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Hull Blisters

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  • Member since
    August 2019
  • From: Central Oregon
Hull Blisters
Posted by HooYah Deep Sea on Friday, July 15, 2022 7:40 PM

I've been thinking about my ALASKA conversion and got to wondering if when adding a hangar bay and flight deck aft, if this were 1/1 scale, would they add hull blisters to improve seakeeping (bouyancy / stability) as they 'tried' to do with MIDWAY?

Real ship riders and drivers; what do you think? (everyone else is also welcome too)

"Why do I do this? Because the money's good, the scenery changes and they let me use explosives, okay?"

  • Member since
    January 2021
Posted by PFJN2 on Friday, July 15, 2022 10:44 PM

Hi,

I am neither a rider or driver, but I have been a naval architect for 30+ years, and in my experience I would suggest that if you are intended to try and convert an Alaska type hull to an aircraft carrier, in the real world my suspicion is that it would likely have blisters added.

Specifically, if you look at the WWII era conversions of Cleveland class and Baltimore class cruiser hullls into the Independence and Saipan class light carriers (respectively) I believe both hullforms had blisters added.

Similarly if you look at the history of many WWII era aircraft carriers that were modified post war, I believe that most, if not all of them ended up getting blisters as well.  Specifically, I believe that the SCB-27 modifications added blisters to many Essex class vessels, and HMS Victorious was blistered when the added her angled deck.  Additionally, I believe that all three Coral Sea class ships were blistered during rebuilds in the 1950s and that it was a second revision to her blistering that caused issues with the USS Modway in the 1980s.

The trick though for a model is to try and figure out what such a blister might look like, and whether it would be noticeable enough on your build.

For example, if you look at Airfix's 1/600 scale model of HMS Victorious, although the real ship had blisters added, they way that the kit is molded, they didn't really make the edges of the blisters distinct and as such the hullform just looks kind of "full form" around midships with a rather blunt/hard shoulder forward.

If you do decide to add a set of blisters you might want to try and get a copy of the Booklet of General Plans for either the Independence Class or Saipan Class.  I believe that this link has a copy of the Independence class (and some other carriers) that may be of help.   Booklet of General Plans (maritime.org)

Additionally, there is a book on the Anatomy of HMS Victorious that also shows that ship's body plan after conversion, where the edges of the blister are shown much more distinctly than on the Airfix model.

Regards

Pat

 

  • Member since
    January 2021
Posted by PFJN2 on Saturday, July 16, 2022 12:09 AM

PS. to the above, here is a link to drawings available at the Royal Museum at Greenwich that also might be of help to you.  They show the body plans of HMS Victorious after having her blisters added, where you can make out the trace of the blisters and how they changed the shape of the ship.

Hms victorious posters | Hms victorious prints (rmg.co.uk)

  • Member since
    August 2019
  • From: Central Oregon
Posted by HooYah Deep Sea on Saturday, July 16, 2022 1:16 PM

Awesome input, thank you. I was not aware that many ships had blisters added; I will check them out. 

Incidently, I figured out that I could add 16' (in 1/1 scale) to the beam and still traverse the Panama Canal. That would be a key point in the conversion.

"Why do I do this? Because the money's good, the scenery changes and they let me use explosives, okay?"

  • Member since
    August 2019
  • From: Central Oregon
Posted by HooYah Deep Sea on Wednesday, July 27, 2022 2:00 PM

Alright, next silly question. Having seen or read about major alterations to ships and their hulls, do you think that 'they' might consider, on a  four-shafted ship, altering a single ruddered configuration to a twin rudder configuration? It's a lot of work and cost, but the potential gain in maneuverability might be worth it.     Thoughts???

"Why do I do this? Because the money's good, the scenery changes and they let me use explosives, okay?"

  • Member since
    January 2021
Posted by PFJN2 on Wednesday, July 27, 2022 2:51 PM

Hi,

That's an interesting question.  On the surface there doresn't seem to be anything stopping you from doing so, especially if you are already doing some major conversion to the ship, like when the WWII axial deck carriers were converted to angled deck carriers, etc.

A couple issues would potentially be how much space you have aft for a pair of rudders offest from the ship's centerline and how the flow from the propellers interacts with the rudders.  If a pair of rudders is too far off cednterline they could potentially extend beyond the width of the waterline aft (when hard over), and could potentially be subject to damage.

On many ships you may typically want the rudders to fall fairly close to directly behind one pair of propellers, though they sometimes will offset them a little so the you can pull a proeller shaft without removing the rudders, if necessary.  Below is a picture of the rudders from USS Iowa, showing how close together the rudders were on that class of ships.

Iowa

And here is an image showing the location of the rudders on the Burke class DDGs, more clearly showing the rudders a little offset from the propellers (to allow for the pulling of the prip shafts)

Burke

Looking at drawings of the Alaska class it might be possible to refit the vessel with twin rudders similar to the installation on the Iowas class.

Pat

Blueprints > Ships > Cruisers (US) > USS CB-1 Alaska (Battlecruiser) (1945) (the-blueprints.com)

RG19_BB61_578106_11_Levelled.jpg (6024×1707) (researcheratlarge.com)

 

 

 

 

  • Member since
    April 2005
Posted by ddp59 on Wednesday, July 27, 2022 7:15 PM

HooYah Deep Sea, does the flight deck width allow the ship to traverse the Panama Canal? i have 3 different Independence class carrier plans: CVL-23 USS Princeton, CVL-26 USS Monterey 1950 & CVL-27 USS Langley 1943 showing the bottom of the blisters starting at the bilge keels not below them.

  • Member since
    August 2019
  • From: Central Oregon
Posted by HooYah Deep Sea on Thursday, July 28, 2022 1:47 PM

That's a great question; I'll have to measure. The flight deck is going to be fairly straight, like those on an LPH / LHA / LHD, but again, I will have to measure my plans. Additionally, I'm looking at installing LHD style elevators, which I believe are able to fold up.

Maximum calculated beam, including sponsons, is right about the same as an IOWA class BB, about 108 feet. As long as the flight deck is no wider, I'm good.

 

As for the blisters, I think I've eyeballed enough pictures to figure out how I will do that; now it's just a matter of 'doing'.

"Why do I do this? Because the money's good, the scenery changes and they let me use explosives, okay?"

  • Member since
    April 2005
Posted by ddp59 on Thursday, July 28, 2022 4:11 PM

cannot use the light carriers blisters as their hull shape is different from Alaska class. could do what the navy did when they modenized Tennesse. California & West Virginia but not as wide as those ships. still have to finish your Arizona hull as blisters are on but have to carve, grind & sand the sides where they meet the bottom. still have to do the armor belt from the aft end of the blisters to almost the end of the hull that supposedly protects the rudder machinery.

  • Member since
    October 2019
  • From: New Braunfels, Texas
Posted by Tanker-Builder on Thursday, July 28, 2022 6:25 PM

I Dunno:

        When they did the F.R.A.M.s they did not add anything to the hulls of either the Gearings that I saw, or the Sumners. We were a little rolly polly for that, but we never got our birds so it didn't matter in the long run. Like the converted cruisers of old, Added heighth added to the roll effect. Blisters? I think some got them and there wasn't time for others.

        When they converted any of the cruisers? I dont have any info on those older vessels, But I do believe on some depending who built them, they did add Blisters. Let's face it Cruisers were an effort that thankfully worked for a time.I don't know of the longevity, but Blisters or not I wouldn't want to try to set my bird down in anything other a calm sea.

  • Member since
    August 2019
  • From: Central Oregon
Posted by HooYah Deep Sea on Thursday, July 28, 2022 8:02 PM

I had originally though that placing the hangar deck a bit above the main deck aft would be a bit odd, but then I saw that the Independence class carriers have the same arrangement. That made me feel much better and confident in my ideas (i.e. I'm not as loony as I thought i was!!). I mean it made sense to me, and would be functional in a 1/1 scale build.

"Why do I do this? Because the money's good, the scenery changes and they let me use explosives, okay?"

  • Member since
    April 2005
Posted by ddp59 on Thursday, July 28, 2022 9:27 PM

HooYah Deep Sea, i wouldn't bother with the blisters as not needed. the Alaska class is 2.7 times the weight of the Cleveland class & twice that of the Baltimore class. the Alaska class is 20' wider than the Baltimore class & 24' 5" wider then the Cleveland class therefore more stable.

  • Member since
    August 2019
  • From: Central Oregon
Posted by HooYah Deep Sea on Thursday, July 28, 2022 10:03 PM

I have two reasons for my concern, and those are both from a ship (actual) design perspective. First off, I'm removing the No. 3 turret and barbette and replacing that structure with several weapons elevators. This removes a lot of low weight in the hull. Then I'm adding a hangar deck, which replaces some of that weight.

But then I'm adding a bunch of weight above that deck, which could replace all of the turret assembly weight but places a bunch of it much higher, thus potentially reducing the stability aft of the pivot point. By design, the area aft of the pivot point should be the most stable as it is broader and normally of deeper draft (if even just slightly). A ship down by the stern is more stable than a ship down by the bow. That is a basic rule in stability and bouyancy.

I'm probably over-thinking this whole thing, but it's a habit of mine after 20 years of playing with big boats in the real world.

 

Yeah, I know .  .  .      It's a non-existant ship in a non-existant scenario. Just let it go;  build the dang model. 

"Why do I do this? Because the money's good, the scenery changes and they let me use explosives, okay?"

  • Member since
    August 2019
  • From: Central Oregon
Posted by HooYah Deep Sea on Saturday, July 30, 2022 1:43 PM

Okay then; anybody out there have either the 1/350 USS WASP, LHD-1, or USS IWO JIMA, LHD-7, kits in their stash .  .  .??? I need to know the length of the hangar deck on one of those kits. PLEASE !!!! 

"Why do I do this? Because the money's good, the scenery changes and they let me use explosives, okay?"

  • Member since
    April 2005
Posted by ddp59 on Saturday, July 30, 2022 4:08 PM

email sent with wasp plans.

  • Member since
    August 2019
  • From: Central Oregon
Posted by HooYah Deep Sea on Saturday, July 30, 2022 6:56 PM

Thank you. To clarify, I am considering buying the LHD kit and using a bunch of the parts to do the conversion on ALASKA. It beats the heck out of trying to fabricate the elevators and other assemblies when I can 'cut and paste' from another kit. This is especially true since the LHD hull and flight deck width measurements work for the canal passage too; I have build parameters already established.

"Why do I do this? Because the money's good, the scenery changes and they let me use explosives, okay?"

  • Member since
    April 2005
Posted by ddp59 on Saturday, July 30, 2022 9:36 PM

why not use an upgraded Essex class carrier as both ships are of the same time period compared to using a LHD that did not exist til almost 40yrs later?

  • Member since
    August 2019
  • From: Central Oregon
Posted by HooYah Deep Sea on Saturday, July 30, 2022 9:47 PM

Frankly, because I need two deck edge elevators. In the 1970's the only substitute would be an LPH as to the configuration, but nobody makes that kit. I could do a single deck edge and a centerline elevator aft, but then the balance is off, and two centerlines just don't work unless I do an angled or semi-angled deck arrangement. Then, the width is excessive for rapid deployment and flexibility (use of the Panama Canal).

"Why do I do this? Because the money's good, the scenery changes and they let me use explosives, okay?"

  • Member since
    April 2005
Posted by ddp59 on Saturday, July 30, 2022 11:20 PM

an angled deck Essex class has 2 deck edge elevators, 1 port & 1 starboard.

  • Member since
    August 2019
  • From: Central Oregon
Posted by HooYah Deep Sea on Sunday, July 31, 2022 10:47 AM

True; so now it comes down to cost. to get what I need, the options are thus:

1 LHD kit at $190, which gives me everything (hangar deck, flight deck, elevators)

1 Angled deck CV at $230, which has the parts but requires much rework

2 WWII CV's at $200 (for both) to get 2 deck edge elevators

 

I'll have to check out a review on the Intrepid kit.

"Why do I do this? Because the money's good, the scenery changes and they let me use explosives, okay?"

  • Member since
    September 2012
Posted by GMorrison on Sunday, July 31, 2022 11:09 AM

I would think fabricating them would be a choice worth considering, given those prices.

After all, your ship is a fantasy anyways so you have lots of leeway.

 

Bill

 Modeling is an excuse to buy books.

 

  • Member since
    August 2019
  • From: Central Oregon
Posted by HooYah Deep Sea on Sunday, July 31, 2022 11:29 AM

Oh, so true !!

The Intrepid kit pieces / parts would be more era correct, as David pointed out (sort of), so that would probably be the better option on that account. I'd have to carve up the hull of the LHD to get the elevator surrounds, and I don't think that the WWII deck edge elevators are big enough for 1970's-80's aircraft (helos).

"Why do I do this? Because the money's good, the scenery changes and they let me use explosives, okay?"

  • Member since
    January 2021
Posted by PFJN2 on Sunday, July 31, 2022 4:20 PM

Hi,

If I am understanding correctly, the Hangar deck on an LHD is only about 1/2 the length of the ship, because there are so many additional things that an LHD has to carry (such as a vehicle deck and stern ramp).  Where as on a WWII carrieer the hangar may actually consume much more of the length of the ship.

For reference, here is an image of a cut away of the LHD Wasp.

Cut Away

Although its not fully clear from the picture the actual air hangar ends about the same location of where the aft deck cut out ends (a little forward of the port side lift).

On a ship like the Essex class though, as shown below, the hangar extends from fairly far aft forward to the forward lift.

Essex

As such, using an LHD as a starting point may leave you with kind of a short hangar.

Pat

  • Member since
    August 2019
  • From: Central Oregon
Posted by HooYah Deep Sea on Sunday, July 31, 2022 6:03 PM

This build is a hybrid large cruiser (Alaska Class CB); thus the hangar deck is about 246' long and the flight deck is about 300'. That's why I was trying to get the length of the LHD kit's hangar deck. 

Below is the basic hangar deck layout (the white part) set on the kit's main deck.

  

With present finances (fixed income) and the now doubled cost of hay (we've got six horses), I can't afford to get both the LHD kit and the angle deck CV kit. So, it's a matter of figuring out what my best option is; bouncing between what would be easier and what would be era 'correct'. Decisions, decisions, decisions .  .  .

"Why do I do this? Because the money's good, the scenery changes and they let me use explosives, okay?"

  • Member since
    April 2005
Posted by ddp59 on Sunday, July 31, 2022 6:41 PM

those sponsons only 9' wide? what aircraft? why not cut back the aft superstructure to just aft of the stack as you have that empty spot between the stack & the forward superstructure to fill in?

  • Member since
    August 2019
  • From: Central Oregon
Posted by HooYah Deep Sea on Sunday, July 31, 2022 6:55 PM

That is do-able. I was going to add structure at that mid ships area, as there will be Armored box launchers above it (similar to the modernized IOWA's). Since I have been fiddling with this off and on for a while, I can't remember why I was keeping the aft super in place. I'll have to check, but it still doesn't change the hangar length much, it just opens it up a bit (quite a bit!) I figured on putting the AIMD spaces at the aft end of the hangar, and I still have not decided as to how many fire doors to put in (one set or two).

In case you had not caught it in other posts, the hangar deck is like six feet above the main deck at it's forward end, and tapers as it goes aft. This would effect what spaces would be chopped out if I removed the aft superstructure.

"Why do I do this? Because the money's good, the scenery changes and they let me use explosives, okay?"

  • Member since
    April 2005
Posted by ddp59 on Sunday, July 31, 2022 8:32 PM

look at Sheet 5 Inboard Profile of the Alaska plans to see what is in that area as most can be removed or relocated. 

  • Member since
    August 2019
  • From: Central Oregon
Posted by HooYah Deep Sea on Sunday, July 31, 2022 9:03 PM

I was just looking at that! Actually, those spaces are primarily repair related; Blacksmith, carpenter, sheetmetal shop, and heavy machinegun repair. The ones that still pertain can move to between the forward and aft superstructures, and the former aircraft hangars forward will become staff spaces. I'm looking at leaving a wide passage between the fwd super and the relocated repair shops. Thus, I can expand the new hangar deck per your suggestion, after rerouting a bunch of vent ducting (in theory) under the hangar deck along with a fan room.

"Why do I do this? Because the money's good, the scenery changes and they let me use explosives, okay?"

  • Member since
    April 2005
Posted by ddp59 on Sunday, July 31, 2022 10:07 PM

what is the sponson widths?

  • Member since
    August 2019
  • From: Central Oregon
Posted by HooYah Deep Sea on Monday, August 1, 2022 9:25 AM

About 11 feet right now, but I was probably going to 'inlet' them into the hull side some, and double doors into the hangar bay for line handling.

"Why do I do this? Because the money's good, the scenery changes and they let me use explosives, okay?"

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