[C320-list] Chain Plate qustion

[catalina at thehares.com]

Hi Matt,

It's unlikely that you'll need to do all of what's mentioned. Warren's hull number is #62 and I believe some changes were made since then. 
I've done this job on hull #809 in the past and I think there are a few things that you might want to consider in the procedure instead to save time and effort.  
I owned and sailed Hull #809 for 20 years.

I'm open to a phone call to discuss how this works if you want.  Just shoot me an email and we can chat about the job.  Catalina @ TheHares.com

1.  There shouldn't be any reason to mess with the lower chainplate/rod bolt since it's unnecessary to remove the chainplate strut as mentioned.  By doing that, you may change the balance of how much tension is applied to the deck and introduce other problems.  
You want the chain plate to pull only on the heavy reinforced fiberglass area of the shelf that's meant to carry that load.  Ie: if the nut on the chainplate rod isn't tight enough, the deck sandwich (inner plate and top plates) will be taking a lifting load it isn't meant to.  If the nut is too tight, you'll actually pull the deck downward as you tighten the machine screws that sandwich the deck and backing plates where the tang comes up through.  Unless the factory says otherwise, I strongly suggest you not mess with the large nut that's at the bottom end of the chainplate that was correctly adjusted at the factory during assembly. 

2. IMPORTANT:  You will *need* to purchase a new set of longer 316 stainless machine screws and nylock nuts ahead of time for this job.  I'll explain why below.

3.  The procedure outlined about reinforcing the mast with halyards is a good safety measure and I won't comment on that.

The chainplate has a few parts to it, but except for possibly some very early hulls, there is no balsa core in the deck where the chainplate comes up through the hull liner and deck.  It should be solid glass. But there is a separate fiberglass hull liner below the deck.  The sealing you'll be doing (I assume you'll be using "Bed-it" brand Butyl tape for the job.  If you aren't you should consider it) is primarily the gap where the chainplate tang comes through the deck, the machine screw holes and the top plate that is through-bolted to the lower backing plate inside the cabin.  So, there should be no reason to have to remove any balsa coring and fill with sealant, but Catalina Yachts customer service should be able to answer that question for your hull.  Warren Pandy is the guy...

As for the machine screw holes through the deck/liner, you'll want to use a chamfering drill bit to create a chamfer through the gelcoat layer.  This will allow the sealant around the machine screws to really work.  See this article on why and how:   https://marinehowto.com/bed-it-tape/    This is good advice regardless of what kind of sealant you use.

There will be several machine screws going down through the top plate, through the hull, hull liner and through the stainless plate inside the boat.  By removing the backing nylock nuts, you'll be able to remove the machine screws and the top plate and begin the process of sealing the assembly.

When you remove the machine screws and backing nuts that are sandwiching the deck, the inner plate will/may pull down away from the hull liner (or the hull liner may separate from the deck just a little leaving a gap.  In either case, the original screws will not be long enough to reuse without a lot of swearing.

This is why you need to purchase screws that are a good couple inches longer than the ones you're taking out.  This will allow you to easily put the longer screws through the deck down through the hull liner and backing plate and still have threads showing to get the nuts in place.  (when ready to reassemble, you'll have someone on the outside holding each of the screws from turning while you work your way around, gradually tighten each screw a little at a time until both the top plate and bottom backing plate are again tight to the deck.  When you've tightened them up properly you'll just use a hack saw or cutoff wheel and trim off the excess bolts.   This is so much easier than trying to reuse the existing screws which I guarantee will be too short and give you fits trying to put the nuts back on.  Perhaps this is why Warren felt the need to loosen the lower nut in order to bring the two plates back together to get the nuts on.

Sorry this is a bit disorganized, long and excuse typos, but I didn't want to see someone do more work than is needed and possibly introduce some problems.

-Jeff Hare
Formerly C320 #809 Woodbine II
Currently C355 #17 Solstice
C320 International Association Webmaster 2003-2022(ish) but still running this discussion list.


-----Original Message-----
From: C320-list <c320-list-bounces at lists.catalina320.com> On Behalf Of M K via C320-list
Sent: Thursday, April 25, 2024 3:39 PM
To: c320-list at lists.catalina320.com
Cc: M K <mknoll8181 at gmail.com>
Subject: [C320-list] Chain Plate qustion

Hello All,
New to the list, and a newbie with the 320, so bear with me.  Hopefully this posting will work properly.

I have read the procedure posted by Warren Updike regarding rebeding the chainplates.  Planning on starting  it this weekend before spashing my boat
in a few weeks.   I need to address a leak at the middle plate (port side)
with dual shrouds attached.

The procedure indicates the need to remove the strut, and be careful to note the position and sequence of the spacers above the nut.  For those that have done this can you share the size of the nut? I have measured with a caliper, but the angle was such that the reading might be inaccurate.  I suspect it is either 1/16 or 1 1/18.  I would like to order the proper crows foot "socket".

My second question relates to a conversation with a fellow 320 owner at the marina that indicated he has rebeded his chainplates multiple times and that his strut will slide down thru the deck once the shrouds are released and the 4 phillips head thru bolts are removed.  I suspect that he is fortunate that he doesn't need to remove the strut to do the job, but  I wanted to ask those that have done it, is it more typical that you will need to remove the strut to properly rebed the chainplate?

Thanks,
Matt Knoll
#315 MaryAnne