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Chainplates

Updated  03/09/2004

The time has come to replace my chainplates...I will be dropping the mast on my Challenger in a month or so to inspect, paint and
wax it and reinforce the mast support but I would like to get as much related work done as possible beforehand.
I think, and this is my question, that I should be fine releasing the main shrouds and leaving the double lower shrouds tensioned long
enough to  replace the chainplates. Should I  wait until the mast comes down or is it no big deal to do this chainplate reinforcement
now?

Thanks all...

Chris
TAURUS
Challenger #156

Chris,
   I do not see any problem with taking the upper shroud off. Heck, I
replaced all my standing rigging with the mast up; and that envolved me (at about 11
stone, 6 pebbles at the time), being at the top of the mast with a shroud or
stay removed. I did use a tensioned halyard to replace the missing shroud in
each case.

    Bruce K
    Challenger # 74
    Los Lunas, NM

Bruce, that´s the time to use the spinnaker poile if you have one; passing the halyard thropugh the pole´s end and bringing it back tio the toerail gives a much bneter angle for the support
john

Another maybenewbie question:  What's a chainplate?  Lots of talk
about repairing it lately, but I couldn't figure out what it is from
the messages I read.

Thanks,
Jim Booth

Jim:

A chainplate is a metal plate to which the shrouds and stays that hold up
the mast are attached. The shrouds and stays are usually attached to the
chainplates with jaws in the turnbuckles or with shackles.

Chainplates may be bolted or glassed to the hull or bolted to a bulkhead.
They take a lot of strain from the rigging, especially in strong winds. Even
when the boat is tied up doing nothing, there's a lot of strain on the
chainplates from the tension in the rigging.

So if a chainplate fails, the mast could  fall down.  That's why it's
importqant that they are in good shape, not corroded and their attachment to
the hull or bulkhead is secure.

The chainplates usually pass through the deck, which is a potential source
of leaks. There's usually a covering plate which protects the slot through
which the chainplate emerges from the deck.  This area needs to be
well-cauked.  Leaks could cause the balsa or plywood in the deck core to get
soft and mushy.  In boats whose chainplates are atached to wooden bulkheads,
leakes from chainplates could cause rot in the bulkkhead, which would not be
able to sustain the load from the rigging, and subsequent failure of the
chainplate and possibly the entire rig..

It would be a good idea to get a book which shows the parts of the boat and
explains how they work. Some good ones are "Royce's Sailing Illustrated" (I
think that's the title) or "The Annapolis Book of Seamanship" or George
Oday's " Sail In a Day."  Any library should have at least one of these.

Just a suggestion.

Steven Gaber
Sanderling, 1967 C-31 #77
Oldsmar, Florida

Steven:  Why are they called chain plates?  Were the original shrouds and
stays attached with chains?
Frank Schenk

Jim:

In the days of sailing ships, chainpates were bolted to the outside of the
hull. I guess the shrouds had chains on them in some cases. Instead of
modern turnbuckles, boats earlier than the late 19th century had deadeyes to
adjust the rigging tension.  These were wooden or iron blocks which allowed
the rope rigging to be tightened.  Some modern replica boats have them.
They're real shippy looking, but turnbuckles are easier.

Gotta gpo to work now. Bye.

Steven Gaber
Sanderling, 1967 C-31 #77
Oldsmar, Florida

(refers to an article in the March, 2004 issue of SAIL magazine)

Great article, Paul, especially after seeing your book at the meeting Sunday.

Did you have to replace the chainplates in photo 2?  Or were they just
cleaned up?


Johnny Revel, C26 MkII #1090, Lady Revel, Solomons, MD

Yes, I replaced all the chain plates. The forward and upper shroud
chainplates went from 3/8" x 3" x 14" to 3/8" x 3" x 42" and were bolted on
top of six layers of fiberglass tape and epoxy that tied into the lower
stringers.

The aft chainplates were replaced by Schaefer chainplates with pin holes top
and bottom. The bottom pin was used for a short baby stay (32" long) that
lead to an eye bolt on the lower stringer. Probably overkill, but the
material costs were slight and it was already torn apart, so why not?

Paul

Paul,  from photo 2 it looks like the original chainplates had 6 screws or
bolts into the bulk head.  I presume that you kept that pattern on the bulkhead
with the new 42 inch chain plates?  How many additional screws bolts did you
add along the length? 

Johnny Revel, C26 MkII #1090, Lady Revel, Solomons, MD\

The upper shroud chainplates had six bolts while the fore and aft ones had
five. I replicated the same bolt pattern at the bottom of the chainplates.
The reasoning was that the tops one could rot out but the bottom ones would
never be affected. The aft chain plates only have one of two bolts in them
as the real strength is in the baby stay to the stringer below.

Paul

The 3M people when asked by a sailor for a good sealant for stainless steel chainplates recommended Uniroyal´s "Silaprene" as a good sealant for stainless. Said sailor said he had no more leaks atr the chainplates after using it. Uniroyal Technology 800 899 GLUE

John