shroud tangs/strap tangs or plates: commercial source? or fabricate?

[Bil]

For her 15th birthday, we replaced Zygote’s chainplates and standing rigging, replaced one conduit in the mast, and repainted her mast, boom, and mast step.

Next on the list is to replace what are variously called shroud tangs, strap tangs, or sometimes shroud plates: the stainless steel plates that are bolted (in Zygote’s case) to the hounds and to which the shrouds (and the forestay) are made.

I include photos to show what I mean.

Based on the rule of thumb that 316 stainless steel has about a 20 year working life, I figure I need to replace Zygote’s shroud and forestay strap tangs within 5 years.

Any commercial sources for BCC shroud strap tangs? Or has it been just a case of taking drawings and going to the local fabricator?

I think the cap shroud tangs and the intermediate shroud tangs are identical. The lower shroud tangs are double, handling both fore and aft.

I’ve not seen specs or drawings for the shroud tangs, other than a post Roger Olson made to the forum in 2008, in which he noted the centre-to-centre length of the cap and intermediate shroud tangs was 3.5" and that for the lower shroud tangs was 5.75" (see: http://samlmorse.com/forum/read.php?5,7229,7239#msg-7239)

I note that Rigrite.com sells some shroud strap tangs, but none that look the right length (see
http://rigrite.com/Spars/SparParts/Tangs-complete/Tangs-complete.htm)

Ron and Stan’s company has a small selection of shroud strap tangs, again nothing of appropriate size (see http://www.ronstan.com.au/marine5/range.asp?RnID=108).

I’d be glad to hear your experiences changing shroud tangs. In Zygote’s case, with a Forespar mast, I know the compression tube on the through-bolt through the lower hounds is captive. But the compression tube on each of the through-bolts at the intermediate and upper hounds is loose, so those through-bolts are best withdrawn with the mast vertical.

And for something completely Off Topic:

While Zygote was up on the hard, one of our friends at our marina started a solo unassisted west-about circumnavigation.

Bill Hatfield spend July thru August getting his Moody 33’ “Katherine Ann” in shape and set off with a notional start/finish line just outside Moreton Bay (i.e. in the Pac O).

Bill ran into trouble early with his windvane self steering, so he aborted and called into Sydney Harbour to get a spare part. That was in early September, 4 months ago (see: http://www.sailblogs.com/member/whatfield1/?xjMsgID=371789).

He is now closing on his turnaround point (Horta, in the Azores - chosen to put him as far N in the N hemisphere as Sydney is S in the S hemisphere). See Bill’s blog at: http://www.sailblogs.com/member/whatfield1/ He’s a good chance of a time record for a solo west-about.

Bil

[traveler]

Hi Bil,

I went through the same process with my mast and boom in 2013. At that time I considered replacing the shroud/strap tangs, but upon close inspection they appeared to be in perfect shape with no signs of corrosion or wear so I opted to wait another seven years before replacing them. I was on the hard at Svendsen’s Boat Works in Alameda California at the time and found what appeared to be exact replacements for all of the tangs in their Chandlery. If it would be helpful I could ask them where they source the parts from but I would need some measurements from you since my mast is presently standing vertical.

Traveler

[Bil]

Thanks, Traveler.

I browsed svendsensmarine.com. Only found external mast tangs for Lasers.

We had detected the start of stress cracks in our shroud chainplates two years back. As expected, the cracks were more apparent in 2015, although apparently still superficial. So we spent much of our effort during Zygote’s 2015 refit removing the old chainplates, fabricating new ones, and fitting the new ones.

I figure the shroud tangs at the upper ends of the shrouds have been subject to the same order of stress as the chainplates. We polished and examined carefully each of the tang plates and also the hounds through-bolts, but found no evidence of stress. Still a concern: stainless steel is famous for failing with little or no warning.

Zygote’s mast is also vertical again. I’m thinking of finding time this year at least to draw the strap tangs for the lower shrouds and the forestay. And perhaps spending enough time further aloft to start the process on the intermediate shroud tangs (and perhaps check that the strap tangs for the intermediate shrouds have the same dimensions as the tangs for the cap shrouds).

I did take notes on the hounds through-bolts, but I need to check my notes against reality at least one more time.

My notes read:

Cap shroud through-bolts: 6.25" x 0.5"
Intermediate shroud through-bolts: 6.5" x 0.5"
Lower shroud through-bolts: 6.75" x 0.625" (i.e. 5/8")

My notes suggest I did not measure the threaded length on each bolt. My memory is that only the minimum length was threaded (just enough for the nylock nut; the jobs of the through-bolts do not include compressing the mast).

Does anyone have contact with Cape George Cutter Marine Works?

I guess that Sam L. Morse Co. had templates for the strap tangs for the shrouds and forestay. And that SLM Co had one of any of the stainless steel fabricators around Costa Mesa fabricate the strap tangs. That suggests to me that Cape George Cutter Marine Works likely has those templates.

Bil

[Bil]

Bil Wrote:

And for something completely Off Topic:

While Zygote was up on the hard, one of our
friends at our marina started a solo unassisted
west-about circumnavigation.

Bill Hatfield spend July thru August getting his
Moody 33’ “Katherine Ann” in shape and set off
with a notional start/finish line just outside
Moreton Bay (i.e. in the Pac O).

Bill ran into trouble early with his windvane self
steering, so he aborted and called into Sydney
Harbour to get a spare part. That was in early
September, 4 months ago (see: ).

Completely Off Topic:

Bill Hatfield rounded Cape Horn. And then was knocked down. Hard. He lost two portlights and several solar cells. The loss of the solar cells compromised his electricity supply, including his ability to start his engine to make a self-rescue run to Ushuaia. And of course wireless signals of his track were lost.

Bill turned E and ran back to the Falkland Islands. And suffered another knockdown. Hard. Shrouds compromised.

He has now made port in Stanley. Dreams of single-handed non-stop westabout circumnav have been dashed. Read more at: http://www.sailblogs.com/member/whatfield1/?xjMsgID=390749

[Bil]

Bill Hatfield has returned to Australia after ending his attempt to be the first non-stop westabout circumnav in a boat under 40 foot.

You can listen to a radio interview at: http://mpegmedia.abc.net.au/rn/podcast/2016/04/lms_20160414.mp3