2134
San Francisco Bay
(Brisbane, CA)

hewebb
Admiral

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USA
761 Posts

Response Posted - 02/10/2015 : 05:29:57

Thanks for the input.

The weather helm on the boat seems OK to me except when the wind is up and I have too much sail in the wind. I did adjusted a bow in the mast with the old main but when I got the new main I straightened it. My 150 was re-done two years ago so is in good condition, however, I am thinking about going to a 135 and adding an asymmetrical spinnaker. ( I have a borrowed one now but it will not be available after February) As far as the adjustable backstay. I would have to redo the bimini to accommodate it and I am not sure I want to get into that. I will check the forward rake to see if I can adjust the forestay some. I am not sure how far forward it needs to be. I need to check, clean and lube the furler anyway.

I do enjoy the boat and have to realize that it is not a good racing boat, however, I do enjoy the races. In the races, if I don't have to beat to weather I do quite well. In the prevailing south winds there is one leg that is directly into the wind and that is where I suffer. The boat does not point as well as others. I am the only wing keel in the group. There are mostly bigger boats in the mix.

1988 WK/SR w/inboard diesel Joe Pool Lake
Hobie 18 Lake Worth

Life is not a dress rehearsal. You will not get another chance.

Steve Milby
Past Commodore

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USA
5851 Posts

Response Posted - 02/10/2015 : 07:15:06

With no backstay adjuster, I would suggest that you not tune the rig with a bend in the mast. Bending the mast is the norm for fractional rig boats, and sailmakers cut the sails anticipating a certain amount of mast bend. The C25 has a masthead rig, and their rigs don't bend nearly as much as fractional rigs. Accordingly, I don't believe most sailmakers design their C25 sails to accomodate much, if any, mast bend.

The mast on my C25 was straight when the backstay adjuster was eased. It was bent a little when the adjuster was tensioned. I think the fallacy about backstay adjusters is the thought that they improve the boat's ability to beat to windward. On a masthead rigged boat, I don't think that's true, at least not to a significant degree. The primary benefit of a backstay adjuster on a masthead rig is that it lets you put slack in the rig, and that powers it up when you're sailing off the wind.

As far as adjusting the rake is concerned, I'd suggest you try adjusting it forward about an inch or so, and then sail the boat in about 10-12 kt winds, and see how it feels. It should be light, but still have a very slight weather helm when you let the tiller go. If you get arm weary from steering the boat, either you need to retune the rig, or you need to reduce your sail area. A well tuned C25, carrying the right amount of sail area for the amount of wind, should have a light helm.

Every boat has it's unique strong points and weak points. Wing keels typically don't point as well as fin or swing keels. As a consequence, you need to maximize her windward ability, and find some way to compensate for it, for example, by using smarter tactics, such as finding a shorter route around the race course, taking advantage of wind shifts and currents.

I've been crewing on a friend's boat for the past 3 years, and, although it's a fast ocean racer, it's slow in round-the-buoys local racing. Nevertheless, we get lots of satisfaction in getting as much out of her as she is capable of giving, even though she can't often win around-the-buoys.

Steve Milby J/24 "Captiva Wind"
previously C&C 35, Cal 25, C25 TR/FK, C22
Past Commodore

sdpinaz
Navigator

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USA
193 Posts

Response Posted - 02/10/2015 : 12:26:26

You racer friend might be comparing your furler to a more rigid furler he has used in the past. If you have the CDI ff4 furler the flexible foil will bow a little bit more than a metal one in my experience.

Scott
'88 WK/SR #5727

Heartbeat
Navigator

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USA
161 Posts

Response Posted - 02/10/2015 : 20:35:07

Hmm. Let me echo others that a backstay adjustment is critical. You just can't control forestay tension without it.

The Catalina 25 mast is a really solid stick. It takes a load to bend the beast. Heartbeat runs a double cascaded backstay with a 6:1 for a total 24:1 purchase. When it kicks into the twenties, we pull the crap out of the backstay. (I think I put over 2k load the backstay.) The rig tightens up and we whistle. We bow the mast about 6" forward at the spreaders. It flattens the main and keeps the forestay tight. All good for powering down when it blows.

The other advantage to an adjustable backstay is that you unload the backstay off the wind. Power it up - the further the bow is down, the faster she goes!

These boats came with a (rudimentary) backstay adjustor. A couple of wheels that pulled the split portion of the backstay down. Not very good, but they gave you some adjustment. Do you have those?

Matt

PS - I really recommend a large purchase on the backstay. I sailed on a Ranger 30 that would put 4klb on their hydraulic backstay in medium/strong air. Go big!

former Captain of Heartbeat
Catalina 25 Tall
#4816

Steve Milby
Past Commodore

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USA
5851 Posts

Response Posted - 02/10/2015 : 21:09:17

Be very careful not to put too much of a load on the backstay adjuster. I cracked the gel coat on my transom with the factory stock adjuster. Fortunately, it didn't cause structural damage. Moreover, it isn't necessary. Rigging wire only stretches so much, and then it stops stretching. If you load it beyond that point, something has to give, and that might be the attachments or the structure of the boat. After you take the sag out of the forestay, any additional tension on the backstay adjuster won't make the boat point any higher.

Steve Milby J/24 "Captiva Wind"
previously C&C 35, Cal 25, C25 TR/FK, C22
Past Commodore

Dave5041
Former Mainsheet Editor

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USA
3754 Posts

Response Posted - 02/10/2015 : 21:57:45

quote:
If you have the CDI ff4 furler the flexible foil will bow a little bit more than a metal one in my experience.

I have an old Harken with a stainless mesh/pvc foil with the same observation. Foil tension is tied more to halyard tension than forestay on my system., and it would take excessive tension to prevent some sag in a breeze

Dave B. aboard Pearl
1982 TR/SK/Trad. #3399
Lake Erie/Florida Panhandle

islander
Master Marine Consultant

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USA
3992 Posts

Response Posted - 02/11/2015 : 07:47:49

Like Steve said above, Be careful about cranking the crap out of it. You might be exceeding the breaking strength of the wire and end up De-masting yourself.

1x19 CONSTRUCTION BREAKING STRENGTH

Type 302/304 Type 316
5/32 4 SC15619LYR 3300lbs SZ15619LYR 2800lbs
3/16 5 SC18819LYR 4700lbs SZ18819LYR 4000lbs

Add the age of the wire and some corrosion in the terminals and I'm sure the breaking strength is far less.

Scott-"IMPULSE"87'C25/SR/WK/Din.#5688
Sailing out of Glen Cove,L.I Sound

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