What Are they Called ?

[Rick Iverson]

Fellas;

Hope your Thanksgiving was memorable and wrapped in the warmth of you families. And one more thing: Merry Christmas!

I am looking at a couple of Tartans, and have noticed the identified plate (or rod) may or may not be present.



So I can talk intelligently to the owners: what are they called; what do they do; are they necessary; and why doesn't this 1992 Tartan 31 have them?

VR

Iverson

Post Scriptum - My wife retires 30 Dec 10. We'll be in Destin FL NLT 7 Jan 11 to begin our sailing adventures. This is going to be great!

[capt.bobfm]

Looks like the chain plate to me. It's the thing that holds the shroud (wire that holds up the mast). Look and see if the shroud is attached to the top (above the deck) of it. I believe on this boat the shrouds are inboard and therefore the chain plates are visible in the cabin. Most boats have their shrouds as far outboard as possible and the chain plates are mounted on the hull,so you don't see them in the open spaces of the cabin,they are burried under cabinitry and such. Boats that have their chain plates mounted inboard are designed for racing and the shrouds being inboard alow you to trim you'r jib sheets a bit closer.

[Vasco]

Yes they're chainplates.

[Bash]

that sort of chainplate is used transfer the stress of an inboard shroud directly to the hull. It tends to be a big-boat thing. On smaller boats you'll tend to see chainplates anchored to bulkheads, or in some cases directly to the deck. On some boats inboard chainplates will be disguised by cabinetry.

Are the necessary? Very.

[delmarrey]

Mine extend from the main chainplate all the way to the main structure of the hull.

As boats get larger the hull rigidity becomes less in relation to the hull size. On boats less then 30', lets say, don't know for sure, have a very stiff deck and hull to support human activity and needs that rigidity to survive in moving waters.

Whereas, larger boats can flex a bit, due to the human activity and that the waves/water action are reduced in relation the the size of the boat. And as boats/ships get even larger, stress joints/beams are put into place to keep the hull from cracking with the flexing.

A little bit off the main subject but that explains some of the reasons for structural reinforcements.


.

[boatman61]

Thingies that stop that metal thing falling of your boat.....???

[delmarrey]

How about chainplate stringer?

[Bash]

I've heard them called "chainplate struts."

[Adelie]

Originally Posted by Rick Iverson

Fellas;

Hope your Thanksgiving was memorable and wrapped in the warmth of you families. And one more thing: Merry Christmas!

I am looking at a couple of Tartans, and have noticed the identified plate (or rod) may or may not be present.



So I can talk intelligently to the owners: what are they called; what do they do; are they necessary; and why doesn't this 1992 Tartan 31 have them?

VR

Iverson

Post Scriptum - My wife retires 30 Dec 10. We'll be in Destin FL NLT 7 Jan 11 to begin our sailing adventures. This is going to be great!

To me a chainplate is a flat plate attached to the hull or to a bulkhead intended to distribute mast loads in the the hull either directly or thru the bulkhead.

On the boat in the attached photo there is not a major bulkhead in line or almost in line with the mast, so the shrouds come down to a deck fitting which transmitts the load thru the deck to a tierod that carries the load thru open air, or thru nonstructural pieces to a chainplate that is bolted to a bulkhead buried in the furniture.

The boat in the attached link has a bulkhead is more or less in line with the mast. Pictures 5 & 13 show the chainplates attached to the bulkhead, especially #5 which is clear enough to show some of the boltheads.

Having the bulkhead in line with the mast is probably somewhat stronger and safer than having a tierod to a chainplate given the smaller bulkhead with less reserve capacity wher it bonds to the hull and more elements in the system to go wrong, but the tradoff is a larger main cabin space.

[delmarrey]

A chainplate is anything that the mast shrouds connect to, to hold the mast in place.
This is the top side of my pictures above.

FYI - the toerail is removed for some work.

If you follow the plate in your picture, I'm sure it runs down to a structure on the hull. If the plates are only attach to the deck or hull it can cause flexing in either allowing slack in the shrouds under load.
.

[Adelie]

Originally Posted by delmarrey

A chainplate is anything that the mast shrouds connect to, to hold the mast in place.

I disagree. On some smaller keelboats, 20ish feet, I have seen shrouds attached to U-bolts thru the deck which worked satisfactorily. On the Cascade 29, in the late 70's or early 80's they started attaching the shrouds directly to the extruded aluminum rail at the gunnels. Some of the recent high-tech boats have loops of glass that stick up from the rail with a pin between the loops for the shrouds to attach to. None of these is attachment methods is a chainplate according to the bulk of definitions I could find online. The general term I have heard that seems to work is shroud base, though this can also refer to the breadth or half-breadth between the shroud attachment points at deck level.

In general I wouldn't make an issue of this as I understand what you mean when you use 'chainplate' to refer to one of the other methods of shroud to hull attachment. However in this case OP specifically asked about the correct terminology.

[sabray]

so if its not a chain plate what term shall we use. (A) Mast holder upper (B) steel plate that holds the mast upper (C) Something else to bang my head on (D) Not a chain or a plate thing (E) lets get it over with and call it women. The one thing that keeps your stick in the air and your sails full corrodes. your stick drops and the wind is no longer in your sails. or lets call it a chain plate.

[daddle]

"Shroud tie rods", or maybe "tie plates". A very good way to make a boat stiff. Loads go directly to the hull and keel. Usually attached to a longitudinal stringer that in turn loads a few ribs in the keel area. The deck and hull can then be made lighter, plus, as mentioned, bulkheads eliminated.

Inspecting the lower end is problematic, but at least it's usually dry.

[sabray]

dammit tie rod it is. You still may need to replace it ever so often

[Adelie]

Specifically regarding the item shown in the OP's photo and the items that can be inferred from that having seen similar arrangements:
1) The shroud attaches to a shroud base deck fitting/stainless deck fitting/pick some term that describes transmitting force thru a deck and on to something else.
2) The deck fitting is attached to a tierod/chainplate tierod/chainplate stringer/chainplate strut or even a very long turnbuckle which transmitts the load down thru air usually to a chainplate. This tierod/... is what the OP was asking about.
3) The tierod/... is attached to a chainplate. The chainplate is a piece of flat stock or occassionally c-channel with some sort of connection detail at it's top for the tierod and drilled with 1 or more columns of bolt holes for screwing or bolting to a bulkhead which then transmitts the load into the hull.