The genesis of a new square rig..!
In search of Speed, Sefety and Weatherly Performance



Square Rig

The ideal rig for sail training should include square sails on at least one mast, particularly if operating world-wide on the Trade Routes when the trainees have time to become conversant with its complexities. The exciting downwind performance is normally offset by an inability to go to windward effectively. This can frustrate plans to reach upwind locations and, in the worst case, increases the risk of becoming embayed.

A modern solution is to ‘motor-sail’ using the engine, making excessive noise, wasting fuel, and creating an uncomfortable motion, which puts unnatural stress on the rig. Not a good solution.

Fore and Aft Rig
The desired weatherly performance can, of course, be achieved with Fore and Aft rigs, which are not so crew intensive, but can become very threatening downwind, in severe conditions. Historically, a compromise has been struck in the Topsail Schooner, but it remains only a partial solution to the dilemma.


 

The Polacre / Xebec Rig

Philip Goode, yacht and sail designer, based in Majorca as the Lloyds agent, had a particular interest in the Barbary coast Xebec, the most successful corsair of the Mediterranean for two centuries and, arguably, the fastest displacement sailing vessel of all time for its size.

 



 

This hybrid sail arrangement of the 'square' Norse sails on the main mast and a massive 'triangular' Lateen on the fore in one ship had spawned a cult of swift and weatherly pirate ships whose ability to outrun their pursuers was legendary.


Using the geometry of the Xebec rig, Philip had designed a number of sail plans for modern yachts which he tested on scale models but, in spite of achieving exceptional results on all points of sailing, they did not appeal to the owners of today's maxi-yachts.  Fortuitously he was put in touch with Graham Neilson and a collaborative project was launched for the PELICAN.



 

The Model "Pelicanina"

As a test vehicle, Philip Goode built a 12½:1 scale model of PELICAN, incorporating the
new long poop and his 3-masted, 12-sail rig. 

Her centre of gravity (CG) and meta centre (GM) had to be scaled to that of the future ship and she had to run on her predicted draught marks.

PELICANINA was 3½ metres long and weighed nearly ¼ of a tonne.

 


 

Test Results

PELICANINA was sailed in the open sea off Palma. The results, recorded on video, were extra-ordinary and spectacular.

She proved to be perfectly balanced, sailing fast to windward in scale winds up to 60 knots - unheard of in a square-rigger.

Her speed off the wind was exceptional and downwind there was no tendency to yaw.

It seemed that the secrets of her Arab forebears were being slowly revealed.

 

Problems Identified

As expected, the Model identified several technical problems to be solved before this performance could be replicated at full scale:


a)    Single pole masts were required. (a la 'polacre').  The tallest to be 100ft.

b)    The yards had to brace within 18 degrees of centreline
       (normally 35 degrees for conventional square riggers).

c)     To avoid distorting the square sails at these extreme angles, the pivot point of each
        had to be in perfect alignment ( not possible in conventionally stepped masts).

d)
    Suspension points of yards and some stays had to be altered.


Verification of the Rig by Lloyds of London

Because the unconventional sail distribution and rigging plan were bound to raise questions of strength and security, it was decided to submit all elements to scrutiny under the 'Verification of Rig' procedure now available at Lloyds Register, in London.

 

Computer Generated Analysis

Here, all sections of the masts, bowsprit and standing rigging were 'modelled' and subjected to the maximum wind speeds acceptable for Full and Plain sail, ultimately reducing to 'bare poles' in hurricane conditions at 122 knots!

From the predicted sail loading and ship movement the mast scantlings were analysed for axial force (vertical thrust), bending and buckling. Rig tensions were then calculated and the standard Safety Factor of 3.5:1 applied to ensure that the chosen wire rigging and terminals would be sufficiently robust.
A 16-page report and annexes, with colour computer graphics concludes: "the minimum acceptance criteria were satisfied in all cases".


The Masts
The masts are 20 sided steel in hollow section.  They are fully galvanised. 
Historically, 'lower' masts were always stepped on the keel, emerging at the weather deck through mast collars, with wedges, packing and aprons to prevent leaking. Now, stump masts, which are integral with the hull and deck structures are Lloyds preferred option, and are fitted in PELICAN.
These terminate in a flange, ½ metre above the wooden deck. The mast itself, with an identical flange at its base, is then bolted to the stump ensuring continuity and water tightness.

More from the maker of the masts: Link



The Times: Link