Both Lower Aft Shrouds Loose After Sail

[svonadym]

I took my Cape Dory 25D out fours few hours for its first sail in more than a year. The wind was mostly light with some stronger gusts. During a deep broad reach I noticed the head stay pumping a few moments when trying to get the sails (roller furling head sail) trimmed. My thinking is that could indicate the stay is loose. The outing went smoothly and other than the momentary pumping of the head stay, which I hadn’t seen on this boat before, I witnessed nothing else out of the ordinary.
After my return to the marina, however, I noticed that both aft lower stays were very (very!) loose.
Rest assured I’ll inspect the entire rig from top to bottom before leaving the dock again. So far, a cursory look at the lower parts of the rigging reveals nothing. The mast still appears in column, though I think I can perceive a slight bend forward, which seems to make sense to me given that those lower aft stats are so loose., but if the head stay is also under tensioned, this confuses me.
My question is, does anyone have thoughts on what changes to other parts of the rig would result in both aft lower stays becoming loose at the same time? For example, leaving out the fact that this happened unexpectedly, what physical change to the overall rigging setup would you have to make to loosen those two stays equally?
Thanks!

[Cheechako]

Hard to say. But I like to look up the mast while the boat is underway to see how straight the rig is holding it. Often I adjust tension underway also. If the lee upper shroud is loose on a beat, I will tighten it under way just enough to take most of the slack out. A forward bend in the upper middle of the mast isn't too unusual and flattens the mainsail a bit. But often you will see the top of the mast bending forward way more than you would have thought and resultant sag in the forestay/furler. It's hard to get that out even with a hydraulic backstay adjuster on some boats.

I had a big hydraulic adjuster on the boat in my avatar. I tried to adjust out the headstay sag and finally realized I was just bending the boat! That boat was a canoe shape, wide and flattish bottom. So less structure to make it resistant to bending, unlike a V shaped deep bottom. Although it had a couple full length large stringers in the hull bottom.

[thomm225]

What is your rigging setup now?

I used to have mine tight like I did with my beach cat's diamond wires which I had prebend at 700 lbs. at times with my Loos Gauge.

First few years I had all stays and shrouds at 400 except forward lowers I had at around 550 for small prebend. My boat is too old though for rigging set too tight.

On the Bristol 27 now, I have all shrouds and stays around 300-350. I'm not racing so don't worry about the prebend.

I don't have my gauge here so can't remember exact number.

I just redid mine because I have a new backstay and new forward lowers.

Some folks with old school boats like ours have a touch of mast tilt forward to help with weather helm due to our long booms.

[thomm225]

Originally Posted by svonadym

I took my Cape Dory 25D out fours few hours for its first sail in more than a year. The wind was mostly light with some stronger gusts. During a deep broad reach I noticed the head stay pumping a few moments when trying to get the sails (roller furling head sail) trimmed. My thinking is that could indicate the stay is loose. The outing went smoothly and other than the momentary pumping of the head stay, which I hadn’t seen on this boat before, I witnessed nothing else out of the ordinary.
After my return to the marina, however, I noticed that both aft lower stays were very (very!) loose.
Rest assured I’ll inspect the entire rig from top to bottom before leaving the dock again. So far, a cursory look at the lower parts of the rigging reveals nothing. The mast still appears in column, though I think I can perceive a slight bend forward, which seems to make sense to me given that those lower aft stats are so loose., but if the head stay is also under tensioned, this confuses me.
My question is, does anyone have thoughts on what changes to other parts of the rig would result in both aft lower stays becoming loose at the same time? For example, leaving out the fact that this happened unexpectedly, what physical change to the overall rigging setup would you have to make to loosen those two stays equally?
Thanks!

Set them all the same with a Loos Gauge.

If you do get a Loos Gauge, make sure it's the right size for your rigging.

https://atlanticriggingsupply.com/products/loprga31

[DoubleD]

Could there be an issue with the mast step or bottom of the mast becoming compressed. I would assume that would result in less tension on the stays and shrouds. Hopefully this is not the case as that could be a major fix.
DD

[JPA Cate]

There could also be an issue with the chain plates for the aft lowers. Is the deck sound there? It seems very odd to me, that both aft lowers would suddenly be very loose. Was someone expected to have tuned the rig, and forgot them? Did the cotter keys stay put in the clevis pins?

When we got a new mast, the builder sent out a rigger who tuned the new rig, who tuned it some at the dock before we left, then under way. We've done our own tuning since then, and had done it previously as well. By feel and observance, as Cheekako described. We did not have a "banana boat", though.

Ann

[svonadym]

Thanks for all of your replies. The chain plates and all connections look sound; no movement or changes otherwise detected. No indications the mast or compression post have sunk (my thought is it would likely result in all/most/more stays becoming loose). The mast is not new, nor are the stays and the rig tension has not been adjusted in quite a while. The split pins on all stays (top and bottom) are properly in their place. It’s a real mystery to me. I have since put some tension on the two aft lowers using my loos gauge. The caps are all tensioned to about 400 lbs and the lowers less. I’ll keep a close eye on things and see how it does on the water.
Thanks again

[Don C L]

One more thing to check, I’d go up the mast and check the bolt and fitting for the lowers going through the mast. In fact if it were me I’d take the mast down and inspect it all closely. The only thing I could imagine affecting the tension on both aft lowers was a problem in the mast, like corrosion around the bolt. It’s a long shot but what you describe would concern me too.

[svonadym]

Thank you, Don. That’s excellent advice. I’ll scrutinize that area

[senormechanico]

Jib stay getting longer for some reason? That would explain it also.

[misssherry]

Originally Posted by senormechanico

Jib stay getting longer for some reason? That would explain it also.

That' a good point. My furler has a locking nut that prevents it from loosening the forestay when furling. It could cause your problem if the nut came loose.

[ebisucapt]

Also the spreaders could have moved. Assuming the stays go through spreaders.