After a fair few weeks wading through some patents, I have whittled them down to the relevant few. These are the backbone of my timeline, which will be filled in along with other documentation and whatnot. I’ve only gone up to 1959, as after that it gets a bit more convoluted and would make this entry twice as long!
The initials in brackets after the name indicates the applicant’s nationality, while the brackets after each entry have the patent number. The letters there are the country in which the patent was made. The dates are those in which the patent applications were made, not in which they were granted (anything up to 5 years after the application).
Adam GB189420323 Patent
Oct 1894 – William Adam (GB) patents a 3 boat pelagic trawl. It’s all a bit odd, but he is thinking outside the box and trying to make a functioning mid-water trawl. [GB189420323]
Nov 1898 – The first patented vertical trawl door by David Sherrit (GB). It is, however, entirely a demersal affair. But like William Adam, the idea and willingness to experiment a bit are there. [GB189824035]
Nov 1922 – Cornelis Pieter Dros (NL) patents what looks lake a trawl that can vary its depth. It is, however, not a pelagic trawl in the true sense, as the impetus for this design lies in engine and fuel efficiency, not in optimising the catch or range of the ship. [GB202887]
1925 to 1935ish – V D Ltd, a company comprising of two Frenchmen, Oscar Dahl and Jean-Baptiste Vigneron (and later on, William Black) make a series of patents for demersal trawls. The innovation here is the idea of not connecting the net directly to the trawl doors. After 1940, almost all pelagic trawl patents distance the trawl doors from the net with cables of some description.
Sep 1930 – Unlike Cornelis Dros, this patent by Marcel Simonin (FR) is specifically designed to be used at whatever depth is desired. The design is quite simple and has a very narrow mouth with the net being directly connected to the horizontal trawl doors. [GB356493]
Dec 1938 – Franz Suberkrub, along with Ernst Karl Ludwig Roscher and Kurt Jaeger Hansing (all DE) patent their vertical trawl door. Made of wood and metal fittings, the door is made for demersal use. [GB523452]
Dec 1948 – Robert Larsen (DK) patents his two-boat pelagic trawl in Denmk.
Nov 1949 – Robert Larsen’s (DK) first patent outside Denmark is made in Ireland – the two-boat pelagic trawl, as before. [IE019864]
Nov 1949 – Karl-Hugo Larsson (SE) was, judging by the amount of research he published and was involved in, a key and influential figure in the development of pelagic trawling. This is his patent for a one-boat pelagic trawl with vertical trawl doors. The vertical doors in this case are curved, very much in the manner of Suberkrub’s patents. [GB670222]
Larsson’s patent GB670222
Nov 1949 – Robert Larsen (DK) makes a British patent for his two-boat trawl. [GB695361]
Nov 1950 – Sterner Persson (SE) patents his trawl capable of functioning at different depths – primarily a pelagic trawl. The trawl has three trawl doors – two at each side, and one from the ground rope to keep the net open. The trawl doors in the more traditional location are vertically orientated. [GB682824]
Feb 1952 – Jon Sigurdsson (IS) patents a pelagic trawl, with a third trawl door attached to the ground rope and horizontal trawl doors. [GB699206]
Aug 1952 – Another Icelander, Agnar Gudmundsson Bredfjord, patents a pelagic trawl. This trawl has the hallmarks of a modern pelagic trawl and has vertical trawl doors. His patent states that one of his reasons for pelagic, rather than bottom fishing, is to not disturb the vegetation and small fry that may be on the seabed. [US2771702]
Breidfjord’s patent, US2771702. By far and away the prettiest, too.
Nov 1954 – Robert Larsen (DK) isn’t taking any chances; this is his Canadian patent for the two-boat trawl. [CA507700]
Dec 1955 – Karl-Hugo Larsson (SE), who made his one-boat pelagic trawl patent a year or so after Robert Larsen in Britain follows his lead and makes his patent in Canada as well. [CA519107]
May 1957 – This time a man of unknown nationality, Donald S Johnson, has his invention patented on his behalf by the Dominion Textile Company, Canada. The patent describes a one-boat pelagic trawl with what appears to horizontal, tubular trawl doors. [CA541497]
Dec 1958 – Moises Larrea Esesumaga (PT) patents a trawl for working at varying depths, from surface through to demersal The trawl has no trawl doors, instead relying on four kites at each corner to hold the net open – the shape of the mouth of the net being controlled by ‘guides’. [GB911666]
GB911666, Esesumaga’s patent
June 1959 – Franz Suberkrub makes a solo patent, for the vertical trawl door. Now designed for pelagic rather than demersal trawling, this door is now a sleeker, version of the 1938 version, no longer being made of wood. [US3079720]
So that’s the boiled down version – the real one is a lot longer and a bit more complicated. But at least you can all see the basics from which I am expanding and researching from. That and having to teach every word-processing programme I come across the word ‘demersal’. Non of the seem to recognise it!