A CONJECTURAL RECONSTRUCTED LINES PLAN OF THE EIGG

Mike Jarvis

(This set of plans and notes was written in 1988)

In 1874 two men digging drains in a bog above the Bay of Laig, Isle of Eigg, discovered what appear to have been the partly-finished stem, sternpost and keel for a boat of Scandinavian-style construction. The stem and sternpost were preserved and are now in the National Museum of Antiquities of Scotland in Edinburgh. It has been argued whether they are of Viking or late medieval date, but in either case they are the only parts of a seagoing vessel so far discovered in Scotland from their era.

One of the pieces, presumably the stem since it is a little longer and less tightly curved than the other, has been essentially finished, except that the scarphs for the plank endings and the keel have not been cut and there are no holes for fastenings. It has frequently been illustrated and compared with similar stems from Viking-age wrecks in Scandanavia and with examples buried for seasoning in Norwegian bogs. It is of the ‘winged’ type, with a deep groove between two wings allowing the plank ends to be attached securely by riveted scarphs, rather than by blind nails or trenails driven through the hood ends. The presumed stern is only partly finished. The stepped landings for the two lowest strakes have been roughed out in profile but the central groove has not yet been cut.

The closest parallels in Scandanavia are amongst the tenth-century wrecks excavated at Skuldelev on Roskilde Fjord, Denmark, particularly Skuldelev 3; only small details differ, like the slight discontinuity in the false rabbet line near the base of the Eigg stem. The proportions are not quite the same as those of the Skuldelev 3 stem, however, and the precise geometrical construction suggested for the latter would not fit the Eigg stem as it projects too little above the sheerline.  Another close parallel is with the four-oared boat found with the ninth-century Gokstad ship in Norway, which had only three strakes scarphed onto very wide wings on the stem. Other published Norwegian examples are rather different with a number of strakes running together to land on each step on the stem.

The beautifully carved galley on the sixteenth-century tomb of Alexander Crotach at Rodel, Isle of Harris has a winged stem and sternpost, and a few other late medieval carvings in the West Highlands show this feature less clearly. There are also some that appear to have a conventional stem and sternpost with a continuous rabbet line. In the Rodel and other carvings, and less markedly in the Irish drawing of Noah’s Ark from the late medieval Book of Ballymote, the scarphed ends of the planks slope aft to give a zig-zag shape to the true rabbet line, in a manner not found in the Scandanavian material. Since the plank scarphs of the Eigg stem were never cut the appearance of the plank endings is not quite certain, but the angles of the stem sides suggest that they would have followed the Scandanavian fashion.

The stem and sternpost are worked from oak. The grain is rather twisted in some places but otherwise straight; it does not follow the curved outer profile. The rings run across the siding of each piece, but at a slight angle so that they cannot have been prepared by cleaving a trunk radially into exact segments. Instead it appears to have been cloven off-centre.

The Eigg discovery was of course prior to the development of modern methods for the conservation of timber. The stem has warped transversely, perhaps through being laid flat after excavation, but there has been very little splitting of the wood through shrinkage. A ‘crackled’ surface layer one or two millimeters thick has unfortunately destroyed the fine surface detail including most of the tool-marks. This layer is now being removed to expose wood in excellent condition.

A number of wide, shallow tool-marks just visible before the removal of the surface layer appeared to mark the position of further steps to be cut in the sternpost. The other surviving toolmarks are mostly in places where the edge of the tool has bitten into the wood across the grain. The tool seems to have been straight or only a little curved both along the edge and across the face. The inner faces of the groove in the stem show no sign of transverse marks such as might be left by an adze, but such marks could have been removed by the surface crackling. An area near the bottom of the sternpost has been mangled by an implement with a wide, sharp blade, possibly the excavator’s spade. The lack of interpretable tool-marks is unfortunate since, unlike Scandanavia where axes were normal in Viking boatbuilding and are still used locally today, the West of Scotland has no surviving tradition of axe-work: the adze is the universal tool.

The rarity of tool-marks also follows from the very high standard of accuracy and surface finish on the stem. Careful selection, cleaving and seasoning of the oak is implied by the fact that it dried out without splitting. The timber is perhaps not as clean-grained as could be obtained in Scandanavia and the strakes were intended to be relatively narrow, suggesting that oak of very large dimensions was hard to find in the West Highlands, but within these limitations it is clear there was boatbuilding of the highest quality, within a mature tradition, on Eigg.

To reconstruct, from only two surviving parts, the hull shape of a boat that was never built is inevitably difficult. It is only possible because because these parts appear to fit into a well-defined and thoroughly researched tradition, and even then it involves many assumptions. But provided they are not taken as definitive, drawings are a convenient basis for discussion. We have therefore prepared hypothetical lines, construction and sail plans, setting alongside them the detailed assumptions upon which they are based.

Eigg boat lines

REASONING LEADING TO PRELIMINARY RECONSTRUCTION OF THE HULL SHAPE

1) The lines of the plank landings on the stem show clearly that it was not intended to make an angle with the keel.

2) The sternpost therefore cannot have made an angle with the keel either or it would be too upright and much higher than the stem. This is confirmed by the roughed-out cuts for the two lowest plank landings on the sternpost, and means that a stern rudder on the pattern of the larger post-C14 galleys is unlikely.

3) The original description of the discovery of the parts suggests that the stem and sternpost may have been roughly in place with the (lost) keel between them. The stem and sternpost were ‘about 30 feet apart’; 30 feet between centres, or was the putative keel length about 30 feet, which would mean a very long, low boat? It has been assumed that the stem and sternpost were set up at 9m (~30ft) centres, giving an overall length of 10.4m. Of course it is quite possible that the parts were simply buried in the bog for seasoning and their position had nothing to do with the size of the boat.

4) The run of the top of the landing for the garboard strake is rather flat, although it is so short that the angle is difficult to judge. This would suggest that the garboard strakes were meant to be ’standing’ to some extent amidships, i.e. that the midship section was to be hollow near the keel. The sheerline suggests a depth of about 0.8m amidships, which is not very much if there was to be some hollow in the garboards; it would not leave room for a lot of displacement. This implies that the boat was intended to be rather light, in keeping with the parts preserved, and suggests a resemblance to the 4- and 6-oared small boats found with the Gokstad ship, which were very long for the number of oars by later standards. So the reconstruction has been drawn as 8-oared, rather than 10- or 12-oared as would be reasonable for a late medieval Scottish boat of this length. It is about 1m longer than the Gokstad 6-oar. The small number of oarsmen keeps the displacement down.

5) The ends are pinched in so tightly that the stem angles give no idea of the overall beam intended. It has been drawn quite narrow in keeping with the general impression of lightness. There should be just enough beam for 1 man/oar.

6) The early Maughold and Iona carvings show a broken sheerline lowered in the way of the oars, although the possibly contemporary seal of Angus Mor and the Kilchattan graffiti do not. A broken sheerline would leave the freeboard rather low so the sheer has been drawn as a smooth curve.