Captain/Owner Sleeping at the Helm

[Adelie]

Originally Posted by BlueH2Obound

Perhaps a moderator should split this thread into two threads:

One dealing with Captain falling asleep while on watch, which I think was the real meat of the original post.

Second one dealing with what to do with the transmission when sailing.

It's too much work and I'm lazy. Sorry.

[grahamj]

If a locked prop provided more drag than a freely rotating one then helicopter pilots would lock their blades when descending to the ground after an engine failure.
They don't, they allow the the rotor to freely autorotate which slows their descent.
That's drag. Compressibility doesn't come into it.

[Adelie]

Originally Posted by grahamj

If a locked prop provided more drag than a freely rotating one then helicopter pilots would lock their blades when descending to the ground after an engine failure.
They don't, they allow the the rotor to freely autorotate which slows their descent.
That's drag. Compressibility doesn't come into it.

In general aircraft propellers are not analogous to marine props because of the much lower ratio of blade area to disk area.

In the specific case of helicopters with engine failure the goal is not to maximize drag on the way down but to maximize rotor RPM which stores energy. The decent rate of an unpowered descending helo might be survivable but it would be a pretty bad landing.

By spinning up the rotor during energy is saved which can be turned into lift to cushion the landing, literally at the last second. A good helo pilot can not just save the crew but even the helo itself.

Spinning up the rotor to soften the landing at the last second is called autorotation.

[grahamj]

Yeah, that's why sycamore seeds fall at the same rate as twigs.

[Cpt Pat]

Originally Posted by Adelie

Did they come up with the program de novo? Or did they compile work from a lot of other parties, add some or a lot of their own and then give it a name?


The Evolution of Airline Crew Resource Management - NYCAviationNYCAviation

https://www.linkedin.com/pulse/histo...iii-paulo-neto

https://code7700.com/crm.htm

PanAm was working on it internally from 1973 when the FAA told them to shape up or be grounded.

NTSB had a lot to say about cockpit culture too in the 1970s in their accident reports.

There’s even a British guy going back to the 1950s who talked about human factors.

Giving NASA all the credit for originating CRM is like giving Bill Lapworth all the credit for the switch from full to fin keela on larger keelboats. There’s a lot of history that came before both.

Something's wrong with my broswer. When I look at what I wrote, I see: "NASA developed CRM" not "NASA invented CRM." Sorry if I omitted an exhaustive list of every entity involved. I try not to write entire books here to make a side point tangential to the topic. Besides, the more you write, the more material you give the nitpickers.

[StuM]

Originally Posted by grahamj

Yeah, that's why sycamore seeds fall at the same rate as twigs.

That reminds me of:

Even a fool, when he holdeth his peace, is counted wise: and he that shutteth his lips is esteemed a man of understanding.


or the more recent adage.

Better to remain silent and be thought a fool than to speak and to remove all doubt.

[OloteleMtn]

(Throws bucket of seawater on sleeping captain/owner) "Wow, that was a big wave, huh Captain! How was your watch?"

[Stu Jackson]

Originally Posted by StuM

So you think it was a good idea to slow the boat and risked potential damage to the engines by locking the props contrary to the skippers wishes and the manufacturer's instructions?

Now how do we deal with know it all crew?

Advisory Number: MSA08-003:

DATE February 8, 2008 Dealers and OEMs
TO: All Marine Distributors
SUBJECT: Gear in Neutral While Sailing All MODELS:

All Sailboat Engines

We continue to get questions regarding the correct gear position while sailing with the engine OFF. This advisory is issued as a reminder; Yanmar requires that if sailing with the engine OFF (not running) the transmission shifter must be in the neutral position or internal damage to the gear or sail-drive will result. This damage will not be covered by Yanmar’s Limited Warranty. Please instruct customers and dealers who deliver the sailboat to the customer, of the correct (Neutral) position for the marine gear while sailing.

Just for clarity, and for newbies reading this thread, the search term : Transmission Position : on this and every other boating forum known to man, conclude that the decision of which position to leave your transmission when sailing is based on one thing, and one thing ONLY:

the manufacturer of your transmission

Not mine, not his, not your broth-in-law's or your uncle's.

In general, StuM is right, but about transmissions on YANMAR engines, whose name starts with a K.

I have a Universal engine, and it has a HURTH transmission. H, not K.

Hurth's owners manual says neutral OR reverse, never forward.

https://www.c34.org/faq-pages/faq-tr...n-sailing.html

[MicHughV]

on a previous boat....I had a Westerbeke...it was fitted with a hydraulic borg warner transmission...whether you wanted to lock the prop or not.....that decision was already decided for you....you couldn't....time to fit a maxprop !!

[Wotname]

Originally Posted by grahamj

If a locked prop provided more drag than a freely rotating one then helicopter pilots would lock their blades when descending to the ground after an engine failure.
They don't, they allow the the rotor to freely autorotate which slows their descent.
That's drag. Compressibility doesn't come into it.

Adelie gave you a reasonable explanation up thread.

Additionally a helicopter rotor is not a fixed pitch device which is what is under discussion. Also there is no mechanism that can lock the rotor in flight

During autorotation the pilot initially selects a pitch that ensure maximum possible rotor rpm is achieved and this gives a corresponding high rate of descent. Just before impact, the pitch is altered to generate some lift which slows the rate of descent enough to survive the impact. BTW, it is one shot method, get it wrong, there is no second chance.

However there is simply no point in discussing helicopter rotors, turbine prop blades, twigs, sycamore seeds etc. None of these things are analogous to a fixed pitch sail boat prop. Stick to presenting arguments about the topic!

Would you talk about how much salt should be horse feed if the discussion was really about the proper amount of sugar needed in chocolate cake.

[Uncle Bob]

Originally Posted by Wotname

Adelie gave you a reasonable explanation up thread.

Additionally a helicopter rotor is not a fixed pitch device which is what is under discussion. Also there is no mechanism that can lock the rotor in flight

During autorotation the pilot initially selects a pitch that ensure maximum possible rotor rpm is achieved and this gives a corresponding high rate of descent. Just before impact, the pitch is altered to generate some lift which slows the rate of descent enough to survive the impact. BTW, it is one shot method, get it wrong, there is no second chance.

However there is simply no point in discussing helicopter rotors, turbine prop blades, twigs, sycamore seeds etc. None of these things are analogous to a fixed pitch sail boat prop. Stick to presenting arguments about the topic!

Would you talk about how much salt should be horse feed if the discussion was really about the proper amount of sugar needed in chocolate cake.

Only if one had extensive knowledge of a horse's salt requirement and very limited knowledge of a chocolate cakes sugar requirement.

[CassidyNZ]

Originally Posted by Wotname

None of these things are analogous to a fixed pitch sail boat prop. Stick to presenting arguments about the topic!

Sticking to arguments about the topic would require no further discussion about transmission positions, props, rotors or aircraft. Just sayin . . . .

[Wotname]

Originally Posted by CassidyNZ

Sticking to arguments about the topic would require no further discussion about transmission positions, props, rotors or aircraft. Just sayin . . . .

Transmission position is on topic though - jus saying....

[Jim Cate]

Trying to stop thread drift after the first coupe of pages is like trying to stop the tides...

Your choice of where to spend energy.

Jim

[PineyWoodsPete]

For those who still have doubts about prop drag fixed vs free, try this simple experiment with your dingy w/ outboard towed by mothership @ 5kn or so. With OB gearshift in N and motor off, you will observe a free-wheeling prop, and motor remains vertical. But shifting into FWD, which stops the prop, the motor leg immediately kicks back with the increased drag of the fixed prop. Think about it: a fixed prop will create a huge amount of turbulence (drag) behind it, while a prop rotating at near the neutral state of thrust vs drag - eg. not much water pressure differential between fwd and aft sides of blade, drag will be primarily from energy consumed making the unavoidable tip vortices - unless you have the radical new Sharrow prop!

Now for you aeronautical types, with a piston driven aircraft engine, can the prop be uncoupled from the engine to truly freewheel if engine quits, or does it continue to turn engine over - albeit at much reduced RPM's than free-wheeling. This would seem to me to create more drag than true uncoupled freewheeling, and feathering the prop would def. reduce drag.

The best alternative though - marine or fixed wing air -seems a fully feathering (or folding) prop.