TomBettle Posted January 17, 2011 Report Share Posted January 17, 2011 I have been asked to take part in some pre product launch tests of what appears to be a very innovative new drive system. Initially designed as a simple(ish) bolt on to be retro fitted to shaft drive boats if the product does what the manufacturer claims then it may absolutely revolutionise shaft drive systems at the point of OEM boat manufaturer. The manufacturers claim to be able to offer between 20% and 40% better fuel efficiency and running efficiency (speed for rpm?) with there gizmo and the idea seems fabulous. In addition handling should also be dramatically improved. 1) a little widget fits between the gearbox and the stern gland 2) a new shaft facility thingy runs through the old stern gland and cutlass bearing 3) twin contra rotating props fit on the end of the shaft facility thingy It's the twin props that make all the difference as anyone who has moved from single to duo props on an outdrive will tell you. My first concerns will be the longivity of the system - will it be as robust as a simple shaft and propeller? My second is how messy could it get if a rope is picked up? It's hard enough to sort out with one prop, will two make it worse or will some form of rope cutter come in to play? My third relates to fishing line getting between the props... those with outdrives know what a pig that can be and that it can be expensive! Will it be similar on this system? So, my question to the esteemed members of this forum is that if the system is as easy as the manufactures reckon to fit and if it provides even the low end of the savings they suggest, without the headaches I am hoping it won't have, do you think it is a product you might consider? If so, what do you think it is worth on the sort of shaft drive boats we own? As a closing thought, the manufacturers do have real test data from a couple of other vessels including a fast twin engine boat. Tom Quote Link to comment Share on other sites More sharing options...
niggle Posted January 17, 2011 Report Share Posted January 17, 2011 Sounds very interesting Tom,please keep us updated. Quote Link to comment Share on other sites More sharing options...
TomBettle Posted January 17, 2011 Author Report Share Posted January 17, 2011 Sounds very interesting Tom,please keep us updated. Will do Nige. I don't profess to fully understanding it yet as I have only seen the pictures, but my boat is not the most efficient (the best yes, but not efficient!) and burns iro 25l/hr at 16 knots. If I can bump the speed up to 20 knots (maybe optimistic due to hull shape) for 20 litres per hour with almost zero shaft maintenance then I will be a very happy chap. Watch this space. It's not 100% defo as I have to provide various measurements to the manufacturers, but the principal does sound very interesting indeed. Quote Link to comment Share on other sites More sharing options...
Maverick Martin Posted January 17, 2011 Report Share Posted January 17, 2011 But Tom will they not require beta testers that use their boats rather than just keeping them as ornaments Sorry couldn't resist Martin Quote Link to comment Share on other sites More sharing options...
niggle Posted January 17, 2011 Report Share Posted January 17, 2011 Quote Link to comment Share on other sites More sharing options...
Jim Posted January 17, 2011 Report Share Posted January 17, 2011 But Tom will they not require beta testers that use their boats rather than just keeping them as ornaments Sorry couldn't resist Martin I'm keeping my mouth firmly shut. Jim Quote Link to comment Share on other sites More sharing options...
duncan Posted January 17, 2011 Report Share Posted January 17, 2011 Tom, Whilst the additional efficiency of duo props will certainly deliver some advantage to a shaft configured boat you, of all people, should appreciate that hull and drive system need to be match to translate this to speed. Further you aren't going to see the full engine power to drive relationship that is enjoyed by DP OD systems because this includes the gain from maintaining a constant thrust angle through various hull trims - without involving the drag associated with trim tabs. Finally OD's generally have less stern gear drag than skeg, p-bracket - rudder arrangements. So, I would expect to see a significant fuel consumption advantage over your existing single prop - but not to the extent of a DP or other, more advanced, drive systems. Without seeing the schematics and understanding any oil seals and pressures involved it's hard to comment on the potential impact of fishing line etc. Obviously it's easier to check such things from time to time with an OD system. DPs will chop smaller/weaker line where it would otherwise wind and constrict on a single prop system (shaft or drive), but it doesn't work wonders and a shaft + cutter is the better solution all round. I'm sure it will be an interesting development. Quote Link to comment Share on other sites More sharing options...
Maverick Martin Posted January 17, 2011 Report Share Posted January 17, 2011 But Tom will they not require beta testers that use their boats rather than just keeping them as ornaments Sorry couldn't resist Martin I'm keeping my mouth firmly shut. Jim and along comes the keeper of the ornaments Quote Link to comment Share on other sites More sharing options...
Jim Posted January 17, 2011 Report Share Posted January 17, 2011 Thank you Gramps ! Jim Quote Link to comment Share on other sites More sharing options...
Maverick Martin Posted January 17, 2011 Report Share Posted January 17, 2011 Thank you Gramps ! Jim Quote Link to comment Share on other sites More sharing options...
great white Posted January 18, 2011 Report Share Posted January 18, 2011 Very interesting and the first I have heard of this. Great White never had a problem with fuel economy, but a 20% boost in speed would have been nice. Although I doubt that this system wuld have worked on her [even without drawings] as she had a deep sea seal and only about 4" of shaft before the RCD coupling to the gearbox flange. I imagine that some other type orf conversion box with a flange input and duo shaft output would need a bit more room than 4", I am sure other craft do not have a lot of room around the shafts on single engine boats Charlie Quote Link to comment Share on other sites More sharing options...
TomBettle Posted January 19, 2011 Author Report Share Posted January 19, 2011 But Tom will they not require beta testers that use their boats rather than just keeping them as ornaments Sorry couldn't resist Martin It's a tough one Martin, but if you are four times as good you only need to run your boat a quarter the amount of time! Quote Link to comment Share on other sites More sharing options...
Maverick Martin Posted January 19, 2011 Report Share Posted January 19, 2011 But Tom will they not require beta testers that use their boats rather than just keeping them as ornaments Sorry couldn't resist Martin It's a tough one Martin, but if you are four times as good you only need to run your boat a quarter the amount of time! OK I'll believe you but thousand of others wouldn't Quote Link to comment Share on other sites More sharing options...
Rob Posted January 19, 2011 Report Share Posted January 19, 2011 Can anyone else smell something? Quote Link to comment Share on other sites More sharing options...
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