Ruminations on Rudders… Dr Adrian Osler
Updated: Sep 14, 2019
This months' guest journal post is written by eminent Shetland boat researcher Dr Adrian Osler. Adrian first came to Shetland during the 1970's researching boats on Shetland's south mainland and on Fair Isle. This research resulted in the publication in 1983 of the seminal work The Shetland boat: South Mainland and Fair Isle which was published as part of the National Maritime Museum’s monographs and reports series. This book has since been republished (2016) and is available for purchase at the Shetland Times bookshop.
Adrian's journal post is the result of a visit that Laughton Johnson and I made to the Shetland Museum & Archives collections Store. During this visit we examined a few models of shetland boats, and in particular the Ness yoal Venerable LK 596 whose rudder we noted protrudes below the keel line of the boat.
Following our visit to the Museum Store I emailed Adrian for his thoughts on the subject of yoal rudders:
"In particular I am very interested by the depth of the rudder, which appears to answer a question that Brian Wishart, Leslie Moncrief and I have debated and that is the length of yoal rudders, all the later rudders end in line with the keel, and Brian has long thought that this was a modern invention, and that historically they were deeper than the keel." [Marc Chivers, 17th June 2019]
This journal post is Adrian's retort to my email which I hope you enjoy reading.
Looking back at my notes of some forty years ago it seems to me that this was a feature that was rather taken for granted – though uncritically so. For example, in a published description of the model yoal Margaret LK 100, it was indicated that ‘the detachable rudder extends below the keel line.’ This feature stays impressed upon my mind since I still remember that after removing the model from its storage box (in Liverpool Museum) in 1973, for some much needed cleaning and re-rigging, it had to be kept on its stand in order to avoid the risk of damage to the protruding rudder (see Fig. 1). Luckily, further research revealed primary evidence concerning this slightly atypical yoal model’s history, confirming its date of construction as the late-1880s (or earlier) and affirming that – although the registration number was probably fictitious – the model had been constructed by the builder of the full-size boat it represented. Quite remarkably, the ongoing cleaning and conservation work then revealed convincing evidence of this finely made model’s provenance, a pencilled signature: ‘J Shewan’, under the forward tilfer.
John (‘Jack’) Shewan (1865-1957) had been brought up in Scatness as the younger son of a boatbuilder/carpenter, serving his time as a boatbuilder/shipwright in Hay & Co.’s yard, Lerwick, where he occupied the position of yard foreman from 1900 until he retired. A keen and talented modelmaker from youth, by the early-1940s his fishing craft models had become recognised out-with the islands for their veracity and quality, many being commissioned for museum collections. The model of Margaret however is clearly an early product, likely dating from the period of his apprenticeship at Hay’s yard, 1883-1888. As a pleasure yoal the full-size original was apparently built longer and beamier than the ‘classic’ Ness Yoal described by Henderson and others, but in all other characteristics matches the later (exhibition standard) models of working yoals built by Shewan. Thus, there is little reason to dispute the proposition that the model’s down-swept protruding rudder reflected common, if not universal, practice for south Mainland yoals at that period (see Fig. 2). A practice which Shewan would have been familiar with through his upbringing and, tragically, through the drowning of an elder brother in a yoal accident in 1880. Comments in his letters to Dr DA Allen clearly indicate his familiarity with the yoals of Dunrossness and Fair Isle, as did anecdotal evidence gathered by the author during fieldwork in the 1970s.
If it is accepted that early Ness yoal rudders were of down-swept protruding form, i.e. with heel pitched below the projected line of the keel by around fifteen degrees, and that later – and modern – practice confines the rudder foot to being flush with the keel line (see Figs. 3, 4), two questions arise. Firstly, did this form of down-swept rudder have a specific antecedent? And, secondly, were the reasons for the adoption of that planform in Shetland functional, cultural, or both?
Superficially at least the first question, that of antecedence, seems the more straightforward to answer. There is a marked correspondence between the Shetland yoals’ down-swept rudder shape and that commonly employed in the open sailing craft of nineteenth-century western Norway (see Fig 4, left). For instance, measured plans by the Færøyviks and others depict visually analogous examples on boats from Hardanger, Hordaland, Sogne, Nordfjord and elsewhere. But qualifications need to be made. Below the waterline these Norwegian rudders exhibit a marked, ‘stepped’ extension of the after edge, a feature which appears to have been absent from the Ness yoals’ relatively narrow blade whose after edge sweeps largely uninterrupted from head to heel. Correspondingly, there were differences in the rudder hangings employed. The Norwegian boats’ down-swept rudder heel was generally reinforced by a lengthy strap that extended across the blade from a slotted gudgeon whose pivot point was towards the bottom of the after stem: at the base of an extended, stem-mounted pintle (‘slide’). However, Shetland practice generally employed a conventional lower pintle – fastened onto the blade – which mated to a gudgeon mounted over one-third of the distance up the after stem. This higher pivot position allowed the toe of the Shetland rudder blade to be rounded off, providing a significant opening (cutaway) between the blade’s leading edge below the waterline and the aft stem, whereas the Norwegian system of having a very low pivot point necessitated rather more infill of blade in the same area (see Fig. 4). 
And, although a down swept shape may often visually suggest protrusion below the keel line in Norwegian boats a close examination of recorded examples indicates that, in practice, the heel of the rudder commonly just kissed the extended line of the keel whilst its toe remained noticeably above (see Fig. 4, left). There would seem to be sound practical reasons for this. Consequently, the fact that the heel of the early Shetland yoal rudder protruded below the extended line of the keel appears to be a singular feature. Nevertheless, there are recorded cases of protruding rudder forms in Norway too, those traced so far including: a six-oared boat from Vest Agder; an Oselvar åttring, whose rudder is remarkably akin to those of the Shetland yoals depicted by Shewan; together with a couple of 1890s-built leisure færings from Hardanger.   Intriguingly, or merely coincidentally, the latter two are from typologies and areas closely associated with the late-eighteenth/early-nineteenth century shipment of disassembled boats to Shetland.
In a broader context however, the points of difference between the Shetland and Norwegian rudders outlined above may be considered secondary rather than primary in nature, for the planforms and axes of rotation that were employed appear common to both. Thus, it could be hypothesised that up until the late nineteenth-century the builders and users of ‘south’ Shetland (Ness) yoals – a type widely regarded as culturally conservative and Norwegian in origin – simply propagated and simplified rudder forms associated with the original Norwegian boat imports.
And such an argument may be given further weight by reference to the rudders of a geographically associated Shetland type, the Fair Isle Yoal. These yoals also formed a subject for Shewan’s modelmaking, and once more he possessed personal knowledge of the originals (see Fig. 5). Caution must be exercised in respect of their rudders however, for these Fair Isle Yoal models – all built late in life – mount rudders that are near identical to those exhibited in the Ness Yoal models that he also made during this period.
Fortunately, at least two further items survive that provide positive, if differing, evidence as to the rudders in use on late-nineteenth century Fair Isle Yoals. The first is a contemporary model by John Robert Laurence of Fair Isle that was exhibited at the ‘International Fish