T-Terminal Plugs and Check Stays

[Kenneth K]

One of the benefits of DIY boat projects is discovering new things about your boat. I've made several trips up the mast the last few months as I'm changing out the masthead sheaves and standing rigging.

A while back, I discovered these, and didn't know what they were.



Turns out they're T-Terminal plugs, designed to plug the remaining opening in the T-Terminal after the rigging has been installed.

(shroud T-fittings)

This set of T-Terminals (first photo) sits about 2' above the upper spreaders, is angled backwards slightly, and is a smaller diameter than those used to hold the shrouds. I asked a guy at the rigging shop about them, and he had no doubt at all that they're for a check stay, to be used with a fitting like this:



I guess the thought is that since the check stay isn't always tensioned, the rubber plug is needed to keep the T-fitting from slipping out of the T-terminal.

Though none of my shroud T-Terminals had these plugs (shrouds are always under tension, so there's no way the shroud fitting will turn itself sideways and come loose from the terminal) I decided to plug all the shroud terminals anyway, with the thought that it might reduce the amount of water that enters the mast. With 10 T-terminals (2ea for uppers, mids, fwd lowers, aft lowers, and check stays), that's about 2.5 sq inches of open holes on the sides of the mast (though, many of these are "hidden" somewhat under the shadow of the spreaders.



The plugs are made by Hayn, with part number HAY SHRPM07 (6-7mm plug, for the shroud terminals), and HAY SHRPM04 (4mm plug, for the check stay terminals). Apparently, these also go by the name "Gibb Plugs." You can see the name "Gibb" stamped on the side of the check-stay plug in the first photo above. The plugs run about $7.50 ea at Fisheries Supply.

Hayn Marine "T" Terminal Backing Plate Rubber Plugs - The Rigging Company

T termainal plub gibb plug

theriggingco.com

While we're at it at, anyone here use a check-stay on their Bruce King E32/35/38? From what I've read, they reduce mast pumping when sailing upwind. Seems I sometimes read about the E36RH guys using running backstays. Is this a similar concept?

 

[Loren Beach]

While we're at it at, anyone here use a check-stay on their Bruce King E32/35/38? From what I've read, they reduce mast pumping when sailing upwind. Seems I sometimes read about the E36RH guys using running backstays. Is this a similar concept?

Thanks so much for updating the info on the "T" fittings and the plugs. The O-34 has these fittings also. I have converted the factory wires to fabric line many years ago. Ours end at eyes, several feet above the deck, and line tails are shackled onto them to bring the tail back toward the stern side deck and thence back forwards a ways to the secondary winches. We do not use them when not in the ocean.

 

[Nick J]

I've started and stopped a rerigging project multiple times. I'm determined this year is the year I finally get it done. I have a meeting with a local rigger tomorrow and a request for a quote in to Colligo. Who did you end up using to make the new rigging? Any words of advice so far?

 

[Kenneth K]

I've started and stopped a rerigging project multiple times. I'm determined this year is the year I finally get it done. I have a meeting with a local rigger tomorrow and a request for a quote in to Colligo. Who did you end up using to make the new rigging? Any words of advice so far?

I've been replacing mine slowly (along with other projects) over a multi-year period. In summary--replacing the standing rigging is easy, except for the forestay, which involves many more decisions, and more work, due to the roller furler.

I decided to replace with all stainless steel. When I first started, the Seattle West Marine Rigging Shop had some experienced folks that had been there for many years. I sent them my old sets of aft-lower shrouds, intermediate shrouds, and the headstay to have them duplicated. Though I was pleased with their work, every time I call the shop now they seem to have new employees that have replaced the experience folks. Not to say they're not capable, but I just don't get the same feeling of assurance I had with the old heads.

For my next batch, I plan on sending my fwd lowers and upper shrouds to Rigging Only, in Fairhaven, MA. Others on this site have spoken well of them, and I used them to make new SS lifelines for me last fall. Unlike West Marine, rigging is all they do, and the guy I spoke with seemed to have lots of experience.

Note that if you're replacing the lower toggles that fit around the U-bolt chainplates, most standard size (7/16", 1/2") toggles won't fit without modification. See more in this post: https://ericsonyachts.org/ie/threads/replaced-your-ss-standing-rigging-what-did-you-do.19750/
In the end, I re-worked the 7/16" Hayn toggles I got from West Marine to fit on the fwd and aft lower shrouds. I had custom toggles made at Garhauer for the intermediate and upper shrouds.

My decision to replace all the masthead sheaves is what has been slowing my project down. The sheaves can be hard to remove. Then, when you replace them with new, tight-tolerance axles and sheaves, it can be difficult to get the new ones to fit. It seems the original Kenyon sheave box relied on a bit of a "sloppy fit" to make things work.

 

[Loren Beach]

If you are asking me, I used a local rigger in Portland, recently retired. That was Butch Bogan, who did two full re-rigs on our double-spreader rig. Once in the late 90's, and recently in 2021. We chose to have it done the more secure way, pretty much "pin to pin". Although some pins were reused after close inspection (far less corrosion threat here in fresh water).
Our local rigger apprenticed, IIRC, at the highly-regarded Brion Toss rigging shop in Port Townsend.

IMHO, it is false economy to look for excuses to re-use most parts, like turn buckles. The riggers hate the added liability, and if filing a claim after the rig is lost, the insurance company can (properly) ask more detailed/embarrassing questions before paying out.

I am aware that some will disagree with my conservative outlook, but I am a "member" of an exclusive little teeny club: mariners who have been on a sailboat dismasted at sea. I did not volunteer for such an 'honor', but really did learn a LOT from the experience.

One note about the recent re-rig. Since the spar was down, I had all the masthead sheaves replaced with new ones from https://www.zephyrwerks.com/
This guy does absolute first rate work.

 

[Kenneth K]

Thanks so much for updating the info on the "T" fittings and the plugs. The O-34 has these fittings also. I have converted the factory wires to fabric line many years ago. Ours end at eyes, several feet above the deck, and line tails are shackled onto them to bring the tail back toward the stern side deck and thence back forwards a ways to the secondary winches. We do not use them when not in the ocean.

Ok, thanks. So they are tensioned for upwind sailing only? Seems like they would limit the full-forward deployment of the main when sailing directly downwind. No?

 

[Loren Beach]

Ok, thanks. So they are tensioned for upwind sailing only? Seems like they would limit the full-forward deployment of the main when sailing directly downwind. No?

Pretty much yes. If we were tacking into steep seas, we would have to tension one and slack the other when tacking. But since we sail on inland waters we have never rigged them for local sailing -- only used to brace the spar from wanting to pump forward when crossing the Columbia Bar, heading out. It was kinda gnarly for an hour or so.
We were under power, and when socked up tight they add more hand holds for us, as well.

To put some perspective on this, I had dinner with an O-34 skipper about 15 years ago. He talked about doing 18 SoCal Ensenada races in his boat including surfing at double digits, and never using the runners at all. His boat did have the standard rig, which is approximately two feet shorter than ours (if I remember it correctly).

My takeaway is that the EY/Olson Kenyon rig is well engineered, in general.

Shorter answer might be that when off the wind I would not want them rigged unless really needed, because an uncontrolled jibe might harm the boom.

 

[Kenneth K]

Thanks Loren.

 

[ConchyDug]

Ah so some Ericson's do have the cut outs for check stays! I've been wanting to install a set. They stabilize the rig going to weather it's not a downwind control. You crank the weather side check on in chop or conditions that make the upper half of the mast pump. Don't over tension them or you can invert the mast. Go forward and look up the mast in chop and you'll see the pumping, snug up the checks until this stops(like a good pull with a wrap on the winch then maybe a full rotation with the winch handle). Once I find this spot I usually band the line with a marker for repeatability. They also help stabilize the mast if you want to add a staysail. If you don't have the aft turning blocks a frictionless ring on a dyneema strop, luggage tagged over a stern cleat works and you just take it to a rail mounted clutch and use a windward side cabin top winch to tune it. You can put a splice in them so you can disconnect them and pull forward to soft shackles on the shrouds so they aren't whipping you in the face on days you don't need them.

 

[Seth]

One of the benefits of DIY boat projects is discovering new things about your boat. I've made several trips up the mast the last few months as I'm changing out the masthead sheaves and standing rigging.

A while back, I discovered these, and didn't know what they were.

View attachment 51892

Turns out they're T-Terminal plugs, designed to plug the remaining opening in the T-Terminal after the rigging has been installed.

View attachment 51890 (shroud T-fittings)

This set of T-Terminals (first photo) sits about 2' above the upper spreaders, is angled backwards slightly, and is a smaller diameter than those used to hold the shrouds. I asked a guy at the rigging shop about them, and he had no doubt at all that they're for a check stay, to be used with a fitting like this:

View attachment 51893

I guess the thought is that since the check stay isn't always tensioned, the rubber plug is needed to keep the T-fitting from slipping out of the T-terminal.

Though none of my shroud T-Terminals had these plugs (shrouds are always under tension, so there's no way the shroud fitting will turn itself sideways and come loose from the terminal) I decided to plug all the shroud terminals anyway, with the thought that it might reduce the amount of water that enters the mast. With 10 T-terminals (2ea for uppers, mids, fwd lowers, aft lowers, and check stays), that's about 2.5 sq inches of open holes on the sides of the mast (though, many of these are "hidden" somewhat under the shadow of the spreaders.

View attachment 51889

The plugs are made by Hayn, with part number HAY SHRPM07 (6-7mm plug, for the shroud terminals), and HAY SHRPM04 (4mm plug, for the check stay terminals). Apparently, these also go by the name "Gibb Plugs." You can see the name "Gibb" stamped on the side of the check-stay plug in the first photo above. The plugs run about $7.50 ea at Fisheries Supply.

Hayn Marine "T" Terminal Backing Plate Rubber Plugs - The Rigging Company

T termainal plub gibb plug

theriggingco.com

While we're at it at, anyone here use a check-stay on their Bruce King E32/35/38? From what I've read, they reduce mast pumping when sailing upwind. Seems I sometimes read about the E36RH guys using running backstays. Is this a similar concept?

So, none of the Ericson models really need running backs/checkstays to safely keep the rig up. On the Bruce King boats, the rigs are so stiff that I think only on the 38 and newer style 34, 35's you might get reduced pumping and better mainsail shape by using them. Sometimes when you have a lot of backstay on to keep the headstay tight, the main might get a little too flat for ideal power and adding some running back tension will reduce mast bend while keeping the headsay tight. But on the older 35-2, 32's, the mast is so stiff that I would not bother with them. The RH 36 has a much bendier mast and was designed with a babystay to induce lower bend and to some extend help steady the rig-although many owners removed them. For cruising, runners are definitely not required for safety, but is definitely a help for performance in mainsail shape. The only boat which really should have them is the RH33. Again the mast section does not need them to stay up, but because the spreaders are not swept, and it is fractionally rigged, the backstay is of limited help to control headstay sag. Mostly it just flattens the mainsail. The only real way to control the sag and on this boat is with running backs. For sure the rig won't fall without them, but it will really settle the rig and allow you to use the proper amount of backstay and control the headstay independently.

 

[southofvictor]

We noticed a fair amount of upwind pumping in the Sea of Cortez chop when we first arrived in November but I had the rig set fairly loose. I increased the tension on the shrouds adding a bit more to the intermediates and lowers relative to the uppers. The rig seems a lot happier now.

I might add runners if we ever install an inner forestay but for now I’m happy.

 

[bgary]

So, none of the Ericson models really need running backs/checkstays to safely keep the rig up.

Agreed. On the 70s-era 34 (the pintail), we had runners and checks, but they were for shaping the rig, not needed for keeping it in the boat.

As a random aside, I've noticed on my 32-3 that if I am at a dock, and the wind is 12-15 knots dead on the beam, it creates some sort of harmonic that results in a low-frequency vibration. You can feel the rig vibrating, especially if sitting in the cabin (or trying to sleep in the v-berth).

Made me nuts until I figured out it was the middle span of the rig pumping ever-so-slightly. Solution? I made a "fake runner" - I installed an extra slide in the Tides track above the head of the main, and whenever I get that vibration I attach a line to that slide, raise it midway up the mast on the main halyard, and snug the line to a cleat at the top of the transom. Problem solved!

 

[Frank Langer]

Agreed. On the 70s-era 34 (the pintail), we had runners and checks, but they were for shaping the rig, not needed for keeping it in the boat.

As a random aside, I've noticed on my 32-3 that if I am at a dock, and the wind is 12-15 knots dead on the beam, it creates some sort of harmonic that results in a low-frequency vibration. You can feel the rig vibrating, especially if sitting in the cabin (or trying to sleep in the v-berth).

Made me nuts until I figured out it was the middle span of the rig pumping ever-so-slightly. Solution? I made a "fake runner" - I installed an extra slide in the Tides track above the head of the main, and whenever I get that vibration I attach a line to that slide, raise it midway up the mast on the main halyard, and snug the line to a cleat at the top of the transom. Problem solved!

Bruce,
I've noticed that slight pumping as well, though on our E30+ it happens more frequently with a strong SE wind over the bow of the boat. My solution is to harden the back stay a bit to induce a bit more mast bend, and that works too.
Frank

 

[bgary]

My solution is to harden the back stay a bit

That totally makes sense for a fractional rig. Boats that have a babystay could also use that to induce a little bend.

On my masthead rig, hardening up the backstay only really tightens the headstay. It *might* add some bend purely due to compression, but... I don't love having that much backstay on. I tried doing a number of things (e.g, snugging up the forward lowers to try to induce a little bend, snugging up the aft lowers to try to add some lower-panel stiffness)... none of it had a discernable effect, as the pumping was all happening above the lower spreaders. So it goes.

 

[ConchyDug]

Interesting takes, I'm wanting to install a sailtec hydraulic backstay adjuster to my 38 so I can depower the headsail and maybe flatten the top of the main. I'm curious if y'all think the bending of the upper mast as the backstay is cranked will be enough to stop the pumping of the upper mast? Also the pumping I'm talking about isn't a resonance feature it's the shock load of the boat hitting the next wave while going up wind. I also have about 1700-1800lbs of tension on the backstay if that gives a better picture.

 

[bigd14]

Bruce,
I've noticed that slight pumping as well, though on our E30+ it happens more frequently with a strong SE wind over the bow of the boat. My solution is to harden the back stay a bit to induce a bit more mast bend, and that works too.
Frank

Mine too although I haven’t sought a solution to it. I’ll try tightening the back stay next time I notice it.

I also have the running back stay attachments points in the mast but have never fitted them out.

 

[Nick J]

Our rigger noticed we don't have any rake or pre bend in our mast. He suggested we order the new rigging with 1" longer headstay and 1" shorter backstay or use toggles. He also suggested we remove the SparTite and go back to regular wedges in the partner to allow for better tunability. Once we get the mast tuned, we could repour the SparTite if I wanted to. I'm wondering if the rake and/or bend would reduce harmonics and pumping. Does anyone else have experience with tuning the rig like this? If so, did it improve anything? Are the runners still helpful?

 

[nquigley]

I used those angled slot for attaching dyneema running backstays - only intending to used them when flying my staysail, which hoists on a removable inner forestay that's tacked to a reinforced spot on the foredeck a couple inches aft of the anchor well.