Weinblum as Scientist and Engineer

The following passages are taken from a treatise [1] written by Horst Nowacki.

Georg Weinblum in his lifetime worked on almost every subject of ship hydrodynamics and ship dynamics that offered new theoretical insights. A review of his personal contributions to any of these subjects reads almost like a history of ship science throughout this period.

This overview does not claim to be a complete summary.

Ship form definition

Weinblum from the beginning of his work was interested in the systematic improvement of hull shapes from a hydrodynamic point of view. This is why he initially favored closed-form analytical hull form representations amenable to flexible systematic variation as in systematic series of hull forms rather than individual case studies. He gave full credit to David Taylor and his Systematic Series and other precursors in polynomial lines representation and proceeded to his own polynomial ship lines systematization. This enabled him to arrive at general trend conclusions and optimization for certain targets (STG 47/1953). He postulated more flexible surface-based hull shape definitions.

Today computational methods have enabled us to progress to polynomial and non-polynomial, piecewise continuous, multisegment surface representations, mainly of spline type, taking into account a great variety of local and global form parameters in naval architecture terminology. Thus, from his starting point, little more than half a century had elapsed before his dream objectives were reached for in practice any desired hull shape.

Wave resistance theory

In the late 1920s, Weinblum and Wigley undertook fundamental studies into ship wave resistance based on linearized theories as initiated by Michell and Havelock. Weinblum progressed to applications to slender and moderately full ship hull forms (STG 35/1934) on the basis of polynomial representations compared with experiments with single-hull and double models. Thereby he determined ranges of validity for the linear, non-viscous theory. The errors in the theory were due to non-linearities and viscous effects in a real medium. These errors became a priority topic in the continuing research after WWII until today, often promoted and encouraged by Weinblum.

Planing boat theory

Weinblum did not specialize in the theory of planing surfaces, but showed himself fully understanding of Wagner's pioneering paper on the planing of water vehicles (STG 34/1933), dealing with the rapid planing of planar and curved surfaces of infinite and finite width as well as keeled planing hulls.

Confined water resistance

In the second half of the 1930s, Weinblum concerned himself with the wave resistance of ships operating on shallow and/or laterally confined waterways (STG 39/1938), a topic whose beginnings date from Britain and France around 1840. Referring to John Scott Russell's early basic experiments with horse drawn canal barges in Scotland, Weinblum quipped:

For if a century ago a pulling horse could discover matters which had escaped the attention of the French Academy, the present scientific state of the art is much more satisfying.


The new insights and results became an important foundation for progress in ship design for ships on confined waters.

Hydrofoil boats

From 1938 to 1943, Weinblum served as the research director of the Schertel-Sachsenberg hydrofoil boat development team. This was a difficult period for this young team, but it was actually the formative time for the hydrofoil boat based on the Schertel-Sachsenberg patents. The developments, i.e., the design, model testing and full scale trials took place in four locations: The Central Development Office in Rosslau, which was under Weinblum's direction, the Project Office in Berlin-Wannsee under Siegfried Schuster's leadership, where the design, construction and testing of the first trial boat of 2.8 t took place, accelerated by high priority orders of the German navy for two larger boats of 90 and 120 t, the Test Office at the TH Berlin, also under Siegfried Schuster who designed the required test equipment for the hydrofoil system, essentially a 6-component balance, and the Detail Design Office in Hamburg-Harburg. These teams were supported by a Trial Group in Travemünde, who from 1940 performed full scale trials on the Baltic Sea. Finally the inventor Schertel had his own small group in Wiesbaden to develop concepts and to conduct trials on the Rhine river. Not surprisingly the coordination of these numerous activities required much effort and resulted in major disputes and rivalries. Hinsch and Sachsenberg jr. in their competent book on the history of the Schertel-Sachsenberg boat family comment on this:

It was owed only to the authority and leadership skill of Prof. Weinblum to reconcile the often widely diverging opinions of the four offices, especially with regard to the Berlin Project Office.


Weinblum left the project in 1943 to take on a professorship in ship theory in Gdańsk. Despite all, these teams had developed and tested a mature concept leading to successful boat construction and commercially viable hydrofoil boat operations in Germany, Switzerland and elsewhere worldwide after WWII.

Ships at sea

Weinblum had emphasized the importance of the seakeeping performance of ships in an overall ship quality assessment, but scientific tools for predicting ship seaway performance at the design stage in a realistic seaway were still missing. The breakthrough to a rational treatment of this issue came about by the adoption of probabilistic methods for ship motion prediction and by the integration of methodologies from oceanography and ship dynamics. Weinblum was involved in both of these steps.

In his paper with St. Denis "On the Motions of Ships at Sea" (SNAME 58/1950) the authors applied a probabilistic approach to define the statistical outcome of ship motions for the various degrees of freedom, also combined, in regular waves of a given frequency and wave length and thereby for the linear case for a full spectrum of wave directions. In the subsequent paper by St. Denis and Pierson (SNAME 61/1953) "On the Motions of Ships in Confused Seas" a naval architect and an oceanographer united the probabilistic methodologies for representing the irregular seaway and the response of the ship in motions and loads. Given the measurement of seaway characteristics in terms of frequencies and amplitudes it was now possible to predict spectra of ship performance in a seaway at the design stage, although linearizations still produced errors, which were later dealt with separately.

It is interesting to note how these probabilistic methodologies migrated and arrived in the ships at sea applications. Telephone connections, especially early long distance phone calls, were plagued by random noise in the whole voice frequency range. Telephone companies worked on methods of communication theory to filter out undesired noise. Norbert Wiener, working for Bell Labs, had by 1930 developed the Generalized Harmonic Analysis for describing a random process by its spectra. Wiener's further work by 1949 contributed the important method of stationary time series for dealing with such spectra. The oceanographer W. J. Pierson around 1950 adopted Wiener's methodology and treated the irregular seaway as a stationary random process. He thus was able to model the seaway by its spectra as a linearized model, thus except for non-linearities and certain extreme conditions.

St. Denis and Pierson then proceeded in 1953 to construct the answer of the ship to the seaway spectrum by a linear model of ship motions and seaway loads. This also met Weinblum's goals of design level evaluations of seaway effects, keeping in mind the errors by non-linear effects and simplifications in the answer of the ship. Meanwhile today these methods have been further refined and extended so that design estimates and trade-offs have become more and more accurate.

This is the story of how noisy phone calls have benefitted the design of ships in irregular seas.


[1] Memories of and Inspirations by Georg Weinblum written by Horst Nowacki