Get home power
We have a standard wing engine aboard Flat Earth which is basically a
40HP Yanmar sail boat engine with it's own dedicated shaft and a
folding Martec prop. It is adequate in calm waters. The last time I
cranked it up it even gave us 6 Kts. It is only marginal in heavy seas.
We have discussed the possibility of another source of source of 'get
home power' using the primary drive shaft. Power would come from
either the 40 HP wing engine mechanically or the generator either
electrically or from a direct power take-off on the generator engine.
The power source would drive a hydraulic motor using the main shaft.
There would be some sort of coupling device to disconnect the main
engine and engage the hydraulic motor to drive the main shaft. We
have not gone beyond this conceptual stage yet.
Phil Eslinger
Flat Earth N50
Wesmar makes a hydraulic get-home drive that slides over the main shaft aft of
the transmission. It can be powered by a PTO from a large generator or wing
engine. It has hydraulic engagement capability from a remote location. It is
belt-driven (60,000 hr rated belt) and does not require cutting the main
shaft.
Keypower makes as similar unit that is geared and does require cutting and
aligning the main shaft for installation. Both of these units are proven
reliable for continuous duty.
We installed and earlier version of the Wesmar unit and power it with an 80hp
JD auxiliary engine with a large hydraulic pump attached (no transmission)
that also provides back-up for our entire hydraulic system.
If you have a large/heavy boat with a large 40+" prop you will likely need
more than a 40 hp engine because of the hp loss that occurs during the power
transfer from the primary engine through the hydraulic motor to the prop.
Bill Bahlburg
Porosity Selene5903
-----Original Message-----
From: Philip Eslinger [mailto:pslinger@mindspring.com]
Sent: Friday, September 11, 2009 10:13
To: passagemaking-under-power@lists.samurai.com
Subject: [PUP] Get home power
We have a standard wing engine aboard Flat Earth which is basically a
40HP Yanmar sail boat engine with it's own dedicated shaft and a
folding Martec prop. It is adequate in calm waters. The last time I
cranked it up it even gave us 6 Kts. It is only marginal in heavy seas.
We have discussed the possibility of another source of source of 'get
home power' using the primary drive shaft. Power would come from
either the 40 HP wing engine mechanically or the generator either
electrically or from a direct power take-off on the generator engine.
The power source would drive a hydraulic motor using the main shaft.
There would be some sort of coupling device to disconnect the main
engine and engage the hydraulic motor to drive the main shaft. We
have not gone beyond this conceptual stage yet.
Phil Eslinger
Flat Earth N50
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We have a 60,000 lb DeFever, 50', with a 42", 5-blade prop. There is a
sprocket on the shaft. We have an 18 hp 8kw Westerbeke genset with a
hydraulic pump attached via belt-driven clutch. The pump drives a hydraulic
motor with sprocket. This drives the boat at 3.5+ kts on a calm sea.
Dean Crothers,
M/V Emily B
Currently in San Carlos, Sonora, Mexico
<If you have a large/heavy boat with a large 40+" prop you will likely need
<more than a 40 hp engine because of the hp loss that occurs during the
<power
<transfer from the primary engine through the hydraulic motor to the prop.
<
<Bill Bahlburg
<Porosity Selene5903
By way of comparison.....our Selene weighs in at 127,000 lbs. half full of
fuel and we have a 5-blade, 42" prop with a 29" pitch. Our 80 hp JD w/pump is
connected to a 40 hp hydraulic drive motor that moves the boat at just over
6.0 knots in calm seas. Since we have proportional control over the hydraulic
flow we have used this auxiliary drive to troll as our main engine idle speed
exceeds 3 knots. I suppose the get-home speed depends on individual
preference, but getting to safe harbor is obviously the most important
function and many drive configurations will work.
Bill Bahlburg
Porosity S5903
-----Original Message-----
From: Dean Crothers [mailto:dcrothers@igc.org]
Sent: Friday, September 11, 2009 20:54
To: passagemaking-under-power@lists.samurai.com
Subject: Re: [PUP] Get home power
We have a 60,000 lb DeFever, 50', with a 42", 5-blade prop. There is a
sprocket on the shaft. We have an 18 hp 8kw Westerbeke genset with a hydraulic
pump attached via belt-driven clutch. The pump drives a hydraulic motor with
sprocket. This drives the boat at 3.5+ kts on a calm sea.
Dean Crothers,
M/V Emily B
Currently in San Carlos, Sonora, Mexico
<If you have a large/heavy boat with a large 40+" prop you will likely need
<more than a 40 hp engine because of the hp loss that occurs during the <power
<transfer from the primary engine through the hydraulic motor to the prop.
<
<Bill Bahlburg
<Porosity Selene5903