Hi,
Sorry if the details are a little thin, but this is all design as I go. I realise that makes it difficult to make suggestions, however I'm after your 'best guess' and I'm happy to work it out from there. I have included photos below.
'We need to know the pack capacity and voltage in order to make a motor recommendation', you're correct in saying that LiPos are able to produce more burst current, however a Li Ion is able to match any current requirements by putting more cells in parallel and spreading the load. Yes the physical size of the battery may be larger, however I am not short on space. Also, these are not '
Electric tool batteries', they are high capacity LG cells with a BMS. The reason for these over LiPo are to get long run times. By putting the cells in parallel the issue of internal resistance (which is limiting burst current) is overcome, and obviously I can put them in Series to meet any voltage requirements.
'
Jet impeller rpm is vital to performance, too slow or too fast will not work', you are on the money and I completely understand how RPM can lead to under performance if not matched to the motor. To higher RPM will cause cavitation and lead to impeller damage and inefficiency, too little and the boat will be severely sluggish. What I have noticed though is that impeller diameter can give you a fair indication of required RPM and I am after a general figure so that I can match a Motor and Battery setup.
The diameter is 75mm and it is a four blade Impeller.
I can adjust the battery voltage to suit, but I need a general figure to build around. I will then find the sweet spot through testing (mentioned above) and I could then redesign the pack to suit the application so that I'm not working at the capacity of the motor or battery.
At the end of the day any advise from those running Jet drives of all sizes is going to help.
Based on RPM Vs impeller diameter, I can make a general hypothesis and then work around it. This is probably the most important piece of the puzzle.
If anyone out there has a Jet Drive, any advise is appreciated.
Interior of hull, pre-fibreglass.
Hull design, skirt will be held in recess.
Jet drive with ruler to give scale.