replacing clevis pin on a forestay
 

Not sure if it's visible in the picture, but the forestay toggle is pushing down on the cotter pin so that it's bent a little and makes me nervous.

[IMG]http://www.sailblogs.com/sbgallery/pics/grybkin_gmail_com/sbdxfnqay/w/sb4hakks.jpg"]http://www.sailblogs.com/sbgallery/pics/grybkin_gmail_com/sbdxfnqay/w/sb4hakks.jpg[/IMG]

Would you switch the direction of the clevis pin or put in a shackle? The pin is 3/8". Does it make sense to put in a shackle of a smaller diameter? I have a Wichard 8mm HR shackle that should be stronger than a no-brand 3/8", but am afraid of a shock load of the pin hitting the chainplate in waves.

Thanks!
Gleb

FWIW Gleb , of greater concern might be the surveyor's creed to never hang a structural fitting on a welded joint and what about the rusting corrosion under that Tee toggle ? :(

Hi, Douglas,

Unfortunately, I don't have a picture of the bow from the anchor side - the chainplate connected to the forestay toggle goes down a foot or so and is bolted to the bow. The welding is not structural, but you're right - there is surface corrosion.

The boat is 35 years old and manufacturing and rebedding of the same bow plate would be a major and expensive undertaking... This bow plate does make me worry - it's the only original chainplate on the boat, even though the new ones have developed just as much corrosion in the last 2 years.

I was on a delivery trip last year on a Tayana 52, and the bow chainplate did fail at some point, so it's a scary thought. Luckily, we noticed it just in time, so the mast stayed in place:

http://www.sailblogs.com/sbgallery/p...w/sbnfu8mu.jpg

It would be great if there was a way to protect the forestay in case the bow chainplate fails, but I can't think of anything that could really help in my case.

Thanks,
Gleb

Cause
 

Hello,
It is unlikely that reversing direction would help; a longer clevis pin is probably the most useful solution. It would be very hard to make a connection with a shackle that wasn't weak, in any event.
That staining worries me, too, because weld decay can easily result in corrosion of the actual stem fitting, as well as the flange that the weld is for.
Finally, what size wire is this for? What size boat?
Fair leads,
Brion Toss

Thank you.

The boat is 1979 Bristol 29.9 = ~30' sloop. Forestay wire is 316 1/4" 1x19. This clevis pin should be 3/8". Last time the stem fitting and flange were professionally inspected was 2 years in the SF bay area. They had corrosion then, and there is more now.

Do you think there is something that can be done as a preventive measure?

Sorry, I didn't understand the part about the weak shackle connection. The forestay slid down either when mounting the mast or in waves - there is about 1/4" of free pin on the opposite side before the pinhead. I was thinking that the shackle body would hold the toggle in place even if the forestay toggle jaw moved up or down the pin. Basically, the shackle pin would be in the same place as the clevis pin now, and the D part of the shackle would hang in the air, like so:



This way I could also quickly attach a jib halyard and/or spinnaker halyard to the shackle in case the forestay breaks...

For example, Ronstan 3/8" wide or regular D shackle should have at least the same strength rating as the wire: http://www.amazon.com/Ronstan-Wide-D.../dp/B005O2QTVS

What do you think?

Many thanks!
Gleb

Getting thicker
 

Hi again,
Ah, I see now. Spacers would help to locate the toggle, to keep it from shifting. The shackle-outside configuration always struck me as a bit ... agricultural. On the other hand, you might have some cause to be concerned about a rig failure, as the correct pin size for 1/4" wire is 1/2", not 3/8."
Would you happen to know the tune on the backstay?
Fair leads,
Brion Toss

PS,
If you think redoing that antique stem fitting is expensive, just imagine what a dismasting would cost.

Hi, Brion,

Yes, the tension should be set to 15% of 1/4 316 steel - probably around 1100 lbs.

Not 100% sure about the pin size, but I doubt it's 1/2". The backstay pin doesn't look 1/2" either.



Here is an old rigging invoice. Is it possible to figure out the pin size from it? I was thinking that 3/8 indicated the pin size, but maybe it's the thread?

258046 COTTER-1/8X1 2.000 1.500 3.00
113670 Marine Eye 1/4" 2.000 15.730 31.46
12SE1412RH !!! EXT STUD 1/4-SWAGE 1/2-20 RH 1.000 21.840 21.84
113664 Marine Eye 7/32" 6.000 13.600 81.60
114043 Swage Stud 7/32" x 3/8"RH 5.000 16.240 81.20
ARC-TS001212 3/8"x3/8" Turnbuckle w/o Stud 7.000 43.350 303.45
114050 Swage Stud 1/4" X 3/8"RH 1.000 17.850 17.85
000188955 1/4" 1x19 Wire Type 316 78.000 2.650 206.70
000156112 7/32" 1x19 Wire Type 316 144.000 1.960 282.24

There is the second item on the list that has 1/2 in it, but it's most likely the thread on the forestay , right?

Realistically, I don't think it's possible to replace this entire SS bow section in the village of Taravao, Tahiti - that's where the boat is - or the solution may be worse than the problem. At least some of the stain visible in the picture is not corrosion, and is from the old rigging. If the stem fitting could hold until 2016 when the mast can be unstepped, and I can take off all chainplates and this bow section and bring them to a metal shop, it would be ideal...

Do you think a temporary solution exists?

Many thanks!
Gleb

Details
 

Hi again,
The third line from the top of the parts list shows a 1/2" pin; the third from the bottom shows 3/8", both for 1/4" wire. 3/8" is actually the appropriate diameter for 1/4" 7x19, but not nearly strong enough for 1x19. It is possible that the size of furler chosen mandated the smaller pin, something that has been known to happen when the right size furler just seems to cost too much... If so, you have a sail that is harder to furl than it needs to be, hanging on a wire that has a weaker foundation than is appropriate.
Or not. Your boat might be small enough that 1/4" is actually needless large (and heavy, and expensive) to no advantage. An incline test might do wonders to ease your mind.
What diameter are the pin holes in the jibstay and backstay fittings?
Glad you are continuing to ask questions, and to provide information.
Fair leads,
Brion Toss

PS,
Thank you so much for the dolphins!

PPS,
You are losing a lot to friction in that first furler line fairlead.

Hi, Brion,



I'm not sure anymore what the pin sizes are... Most likely all of them 3/8". The roller furler may be oversized requiring a 1/2" pin where the stemplate only provides 3/8". I vaguely recall the rigger from KKMI who was working on the boat (Kevin) telling me something about 1/4" wire and 1/2" vs 3/8" pins and that he had to take a toggle with a 3/8" hole and install it on a 1/2" stud to match the hole on the stemplate. At that time it didn't make much sense to me, so I trusted his judgement... It's possible the previous owner "upgraded" the wire from 7/32 to 1/4 on the forestay and backstay since I also vaguely recall Kevin telling me that it's strange to see wire of different sizes on the forestay/backstay and shrouds.

Or maybe I'm imagining this :)

Thank you for the tip on the fairlead - I think you're right and I need a block on the bow rail.

Many thanks!
Gleb

P.S. Not sure if it's helpful, but the rope with green and blue patterns is 1/2" and the beige on an external block is 3/8". It looks like the pin is 3/8" to me....