Sohmitke and Jones 



in large hydrofoil ship design. 



It is difficult to relate seakeeping data directly to habitability 

 or to compare the capability of different systems, other than subjec- 

 tively. The behaviour of the BRAS D'OR canard system was well up 

 to expectation in seaways encountered, both for straight runs and 

 turns. There was a complete absence of slamming and motions were 

 modest, particularly in pitch and heave. Motions were almost certain- 

 ly greater for BRAS D'OR than for a comparable fully- submerged 

 system but less than for other types of craft with surface -piercing 

 foils. There were no particular problems for the crew when seated. 

 Personnel moving about and standing, tired quickly, mainly because 

 of the roll motions, but this situation would not arise in an operation- 

 al ship. 



For BRAS D'OR, a deciding factor in the choice of foil sys- 

 tem was the exceptional hullborne seakeeping offered by the canard 

 surface-piercing arrangement. For the tasks envisaged, the habita- 

 bility is more important under hullborne cruise conditions than for 

 short periods of foilborne operation. Experience with BRAS D'OR 

 supports the contention that foilborne motions are acceptable for con- 

 tinuous periods of several hours and has confirmed the promise of 

 exceptionally good hullborne seakeeping ' ' 



V. CONCLUSION 



The Canadian hydrofoil program has significantly advanced 

 both the performance and the fundamental understanding of surface- 

 piercing hydrofoil systems designed for open ocean operation ; the 

 development of a successful super -ventilated bow foil unit is especial- 

 ly noteworthy. As regards simulation, the extension of aerodynamic 

 methods into the hydrofoil field has proved reasonably successful, 

 yielding satisfactory predictions of both steady state and dynamic per- 

 formance ; of particular importance is the good characterization of 

 BRAS D'OR pitch and heave response derived from a linear mathe- 

 matical model. 



308 



