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Post by Andyberg on Mar 3, 2021 12:03:55 GMT
the very long hydraulic hoses (or preferably rigid pipes) from the engine at the bow to the stern will result in significant loss of energy through pipe friction (just like very long leccy cables). Obviously the larger the pipe diameter the better. May not be an issue if the engine is adequately sized and you are not anal about wasted energy. Its got a 28hp Beta in there, the problem with losses is something that I have thought about.... Ill see how it is once underway I suppose.π
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Post by JohnV on Mar 3, 2021 15:19:53 GMT
the very long hydraulic hoses (or preferably rigid pipes) from the engine at the bow to the stern will result in significant loss of energy through pipe friction (just like very long leccy cables). Obviously the larger the pipe diameter the better. May not be an issue if the engine is adequately sized and you are not anal about wasted energy. Its got a 28hp Beta in there, the problem with losses is something that I have thought about.... Ill see how it is once underway I suppose.π You may have losses in the pipework but you also have (what I suspect are higher losses) them in a conventional engine gearbox situation.
With hydraulic you can run the engine at it's most efficient speed all the time.
The hydraulic motor, much like an electric drive has the same horsepower at the prop as is applied by the engine at any speed .... not the same as a conventional gearbox where efficiencies vary greatly depending on revs as well as the mechanical losses in the gears themselves
I await Gazza's comments
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Post by Deleted on Mar 3, 2021 15:39:05 GMT
Its got a 28hp Beta in there, the problem with losses is something that I have thought about.... Ill see how it is once underway I suppose.π You may have losses in the pipework but you also have (what I suspect are higher losses) them in a conventional engine gearbox situation. With hydraulic you can run the engine at it's most efficient speed all the time. The hydraulic motor, much like an electric drive has the same horsepower at the prop as is applied by the engine at any speed .... not the same as a conventional gearbox where efficiencies vary greatly depending on revs as well as the mechanical losses in the gears themselves
I await Gazza's comments
Parasitic loads are inevitable, the hydraulic system will win as long as itβs been well designed. The mechanical system has simplicity on its side but as you point out looses out in flexibility, particularly so when you consider boat gearboxes have one forward ratio and one reverse ratio, unlike automotive applications we donβt take advantage of torque multiplication by having several gears to choose from. Although this is getting a bit out of hand now many high end diesels cars and pickups have 10 - yes 10 gears to razz through the box! bodger has a theoretical point, but in practice it is overcome by oil cooling and letβs face it, the stresses and loads that farty little hydraulic motor will be under is nothing compared to the beasting a mini digger will get in the hands of an unhinged ground worker. An application that will use a an engine ranging from about 20 - 30hp.
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Post by Deleted on Mar 3, 2021 15:41:37 GMT
the very long hydraulic hoses (or preferably rigid pipes) from the engine at the bow to the stern will result in significant loss of energy through pipe friction (just like very long leccy cables). Obviously the larger the pipe diameter the better. May not be an issue if the engine is adequately sized and you are not anal about wasted energy. Its got a 28hp Beta in there, the problem with losses is something that I have thought about.... Ill see how it is once underway I suppose.π I wouldnβt worry too much, huge fleets of broads cruisers managed well enough for donkeys years with 35 bhp 1500 BMC diesels.
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Post by Isambard Kingdom Brunel on Mar 3, 2021 16:39:54 GMT
the very long hydraulic hoses (or preferably rigid pipes) from the engine at the bow to the stern will result in significant loss of energy through pipe friction (just like very long leccy cables). Obviously the larger the pipe diameter the better. May not be an issue if the engine is adequately sized and you are not anal about wasted energy. I have seen a tidier butty installation than the one shown where the hoses entered the top of the "elum" and run inside down to the motor. Followed one a few years ago on the S Oxford I think, but it went very slowly, annoyingly so. Can't remember the name. I also know of a Dennis Cooper 70ft boat with a remote engine part way down the boat and at one side, hydraulic motor conventionally on the shaft, worked well but not a butty.
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Post by Deleted on Mar 3, 2021 17:32:48 GMT
I see Andyberg misidentified me but this has since been corrected.
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Post by Deleted on Mar 3, 2021 17:35:15 GMT
the very long hydraulic hoses (or preferably rigid pipes) from the engine at the bow to the stern will result in significant loss of energy through pipe friction (just like very long leccy cables).Β Obviously the larger the pipe diameter the better.Β May not be an issue if the engine is adequately sized and you are not anal about wasted energy. I have seen a tidier butty installation than the one shown where the hoses entered the top of the "elum" and run inside down to the motor.Β Followed one a few years ago on the S Oxford I think, but it went very slowly, annoyingly so. Can't remember the name. I also know of a Dennis Cooper 70ft boat with a remote engine part way down the boat and at one side, hydraulic motor conventionally on the shaft, worked well but not a butty. Capella GU star class butty has a nice tidy hydraulic drive in the elum. BMC 1.8 diesel but I don't think it's up the front of the boat in that particular boat. I do agree that the one in the OP is slightly untidy and could easily have been done better.
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