Trans RINA, Vol 152, Part A4, Intl J Maritime Eng, Oct-Dec 2010


An alternative practice of speeding up before the waves is also described, and also the trimming of the boat by the stern in order to minimise the area acted upon by wind and waves:


“Proceeding then to the opposite practice of giving a boat speed, in fact


running away from the sea, which


constitutes the other important distinction in practice. The principle then acted on is to escape from the danger as fast as possible and other expedients are then resorted to prevent the risk of broaching-to. The most common of these is to trim the boat by the stern, by bringing all moveable weights aft (this supposes her


stern to be


outwards; if she were being taken in stern foremost, she would then be trimmed by the head). The force of the sea or wind on either quarter has then less power to beat it off, and cause the boat to broach-to, than it would have if the stern were light.”


A question as to the causes of broaching-to, leads to a detailed account broaching-to


of the authors’ understanding of (interestingly, the question about the


criticality of rudder’s emergence for realising broaching- to continued to be raised till our days [4]):


“In reply to another question as to the cause of a boat's broaching-to, the almost invariable answer is, “because the stern is thrown out of the water and the rudder therefore ceases to act”. From our own observation we have formed the opinion that this is not the case, although it is quite true that, at the moment of broaching- to, a boat will not answer her helm.


The phenomenon of broaching-to, we believe, may be correctly accounted for as follows: - on a boat encountering a heavy broken sea or roller end on, if she be stationary or is being profiled in a contrary direction to the wave, she will receive its blow, and it will quickly pass by her, her own inertia preventing her being carried away by it. If however she is being propelled in the same direction as the waves, and running rapidly through the water with her stern towards them, on a wave overtaking her, its first effect is to throw her stern up and to depress her bow, but so far from her rudder being out of water, both it and her stern are buried in the crest of the wave; in consequence, however, of her previous motion being in the same direction as that of the wave, she now offers so slight resistance to it, that instead of its passing her, she is hurried along with it at a rapid rate over the ground, her stem high up still immersed in the crest of the sea, and her bow low down at its base; as the wave approaches shoaler water, its inshore surface approaches more end more nearly to a perpendicular, and the tendency of the boat to run down this steep inclination added to the momentum she has already from her previous motion, causes her to run her bow under water, when her buoyancy at that end being destroyed her stern still light is pressed onward by the summit of the wave, and the undercurrent from the last receding wave at the same time acting on her bow, she is instantly, if a short


boat, turned “end over end,” or if a long one, capsized quarter wise If she have so high a bow that it does not become altogether immersed, or if, as in a life-boat, the end of the boat is occupied by a water-tight air-case to the height of the gunwale, so as to prevent the admission of the water over the bow, the effect then is that the boat is instantaneously turned round broadside to the sea, when again, unless she be a life boat of a superior description, she is almost certain to be upset. In the circumstances thus described, the sole cause of a boat's running herself under water or broaching-to is that of running from a sea instead of awaiting it, and suffering it to pass by; and the cause of the rudder being useless to keep the boat end on to the wave, is not that it is thrown out of the water, (although at other times it doubtless is so), for it is actually buried in it as is also the stern of the boat up to her gunwale, but it is because it is stationary in it the crest of the wave having acquired an actually progressive motion equal to that of the boat.


If on the


other hand the wave passes the boat, as its crest advances from the stern to the fore part, the rudder and stern are thrown out of the water; steering oars are therefore a most valuable auxiliary aid when running before a sea, but we would recommend the use of a rudder as well.”


Reference to broaching-to exists also in later issues of the same journal. The following piece, from the January 1856 issue, is particularly noteworthy, referring to the frequent occurrence of broaching-to near to the English coast town Deal to the North-East of Dover [25]:


“…nevertheless, we are positively informed that boats have been lost by broaching-to when running for the shore at Deal; and we have known a Suffolk yawl of 18 or 20 tons burden, broach-to, upset, and drown the greater part of her crew, when running under sail for the shore on as steep a beach as that at Deal.”


J.R. Ward, Commander of the Royal Navy, writes to the Times and advises on the occasion of a capsized life-boat [27]:


“It is a well known thing to the seamen on the most exposed parts of our coasts that the chief danger to a boat does not occur when going off against a heavy sea, but on returning before it, at which time the greatest skill and carefulness are necessary, even under oars, to prevent a boat from broaching to and turning broadside on to the sea. Their experience has taught them that, when seeing a heavy breaker


following their boat up from astern,


instead of yielding to the natural impulse of giving her all possible speed away from it, and so, as might be expected to lessen the violence of the shock, their only safety lies in checking the boat's way through the water, and keeping her end on to the sea until it has passed them to effect which they back their oars, or even face a portion of the crew round the reverse way, who row backwards with all their force against the heaviest of the seas as they approach. If this precaution be neglected it is


A-168


©2010: The Royal Institution of Naval Architects


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