"get home" systems

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Trans,
I have got a hydraulic get home as you describe on Klee Wyck. As it came with the boat as OEM, I did not build it so have only a rudimentary working knowledge of it.
The pump itself is coupled to the non electrical end of a 15 kW Westerbeke genny so expect the motor is around thirty HP. Reservoir looks to be around 20 gallons with valves that are normally open to run a big thruster but can be switched to run the orbit motor that powers the get home function. The motor spins a cogged belt coupled to the main shaft.
This setup will give me about 2.5-3 knots in flat seas with moderate steerage all of which disappears rapidly as any weather becomes part of the picture. The boat weighs around 55K.
I will try to get a look at ID on the hydraulic pump and motor next time I am on her and try to remember to report back.
I have been thinking about this lately a bit as the generator is showing its age and a refit is probably in the cards. If it were only for the get home, I am not sure I would re-do the hydraulics in a generator refit, but, I do love the big thruster so the hydraulics are a must should that re-fit day come.
 
Funny you bring this up. I was just discussing something along these lines with a friend. The idea was that in place of a generator and wing engine, use an oversized generator with PTO hydraulics to drive an sux prop shaft. There are a few considerations, at least one of which has already been brought up.

Wing engines have the advantage of a separate prop and shaft, so work if you have a damaged main shaft or prop. If your aux power drives the main shaft, you lose that extra measure of redundancy. It's a tradeoff you will have to make.

A wing engine is typically a lot higher power than a generator. A wing moves a boat slowly, and if you further reduce the power it will move even slower. I'd suggest using one of the prop calculators to figure out how fast the boat will move with whatever power source you finally pick.

Consider putting a clutched PTO on a generator to get your hydraulics. You will be able to pull full power from the engine, but still have a fully functional generator.

There is a conflict in engine use between operation as a generator and use to power hydraulics. For a generator, the engine needs to run at a constant 1800 RPM assuming 60hz power. For hydraulics, you will get Mac power out of the engine at Mac RPM. If you run as a generator with PTO hydraulics, you will get less than full possible power, but will have a good generator. If you run the engine for hydraulics at full speed, you will either need to throttle back to generator electricity? Or do an AC to DC to inverter to AC setup which gets pretty Rube Goldberg. This is yet another tradeoff you will have to make.

The good news is that hydraulic aux drives are well proven. The only complaint I have really heard it that they often end up under powered and slow.
 
twistedtree said:
Funny you bring this up. I was just discussing something along these lines with a friend. The idea was that in place of a generator and wing engine, use an oversized generator with PTO hydraulics to drive an sux prop shaft. There are a few considerations, at least one of which has already been brought up.

There is a conflict in engine use between operation as a generator and use to power hydraulics. For a generator, the engine needs to run at a constant 1800 RPM assuming 60hz power. For hydraulics, you will get Mac power out of the engine at Mac RPM. If you run as a generator with PTO hydraulics, you will get less than full possible power, but will have a good generator. If you run the engine for hydraulics at full speed, you will either need to throttle back to generator electricity? Or do an AC to DC to inverter to AC setup which gets pretty Rube Goldberg. This is yet another tradeoff you will have to make.

The good news is that hydraulic aux drives are well proven. The only complaint I have really heard it that they often end up under powered and slow.
Click to expand...

I was thinking about my post to this thread last night and then again today based on Twisted's post.
If you want a little extra power on the get home hydraulics and there is this conflict with the 1800 RPM genny thing, I got to thinking about how bad do most boats really need a generator if they have a big house bank and a big inverter. It would sure make my life easier in a refit if I just thought about a good marine motor to run the hydraulics and stuck a high output heavy duty alternator on it. With a 1200 AH house bank and a 3000 watt inverter, wouldn't the alternator suffice as a source of house bank recharge. Doesn't a coupl of hours of run time on a big alternator give you a days worth of power? I am not in AC country and my heat is diesel so I do not think I have loads on my boat that the inverter cannot handle.
I would like the idea of repowering the hydraulics and skipping the electrical end of that motor. Better get home power, easier to slide in over my main, and no rpm conflict.

Comments on this please?
 
If you use the sundstrand 23 pump with the 23 motor you are going to have 1:1 speed on your prop shaft. If your turning your pump at 2000 rpms and stroke it wide open your motor is turning 2000 rpm's. I would think your sprockets are going to be overly large to get your reduction to the prop shaft.
John
 
If you use the sundstrand 23 pump with the 23 motor you are going to have 1:1 speed on your prop shaft. If your turning your pump at 2000 rpms and stroke it wide open your motor is turning 2000 rpm's. I would think your sprockets are going to be overly large to get your reduction to the prop shaft.
John
 
klee wyck said:
I was thinking about my post to this thread last night and then again today based on Twisted's post.
If you want a little extra power on the get home hydraulics and there is this conflict with the 1800 RPM genny thing, I got to thinking about how bad do most boats really need a generator if they have a big house bank and a big inverter. It would sure make my life easier in a refit if I just thought about a good marine motor to run the hydraulics and stuck a high output heavy duty alternator on it. With a 1200 AH house bank and a 3000 watt inverter, wouldn't the alternator suffice as a source of house bank recharge. Doesn't a coupl of hours of run time on a big alternator give you a days worth of power? I am not in AC country and my heat is diesel so I do not think I have loads on my boat that the inverter cannot handle.
I would like the idea of repowering the hydraulics and skipping the electrical end of that motor. Better get home power, easier to slide in over my main, and no rpm conflict.

Thanks to all the replies from some of you more experienced boaters. I know my way around all this stuff on dry land, but boats are different!! Thanks! Your second post KW is exactly what my research has come up with. The single prop/shaft is a drawback but the full keel and struts really protect the prop so I would say my risk there is not zero but reduced significantly. If you read the specs on these little diesels you see that at 1800 rpm they only produce about 2/3 of the power that they are capable of at mid 2000s and in a bind you can crank these things up to 3-3500 rpm for short periods and double the hp of the 1800 rating. Not that you should run over 3000 in all but an emergency, but it is there. Without the necessity of running at a constant 1800 rpm,(engine not tied to a a/c gen but using a 160 - 200 amp truck alt would be 2.5 kw) you can order a variable speed governor that just like a tractor, will run at whatever rpm you set it at and the dc generator continues to put out 14 volts. I think I have read that the wing engine hp on some of the bigger boats, like a Nordhaven 47, is mid 30s. That is probably continuous hp?? So on my boat at 1/2 the weight I am thinking 30 continuous hp should do a decent job of moving it. Britannia posted a nice fuel consumption chart for his KK 54 weighing 80,000 pounds, #89 in the thread "New to me 50, steel full disp" on TF. This is consistent with several other sources of fuel consumption in bigger boats. Basically at under 2 gal/hr they are only using 32-35 hp, based on the formula that one gal makes 16-18 hp. Is this math correct? So if my boat can cruise at 7 kts and burn under 2 gal/hr with engine rpm of 1500 running through a 2.91:1 BW transmission, the prop is turning a little over 500 rpm. So we sized the 20 series pump to run the 23 motor at a top speed of about 1000 rpm and is infinitely variable to any speed down to zero, including reverse. We are reducing motor speed by 2:1 with sprockets onto the prop shaft. I am hoping to be able to cruise at 5-6 kts on get home power. I appreciate anyone questioning my figures because I want to get it right the first time!! I agree on the a/c power demand question. My boat does not have or need a/c and other loads are small, easily handled by a battery bank with a 2500 watt inverter. With the ability to run the dc generator for an hour or two, maybe while trolling for salmon, everything should be well provided for.

Thanks for all the input, it is much appreciated.

Comments on this please?
Click to expand...

Comments on this please?[/QUOTE]
 
johnma said:
If you use the sundstrand 23 pump with the 23 motor you are going to have 1:1 speed on your prop shaft. If your turning your pump at 2000 rpms and stroke it wide open your motor is turning 2000 rpm's. I would think your sprockets are going to be overly large to get your reduction to the prop shaft.
John
Click to expand...

Sounds like you know these pumps pretty well! I had a 20 series pump that we are checking over and reversing direction on to direct couple to the motor flywheel. That should be CW , same as the diesel. Am I right? I am using a 23 series motor to increase torque and stay in the 1000 rpm motor range, and then 2:1 chain and sprocket reduction to the prop shaft for about 500 rpm. This pump/motor combo is way over rated for this application but it should give a long life and be pretty well bullet proof. I am using a common 15 gal reservoir with a clutch pump for the thruster and future additions. Is a 10 micron filter on a standard hydraulic filter base with 1 1/4 fittings good enough? What do you think about cooling. I have a 6" dia x 24" tube cooler that I plan on installing on the return flow line. This cooler only has a rating of 7,500 btu so seems really undersized, like only 10% of what may be needed. No specs on temp differential provided. Not much return on this closed loop system though. Will it cool enough by running the engine antifreeze directly from the keel cooler to the heat exchanger before going to cool the little diesel? Or should I run sea water somehow with a separate pump? Don't really want to run that salty crap through my cooler.

Thanks for your help.
 
Transaxial said:
Comments on this please?
Click to expand...
To be clear - for my KK54 to be burning 2 gph I have to be doing about 1250 rpm with a speed of about 6 kt. If I'm doing 1500 rpm and 7kt my fuel consumption is around 2.8 gph.

Your gph to HP conversion lines up with what I have read.

The zone I am looking at with my 20kW genset would be about 1.2 gph - which I get with 1000rpm on my main and make 4.8 kt. This translates to about 20HP. That would be great for a get home - but doesn't seem to line up with people's experience in real life. I'm concerned that in practice I won't get these results.

Richard
 
To steer straight on a wing engine the shaft is angled a few degrees.

The old Hyde feathering props have the blacd area and diameter to function well.
 
Britannia said:
To be clear - for my KK54 to be burning 2 gph I have to be doing about 1250 rpm with a speed of about 6 kt. If I'm doing 1500 rpm and 7kt my fuel consumption is around 2.8 gph.

Your gph to HP conversion lines up with what I have read.

The zone I am looking at with my 20kW genset would be about 1.2 gph - which I get with 1000rpm on my main and make 4.8 kt. This translates to about 20HP. That would be great for a get home - but doesn't seem to line up with people's experience in real life. I'm concerned that in practice I won't get these results.

Richard
Click to expand...

That is very good fuel economy, specially a boat that size. My 40' looks like it will weigh in around 32,000 full load. Being a much lighter boat I should burn somewhat less fuel which is less HP required. If I can travel even 4-5 kts in get home mode I will be happy. I am told by the company that is setting up these little Mitsubishi diesels for gen set and other apps, that they are very good on fuel. I have heard another rule of thumb is 5 HP/ ton of boat but that is main engine power to achieve hull speed I would think.

Thanks for the info.
 
I would suggest checking out the boatdiesel prop calculator. You need to be a member to run it. It will give you a really good number on how many HP you need to move the boat any given speed.
 
?I have heard another rule of thumb is 5 HP/ ton of boat but that is main engine power to achieve hull speed"

2 -3hp per ton (2240lbs) is where most displacement boats travel.

For a prop built to push a boat, rather than be less drag under sail,

http://www.peluke.com/marine-hardware/boat-props/
 
Last edited:
Transaxial said:
Sounds like you know these pumps pretty well! I had a 20 series pump that we are checking over and reversing direction on to direct couple to the motor flywheel. That should be CW , same as the diesel. Am I right? I am using a 23 series motor to increase torque and stay in the 1000 rpm motor range, and then 2:1 chain and sprocket reduction to the prop shaft for about 500 rpm. This pump/motor combo is way over rated for this application but it should give a long life and be pretty well bullet proof. I am using a common 15 gal reservoir with a clutch pump for the thruster and future additions. Is a 10 micron filter on a standard hydraulic filter base with 1 1/4 fittings good enough? What do you think about cooling. I have a 6" dia x 24" tube cooler that I plan on installing on the return flow line. This cooler only has a rating of 7,500 btu so seems really undersized, like only 10% of what may be needed. No specs on temp differential provided. Not much return on this closed loop system though. Will it cool enough by running the engine antifreeze directly from the keel cooler to the heat exchanger before going to cool the little diesel? Or should I run sea water somehow with a separate pump? Don't really want to run that salty crap through my cooler.

Thanks for your help.
Click to expand...

I'm very familiar with them. Until I retired last year I was GM of one of the largest remanufacturers in the US. If you want your motor to turn 1000 rpm's you can only turn your pump 1000 rpms. I doubt that you want to do that. As far as cooling, run a hose from the top case drain port on the motor to the bottom case drain port of the pump; then connect a hose from the top case drain port on the pump and run that to your cooler then to your filter and then back to tank. Before you start the pump make sure to fill the case on both the pump and the motor with fluid then connect your hoses. Use AW46 hydraulic fluid. Do you have enough horsepower to turn the pump at system pressure? The 23 series pump is 5.43 cu/in (89cc) per revolution. At 2000 engine rpm's that is 47 gpm and will require 47 hp input at 1500 psi operating pressure. If you turn the pump at 1000 rpm your input hp will need to be half of that. Do you have the hp curve info for your engine? Since the pump is variable you can reduce pump flow by not going full stroke on your control lever. You can put a physical stop on the control lever. You said you met with a local hyd shop; did they tell you this?
John
 
twistedtree said:
I would suggest checking out the boatdiesel prop calculator. You need to be a member to run it. It will give you a really good number on how many HP you need to move the boat any given speed.
Click to expand...

I just signed in to Boat Diesel a couple weeks ago. But all I know about my prop is that it is 4 blade and 24" I think. I understand that it is critical on any conventional boat to match the speed and pitch of the prop to the power required to move the boat at what desired speed and it is all regulated by available power. My approach to my problem is different I think, in that I have infinitely variable prop speed at whatever engine speed I choose. If I am looking for maximum speed, I can rev the engine to say 3000 rpm and then push on the hydro lever until the engine is at maximum load. What ever speed that is will be top speed that day. If I am looking for a slow cruise at 2100 engine rpm, same procedure. Just be sure to not overload the engine but again however fast the engine will pull the load comfortably, will be your cruise speed. It is a different concept than propping a boat with a fixed speed and ratio. My situation is more like a heavily loaded semi with an 18 speed transmission. You just drop down in gears which is drive ratio, until you can pull the load.

This seems right to me. Do you think this is correct?
 
johnma said:
I'm very familiar with them. Until I retired last year I was GM of one of the largest remanufacturers in the US. If you want your motor to turn 1000 rpm's you can only turn your pump 1000 rpms. I doubt that you want to do that. As far as cooling, run a hose from the top case drain port on the motor to the bottom case drain port of the pump; then connect a hose from the top case drain port on the pump and run that to your cooler then to your filter and then back to tank. Before you start the pump make sure to fill the case on both the pump and the motor with fluid then connect your hoses. Use AW46 hydraulic fluid. Do you have enough horsepower to turn the pump at system pressure? The 23 series pump is 5.43 cu/in (89cc) per revolution. At 2000 engine rpm's that is 47 gpm and will require 47 hp input at 1500 psi operating pressure. If you turn the pump at 1000 rpm your input hp will need to be half of that. Do you have the hp curve info for your engine? Since the pump is variable you can reduce pump flow by not going full stroke on your control lever. You can put a physical stop on the control lever. You said you met with a local hyd shop; did they tell you this?
John
Click to expand...

Thanks for the response! I am loving your input here but I think you missed that my pump is a 20 size running to a 23 motor. That is pumping less oil and allowing my diesel to run up to 3000 rpm to make it's maximum HP. I would be happy if you check my numbers and keep the comments coming.

The 20 pump is 2.03 cu in X 3000 rpm divided by 231 = 26.3 gpm. at upper end of diesel engine speed.

The 23 motor is 5.43 cu in so 26.3 gpm X 231 divided by 5.43 = 1119 rpm output speed. I am running a 17:34 sprocket combo to the prop shaft so the main shaft should turn 560 rpm. With the main engine running 1600 and a 2.91 ratio BW transmission, the prop speed is 550, pretty close to what the get home will be doing at top end. I figure the main is burning about 2 US gph which would indicate it is producing mid 30s for hp while cruising 7 kts. So the get home at upper end of max power could possibly push the boat at 7 kts, although I would be very happy with 5 kts.

Some specs for the S4L2 Mitsubishi 4 cyl diesel are 1500 rpm- 19.7 hp, 1800-24.1, 2000-27, 2200-30, 2500-33.7, 3000-38.6. Fuel consumption at 16 kw or 21.5 hp is 1.26 gph us. This is 17 hp/gal fuel used.

Do you think we are in a good spot as far as engine speed and power and for speed power and torque of the pump/motor setup. It is a while since I did all the psi and torque calculations but I think this system will be well below peak specs for psi and torque and rpm. The shop setting up the pump said they were putting relief valves on the main supply line at 2000 psi. I thought that might be too low. I look forward to your thoughts. Thanks a lot.

PS I have a supply of Case Hytran Ultra to run in this system. It has been exceptional oil over the last 46 years in equipment for me. Your thoughts since you mentioned oil. Running a big 10 micron hyd filter on the return. Any thoughts on the size of the cooler?
 
"Just be sure to not overload the engine"

Always a good idea , the new EGT gauges do not require a "special" wire from the sender, a great $100 or so investment.
 
FF said:
"Just be sure to not overload the engine"

Always a good idea , the new EGT gauges do not require a "special" wire from the sender, a great $100 or so investment.
Click to expand...

That is a very good idea because I am definitely overpropped for a 30 hp engine. Is this EGT system a stand alone gauge? I am familiar with the old Isspro pyrometers that had a pair of wires running from the sensor to the gauge. Maybe another way to do this is with the Simrad NSS12 that has the ability to monitor a bunch of engine and other functions.

Thanks for the idea!
 
IMG_9317.jpg
My proposed "get home" system.
 
Transaxial said:
Thanks for the response! I am loving your input here but I think you missed that my pump is a 20 size running to a 23 motor. That is pumping less oil and allowing my diesel to run up to 3000 rpm to make it's maximum HP. I would be happy if you check my numbers and keep the comments coming.

The 20 pump is 2.03 cu in X 3000 rpm divided by 231 = 26.3 gpm. at upper end of diesel engine speed.

The 23 motor is 5.43 cu in so 26.3 gpm X 231 divided by 5.43 = 1119 rpm output speed. I am running a 17:34 sprocket combo to the prop shaft so the main shaft should turn 560 rpm. With the main engine running 1600 and a 2.91 ratio BW transmission, the prop speed is 550, pretty close to what the get home will be doing at top end. I figure the main is burning about 2 US gph which would indicate it is producing mid 30s for hp while cruising 7 kts. So the get home at upper end of max power could possibly push the boat at 7 kts, although I would be very happy with 5 kts.

Some specs for the S4L2 Mitsubishi 4 cyl diesel are 1500 rpm- 19.7 hp, 1800-24.1, 2000-27, 2200-30, 2500-33.7, 3000-38.6. Fuel consumption at 16 kw or 21.5 hp is 1.26 gph us. This is 17 hp/gal fuel used.

Do you think we are in a good spot as far as engine speed and power and for speed power and torque of the pump/motor setup. It is a while since I did all the psi and torque calculations but I think this system will be well below peak specs for psi and torque and rpm. The shop setting up the pump said they were putting relief valves on the main supply line at 2000 psi. I thought that might be too low. I look forward to your thoughts. Thanks a lot.

PS I have a supply of Case Hytran Ultra to run in this system. It has been exceptional oil over the last 46 years in equipment for me. Your thoughts since you mentioned oil. Running a big 10 micron hyd filter on the return. Any thoughts on the size of the cooler?
Click to expand...

Sorry, I went back and read your original post. Yes your sizes will work. As far as the cooler is concerned make sure it will handle the charge pump flow which is probably about 5-6 gpm. Also I looked up your Hy Tran fluid and that will work fine. Make sure you follow my instructions about filling the case before start up. If you don't the pump and motor will fail in less than a minute. Good luck with the project.
John
 
GlowShift Gauges have EGT that is simply hooked up with normal wire.

Have used them for 5+ years and the dual analog plus digital read out is great.

Auto, so not waterproof for a fly bridge.
 
When was the last time a boat without a "get home" device did not get home?
 
Wxx3 said:
When was the last time a boat without a "get home" device did not get home?
Click to expand...

Where I live (north coast BC, Canada) there is no tow service, low population density, complex/deep waterways, and the local volunteer marine rescue boat doesn't go out for mechanical failures.

There are pretty regular calls for a tow back to Kitimat given the low number of boats. (We've never towed anybody back because there are usually faster boats closer to the boater in need than we are). That's why we have the 9.9 kicker...to get home or at least to a safe anchorage to work on the main engine if it ever (knock on wood) breaks down.

I don't want to be responsible for changing/ruining somebody else's plans because I can't fend for myself.
 
Last edited:
Wxx3 said:
When was the last time a boat without a "get home" device did not get home?
Click to expand...
My concern would be the middle of an ocean. Of course you've been there - more than once!

I'd be very interested to hear your thoughts on this one...

Richard
 
johnma said:
Sorry, I went back and read your original post. Yes your sizes will work. As far as the cooler is concerned make sure it will handle the charge pump flow which is probably about 5-6 gpm. Also I looked up your Hy Tran fluid and that will work fine. Make sure you follow my instructions about filling the case before start up. If you don't the pump and motor will fail in less than a minute. Good luck with the project.
John
Click to expand...

Thanks for the info John. It is always reassuring when someone with your experience weighs in. I will keep you posted in a month or so when I get all the pieces together and start installing.

Wxx3, in response to your question of "when was the last time a boat without a get home device did not get home". I am in total awe of the trip you did last fall and followed your return to America on this forum. Thanks for the very interesting and informative commentary! I am brand new to the boating world- ocean going boats anyway. It is pretty intimidating to be heading out into "the void" with an old and somewhat unknown vessel and combine that with my personal lack of knowledge of the sea. I have been driving and maintaining equipment and trucks for over 50 years and have a pretty good feel for how to keep things working, but there is always that unexpected little thing that can shut you down. It is no big deal when one can simply catch a ride back to the shop and pick a spare off your shelf to be going again in an hour. It is very intimidating to be thousands of miles from the security of my shop and have the same problem. It just seemed like a no brainer that if I was going to invest in a gen set anyway, and I already have the pump, the reservoir and filter system, the motor mounting plate, the steel and the know how to build the mounting brackets for the engine and the whole system, that I just put this relatively simple little system together just in case. If I never use it, great, no harm done. If it keeps me from an inconvenient situation great. If it keeps me from from getting smashed on the rocks and drowning, what is the value of that? I did not mention that this boat is moored in Nanaimo BC and the west coast, including Alaska is where it will live and cruise. I understand that north of Campbell River there is not much of anything in the way of normal communication, repair or towing facilities, or few other helpful boaters. You are on your own there. I am ok with that if I am prepared. I do not want to appear to know more than some of you truly experienced captains. I like what MurrayM and Britannia have to say in their posts about not putting yourself or anyone else in the position of having to come and rescue me when there was something I could have done at this level to be more independent and have some redundancy built in to my boat. Maybe just my opinion.
 
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