Chain plate replacement confusion

[dmksails]

I have a '86 Tashiba-31 that needs to have the chainplates replaced. I've been reading up on this and getting a lot of good information, but the one thing that escapes me is the process for getting the replacements. I've gone online and found a few sites that will do custom plates and I also assume I can find some local machine shops. They all require either drawings or the original chainplate.

So, I have to remove all the chainplates, then send away/ give them to someone to make replacements? Sounds like a process that's going to take months! And what do I do about the mast in the mean time? Do I need to pull it while doing all this work?

Any tips on how to proceed?

[model 10]

You won't have much trouble keeping the rig up with lines or whatever. You might take a more active role and have one shop cut the stock and drill the holes and another do the polish job. Or buy the stock yourself and go on from there.

[Reefmagnet]

You could always measure them up, draw a sketch with the dimensions and give that to a fabricator. For a simple job a sketch will usually suffice. Just make sure you double check your dimensions. If you want to take it to the next level, download a free 2D CAD program onto a PC and do a proper technical drawing. A little bit of learning is involved, obviously, but it is a handy skill for the myriad of bits and pieces that need to be fabricated for a boat at times.

Sent from my SGP521 using Cruisers Sailing Forum mobile app

[zeehag]

i did mine by 2s, and only 2 needed replacement at that time. i took my 2 in, making sure i made fast the mast using halyards to secure--mine is keel stepped mast, so i can do this--and had them machined in a san diego machine shop across street from downwind marine. he rocks. i then replaced the old ones i kept so i could remake if need be, and went to work bolting on the new ones, which i had picked out in 304 stainless. less than 50 bux each . rousing rahhh.
an alternative is to step mast and redo all of em
another option is singly one by one redo all of em. check tangs and backing plates also. may as well check turnbuckles and cables also so no surprises.

[RainDog]

Originally Posted by dmksails

I have a '86 Tashiba-31 that needs to have the chainplates replaced. I've been reading up on this and getting a lot of good information, but the one thing that escapes me is the process for getting the replacements. I've gone online and found a few sites that will do custom plates and I also assume I can find some local machine shops. They all require either drawings or the original chainplate.

So, I have to remove all the chainplates, then send away/ give them to someone to make replacements? Sounds like a process that's going to take months! And what do I do about the mast in the mean time? Do I need to pull it while doing all this work?

Any tips on how to proceed?

I think if you arrange a time in advance, you could get 5 day or less turnaround from the machine shop. Should be able to make the whole project take just two weekends with a little planning.

[HBWT]

You have a 2 options here.

Option 1 - Unstep the Mast at one of the few facilities around Elliot bay or motor out to Shilshole. I think we paid $380 a few years back to unstep and $100 per month for storage yard. Might be a good time to review everything on the mast, replace sheaves, lights, halyards. Then take out all chainplates and send to machine shop. We used a company in Everett called Eckstrom :2803 Hewitt Ave, Everett, WA 98201. They had the best price and made with 316 stainless (important!). About 2 weeks turn around and turned out perfect. We then took to Railmakers NW ( 2 blocks away) 2944 Cedar St, Everett, WA 98201 who Electropolished. Total Cost was $1120.

Option 2. Do 2 at a time and leave mast in place. Start with the lowers (aft). Remove/replace, lowers (forward)... etc....

We have a HC43 (somewhat similar). The biggest cost was getting new chain plate bolts made by Fastenal. This was over $1800 for custom bolts to match the original.

I am sure your tashiba would be significantly less but just a guideline for how and how much.

Good luck

[bletso]

Originally Posted by HBWT

We have a HC43 (somewhat similar). The biggest cost was getting new chain plate bolts made by Fastenal. This was over $1800 for custom bolts to match the original.

What was so special about the bolts? Yes, 316 bolts are dear, but $1800.00. Fastenal is probably 4 X or more the cost from McMaster Carr.

[Rhapsody-NS27]

my mast was already down anyway.

Last year, I contacted a Mike at Garhauer Marine and was able to send all my chainplates and got replacements a month after I sent them. for 9 pieces, it was around $550.

[um saudade]

In my humble opinion most chain plates that get replaced don’t need replacing. Owners hear scary stories and pretty soon they just have to replace what they have or they won’t sleep at night. What I have seen in a majority of cases is when taken out for inspection, the chain plate is just fine and even many of the bolts are still serviceable, though it is good logic to replace the bolts as long as you have it apart.

Of equal if not greater importance is to carefully inspect what the chainplate bolts into. Look for cracks in the glass indicating the hull or thwart is not up to the task and is working under load. Many boats bolt the chainplates to laminated ply that is glassed into the hull, especially in the case of shroud plates. Make sure the ply is in good shape with no sign of delamination. It may be a good time to do some reinforcement in the FRP or hardwood backing before the chainplate goes back in.

Take a pair out, clean them up and inspect carefully. If the rigging angles are correct there will be little if no working of the chainplate so the issues of concern will not be fatigue but badly elongated holes where the rigging attaches and possible corrosion. If the chain plate is adequately sized, holes can often be drilled one size bigger and bigger pins used.

As to corrosion, to determine if it is serviceable or not is somewhat a judgement call but if there is no obvious corrosion look at the cleaned up part under a magnifying glass or loupe. You are looking for tiny cracks and tiny pits in the surface of the metal, especially on or in the bolt holes. If you don’t trust your own judgement take it to someone you can trust but not someone who has a vested interest in selling you new parts.

316 is more resistant to corrosion but not as strong as 304. If the chainplate is sealed against water getting trapped around the plate or the bolts, 304 will last forever. Bobstay use 316 for sure, the rest of the plates every boat has a slightly different situation. I look at standing rigging like I look at control cables on an aircraft. I want to do an inspection on a regular basis to insure everything is good and serviceable. No matter what material you use, you can’t ignore it, for if you do it will fail some day at the worst possible time.

I have no idea what your plates look like or how hard they would be to fabricate. A bend in the plate usually takes fabrication beyond casual work but if they are straight and common size it is not that hard to purchase stock and drill them yourself. There are some good tutorials on line about how to drill stainless. If you try to use a drill bit with a standard angle you will have nothing but frustration but with the properly ground drill point and a drill press, holes in stainless are not all that difficult to do. You want about a 67 degree point and a about half the relief angle of a standard drill bit. Drill slow, don’t use pilots and use lots of down pressure. Never give stainless a chance to work harden. Clamp the old to the new, transfer the centers of the holes and start drilling.

Buffing all depends on how pretty you want the finished product to be. A serviceable buff can be done with basic tools like a sidegrinder and remember that you don’t have to buff out what won’t show. Don't get overzealous and take off too much stock. Don’t work stainless with any tool that has been used on any other metal! Use all virgin grinding and buffing wheels. All new stainless should be passivated but that can be done with chemicals easily available.

Good luck

[barnakiel]

When we replaced ours, we replaced tops while the mast was held by the lowers. Then we replaced the lowers while the mast was held by the new tops. Old ones were used as templates.

It took maybe 48 hours altogether. On two separate days.

Normal garages and craftsmen have less than 24 hours turnaround.

b.

[Stu Jackson]

If all of your chainplates are the same (mine are) all you need to do is take one out and have them make six of 'em.

[zeehag]

i willbe letting ye know how much in mazatlan it willbe to replace 2 more cracked plates and backing plates onmy forward chainplates.
as mine are 40 yrs old, and original, i think it may well be time for a change. i see cracks in some, and the others are taiwanese stainless which was prolly made in usa and sent over
btw--as short term emergency dont wanna pay 1800 usd for bolts--sucker born every minuet-- i used grade 8 bolts which i changed out 8 yrs later to stainless in barra de navidad. the grade 8 were ugly but still serviceable when replaced.
my bent and perfect chainplates i had made cost me about 50 usd for 2. perfect.
there is no reason for the excessively high prices of boat goods.

[chris95040]

Originally Posted by um saudade

316 is more resistant to corrosion but not as strong as 304. If the chainplate is sealed against water getting trapped around the plate or the bolts, 304 will last forever.

Lots of good info in your post BUT...

1. The anecdotal '304 is stronger than 316' claim seems overstated to me.

300 Series Stainless Steel Alloys - 302, 304, 316

90,000 vs 95,000 psi? I'd think allowances for a 304 part's corrosion will often surpass that difference in strength. Which brings me to my next point....

2. No one beds a chainplate cover thinking 'I'm gonna make sure this one leaks pretty soon.'. Everyone thinks 'leaks are the other dudes problem, we are more careful than that. ' Water never takes a break, it's always looking for an in... I think it's wise to use 316 for chainplates..

[zeehag]

Originally Posted by chris95040

Lots of good info in your post BUT...

1. The anecdotal '304 is stronger than 316' claim seems overstated to me.

300 Series Stainless Steel Alloys - 302, 304, 316

90,000 vs 95,000 psi? I'd think allowances for a 304 part's corrosion will often surpass that difference in strength. Which brings me to my next point....

2. No one beds a chainplate cover thinking 'I'm gonna make sure this one leaks pretty soon.'. Everyone thinks 'leaks are the other dudes problem, we are more careful than that. ' Water never takes a break, it's always looking for an in... I think it's wise to use 316 for chainplates..

if you have bends in chainplates 304 is superior as it does not crack as beautifully as more brittle 316 does. thankyou. i prefer 304, built heavier than the original 40 yr old cracked 316.
recommended by my machinist.

[chris95040]

Originally Posted by zeehag

if you have bends in chainplates 304 is superior as it does not crack as beautifully as more brittle 316 does. thankyou. i prefer 304, built heavier than the original 40 yr old cracked 316.
recommended by my machinist.

Hmm, maybe, although I wouldn't have guessed 316 was significantly more brittle than 304. And doesn't strain give corrosion an 'in', making 316 all the more important for a bent part out in the salty air? Honestly don't know.