What is function of this tackle on the boom of an 18th Century Cutter?

[tkay11]

In his book on Rigging Period Fore and Aft Craft, Petersson shows a diagram of a boom as follows:

 

 

The arrow I have added shows some tackle fitted to the underside of the boom, quite separate from the mainsheet tackle (which is given the honour of a full diagram later), but there is no other mention in the book or diagram of how this might be used.

 

I'd be very grateful if someone could explain it to me or give me some idea of its function and the points to which it might be fixed.

 

Oh, and by the way, I'd also be glad of some explanation of the function of the bees at the end of the boom as displayed (just to grab as much info as possible in one swoop!).

 

Thanks in advance for any ideas

 

Tony

Edited May 2, 2015 by tkay11

[Tadeusz43]

Hi,

From RiggingPeriod Ship Models by Lenarth Petersson

 

Tadeusz

[tkay11]

Thanks, Tadeusz and Spyglass. That's the very one! It shows I have a lot more to learn about sails.

 

That was very helpful indeed!

 

Tony

[Bob Cleek]

To put a finer point on it, it is the clew pendant tackle.  Aft block of the tackle is hooked on the eye as illustrated when the mainsail is not bent to the spar or furled and lashed to the boom.  The fall of the tackle is secured to the cleat on the boom, as illustrated.  In a model without the sail raised, The after block would be hooked to the eye on the boom, pulled up tight and the fall secured to the cleat on the boom.  Neatly done, the remaining fall would be coiled, frapped and hung on the cleat on the boom.  In use, the mainsail clew and each reefing clew would have a clew pendant running either from the main clew and each reef clew.  Depending on the size of the vessel, the pendents would run from either the boom at the turning block, often tied around the boom with the turning block providing a "stop" to prevent the end from being pulled aft when set, or the end simply secured directly to the clews (with an eye splice, or just a knot.)  Secured to the boom and run up to the clews and then back down to the turning blocks provides a further purchase, unlike a direct connection to the clews. The pendents would then be run down from the clews to their respective turning blocks and through the turning blocks. Depending on the size of the vessel, the turning blocks may have sheaves or simply be fairleads. You've referred to the turning blocks as "bees," which is perhaps not the accurate term. (A "bee's seat" or "bees" are longer rails generally fastened on either side of a bowsprit or jib boom to which bowsprit netting is tied.)  The plan illustration does not provide the detail to show the sheaves, but the shape of the turning blocks leaves no doubt that they contain sheaves.  If they did not contain sheaves and thus were fairleads, they would be shorter and simply consist  of a block of wood with a round hole with the edges relieved drilled into them.    Beyond the turning blocks, an eye is worked into each clew pendant so that when the sail is raised fully each eye hangs free (without tension) just below the turning block or fairlead.  When the sail is set, full or reefed, the clew pendant tackle is hooked to the eye of the respective clew intended to be pulled taunt and hauled up tight (or loosened if more belly is desired to the set of the sail) and tied off to the cleat at the forward end of the boom with the tackle fall coiled and secured to the tackle cleat.

Edited May 2, 2015 by Bob Cleek

[Tadeusz43]

A few more photos.

 

Tadeusz

[JerryTodd]

Based on the original image - it's a preventer tackle, to hold the boom out against a gybe.  It's not shown connected as clew tackle would be.

[JerryTodd]

It's connected while the sail is set.  It's disconnected on a sail that brails - sometimes.

 

Here's the version Pride of Baltimore had and I recreated on my model.  Her mains'l was lowered rather than brailed and except when reefing, the clew pendant was hardly touched.

Edited May 7, 2015 by JerryTodd

[tkay11]

Thanks, everyone, for the rich detail. These are the kinds of explanation that make the making of a model more deeply satisfying and interesting.

 

I can certainly see that what I was calling 'bees' are in fact turning blocks -- the small point opposite each one implies a sheave. Interestingly, none of the 5 cutter models I saw at Chatham (see the discussion at http://modelshipworld.com/index.php/topic/10370-18th-and-early-19th-century-cutter-models or in the Gallery) had either the tackle or the turning blocks, even though it seems from this discussion that they are quite normal aspects of sailing.

 

Tony

[JerseyCity Frankie]

I agree its a preventer. In light air when running before the wind its easy to have the sail get backwinded- a gybe-and have the boom swing entirely across the deck to the other side, unintentionally. To prevent this, the forward tackle of the Preventer is unhooked from its stowed position and the hook is place on a ring or an eye on or near the aftermost shroud on the leward side and taken up on. On vessels where I have seen this line, there is a cleat all the way forward under the jaws of the boom and this is where the line is tended. Now the preventer opposes the sheet and is preventing the boom from going inboard unless you let it.

[Bob Cleek]

Both blocks contain hooks.  It certainly could be used as a gybe preventer, but that ignores the fact that there are reef clew line turning blocks on the aft end of the boom, yet no other cleat upon which to belay them.  There is an eye at the end of the boom to which the main clew could be fastened, which would permit the tackle to be used as both a preventer (when the main was fully set) or a reef clew tackle when sail was shortened.  My money remains on it being a clew reefing tackle, though.  Preventers are generally single part lines without any blocks for purchase.  They are not set up to haul under tension, but rather just tied off once the main boom is run out on a run and cast off before hardening up or commencing a controlled gybe. They aren't intended to apply any forward tension to the boom, but rather to simply prevent the boom from swinging aft.  Also, any rigger worth his salt wouldn't use a full length tackle as pictured even if he wanted purchase on a gybe preventer.  It would be a waste of line.  He'd run a pendant from the end of the boom and then clap on a short tackle (a "handy billy") only long enough to provide the purchase.  There'd be no point to using up all that line running through the blocks to the extreme ends of the attachment points. Capice?  Gybe preventers are not to be confused with boom downhauls rigged on modern jib-headed mainsails, which are intended to pull down on the boom to flatten the main on a reach or run and so do require purchase.

Edited May 7, 2015 by Bob Cleek

[Tallshiptragic]

It's a preventer. I've attached a photo of my ship with the preventer rigged. We rig it in winds over 10knots when at sea. The tackle from the boom to the deck is the preventer.

 

Working as crew and a deck officer on various tall ships, Europa, Leeuwin, Gothenburg,topsail schooners Spirit of Bermuda, columbria etc there is always a preventer stay rigged or attached made up of double block tackles and never a single line. The preventer is also used when tacking a tall ship to spank the mizzen gaff boom across. The only ships I've sailed without these are Duyfken and endeavour as they don't have a boom.

Edited May 10, 2015 by Tallshiptragic

[Tallshiptragic]

On the attached photo if you look at both booms of the main and mizzen, you will see a block and tackle on each under the boom itself. This is the preventer in its stowed position, which may help to describe the original sketch.

 

The fixed part of the preventer is a little more than 2/3 aft of the length of the boom, the forward part attaches to an eye on deck just aft of the last shroud for when we're sailing full and by. When sailing with the wind and the booms are needed to be pulled out, this same preventer is attached to a single line which is fixed forward of the shrouds of that mast.

[Maury S]

What a great range of knowledge we have available!

Maury

[tkay11]

Marquardt in 'The Global Schooner' shows the following as being used for the main sail sheet on page 185:

 

 

This is very similar to the rig that Petersson shows, although in this case it is for a schooner rather than a cutter.

 

Then on page 176 there is a rather interesting (though quite different) rig described as a 'small topping lift for smaller vessels':

 

 

I'm showing the latter just as interest!

 

Tony

[Bob Cleek]

A preventer on a larger vessel is as described and pictured above.  In that application, there are far larger forces involved, and, as illustrated, many such applications on larger vessels are connected to the middle of the boom where they apply a stronger pull downward and also serve as vangs.  That hasn't been my experience with the far smaller sailing craft.  But, as they say, "different ships, different ropes."

[JerryTodd]

What tkay shows is only present on loose footed sails where it is a clew -outhaul and apparently serves as part of the reefing tackle.  The sheet attaches to the boom.  A sail who's foot is laced, lashed, jackstayed, etc to the boom wouldn't have this gear as such, though it could be reefing tackle.

 

The original sketch didn't show the tackle connected to anything in this manner which is why it looked to me like a stowed preventer.