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Shroud attachment, improving
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Repair and Maintenance of a Drascombe Lugger

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Improving the Shroud Attachment

This modification came about when I discovered that I needed to replace the cracked plastic inserts in the U-bolts of the shroud attachment plates on the side decks of Sospiri. At about the same time I decided that I wanted a method of attaching the shrouds that was quicker and more secure than using the standard method of tying the rope lanyards at the end of the shrouds to the attachment points on the deck. The idea of using a 'kicking strap tackle' was suggested to me by veteran Drascombe sailor Douglas Hopwood who had tried and tested the method on his Lugger. I am most grateful to Douglas for his advice on this.

Overview (Read this first!)

To get an idea of how the new system compares with the standard method, look at the two methods side-by-side in the sketches below.

The left hand sketch shows the traditional 'standard' shroud attachment rig with a polyester 3-strand lanyard, 5 mm diameter, and about 1,200 mm in length, spliced on to the stainless thimble forming the eye at the end of the shroud wire. With this arrangement the shroud is attached to the side deck attachment point (which is typically a U-bolt with a plastic insert), by passing the lanyard through the U-bolt, taking the end back up and passing it through the thimble eye, down to pass through the U-bolt, up again through the eye, down through the U-bolt, pulled tight and finished off with a round-turn and several half-hitches on the standing ropes.

The right hand sketch shows the replacement rig which is based on a triple block 'kicking strap' tackle. The top triple block with integral V-jammer also has a built in shackle which attaches directly to the thimble eye of the shroud. The bottom triple block also has an integral shackle which is attached to a stainless hook that engages with the U-bolt (shroud attachment point) on the side deck. The blocks are connected by means of 6 mm braided polyester rope which runs through the pulleys and attaches at one end to the upper block. The rig is tensioned by pulling down on the tail rope leading out from the upper block, and then cleated by means of the integral V-jammer cleat. Note that the distance between the blocks is diagrammatic & not to scale. The correct working distance is shown on the right of the sketch.

What are the advantages of the new system?

• Quicker to set up when rigging the boat
• Easier to tension the shrouds (so don't overdo it, a Lugger is NOT a racing dinghy!!)
• Easier to get each shroud the same length and of equal tension.
• Minimal risk of shrouds becoming slack when afloat, but easy to adjust afloat if necessary.

Apart from the new tackle, does any other part of the boat have to be modified?

You need to check the following on the boat:

• With the mast erected in the boat and the shrouds attached, the gap between the eyes at the end of the shrouds and the deck U-bolts must not be less than about 280 mm. If it is less than this then there is not enough space to accommodate the new tackle (see sketch above).
• It is useful (but not essential) to be able to remove and modify the existing shroud anchor points. This may be difficult with some boats depending on manufacturer & age.

In More Detail:

Shrouds
If your shrouds are too long (as mine were), then you will need to replace them with shorter ones (Note that you cannot shorten existing steel wire shrouds). The length will largely depend on the height of your mainmast. With my 16 foot mast the new shorter shrouds measured 4,035 mm from eye to eye (including the two 25 mm x 12 mm stainless thimbles).

Shroud Anchor Points
Ideally you need to be able to remove the plastic inserts of the shroud attachment U-bolts which are placed at the back of the port and starboard side decks of the Lugger. The easiest way to do this is to undo the nuts beneath the side decks, holding the U-bolts in position, so that the bolts can then be pulled out. This means gaining access underneath the side decks, which, depending on the make and year of the boat, can be a problem.

In the earlier Mk1 and Mk 2 Honnor Marine boats there is no problem as the forward side deck hatch openings give access to this area. Typically, a sheet of polystyrene (wrapped in polythene sheet, forming the ceiling of the hatch area and constituting part of the buoyancy of the boat), needs to be temporarily removed (NB This MUST be replaced after the bolts have been replaced to maintain the boats flotation capacity in the event of a capsize).

In DEVON Luggers, there is no hatch in this area which is sealed and also packed with buoyancy. As far as I can see, it is not possible to easily gain access and the only way of adopting the described method is to either open out the hook or else use a larger hook which will fit round the plastic insert (See step-by-step guide below). The same restriction may also apply to Luggers manufactured by McNulty and current Churchouse Boats although I have not been able to check this out yet.

Components

The hardware needed is shown below. In addition, two lengths of 2,200 mm, 6 mm diameter pre-stretched polyester braided rope is needed to run through the blocks.

The Required Hardware This photograph shows the hardware required. A front and side view of each block illustrates the essential features. All the components shown here are made by Seasure and the part numbers are given for easy reference. 2 triple blocks with integral shackle & V-jammer (Part No. 00-35) 2 triple blocks with integral shackle (Part No. 00-31) 2 'S' hooks made of 8 mm stainless rod (Part No. 25-28) (Click on image for larger view)

Step by Step Guide

	The Original U-bolt shroud attachment points Photograph of the original shroud attachment points showing how the plastic inserts have degraded, cracked and split. The A2 stainless steel has also started to rust. This photograph also shows the nuts and washers used to secure the bolts beneath the decks. (Click on image for larger view)
	U-bolt shroud attachment point Photograph of a replacement U-bolt shroud attachment point on one of the side-decks. This photograph was taken before I decided to implement Douglas Hopwood's suggestion of modifying the shroud attachment system. The black plastic insert with stainless sleeve needs (if possible) to be removed to accommodate the hook of the new rig. (Click on image for larger view)
	U-bolt Before & After Modification The left sketch represents a cross-section through part of the deck showing the un-modified U-bolt with the plastic insert on top of a thin stainless backing plate. Beneath the deck the bolt is secured in place by two nuts which back up to two washers which spread the load against the GRP of the deck. The right sketch represents the modified U-bolt with the plastic insert removed. With the insert removed there is a problem when the nuts are tightened beneath the deck, as there is now nothing to prevent the bolt pulling down and the backing plate riding up. This is easily remedied by screwing on two additional nuts right up to the top of the threaded parts of the bolt before the backing plate is replaced and the bolt secured with the nuts and washers beneath the deck (The thread on my bolts was M8 so getting two additional stainless nuts was no problem). (Click on image for larger view)
	U-bolt Modification Completed The U-bolt has been removed from the side-deck (by undoing the nuts on the threaded ends of the bolt), the black plastic insert has been slid off the bolt (pictured on the left), and the U-bolt re-attached to the side-deck (pictured on the right). It would have been cheaper to purchase replacement U-bolts without the plastic insert. Note the two additional nuts above the backing plate. The modified fitting is now ready for use. (Click on image for larger view)
	Rigging the Blocks The line is tied (or better seized) to the attachment bar on the top block. It is then led down & round the front of the left pulley on the bottom block. Then up and behind and round the left pulley on the top block. From there it is lead down and across in front and round the right pulley on the bottom block Then up and behind the right pulley on the top block .... ... before coming down for the final time to the central pulley on the bottom block ...and up behind the central pulley on the upper block and exiting through the jamming cleat. (Click on image for animated view)
	The Rig in Use To set the rig up, the hook is engaged with the deck-eye, and a firm pull on the rope tail is sufficient to apply all the tension required (A Drascombe is not a racing dinghy and high shroud loadings could severely damage the mast step, forestay/furling fittings and also the mast itself), but the 6:1 purchase allows a reasonable tension without having to bust a gut applying it. After setting up the first time I was able to borrow a shroud strain gauge, which gave a reading of 70Kg (approx 155lbs) tension. From the jamming cleat the rope leads up and is tied off with a couple of half hitches through the lower eye of the shroud. This prevents it dropping down out of the 'V' of the jamming cleat. In use the result of a slightly higher tension rig on the water was marked with a definite improvement in pointing ability (through a tighter jib wire), with none of the usual slackening off of the leeward shroud.

Project started April 2008 and completed May 2008