Transertttcal Flow Past Slender Shtps 
1. Were the model results, used as a comparison in this 
paper, obtained with self-propelled or towed models ? 
2. As the effect of self-propulsion on trim seems to be quite 
marked in our experience, is it possible to take account of this theo- 
retically ? 
REPLY TO DISCUSSION 
George K. Lea 
Nattonal Setenee Foundatton 
Washtngton D.C., U.S.A. 
We did not run any model tests ourselves and all comparisons 
were made with the data of Professor Weinblum and others given in the 
list of references. Test were towed tests. 
Self-propelled models may be under additional moments due 
to the onboard thruster which could cause an initial trim even at zero 
Froude number. The result is that the water plane area could be dif- 
ferent and this can be accounted for by changing the area distribution, 
S(x), in our computations. I would expect the differences between tow- 
ed and self-propelled models to be the least for trim when you are 
dealing with full-forms like tankers. 
