Jib Shaking on CD 25

[casampson]

When I sail close-hauled in heavy winds, my jib shakes terribly. I'm not sure if it's luffing or just plain shaking. Either way, it drives me crazy. The main is nice and taut and does not luff, but the jib just won't set. I have a theory that the main can point higher than the jib, for whatever reason, and, because we always choose a point of sail based on the status of the main, the jib is left to luff. This means that we have to fall off considerably to get the jib to quiet down, which is a shame. It doesn't happen in light winds.

Here's a video I took today while we sailed in 20 -25 mph winds in Buzzards Bay. By the way, the main is a new loose-footed sail by Doyle. The jib is also new, and it was made by Quantum-Thurston.

https://youtu.be/7Y-WpygfK34

Please check it out and let me know what you think. Thanks!

Chris

[Frenchy]

Hi Chris, By the looks of the main luff, I would say you need more halyard tension on the main. Others will probably have
better ideas on what the problem is with the jib, but I suspect there's not enough backstay/forestay tension. You could
try raising the backstay tension to 15% of the breaking strength of the wire and see what that does. Also, make sure
you have good halyard tension on the jib. That may not solve the problem, but I think it's a good start. - Jean

[tartansailor]

Yes, a CD 25 with new sails does rock!
Your bottom tell tail is really agitated.
Could not see what the top one was doing.
I am going to quote Wally Ross's "SAIL POWER
page 101: "Jib and Genoa Draft Controls":
"If the sheet lead is too far forward, the sail will be
so full at the bottom that it will luff there while
the upper portion is still full and drawing."
Hope this helps.
Dick

[Maine_Buzzard]

+1 on more main tension. Pull the headboard up another 4” or so, or add a cunningham for strong wind.

Another 2”of jib halyard and mark both main and jib with sharpie. Always easier to return or adjust to an existing mark. Pick a padeye just above the winches and mark the halyards next to it.

Look at the inner telltails top and bottom. If the upper inside breaks up first, move the sheet block forward.

Regarding forestay tension, go to the bow in conditions like that and hard on, just as the video. Eyeball the amount of curve in the forestay, it should be about 5-6” for a CD25. How much weather helm was there? Less than 4” tiller off center and I’d put two turns on the backstay first.

Check with your sailmaker too. They cut the sails for a particular shape, and should specify much of this.

Nice video, get on the rail next time and make a loop from head to tack, then to the main all the way back, then up the main luff.

[John Stone]

Hi Chris.
I looked at the video. Without being there I can’t say for sure. And commenting by forum post is not the best way. But...a couple things come to mind.

1. The jib is the driver. It determines how how you point. If it’s luffing, you’re pointing too high. Which you are. Sure, check your headstay back stay tension and if either is too lose it will affect your pointing ability. A luffing jib and tight main will kill your forward drive. In fact, when the wind is up you control helm balance by easing and tightening the main. Minor luffing in the main is acceptable. A luffing jib is not unless you are depowering the boat to avoid a knock down and that means you have too much sail up.

2. Way too much slack in main halyard and jib halyard. You don’t want to see any scallops in this kind of wind. Yes, you can slack your halyards some in very light air but that’s not the case here.

3. Looks like the foot of the main is too loose. You want a flatter main when the wind is up. Tighten the outhaul.

4. As Tartan Sailor commented, I can’t see the upper tell-tails on your jib but it looks like the the jib lead is much too far aft. That causes the foot to be tight and the leech and upper part of the sail to be loose and luff early. Do some reading on jib leads and how to use tell tails. Nice article in this months WoodenBoat magazine covering the basics. That would be a good place to start. Generally speaking you want all the jib tell tails to break at the same time. To get you started draw a line perpendicular to the luff and through the jib clew. The sheet should continue that line to the sheet block. Fine tune with your tell tails.

5. I was, obviously, not there but I think you are over canvased. The boats looks like it’s being pushed hard. Frantic luffing like that will shorten the life of the sails and could lead to broken hardware or worse. Did you have a reef, or two in the main? I was out two weeks ago in 25 knots. Yes, I have a tall rig on my CD36 but I was sailing with a double reefed main and a stays’l. Very comfortable and manageable sail with 15-20 degrees of heel.

[fmueller]

definitely both halyards are very loose and you should have a reef in the main if you have it ... boat is over powered.

[casampson]

Thank you for the very helpful replies. A couple of points in response:

1) No, I did not put a reef in the main. When we cast off, the wind seemed quite manageable. It was not until we were out of the harbor that we realized how strong the wind was, and then it got even stronger. I admit that -- against all the advice put forth in this forum -- I have not yet learned how to reef my boat while underway. So we kept sailing. The boat handled it well, but it was quite a ride.

2) The halyards are a little slack, particularly on the main. I simply don't know how to make them any tighter. I used a winch on the jib (although I did not use the winch handle) and got it as tight as possible. I pulled the main halyard as tight as I could, but there is no winch on the starboard side to help. I wonder if the main halyard should be on the port side where the winch is. Plus a big golden retriever knocked me down a few weeks ago and blew out my left shoulder. This doesn't help my ability to pull down on a halyard.

3) The jibs leads are as far forward as they can go. The sheets are routed outside of the shrouds and then to blocks on a short track on either side of the cockpit. I am confused as to whether I should move the leads aft or forward. I don't see how I can move them forward anyway, as there is nothing there to move them forward to or on. There are a couple of fairleads forward on the deck of the boat roughly alongside the mast. We tried passing the sheets through them, but it did not work, as we couldn't sheet in all the way with the sheets routed this way.

4) I never gave any thought to the foot of the sail, never having had a loose-footed sail before, and will certainly tighten up on the outhaul. Thanks for the tip there.

5) I will check out the tension on the stays, although I don't think that is the problem. Thanks for that advice, as well.

6) There is still something fundamentally wrong with the way the jib is set up. If I push down on the sheet while the jib is shaking, the jib calms down. Sometimes I think the clew of the sail is too high and needs to be pulled down so the foot is more parallel with the deck. Does this make any sense?

There is really much to learn about sailing that I never knew I didn't know, and I admit I am still a newbie after twenty years of sailing out of Marion harbor. The truth is that I never intentionally go out in weather like I faced today, partly because I always sailed smaller boats. I was impressed with the CD 25 this afternoon. I am now very confident in my boat's ability to handle 20-plus mph winds and will be less reluctant to head out into that kind of weather in the future. I just need to learn how to reef. : )

[fmueller]

Chris,

Looked at your video again a few times ... your standing rigging really looks loose. You should remedy this before you sail again, especially in this much breeze, or risk rig failure. This year for the first time in my ownership if Jerezana I had a professional rigger from R&W Rope, New Bedford help me step my mast and set initial tensions, including getting the mast dead vertical and in column ... I have always just done this myself, I admit, and not very carefully, and decided I needed to enlist someone who does this day in and out. All I can say is, it has made quite a difference. My boat, with the same sails as last season, is just sailing so well comparatively; its quite remarkable. Correctly set now the rig is much tighter than I had been setting, really quite firm - the wires just barely show any looseness at all on the leeward side, and only in 20 plus and going hard to wind in headers. Most of the time no observable slack, and I think I even see looseness in your windward side stays in the video, and if that is the case - that is just not right.

Your jib looks like a small one, maybe just a working jib, or 100% ?. It will never trim very close to wind if you are taking it out around the shrouds and back to a block/track that is really positioned for a genoa. As has been pointed out, in that case, you can probably trim your main tighter than your jib and it will always luff first. I have coach roof jib tracks on my boat for the working jib, as well as genoa tracks on the toe rails (mine are about 3' long and go from the winch then forward for the length of the track) ... Don't you have working jib tracks on your coach roof ?

good luck

Fred

[North Branch]

I agree with Fred on the working jib leads. My CD 27 has jib blocks with tracks on the cabin top. After leading the jib sheets through these, I lead them through the genny blocks so they can be tended from the cockpit. Works great. Also, reef your main before setting sail. You can always shake it out if the wind is too light.

[Steve Darwin]

Hi Chris. My $0.02:

I second the opinion that your halyards are too loose, and the main outhaul also. Use the winch handle to crank some tension into the jib luff, especially in strong wind (you'll never get enough tension pulling by hand). Is the gooseneck adjustable on the CD25? On my 25D, the gooseneck is fixed and tension on the main luff requires winching; otherwise, if you have a sliding gooseneck, use the gooseneck downhaul to increase luff tension, and you can step on the boom (put your weight on it) to push the gooseneck down.

I as out on Buzzards Bay yesterday (21 kts in the afternoon), West Island to Weepecket and back. 100% working jib and one reef in the main and everything was a-ok. You can reef even in a strong wind by heaving to (find discussion of this technique elsewhere on the board). One way to check conditions before you get out on the Bay is to access real-time wind velocity at BUZM3: https://www.ndbc.noaa.gov/station_page. ... tion=BUZM3, or use your phone (dial-a-buoy): https://www.ndbc.noaa.gov/dial.shtml#howdo. A private West Island weather station is also useful (wind speed in mph): https://www.westislandweather.com/homequickview.htm

Steve Darwin

[Dick Villamil]

YUP ! Your halyards are WAY too loose, reef the main and then let the traveller fall off to leeward to reduce heel giving a better balance to the boat. Also, move the jib car forward a lot. The jib sheet should bisect the jib approx 50% of the way up the luff - then fine tune with the windward and leeward telltales - upper inner telltales luff then move car forward a notch, opposite if the lower ones luff first. The scallops in the sail due to the loose halyard and loose foot are actually creating more heel and make it harder to steer (weather helm). With a loose-footed main you should have the foot tight so the sail is almost attached to the boom. For light wind you can let her bag out to create more lift and forward drive. Sailing in the heavy wind with the halyards so loose is not doing your sails any good - creating stretch points at each shackle. Go out in lighter wind and try these things out then gradually work up to heavier wind - don't be afraid to reef because it keeps the keel in the water and allows a lot less leeward sliding! Your video m :makes me envious since I just had the boat hauled today due to low water levels on Lake Champlain!

[casampson]

I cannot deny that my halyards are too loose. I will work on that in future sails. As for the jib leads, several have suggested that I move them forward. I cannot. The blocks are as far forward in the tracks as they will go. There is no other hardware available to handle the sheets on the boat. If anyone has any pictures of how they run their jib sheets on a CD 25 or similar boat, I would love to see them. I will try to work out a new system for next spring.

This week I will work on fine tuning the standing rigging. As suggested, I will most likely hire a professional rigger to do the job in the spring.

Thanks again for all the responses. They have been most helpful.

Chris

[Jim Walsh]

The use of a professional rigger is never a bad thing but a little homework and the use of a Loos Tension Gauge is a worthwhile one-time investment in my opinion.

[John Stone]

Chris, I gave you bad info. The general angle for your lead is from a point about 40 percent up the luff from the tack of the jib. Then draw a line from that point through your clew to the gunwale. You will sometimes see these lines marked on headsails so the crew and quickly check their leads.

The article also describes recommended jib sheeting angles which are for fin keel boats and inboard shrouds. The sheeting angles on our boats are going to be wider.

Photo attached is from Sail magazine. Article written by Dave Gerr.

[Frenchy]

That's terrific, John. I"ve never seen that before. I'll have to dig up and read that article. - Jean