Allow me to resurrect this post...
I have been exploring a new approach to applying a bulbous-bow to a single scull.
I have tested a range of prototypes and found an elegant solution which preliminary testing are giving positive and measurable speed improvements.
My hypothesis - PDF document found here
https://drive.google.com/file/d/1FLYJC0Cjm5Bj3bDggGROtxmT-r80GoUS/view?usp=sharing
[Summary ... a tapering bulbous-bow form accounting for the varying speeds, position in the water, ploughing and lunging surges of a rowing stroke cycle]
Image files found here - 1Vgto7Gy9jmlZ7F322DMJduP8DC6eAbzr
Unsuccessful Prototypes Designs - Bows 1, 2 and 3
My first prototype placed the design around an existing bow-ball however there is too much variation of bow-ball placement.
Results: These prototype bulbous bow forms ultered the flow of water onto the hull but deemed to be inconsequencial.
Successful Design - Randall Bow
I have now incorporated the bow-ball into the bulbous-bow design itself and attached the form to the hull. The design has a 5cm maximum diameter.
I am awaiting a determination from FISA if this approach is legal.
This form should make the bow safer and serve as a bumper against pontoons and debris.
My observations
- there is a peacock fanning of splashing water at the bow during the drive phase which deminishes on the recovery as the bulbous-bow is lifted out of the water.
- the bow-wave coming from the hull is much reduced, smoother and in some conditions almost non-existent.
Results: Testing with competitive Masters athletes is showing a measurable positive speed improvements with the Randall Bow bulbous-bow design.
Randall Bow 3D File :
https://drive.google.com/file/d/1regpIa0BnL3mHgwGiQ2DKum_IilSyKIz/view?usp=sharing
Material - Ninjatek Cheetah (or similar flexible material)
Layer height - 0.2mm
Infill - 20%
Nozzle - 0.4mm
Fitting
1. Remove Bow Ball
2. Position Top of Randall Bow in relative position.
3. Attach with Hot Glue Gun.
Happy sharing my findings ... so much fun playing around in boats!
Ian Randall
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