- Joined
- Feb 8, 2005
- Messages
- 266
Here in the UK, we have an offshore racing association (actually two now). Races are mostly endurance - approximately 1/2 hour heats - hence a lot of fuel is needed. Because of the fuel needs (eg 2 litres plus for a .45 engine), the boats tend to be very big for the engine sizes - compared to oval racing boats for example. Many are running a straight drive .45 in a Challenger 48 for example. From what I can see, we have a conflict between the prop which the boat needs to run efficiently, and the prop which the engine can drive without going too far out of its powerband. We seem to get reasonable results with similar prop sizes to the circuit boats (eg X447/3, sometimes X450/? for the .45s), but speeds are much less - presumably, largely due to prop slip. Wait times for the prop to bite can also be very long. I know that this kind of setup will never acheive the same top speeds etc as circuit boats, but I think the available props are the biggest limiting factor at the moment. In an ideal world, the answer would probably be a lower Pitch to Diameter ratio, but 1.4:1 is the lowest commonly available. Gearboxes are one answer, but add complexity, cost etc. Wondering if anyone has any useful info on props I may not have heard of, custom modded props, or what kind of prop mods may work. In terms of prop mods, I guess the way forward would be to take a bigger prop, and mod it to load the engine less.
Thanks in advance for any info:
Ian
Thanks in advance for any info:
Ian