RN battleship screw diameter?

[ArnoldAmbrose]

Gidday All, I don't suppose anyone knows the diameter of the screws of the Nelson and KGV classes of battleship? Several references state that the screws of the Nelson class were rather large but not the actual size. I believe HMS Hood had screws of 15-feet diameter. Most references seem to state the number of shafts and hence screws of ships but rarely their size or the number of blades on them.

       Many thanks. Regards, Jeff.

[Jamie @ Sovereign Hobbies]

Hi Jeff, I have a copy of a document from a dry docking inspection of HMS Duke of York in Sydney, April 1946 stating the diameter of both inboard and outboard propellers on was 14ft 6in. If you're interested, it also says the pitch was 14ft 9in and that they had an area of 112 square feet. There's a diagram given in a second page actually.

 

I don't have anything for the Nelson class, I'm sorry.

[ArnoldAmbrose]

       Gidday @Jamie @ Sovereign Hobbies, many thanks. I've seen stats of other screws that say a pitch diameter as well as the actual diameter and it's slightly larger as I recall. I'm not quite sure what that equates to but it probably wouldn't matter for scratch built screws for model warships.

       Thanks for getting back to me.       Regards, Jeff.

[Graham Boak]

I believe the pitch is not a diameter, but the distance travelled forward in one rotation.  Or something similar.

[foeth]

58 minutes ago, Graham Boak said:

I believe the pitch is not a diameter, but the distance travelled forward in one rotation.  Or something similar.

In case of a screw in wood that would be the case, but for a propeller a) the distance travelled is usually not constant over all radii of the propeller and b) the actual distance travelled is typically less (called slip).

 

 

Iirc the prop diameter was not the same for all kgvs; will check tomorrow, I’m off to very fancy dinner…

 

[ArnoldAmbrose]

1 hour ago, Graham Boak said:

the distance travelled forward in one rotation.

Gidday and thanks. I've just looked it up. Regards, Jeff.

[ArnoldAmbrose]

2 minutes ago, foeth said:

Iirc the prop diameter was not the same for all kgvs; will check tomorrow, I’m off to very fancy dinner…

Gidday and thanks also. As I work in 1/600 scale the difference probably would be very small. But first things first - enjoy the dinner. 🙂 Regards, Jeff.

[Rich75]

Hey Jeff, is there a KGV In the pipeline?🤞🏻

[Dave Swindell]

3 hours ago, foeth said:

a) the distance travelled is usually not constant over all radii of the propeller

Correct, but there's usually a nominal, design or theoretical pitch quoted on the prop drawings I've seen, the Chief Engineer needs it to work out the slip for the day.

 

3 hours ago, foeth said:

the actual distance travelled is typically less (called slip).

Sometimes more (downhill with the wind behind! but usually less, the engineers generally get there before the navigators....

[Seahawk]

Prop diameter for KGV 14.5 ft (ie 14' 6") according to V E Tarrant's King George V Class Battleships, matching the measured DoY figure quoted by Jamie.  Tarrant doesn't list any variations for other ships in the class.  

 

Can't find anything on Rodney/Nelson in Raven & Roberts' Man o'War 3: Rodney & Nelson or Burt's British Battleships 1919-1939.

[ArnoldAmbrose]

7 hours ago, Rich75 said:

Hey Jeff, is there a KGV In the pipeline?

       Gidday Rich, not at this point but the ATF traditionally has a whiff GB over December and January. I have a couple of ideas in my head using Airfix Nelson kits. As their GBs usually run for only two months the most probable is a standard Nelson but with the more traditional main turret arrangement (2 fwd, 1 aft). I know this has been done on Britmodeler before but ATF rules and time restraints mean I'll have to restrict alterations as much as I can, including hull and screws. Hence the question about Nelson's screws.

       In the future I'd also like to do a larger whiff of the kit with a lengthened hull and four turrets. Such a ship would need four screws I think hence my question regarding KGV's screws. I do have an Airfix KGV kit that I was thinking (a loooong way down the track) of converting into the proposed Lion class. While the Airfix KGV screws are OK those of the Nelson kits are crap leave a bit to be desired so I was going to make my own. I thought I'd ask about both ships at the same time. I didn't think to ask about HMS Vanguard but I suppose her screws would be similar to Hood's and KGV's.

       Thank you all for your help.       Regards, Jeff.

[foeth]

I checked my copy of the lines drawing of HMS Prince of Wales; it shows that the propellers were initially dimensioned at 15ft, but the approved diameter ended up at 14ft6in. These lines show the difference with (as per the drawing) HMS King George V, Jellicoe, Anson and Beatty*. I remembered there was a change in diameter but apparently towards the final diameter of 14.5ft.

 

*(For HMS Prince of Wales there is this tiniest of differences in the stern region and the small knuckle just below the deck in the forepeak).

[Rich75]

10 hours ago, ArnoldAmbrose said:

       Gidday Rich, not at this point but the ATF traditionally has a whiff GB over December and January. I have a couple of ideas in my head using Airfix Nelson kits. As their GBs usually run for only two months the most probable is a standard Nelson but with the more traditional main turret arrangement (2 fwd, 1 aft). I know this has been done on Britmodeler before but ATF rules and time restraints mean I'll have to restrict alterations as much as I can, including hull and screws. Hence the question about Nelson's screws.

       In the future I'd also like to do a larger whiff of the kit with a lengthened hull and four turrets. Such a ship would need four screws I think hence my question regarding KGV's screws. I do have an Airfix KGV kit that I was thinking (a loooong way down the track) of converting into the proposed Lion class. While the Airfix KGV screws are OK those of the Nelson kits are crap leave a bit to be desired so I was going to make my own. I thought I'd ask about both ships at the same time. I didn't think to ask about HMS Vanguard but I suppose her screws would be similar to Hood's and KGV's.

       Thank you all for your help.       Regards, Jeff.

Hey Jeff, while I've been reading about the KGV class I got an idea for a whiff and immediately thought there's someone who could definitely pull it off! Apparently Churchill was none too pleased at the idea of 10 14" guns and much preferred the 9 16" arrangements of the US BB's and Nelson/ Rodney, I could quote one of his letters later if you'd like, anyway that would make a fine looking ship in any case don't you think 😉 

[ArnoldAmbrose]

1 hour ago, Rich75 said:

Apparently Churchill was none too pleased at the idea of 10 14" guns and much preferred the 9 16" arrangements of the US BB's and Nelson/ Rodney, I could quote one of his letters later if you'd like, anyway that would make a fine looking ship in any case don't you think 😉 

       Gidday, I was reading about that only yesterday, while researching the KGVs for their screw size. I think the reason the KGVs had 14-inch guns was because the British were loath to invoke the 'escalator clause' of the London Treaty. When that treaty didn't get ratified by the Japanese the parameters of the earlier Washington Treaty came back into effect anyway, which allowed 16-inch guns. But the delay in the ship's completion that the manufacture of the 16-inch guns and triple mountings would have caused wasn't acceptable to the British, who needed the ships earlier rather than later. Another benefit of the smaller caliber guns was the more armour that could be carried. I believe that they were quite tough ships. There's no doubt much more to this however.

       As for a model of a KGV with nine 16-inch guns, that was going to be the basis of the Lion class anyway. Yes, it would be a good looking ship and a great model I think.🙂 And without denigrating Churchill personally, I don't believe he was an expert on the practicalities of naval issues.

       Regards, Jeff.