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Old 12-08-2012, 05:33 PM   #1
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come home motor use

anybody out there ever use their comehome motor? Some passagemakers and downeaster's had the factory option for a comehome motor.
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Old 12-08-2012, 07:06 PM   #2
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Your gen set powers a hydraulic pump that can power a get.home by couimg the motor and shaft with a chain. We have tried it a coue of times, repla e the chain and hydraic hoses. The gen set hydraulic also powers the bow thuster. We have not had to use, but I make sure it will work if needed.
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Old 12-08-2012, 10:15 PM   #3
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Your gen set powers a hydraulic pump that can power a get.home by couimg the motor and shaft with a chain. We have tried it a coue of times, repla e the chain and hydraic hoses. The gen set hydraulic also powers the bow thuster. We have not had to use, but I make sure it will work if needed.
I like the concept. DeFever used a 10hp AC electric motor driving the propeller shaft through paired v belts and a jack shaft. Supposed to give a Downeast 40 5knts on a flt sea. turns the trawler into kinda like a railroad engine. I found one of these for sale and may go see if i cant try it out. 5k on 10hp?? it that works will be more fuel eficient than runnin the main engine I'm sure
The details above are off the survey report
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Old 12-09-2012, 10:22 AM   #4
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It seems to me that 10 HP is going to take a pretty serious noisemaker to start it. In a perfect world with no losses that's roughly a 7.5 KW genset but it seems to me that starting loads would be way higher and obviously there would be efficiency losses along the way. I'd be curious to see if anyone has such a system running and if so what it really requires to operate. I'm not concerned about a get home system on Gray Hawk - as Marin points out ad nauseum, that's what the 2nd Lehman is for. What I would like to do is come up with a trolling solution - imagine that - a trolling system for a trawler - but I digress. We can't get under 4 kts even with one engine shut down. I'm not prepared to spend much on a rig but if I could run an electric motor to drive one shaft I might consider it.
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Old 12-09-2012, 10:50 AM   #5
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bobofthemnorth,
You're probably over propped.
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Old 12-09-2012, 11:32 AM   #6
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I don't think so. Full RPM runs are 2200 - 2300 RPM. The governor might be a little higher than that but that's close enough for the girls I go with.
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Old 12-09-2012, 08:03 PM   #7
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It seems to me that 10 HP is going to take a pretty serious noisemaker to start it. In a perfect world with no losses that's roughly a 7.5 KW genset but it seems to me that starting loads would be way higher and obviously there would be efficiency losses along the way. I'd be curious to see if anyone has such a system running and if so what it really requires to operate. I'm not concerned about a get home system on Gray Hawk - as Marin points out ad nauseum, that's what the 2nd Lehman is for. What I would like to do is come up with a trolling solution - imagine that - a trolling system for a trawler - but I digress. We can't get under 4 kts even with one engine shut down. I'm not prepared to spend much on a rig but if I could run an electric motor to drive one shaft I might consider it.
the main problem besides keeping the engine sipping dry air and the prop in the water in a chop is getting the prop either below the bottom of the boat or out far enough away from the transom so that the prop can get a good hold of the water to provide thrust. outboards boats gain a great deal of eficiency just by moving the engine a few inches away from the transom. If they didnt the offshore braket would not be so popular
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Old 12-10-2012, 05:42 AM   #8
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Hummm,

"Outboards boats gain a great deal of efficiency just by moving the engine a few inches away from the transom. If they didn't the offshore bracket would not be so popular"

Could be, could be, yet I rather believe that the addition of a offshore bracket as you describe, is really a method of placing the outboard on a normally high stern to allow the engine to be at the proper position in relation to the engineered depth between the mounting and the bracket. This allows the stern of the boat to remain in a high profile. If you didn't use an extension, the stern has to be cut down to affect the mounting of the engine. Thus you open the boat to being "Pooped" in certain sea conditions or overloading allowing sea water to enter the boat. Yes, normally there is a firewall between the engine mount and the interior of the boat, however there are accesses for the use of controls and or fuel lines which are subject to that sea water should it be active enough.
Not intending to take a point away, only to clarify the main reason of using an extension. To, the application is most prevalent on boats where the inboard/outboard unit has been replaced along with the elimination and removal of the inboard/outboard power plant.
Others add fuel or ballast space in the extensions, others use the extension as floatation. Lots of different applications.

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Old 12-10-2012, 11:05 AM   #9
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Old 12-11-2012, 04:35 PM   #10
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[QUOTE=Al;118571]Hummm,

"Outboards boats gain a great deal of efficiency just by moving the engine a few inches away from the transom. If they didn't the offshore bracket would not be so popular"

Could be, could be, yet I rather believe that the addition of a offshore bracket as you describe, is really a method of placing the outboard on a normally high stern to allow the engine to be at the proper position in relation to the engineered depth between the mounting and the bracket. This allows the stern of the boat to remain in a high profile. If you didn't use an extension, the stern has to be cut down to affect the mounting of the engine. Thus you open the boat to being "Pooped" in certain sea conditions or overloading allowing sea water to enter the boat. Yes, normally there is a firewall between the engine mount and the interior of the boat, however there are accesses for the use of controls and or fuel lines which are subject to that sea water should it be active enough.
Not intending to take a point away, only to clarify the main reason of using an extension. To, the application is most prevalent on boats where the inboard/outboard unit has been replaced along with the elimination and removal of the inboard/outboard power plant.
Others add fuel or ballast space in the extensions, others use the extension as floatation. Lots of different applications.

Actually it is a bit of both And to confuse things more....High performance boats use the bracket to get the motor high enough to effect a surface pierceing prop, where 1/2 the prop is out of the water while on plane
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