what are H Drives

[traceyandsteve]

can anyone tell me please what H drives are? also can a shaft drive boat have 2 props on each shaft?

thanks
Steve

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[Kevin]

Hi

when you say two props on one shaft are you meaning counter rotating as in duo props? If so there are designs for these, but due to the cost of producing them for each boat being so high and not cost effective (each boat needing its own specific shaft diameter, length etc etc unlike outdrives where they are all made the same e.g Merc Bravo 3 etc and just bolt on to any boat) they are not produced (as far as i know) for recreational boats. Also with most shaft drive boats being twin engined with the props either spinning 'outwards' or 'inwards' they have the same charactoristics as duo props- although not as effecient as actual duo props, but very close to it.

You can get different performance charactoristics from twin shafts by changing the pops from inward spinning to outward spinning. inward raises the bow giving a higher top speed with a smaller wetted area but with flightier handling the outward spinning having a lower top speed (bow lower) but more stability and easier control at docking speeds.

I have just come in from a night out so if I have miss understood your post I apologise and please ignore this ramble!

all the above written based on my very modest knowledge of things boaty

Kevin

 

[bruce]

don't know what H drives are, but could be what they are called when a small motor is attached to a main drive motor such as having a 2500 hp turbin and a small motor driving reg shaft , connected with belts, for docking. saw an ocean racer, deep v, with twin 2500 turbos and gm 671 belted to one dhaft for docking. its a thought...

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