Single screw limping home

[tashmoo2]

A guy with two engines can limp home on one if the other breaks down.

What can the single screw guy do other than call for help?
I've seen expensive back up sytems advertised for around $20k. $20k pays for more than a few tows back from canyons. It seems to me that there should be a way to turn the shaft using a generator for power and an electric motor or hydraulic motor if the boat has hydraulics. Only problem might be turning gear in neutral for extended period of time. Why hasn't someone come up with a simple system?

 

[fishinwishin]

A guy with two engines can limp home on one if the other breaks down.

What can the single screw guy do other than call for help?
I've seen expensive back up sytems advertised for around $20k. $20k pays for more than a few tows back from canyons. It seems to me that there should be a way to turn the shaft using a generator for power and an electric motor or hydraulic motor if the boat has hydraulics. Only problem might be turning gear in neutral for extended period of time. Why hasn't someone come up with a simple system?

If you are talking about a single engine and it stops running... more than likely the hydraulics that are rigged to it won't work either. If that is so much of a issue, how about a small outboard...... they use to make a diesel outboard, don't know if they still do. It couldn't cost $20k.

 

[tashmoo2]

I was thinking about electric motor connected to shaft with belts and pulley on motor and shaft.

 

[fishinwishin]

I was thinking about electric motor connected to shaft with belts and pulley on motor and shaft.

I didn't think you would mean that. How would you steer?

 

[El Mar]

There is a company that makes a generator coupling device, I'll see if I can find it.

 

[tashmoo2]

Stearing is the same.

Electric motor is mounted on a slide rail base and parallel to shaft. Put one pully on the motor and another on the boat shaft. Slide base to tighten belt. Keep transmssion in neutral.

Issue might be the size of electric motor and gnerator to turn prop at an rpm sufficient to generate 5-6 Knots

 

[BillD]

Single screw DEs run 50-80-120 miles offshore and back all the time.
Diesel marine engines are VERY reliable, the base engines do not generally "quit" out-of-the blue.

There are many many factors that kill a marine diesel or cause it an early demise.

I guess if I was THAT worried about calling for a tow 50 miles offshore, I'd own a twin screw boat LOL.

 

[fishinwishin]

Stearing is the same.

Electric motor is mounted on a slide rail base and parallel to shaft. Put one pully on the motor and another on the boat shaft. Slide base to tighten belt. Keep transmssion in neutral.

Issue might be the size of electric motor and gnerator to turn prop at an rpm sufficient to generate 5-6 Knots

I guess if you are broken down, any movement is better than no movement. Turning the engine to turn the powersteering pump sound like where a waiste would be.

 

[GoodChance]

You are searching for a rose amongst a trash heap. There is no such "backup" plan or aux. motor for a diesel engine taht stops turning. No generator is going to spin a shaft in any type of practical design.


As BillD said, a diesel engine doesn't just "stop" without giving some type of warning long before it dies. Pay attention to the engine room and you will be fine with a single diesel for 100's of miles offshore.

 

[steveinak]

I guess if you are broken down, any movement is better than no movement. Turning the engine to turn the powersteering pump sound like where a waiste would be.

Don't know about what to do about power but for steering unhook the steering ram and have a rudder post extension made up out of pipe & fittings or use the old standby a big pipe wrench.

 

[fishinwishin]

Don't know about what to do about power but for steering unhook the steering ram and have a rudder post extension made up out of pipe & fittings or use the old standby a big pipe wrench.

I've use the standby before boy is that tougher than I thought it would be. I probably didn't havre to be doing 12kts at the time.

 

[tunafishhkg]

Got to be careful if you unhook ram unless you have rudder stops. Bad things happen when the rudder hits the prop. On the ones I have built, I put valves that will dampen the feedback as long as you have fluid left or you can get fancy and plumb in a closed loop. I carry a light wieght alum tiller that will drop into a receiver on the rudder shaft since any tiny nick in hyd hose will blow in short order since its steel mesh that rust very easy.

 

[El Mar]

Got to be careful if you unhook ram unless you have rudder stops. Bad things happen when the rudder hits the prop.

Good point!!

 

[Pedlyr]

I fished on draggers offshore for years. I had to get towed in twice. Once for a broken shaft, the other for a blown gear. Many things can go wrong besides the engine.

 

[offshore31]

Pedlyr's right. New diesels are pretty reliable, esp if you maintain them and feed them clean fuel. many times its something else (shaft, fuel, etc) that stops you in your tracks. if you're real paranoid, do the belt and suspenders thing with twin engines, twin fuel tanks, etc.

how about something completly different for a backup plan, sail? With the price of fuel too? just thinking out of the box. but i'm not ready to slow down that much, yet...

 

[maccaffray]

back up plan for a 38 northern bay.

 

[El Mar]

Is that by chance a diesel?? If not does the boat carry a gas tank?

Interesting solution to say the least, I think I remember seeing that on your Facebook page.

 

[steveinak]

Got to be careful if you unhook ram unless you have rudder stops. Bad things happen when the rudder hits the prop. On the ones I have built, I put valves that will dampen the feedback as long as you have fluid left or you can get fancy and plumb in a closed loop. I carry a light wieght alum tiller that will drop into a receiver on the rudder shaft since any tiny nick in hyd hose will blow in short order since its steel mesh that rust very easy.

Rudder stops or some lengths of chain will take care of that problem.

 

[captainlarry84]

Most commercial boats and single screw. So anything can happen. The name of the game is maintenance and plenty of it.

A snapped shaft…..wow that is a deal breaker. Each year your propeller must be removed. Not so much to recon but to carefully examine the taper of the shaft for any electrolysis, cracking or key way wear plus that the wheel has been tight all year. Lose wheels can snap shafts and key riding will also do it part.

Steering. Also hard to check. It is very important that the fluid level is check weekly to make sure that you are not losing fluid which can lead to failure. I drop on tiller is also a must with a single screw boat.

Marina gear. 99% of gear failures as cooler related. If your transmission cooler does not have a zinc pencil it should be changed every seven years.

The motor. Visual inspections are very important. Spare belts, hoses and fuel filters are a must. In addition raw water impellers should be changed and changed often with a spare on board.

You can only do so much but every little bit will help to keep you off the end of a rope.

 

[Downeaster]

A guy with two engines can limp home on one if the other breaks down. What can the single screw guy do other than call for help?

Catastrophic diesel failures are rare (as has already been pointed out here) especially so with a properly maintained engine even with thousands of hours on the clock. Your concern just isn't valid (were it, how would you rationalize driving somewhere with a car with just one engine or flying somewhere in anything other than a biplane, right?).