what do you think of this?
- Thread starter Brian M H23
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I wonder if the chain drive
is really necessary? A pure hydraulic drive, direct coupled to the prop drive shaft (i.e., the prop shaft IS the hydraulic motor's output shaft) all contained in a pod would be less lossy through friction, oil drag, etc. You would surely lose more HP through the chain drive than going direct. How 'bout high speed electric with the engine driveing a genny? Like the diesel hybrids?
is really necessary? A pure hydraulic drive, direct coupled to the prop drive shaft (i.e., the prop shaft IS the hydraulic motor's output shaft) all contained in a pod would be less lossy through friction, oil drag, etc. You would surely lose more HP through the chain drive than going direct. How 'bout high speed electric with the engine driveing a genny? Like the diesel hybrids?
Note the date of the patent
Its been about 10 years since the patent was granted, and we still haven't seen anything like it on the water. My guess is that whatever prototype was developed was less than successful. Not surprising. I don't see how driving the outboard unit's propeller shaft with a belt or chain is inherently more efficient than with a solid shaft and bevel gears. Chris' question about the "hybrid" engines is well-taken. This arrangement has been used for over fifty years on locomotives and in other non-marine environments; it is more reliable and easier to maintain than a direct transmission for very large diesel engines. However, other than submarines and I think cruise ships, it hasn't been popular in the marine world. I suspect the big reasons are the weight, expense and space considerations: you need two engines (internal combustion and electric), plus a generator of sufficient size. Also, I would think that many designers would be reluctant to put that much high voltage electrics near the water. However, recent advances in electronics and the price of fuel might give the market a kick to see if they can overcome at least some of the issues.
Its been about 10 years since the patent was granted, and we still haven't seen anything like it on the water. My guess is that whatever prototype was developed was less than successful. Not surprising. I don't see how driving the outboard unit's propeller shaft with a belt or chain is inherently more efficient than with a solid shaft and bevel gears. Chris' question about the "hybrid" engines is well-taken. This arrangement has been used for over fifty years on locomotives and in other non-marine environments; it is more reliable and easier to maintain than a direct transmission for very large diesel engines. However, other than submarines and I think cruise ships, it hasn't been popular in the marine world. I suspect the big reasons are the weight, expense and space considerations: you need two engines (internal combustion and electric), plus a generator of sufficient size. Also, I would think that many designers would be reluctant to put that much high voltage electrics near the water. However, recent advances in electronics and the price of fuel might give the market a kick to see if they can overcome at least some of the issues.
Chain Drive????
OK while I'll admit that chain is a viable way to transmit power from one place to another you have to understand that chains stretch and need periodic adjustment. Shafts and bevel gears, which are apparently really really bad, do not require adjustment. Do you really want to "shim" your engine??? You clearly can't change the location of the prop shaft as there are sealing issues. So I guess you have to shim up the motor mounts to adjust the chain tension. DUMB!
OK while I'll admit that chain is a viable way to transmit power from one place to another you have to understand that chains stretch and need periodic adjustment. Shafts and bevel gears, which are apparently really really bad, do not require adjustment. Do you really want to "shim" your engine??? You clearly can't change the location of the prop shaft as there are sealing issues. So I guess you have to shim up the motor mounts to adjust the chain tension. DUMB!
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