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Learning the HARD way...
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Discussion Starter · #1 · (Edited)
I recently bought an '87 Oday 35. You may find this weird, but I have actually enjoyed working on many of the little projects that buying an older boat entails.

SD came by yesterday and helped address some of the electrical opportunities... (Just don't count the electrical splices that we had to toss:eek::laugher - and don't ask:rolleyes:)

One project that is really vexing, however, is the removal of the port forward chainplate. Long story short, I would love to locate a supplier for replacement stainless steel U bolts. If I can cut this U bolt, I believe that I will save myself a series of ongoing headaches...

Here is a picture of the specific U bolt that is providing the motivation:

(That's my ratty shoe too...)

Whoever designed this system really out did themselves. The U bolt that you see above is set through the deck to an aluminum block (I really can't call it a backer plate - it's about an inch thick). This block has recesses that the nuts that secure the U bolt go into. The block, in turn, has a short length of rod that runs to a reinforced raised section of the floorpan, and is secured with another nut and washer. The rod, raised section of floorpan, and adjustment nut are all located BEHIND the liner which comprises the head:mad:.

The problem is that this particular chainplate (forward port) was only secured for who knows how long with one nut:eek:! Because it sat for many years like this, the backing block does not sit flush with the deck, and fused to the U bolt. Because the nuts are recessed, I cannot simply install a new nut and tighten it up, for fear that I will loose my grip on the nut with a deep set socket.

SD has access to a machine shop, and is going to try to fashion a tool to allow me to tighten the loose side up. The hope is that by tightening up the loose side, and re-squaring the backer block with relation to the deck, that the bond between the U bolt and the block will break. Then the plan is to rebed and properly re-install the U bolt.

Adding to the fun is that the access is in the locker in the head. The aluminum backing plate is accessed through a hole cut into the headliner that is right behind where the over the sink locker doors meet - or used to, I had to remove them to gain access. Access to the rod which goes into the pan is impossible without cutting an access hole in the fiberglass right next to the sink in this picture:

I can see the original access hole, but cannot see the fastener through the open locker. I have been able to feel it though, so I know it's there.:rolleyes:

Does anyone out there have any other ideas - or a source for the chainplate for an O'day 34/35???
 

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Learning the HARD way...
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Discussion Starter · #3 ·
Thanks Rich.

I've already spoken with Rudy. He indicated that the rod and backer plates were originally made by Navtec. He also said that he'd look into a source, but he hasn't turned up anything in over a week...
 

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Learning the HARD way...
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Discussion Starter · #5 · (Edited)
For posterity;

I got the bugger out!:) :cool: :) :cool: :) :cool: :)

The way that I did it was to first remove both nuts from the U bolt. Then I tightened the shroud as much as I dared... The U bolt didn't budge. I tried hammering, drilling (broke two bits), swearing, a hammer drill... nuthin' worked. Looking at the bottom of the U bolt, it appeared that there was epoxy, or something fusing the U bolt to the backing block... I briefly considered solvents to break the bond (MEK or Methelyne Chloride), but the fear of a spill, and the fumes, and the fact that I had none, put me off.

Then I thought of heat! I had a torch for heating heat shrink with me, and I figured it was worth a try... As I started heating, I could hear the U bolt pulling through the deck, and the tension on the shroud releasing. I heated for about 5 minutes, when "POING." The U bolt popped up through the deck, and the backing block was finally free.

I took some pix with my cell phone of the backing block. I'll post that later. Here is a picture of the U bolt, and shroud hardware;
 

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Learning the HARD way...
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Discussion Starter · #6 · (Edited)
Here are the pictures of the backing block... If any of you with an O'day 34 or 35 have the need to work on the shrouds, these pictures may come in handy. Apologies for the fuzziness.. I took these with my cell phone.

This thing was in a hole in the cabin liner, that was only accessible through the locker in the head. To get at it, I had to remove the track that the locker doors slide on... What a pain:mad:! To take these pictures, I slid the block down on the support rod. Therefore, the hole in the liner is not visible.

From the bottom (note that the U bolt has been removed);

You can see the rod which runs through the block, and provides tension on the block. The rod ends with a tang.

From the side;

Here you can see that this block was 5/8" thick, but has been eaten away at by corrosion (and a dremel). I do not believe that the structure has lost strength, however.

From the top;

Here you see the top of the block, and the detent that the end of the rod sits in. Again, a good deal of corrosion ('ya think that the chainplate might have leaked?), but not so much that the ability to hold a lower shroud has been compromised.

The block is 2 5/8" long X ~2" wide x 5/8 thick. 3/8" holes for the U bolts are on 1 5/8 centers. It is hard to see in the pictures, but the 3/8 hole for the rod is drilled at an angle ~75º (not 90º) to compensate for the angle that the rod must maintain. You can see in the view from the bottom that the center of the hole is not in line with the U bolt holes.

I hope that this helps someone in the future.
 

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Learning the HARD way...
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Discussion Starter · #7 ·
More pix of the dreaded backing block...

Here is the locker through which the rod runs;


Here is a pic (now looking vertically) at the hole in which the port forward backing block normally lives (and why it was incorrectly installed);


As it turns out, this is not the only such block. The three other shrouds each have one too!
Starboard forward (in the hanging locker);


Starboard aft (over the setee);


and Port aft;


You can see that the Port Forward is the hardest to reach, and hardest to inspect. Therefore this problem was left to fester for a while, resulting in the corrosion that you see here.

 

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Learning the HARD way...
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Discussion Starter · #9 · (Edited)
Very weird! Glad you got to the bottom of it - I mean top... :D
Thanks - though I still have to dry the core. I put duct tape & butyl over the holes that I drilled in the deck temporarily. Here's a pic of the top of the problem;


Then I hope to fix the problem (as outlined in another thread) and reassemble the locker doors... Then I have about 20 other projects going concurrently that I hope to finish some day....

All I've been doing is fixing problems from the previous owners... at some point I actually hope to sail this vessel:rolleyes:.
 

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I don't understand why you couldn't just put a nut on the u-bolt and tighten it up. It may not have flattened the block but it seems it would have been worth a try. Also why did you drill out the bolt holes? It looks like the core was marine plywood and in good shape. Couldn't you have just rebed the existing holes?
 

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Discussion Starter · #11 ·
I don't understand why you couldn't just put a nut on the u-bolt and tighten it up. It may not have flattened the block but it seems it would have been worth a try.
The problem was that the block was out of square with the U bolt - because only ONE nut was in place and had been tightened. Coupled with the fact that the nuts fit in recesses in the block, I was initially unable to put a nut on the other leg of the bolt.

Once I flared open the recess with a dremel, I could get a nut started, but was concerned that I would loose the nut if I tightened it into the block.

Also why did you drill out the bolt holes? It looks like the core was marine plywood and in good shape. Couldn't you have just rebed the existing holes?
Once the U bolt and top plate were removed, I could see that there was a depression in the deck. I had already detected moisture around this chain plate, but could not see the core because everything in there was covered with some kind of sealant (at least somebody had tried to rebed this plate at one time). I assumed the worst, and broke out the hole saw.

Actually, I believe that there was degraded marine ply. immediately around the holes. To see how I plan to address the holes in the deck, look here.

I agree that the exposed marine ply looks to be in good shape.
 

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Learning the HARD way...
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Discussion Starter · #12 · (Edited)
Contact D & R Marine - drmarine.com - as they are *THE* source for O'day parts, etc. and may give you specific 'hints' of specifically how to 'easily' tighten/replace, etc.
I want to follow up on the above quote in the hope that someone can leverage my research.

I never heard back from Rudy, even after I called him about a week later to inquire if he had found a source. He had my number and remembered speaking with me, but never contacted me again. My impression is that D&R specializes in the O'days of under 25 feet overall.

I eventually stumbled on the RigRite website, as a source of chain plates and backer blocks. The O'day 34/35 uses NavTec U bolt type chainplates. Here is a pic


These are available in 3/8" and 1/2". Here is what the RigRite website says about them;
3/8" Navtec U-Bolt Chainplate Assembly: Nav UBA-6S-2:
Navtec 3/8" U-Bolt Chainplate Assembly bolts through Deck to special Tie-rod Block which accepts SS tie-rod at a specific angle. Formed, flattened SS U-Bolt has 3/8" thread with 1 5/8" between centers, and extends 2" below deck surface. Note that some units were produced extending only 1 3/4" below deck, these are no longer stocked. Assembly includes U-Bolt with SS Top and bottom plates, lock washers and nuts. As used on a variety of boats including Bristol, Cal, C&C, Ericson, O'Day, the Hobie 33, and others.
RigRite has part numbers on their site for the entire assembly, and the components.
... and;

1/2" Navtec U-Bolt Chainplate Assembly: Nav UBA-8S-2.5:
Navtec 1/2" U-Bolt Chainplate Assembly bolts through Deck to special Tie-rod Block which accepts SS tie-rod at a specific angle. Formed, flattened SS U-Bolt has 1/2" thread with 2 1/8" between centers, and extends 2 1/2" below deck surface. Note that some units were produced extending only 1" or 2" below deck, these are no longer stocked, but can be produced by cutting the longer ones, if necessary. Assembly includes U-Bolt with SS Top and bottom plates, lock washers and nuts. As used on a variety of boats including Bristol, Cal, C&C, Ericson, O'Day, Southern Cross, and others.
More info can be found here: U-Bolt Type Chainplates

Note: I have no interest in Rig Rite. I am only trying to help expedite someone else's search.

I have decided that the backing block pictured in my earlier post is "good enuf" and that the visible corrosion is cosmetic and not structural. Once the plate is rebedded correctly (if this cold weather ever ends:mad:) I believe that the block will be fine. Should I ever need it, Rigrite sells this block too;
3/8" U-Bolt Chainplate Tie-rod Block: Nav UB-6S-TRB-__:
Tie-rod Block for single 3/8" U-Bolt Chainplate. Anodized Aluminum Tie-rod Block is 2 9/16" long x 1 1/2" wide x 5/8" thick, with (2) recessed holes for nuts and washers, and a machined socket for 3/8" cold-headed tie-rod. Note: These items were produced with the socket machined for a wide variety of simple and compound tie-rod angles, please specify.
 

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Patrick
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I hope that this helps someone in the future.
Thanks for this post! The pictures are very helpful. I'm going through the same thing now - trying to get out 1/2" Navtec U-Bolt tie rod design chainplates non-destructively in order to inspect the U-bolt. There are very few people who have done this and documented it on the Internet.

Did you ever pull more than that one U-bolt? It's good to know the shroud tension + heat trick worked. I've done everything except shroud tension so far (the mast is in the yard at the moment). I have slightly better access to the underside backing block, so I've been hitting it with vinegar, PB Blaster, BoatLife Release, heat, hammering, hammering with a cold chisel as a wedge, hammering upwards on the U-bolt legs, etc. None of that has helped budge the aluminum to SS corrosion yet.
 

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Learning the HARD way...
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Discussion Starter · #14 ·
Thanks for this post! The pictures are very helpful. I'm going through the same thing now - trying to get out 1/2" Navtec U-Bolt tie rod design chainplates non-destructively in order to inspect the U-bolt. There are very few people who have done this and documented it on the Internet.

Did you ever pull more than that one U-bolt? It's good to know the shroud tension + heat trick worked. I've done everything except shroud tension so far (the mast is in the yard at the moment). I have slightly better access to the underside backing block, so I've been hitting it with vinegar, PB Blaster, BoatLife Release, heat, hammering, hammering with a cold chisel as a wedge, hammering upwards on the U-bolt legs, etc. None of that has helped budge the aluminum to SS corrosion yet.
Yes. Later that season I pulled ALL of the U-bolts, and rebedded them with butyl tape. They have held up fine for the past 7 (going on 8) years.
 

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Patrick
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Yes. Later that season I pulled ALL of the U-bolts, and rebedded them with butyl tape. They have held up fine for the past 7 (going on 8) years.
Thanks - and you used the same method (shroud tension + heat) to pull the other U-bolts? Would you say about 1000 - 2000 lbs of shroud tension was adequate? (1000 lbs would be comparable to a slightly loose rig tune)

I'm concerned that the shroud tension will not be a perfectly direct inline pull, since the shroud toggle makes about a 10 degree angle at the U-bolt.
 

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Discussion Starter · #16 ·
The U-bolt that this thread is about was the worst, and it probably took about 1000 pounds of tension and heat. The others came out MUCH more easily (<500 pounds), but the real trick was to use heat and a steady pull to get the bolt to release.
 

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Old thread, but I thought I'd add some info that might help someone that stumbles across it. A number of builders back in the 80s used these Navtec U-bolt chainplates with tierods to carry the loads into the hull structure. Overall great system. Rig Rite does sell parts, but their prices are insane. The U-bolts seem to be the most common issue, with some reporting cracks. Garhauer will make custom replacements at a small fraction of what RR charges. Think around $40 versus over $200.
 
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