Lowering and Raising Screw on HMS Warrior

[OpanaPointer]

Hi! Yes, it causes drag. Even today modern salilboats have collapsables propellers. And I am 99% sure the one in Warrior was not freewheeling, as that would need some type of disegengament from the crankshaft.

That could be as simple as a clutch. Pull a lever to disengage. Some aircraft carriers have them.

May be...but in 1860...? You would need a friction surface, do not think was available at the time.

The crown clutch was available IIRC. Pull a pin, slide the inboard crown forward about a foot, lock in place. Free wheeling from there until you reverse the process. (I don't know if "crown clutch" is a term in use in Britain then or now.)

[marcelo_malara]

The crown clutch was available IIRC. Pull a pin, slide the inboard crown forward about a foot, lock in place. Free wheeling from there until you reverse the process. (I don't know if "crown clutch" is a term in use in Britain then or now.)

Event today it is a common discussion between sailboat owners about f it is better to freewheel a propeller or lock it in place. I am not sure that freewheeling is less draggy than locking. Look at this Boeing 377 accident where a damaged propeller failed to feather creating excess drag to the plane.

https://en.wikipedia.org/wiki/Pan_Am_Flight_6

Another question is the wear and tear caused to the shaft bearings by a propeller that is not actually pushing the ship. In small sailboats the ultimate solution is the folding propeller, that when not turning will align its blades with the shaft.



I agree that the raising propeller is cumbersome. But I tend to believe that it must have been the only solution then available. According to the book Evolution of Engineering In the Royal Navy, the next step in the evolution of the raising propeller was powering the rising mechanism by a steam engine, and the ultimate solution was the self feathering propeller towards the end of the mixed propulsion period. It does not mention anywhere a clutch for the shaft.

[OpanaPointer]

I agree that the jury is out on freewheeling. Too many other factors at play there.

[Byron Angel]

I can't recall whether I read this in DK Brown's "Warrior to Dreadnought" or in the previously mentioned book on HMS Warrior by Rose, but at some point there was discussion about employing (when the ship was nominally under sail alone) a small "donkey engine" to provide just enough power to the propeller to rotate it, thereby reducing drag to some practical degree.

I also took a look into Oscar Parkes' "British Battleships" and found some interesting commentary re Warrior and Black Prince -

p.20 -
"In the Warrior the screw was a two-bladed 10-ton Griffiths - the largest hoisting propeller ever made - needing 600 men on the falls to the old-fashioned sheers over the stern by which it was raised. Black Prince had a fixed propeller.
For the first twelve years there was no auxiliary machinery whatsoever on board except a steam pump, but during their big refits this was geared to work the main deck capstan. Hitherto their ground tackle was the heaviest ever recorded to be dependent upon manual working, and when this gearing was arranged the Black Prince became the first ship in the Navy to have a steam capstan, although steam steering was not installed until 1880. The steering gear did not give satisfaction, as the extreme angle of helm did not exceed 18 to 25 degrees; and to secure this there was such a multiplication of tackles between the steering wheels as made the loss of power in friction very considerable and the time of putting the helm over very long. On one occasion the Black Prince was turned in a circle with her rudder 30 degrees from the keel line; to put the helm over required 1.5 minutes, to complete the circle 8.2 minutes, and forty men were engaged at the steering wheels and relieving tackles (White, Naval Architecture, p.612)."

p.21 -
"On account of their great length and slow turning powers they were unreliable when wearing and staying, or rounding-to and scudding."

p.22 -
"In general equipment the two ships were on a par with the other steam line-of-battleships, having hand steering, man-power at the capstan for raising the anchors, hoisting tackle for the heavy boom boats, and sheer legs for raising the propeller. Hoisting screws were only fitted in a limited number of ironclads as the gain in sailing speed was more than offset by the structural weakness caused by the screw well; so for this and other reasons of expediency the hoisting screw was abandoned in the course of few years."


Personal note:
I have owned my copy of this book by Oscar Parkes for about fifty years. It cost me half a week's wages to buy it back then. Fifty years later, I still consider it money well spent.


Byron

[OpanaPointer]

Trailing a screw doesn't create that much drag, except maybe in the CO's mind. Personally I'd rather have it ready to get us out of trouble if push came to shove. A lot of this kerfuffle is the result of "unknown territory terror". We didn't know what was important and what was just silly.

[Byron Angel]

Trailing a screw doesn't create that much drag, except maybe in the CO's mind. Personally I'd rather have it ready to get us out of trouble if push came to shove. A lot of this kerfuffle is the result of "unknown territory terror". We didn't know what was important and what was just silly.

Based upon Parkes’ comment about the relatively rapid disappearance of hoisting propellers, I am prone to agree with your assessment.

Byron

[OpanaPointer]

When I did my last deployment with USS Peleliu (LHA-5) we had a main engine shaft spring bearing burn out.* My team spent forty-some hours removing the old bearing and mounting and aligning the new one. Our shaft was locked and trailing. The stbd screw was doing some heavy turns and we kept up with the rest of the amphib squadron. We were doing 15 knots on one screw. Yeah, that's logarithmic, pushing twice as hard doesn't produce twice the speed.

Peleliu specs:
Class and type Tarawa-class amphibious assault ship
Displacement
39,438 long tons full and
25,982 tons light
Length 820 ft (250 m)
Beam 106.6 ft (32.5 m)
Draft 27 ft (8.2 m)
Propulsion
2 steam combustion engineering modified super 6 boilers
2 Westinghouse steam turbines
Speed 24 knots (44 km/h; 28 mph)


*Yeah, leaving the lube oil drain plug out will do that. Somebody thought we'd turn around and return to Pearl or even Long Beach. No, no, no.

[marcelo_malara]

When I did my last deployment with USS Peleliu (LHA-5) we had a main engine shaft spring bearing burn out.* My team spent forty-some hours removing the old bearing and mounting and aligning the new one. Our shaft was locked and trailing. The stbd screw was doing some heavy turns and we kept up with the rest of the amphib squadron. We were doing 15 knots on one screw. Yeah, that's logarithmic, pushing twice as hard doesn't produce twice the speed.

Peleliu specs:
Class and type Tarawa-class amphibious assault ship
Displacement
39,438 long tons full and
25,982 tons light
Length 820 ft (250 m)
Beam 106.6 ft (32.5 m)
Draft 27 ft (8.2 m)
Propulsion
2 steam combustion engineering modified super 6 boilers
2 Westinghouse steam turbines
Speed 24 knots (44 km/h; 28 mph)


*Yeah, leaving the lube oil drain plug out will do that. Somebody thought we'd turn around and return to Pearl or even Long Beach. No, no, no.

True, powering varies approximately with the cube of the speed. If full power does 24 knots, for 15 knots you will need just 1/4.