Area Defence Vessel - HMS St Vincent (1909-1937)

[Krakatoa]

The two battleships St Vincent and Collingwood were used as static training ships from 1919 to 1927, in a demilitarised condition. Boilers, turrets and armour had been removed to comply with the Washington Treaty. In 1927 they were reactivated to seagoing condition to replace the aged WW1 County class armoured cruisers that had previously been used. One set of boilers, the fore tripod and the fore funnel had been removed completely. Only one 12" turret remained and two single 6" replaced what had been the wing turrets. A few single 4" and 3"AA guns were placed in and around the superstructure. In this condition the ship undertook training cruises to the Caribbean, Mediterranean and Africa. In 1935 a further modernisation of the ship took place. The bridge was replaced with a cruisers structure, new trainees accommodation and classrooms was constructed amidships. The biggest change was the fitting of a hangar and catapult on the stern of the ship. A new type of ship was being promulgated for the RN, the Area Defence Vessel. The envisaged uses for the vessels were their common use as Training Ships, static or mobile seaplane bases, assault vessels with the hangar and trainee accommodation being filled with troops that could be landed by the ships boats, local Headquarters ship in those out of the way places that did not have command structures in place, and many more.

[Hood]

An interesting idea, reminds me of the planned post-war Mobile Naval Base rebuild for Agincourt which would have retained the two forward 12in turrets.
I assume at some point the remaining boilers and turbines were replaced by an all-oil firing set of machinery? The original machinery would be outdated by the 1930s.

[acelanceloet]

I'm taking a risk here, talking about something mildly technical......
watch out with the weights. your hangar and stores must offset the weight of the removed machinery and 2 main gun turrets (and most likely part of the weight of the beam turrets as well) otherwise she will no longer lie on the same waterline. I do know very little about the hull shape, so I do not know what would happen with stability, but it is a fun thing to think about and at the very least to draw out the new waterline if you are not fitting additional ballast

[Krakatoa]

Thanks for your comments Hood,

I never know how far the beginning scene setting should go. The 1927 reactivation refit included the removal of the deck armour and the replacement of half the boilers with oil fired ones (the other half were removed completely). This allowed a clean slate for building the new accommodation and school rooms for trainees.

Howdy Ace,

I did take note of the balance of the ship, I was going to extend the hangar further back to increase the air complement, but it looked ungainly so everything got moved forward. I have added an extra two deck levels amidships which I thought might help to balance up the loss of weight from the wing turrets. The large space that contained the forward boiler room has been honeycombed with new accommodation and office rooms and decks. It would be the removal of the side and deck armour which would alter the height above water most. Exactly by how much I do not have the knowledge to quantify. I was hoping to find an amount of how much armour there was either as a tonnage or percentage, but nothing I have read gives any figure for that. Whether the RN would add ballast to balance it all out, I would guess they would.

[eswube]

Very interesting work.

[acelanceloet]

the fact is, if you are going to remove armour but add ballast, then... why bother.
for the turrets and the machinery I can approve of adding ballast, but it seems more sensible to keep the armour in place.
hangars, offices, decks etc are very light compared with barbettes, turrets, boilers (which are partially filled with water, and the rest is metal tubes and completely pressurized, so thick metal) and machinery (which are, in weight terms, almost pure metal). you also loose the magazines, which bring the center of gravity to roughly what it was, but the ship will be lighter unless you fill the double bottom with lead.

estimations for these kind of things can be done. if we take a shoebox with the dimensions of the ship (or the dimensions of the armoured part of the ship) and fill it with the armour thicknesses for side and deck armours we can get estimates of how much weight this gives, and how much is lost when we remove the steel.

for boilers and machinery, I know friedmans books have weight data for this, so there should be numbers to be found for that. navweaps often has turret weights, and shell weights should be possible to find, it is the amounts that is troubling. however, if you use the shells as correction for the weight of the additional structures, I would think this acceptable.

I also just noted, what did you remove of the machinery? because you still have 4 shafts, so I think you only removed the boilers, right?

in addition, I don't think I have seen many ships where there would be office rooms and accomodation anywhere around the boiler rooms. accomodation was IIRC mostly above the waterline. I would think it more likely that the former boiler space would be used for fuel and stores instead.

[Krakatoa]

Thanks for that Ace,

Unfortunately, to keep the ship, it must be in a condition that complies with the WNT, which means the armour must go. Yes the engines are kept as is. Despite having fought a war, as per normal the battleships spent less time at sea than most, which meant their machinery did not get the same hammering as the BC's and below. I am happy with using the removed boiler space for extra fuel and stores, young trainees always seem to eat more than the more mature sailors. Using the removed boiler space for extra fuel is done in WW2 to extend the range of destroyers converted to long range escorts.

Would filling the double bottom with bits of removed armour and turret do instead?

My original thought was to use the 4 turrets removed from each ship to arm the BC Sud Afrika (and a sister) in the other thread. But since I got a bit of flak in using refurbished turrets for new ships I redesigned the 14" to a 12" for that ship type.

Overall the RN would be aware of the changes made and would have exact amounts as to what was necessary to be replaced and where any ballast might need to go. So I have no problem in your queries, questions, and solutions put forward, as it keeps me thinking about 'balance' when I am hacking bits off ships to create my monsters.

[acelanceloet]

well, really the easiest thing was to just move the waterline and only fill in ballast for what is required for the stability.

[ussnimitz1968]

Me likey!