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Chainplate removal w/ Mast up

Apr 22, 2014
10
Does anyone have experience or knowledge regarding pulling to 2 main chainplates for the top mast shrouds? I have one out for plate and backing plate replacement. The fabricator wants both or about 2 times the money for one at a time. I just started this research and don't have any other information yet on how safe or unsafe this is. The area does get some higher winds, 50 mph a few weeks ago. I have one halyard tied off to the side that is currently out. My boat is a 1961 Alden Zephyr 959A with rust showing through the hull in 3 chainplate areas. The backing plate I have out was very rusted, but seemingly sturdy. I'm replacing to two main plates and backing plates this year.
thank you,
Nathan
 

TomY

Alden Forum Moderator
Jun 22, 2004
1,940
Alden 38' Challenger yawl Rockport Harbor
Does anyone have experience or knowledge regarding pulling to 2 main chainplates for the top mast shrouds? I have one out for plate and backing plate replacement. The fabricator wants both or about 2 times the money for one at a time. I just started this research and don't have any other information yet on how safe or unsafe this is. The area does get some higher winds, 50 mph a few weeks ago. I have one halyard tied off to the side that is currently out. My boat is a 1961 Alden Zephyr 959A with rust showing through the hull in 3 chainplate areas. The backing plate I have out was very rusted, but seemingly sturdy. I'm replacing to two main plates and backing plates this year.
thank you,
Nathan
I have some experience in replacing and in fact, I'm replacing a main mast shroud chain plate - backing plate and building up a new Hat frame for it.

I also have quite a few photos from Alden Mistral TI which had all her backing plates replaced just a few years ago (after she won a Bermuda race).

I'm taking photos and planned to post my replacement soon.

I can help you with the preferred way to cut open the hatframes to replace the backing plates, and then glass those back up.

Doing this with the mast up is new! You'll have to find ways to securely guy the stick as you'll need time not only to fabricate the pieces but to also re-glass the hat frames.

Ask away:

Here's one backing plate cut out in a hatframe on TI.

IMG_0946.JPG


And backing plate replaced, 2 hatframe glassed back up. After curing, the bolts are removed and the new chainplates bolted to the backing plates.
IMG_1253.JPG


Incidentally, my fabricator is going to tack weld the new SS backing plate and new SS chainplate together - drill the tap size bit through both, split the 2 pieces, thread the backing plate and enlarge the hole in the chain plate for the new 3/8" bolts. I thought that was brilliant as it's tricky to get the holes aligned on the two pieces.
 
Apr 22, 2014
10
Hi Tom,
I'm interested in any and probably all the photos you have on your job and Ti. I've taken some advice from my boat yard that I think may have been more than is need and already started, sorry to say. I temporarily removed some bulkhead to be able to reglass over the hatframe cutout front section and build up to the next ribs on each side of the hatframe, but only on one chainplate. So this would be fiberglassing over the entire hatframe and I'm guessing about a foot or more out forward and aft of the hatframe and about 3-4 inches below. On the opposite side main mast shroud plate I was planning to try removing the backing plate from the bottom of the hatframe, reglassing that area and probably adding some glass over the rest of the hatframe for good measure and out several inches forward and aft.

Correct me if I'm wrong please - It appears in the 1st photo the hatframe is cutout from the side removing the backing plate and filler behind the plate, which is what mine has - a half filled area that seems to be poured resin, which is currently in about 3 block pieces and able to move slightly. I've been told not to pour that much resin as the heat may adversely impact the surrounding existing and/or new glass, so not sure how to replace or add to the existing resin filler. The top half of the area between the hull mold and the backing plate is empty on my boat.
On the second pic - it looks like only the side of the hatframe was reglassed and only a couple of inches past the removed area. What is the black material or coloring and the white area?
It may be helpful for me to talk by phone if okay with you. Is there a private message mechanism for number exchange here? thanks
 

TomY

Alden Forum Moderator
Jun 22, 2004
1,940
Alden 38' Challenger yawl Rockport Harbor
Hi Tom,
I'm interested in any and probably all the photos you have on your job and Ti. I've taken some advice from my boat yard that I think may have been more than is need and already started, sorry to say. I temporarily removed some bulkhead to be able to reglass over the hatframe cutout front section and build up to the next ribs on each side of the hatframe, but only on one chainplate. So this would be fiberglassing over the entire hatframe and I'm guessing about a foot or more out forward and aft of the hatframe and about 3-4 inches below. On the opposite side main mast shroud plate I was planning to try removing the backing plate from the bottom of the hatframe, reglassing that area and probably adding some glass over the rest of the hatframe for good measure and out several inches forward and aft.

Correct me if I'm wrong please - It appears in the 1st photo the hatframe is cutout from the side removing the backing plate and filler behind the plate, which is what mine has - a half filled area that seems to be poured resin, which is currently in about 3 block pieces and able to move slightly. I've been told not to pour that much resin as the heat may adversely impact the surrounding existing and/or new glass, so not sure how to replace or add to the existing resin filler. The top half of the area between the hull mold and the backing plate is empty on my boat.
On the second pic - it looks like only the side of the hatframe was reglassed and only a couple of inches past the removed area. What is the black material or coloring and the white area?
It may be helpful for me to talk by phone if okay with you. Is there a private message mechanism for number exchange here? thanks
First: I've never found or seen an Alden hat frame with epoxy used as fill inside. It may have been used to hold the backing plate in place so chain plate attachment later(?)

Hat frames I'm familiar with were formed around an aluminum former that was pulled after the hat frame was cured. The backing plates would have been inserted from the top before the deck was fastened and glassed to the hulls.

This old drawing may have been a mizzen hat frame as it is half the size of my main mast hat frame:

949 Hat frame detail 2 copy.jpg




Here is another hat frame cut on a Challenger. Most of these photos were supplied by owners that didn't do the work so the actual process isn't always known:
Chainplate 1-2 copy.jpg


Then a repaired hat frame that was right next to a glassed in bulkhead.
Chainplate 3-2 copy.jpg

As long as the hat frame is well bonded to the hull - the glass itself sound and not fractured, and the mating surface of the existing glass properly prepared for adhesion, there is no need to add to the structure of the hat frame. It's load is spread and adhered to the hull lay up.

Here's a hat frame removed on a Mistral. The boat yard wasn't aware of the side incision method. They had to build a whole new hat frame.

In fact, I'm in the process of forming a new one on my boat as the existing was damaged by the rusting backing plate. I plan to put the process, and photos, in a post on the Alden forum as we need that information where others can access it.

Marston chain plate 1.JPG


Note the layup thickness and structure. That has to be duplicated in either patching a side incision or building a new one. These hat frames are structural girders.

Here is that boatyards built in place hat frame on the Mistral. I believe the boatyard said that was a paint (but it looks like it's in the layup). This yard does extensive glass work.
IMG_1254.JPG



Do you have any photos of the work you're doing? It would be great to get them posted in this thread for others. Let's try to keep the info here but you can PM me on this forum for contact info.

Pics would be best though, we could spend a lot of time on the phone trying to figure out what a photo would say in a glance.

I plan to install the new backing plate this weekend on my boat, and begin the lay up of the new hat frame.
 
Apr 22, 2014
10
On the left are the 2 new chainplates and corresponding backing plates from my Zephyr 959A. On the right are the old.
301871D1-674A-4B58-A1F3-3538AB6B4CB4.jpeg
As you can see the plates both have 2 bends. I’m hoping they are identical as I only removed one for reproduction. Are similar Alden’s chainplates bent like theses, anyone?
 

TomY

Alden Forum Moderator
Jun 22, 2004
1,940
Alden 38' Challenger yawl Rockport Harbor
I'm familiar with Challenger and Mistral top hat frames. The backing plates and chainplates have all been straight until the chainplates reach the deck. Then most have a bend to match the stay angle.

I've never seen a Zephyr hat frame which must have a bit of shape to it?

At any rate, your bend is not severe and will conform to the mating surface - inside and out - of the hat frame, even if it's not exact.

How did you cut the backing plate out of the hat frame, Nathan?

Because I had to build a new port side outer stay hat frame (Alden Challenger hat frame repair thread), I mounted the new chainplate that was flat.

Then I used a scrap of wood to trace the angle of the existing starboard outer stay chain plate from the deck.

From that template, the fabricator put the deck bend in for me.
 
Apr 22, 2014
10
I’ll get photos soon...hopefully, and update this post! At least by next week.
Thanks for the posts Tom. They’ve been very helpful.