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[Bob K]

Ideally, both halves, when ballasted, should float close to their waterlines.  However, it is imperative that the halves are joined before lowering into the water.  I cannot kneel by the waters edge, so trying to thread long rods under water and fiddle with clamps on my knees would be as impossible as fiddling with bolts nuts and washers between just two bulkheads (nowhere near as strong). 

Once the long rods are slid home and the clamp is latched it will be stronger than a one piece hull, but around 15 kg lighter as much of the ballast will be water added after launch, and pumped out before recovery.

[derekwarner]

Evening Bob....I went thru with you with unfledgling support .....word by word, line by line , page by page , and month by month with your build of the brilliant semi submersible Polyphemus  as I always knew there was the light at the end of the tunnel 

I wish you well with this new planned build........and will be reading and watching................. Derek

[Bob K]

Greatly appreciated Derek.  I know it will not be easy, and that is the challenge.  I expect a lot of mid course corrections along the way, a steep learning curve. 
At least I can ballast test each half in the bath separately !

This is a ship I really want to build and sail, dodgy legs and all 

[Capt Podge]

I'm no engineer, I'm no technician but it seems, to me at least, that some kind of lifting gantry may be called for. (Your problem seems to be somewhat akin to that experienced by TigerTiger, but without the massive drop).

My first thoughts are along the lines of lifeboat davits but without the need to be affixed to chains/pulleys. A pair of good lifting strops might then be utilised and the gantry pushed (wheeled) to the lake edge. The bottom frame would just be a basic frame with the "davits" affixed to it and removable for transportation.

Hope this helps to get the thoughts into gear...

Regards,

Ray.

[C-3PO]

This would do the job - only problem is how do you transport it!!!

[Bob K]

 Displacement

Before we get carried away, I believe the launch weight is practical without resorting to heavy lifting gear.

My HMS Polyphemus has a dry weight of 11 kg.  With ballast tanks full that is an extra 3 kg, but I don’t have to lift that.  11 kg is quite manageable with basic lifting straps.

If I can get HMS Agincourt to around 16 kg dry I will be able to manage lifting that, it is only 5 kg more than the Poly’.  The key to practical liftability will be pumping in/out 16 kg of water ballast afterwards.  The same principle as Polyphemus, but a lot more water.

However, at this stage the actual sailing weight of the prototype needs to be confirmed, then I can work out how much can be water ballast vs internal equipment.  All R&D right now.

[radiojoe]

Watching this with great interest Bob, should keep you busy for a few weeks   




Joe

[warspite]

Here we go again, if a section of the deck is removed to secure the latches and the tubes on the mock up are exposed, then why not make the tubes the lifting handles - turn the three point fixing system upside down.

Oh and the open rear door system is already employed for a pet - it leaves the rear open just enough for the air to circulate without opening the car up to thieves.

[ballastanksian]

To balance the water between the two hulls in a similar manner to a jaguar Xj6's two fuel tanks, replace the bottom tubes and rod with wider tubes and a telescoping connecting tube to slide into them both joining the hulls together and also providing pump free water transfer. have baffles at each end of the housing tubes to stop any 'hunting' caused by a rapid stop or similar forward/reverse motion. With a good fit, there should be no more issue with water surge between the hulls than in any normal operation. With an internal water tight link between the halves, you might only need one pump.

I doodled a small diagram which also gave me the idea that the upper connecting tubes should be sealed at the ends to stop any seepage from the join between the hulls getting into the halves possibly causing much dissagreement with electrickery. Hopefully the holes for the retainers will also double as vacuum release for when inserting or removing the rods.



Obviously the digram does not include the drive train compartment or how you plan to house this along with the water tight compartments.

[Bob K]

Thanks for all the ideas, with varying levels of practicality, but it shows you are all thinking about it.
Cheers !

Mock-up

The half scale mock-up of the joining sections of the ship went well, highlighting some improvements that will be incorporated into the construction method.
A roughly half scale toggle latch proved more than adequate to securely clamp the interfacing 9 mm bulkheads together, with the removable rods giving more than adequate stiffness and support.  The aim being to provide at least the same strength as the one-piece “U” channel section of the GRP hull.
An adjustable latch will be essential as even a tiny slackness in the joint will impair strength,

The hull is on order from Dean’s, and I will discuss cutting the hull with Ron at Wicksteed.  I have asked Ron if they could lay up an extra layer of GRP on the inside of the centre section.  So, it may be a few weeks until I can arrange cutting and collection just in case you think this thread goes quiet for a bit. 

[Capt Podge]

Thanks for the update Bob. Your sequential planning should ensure a good quality build and hopefully many, many hours of pleasure when the actual build goes ahead.

Regards,

Ray.

[Bob K]

Thank you Ray.

I've just unrolled the plans across the living room to double check the length then measure the cutting point, 48.9% from the tip of bow.  But - Heck that really brought home just how darned big it is 
I must be totally crazy. 

"Money can't buy you happiness, but it can build you a boat big enough to tie up alongside it"

[ballastanksian]

We all need one crazy project 

[Bob K]

 ’Arthur boat is better than one

The more I think about it, the more cutting the Agincourt hull in half appeals to me.

Each half can be built separately, bath tested, and ballasting systems be developed and tried indoors.  The two half ships will fit side by side on my car’s back seats, folded down.  Two 1,075 mm ships are a lot easier to manage, and to get from the workshop to the car, although at the lake it may mean two trips from the car park to the water.  My existing Silver Cross trolley should be amply large enough.

Now here is a silly idea !   I could build a short blunt false bow, like an oil tanker, to attach onto the interfacing spigots, so that I can do a maiden voyage test on just the back end.
Plenty of scope for puns such as commanded by a Rear Admiral with a stern expression, saluting with his hand - but no bow.  I might even christen it HMS “…court”.

The front end, HMS "Agin...", needs only ballasting simulations.  No point in building a powered short stern unit add-on for that. 

The one outstanding question remains - how heavy will the sailing weight of the original prototype be.  My calculations reckon 32 kg, but I could be wrong.  I really need to get the “lift” weight down to 16 kg before pumping in water.  Fingers crossed, hopefully it may be at Wicksteed this weekend.

[Colin Bishop]

Agincourt displaced about 28,000 tons so the model at 1:96 should displace 0.03 tons or about 60lb or 27kg standard load.

Colin

[Bob K]

Thank you Colin.  I was working on 27,850 long tons, but I'd be happy with 27 kg. 

[Colin Bishop]

Depends on how accurate the hull is though! The reality with warships of that era is that displacement varied a lot depending on their loading and it was common for them to get heavier and heavier as they got older with additions and even the weight of the paint! Hood was regarded as being almost waterlogged at the time of her loss I believe.

I would think you have quite a bit of leeway to play with really. However big models do pose their own problems. I normally only build small ones but my recently completed fishery cruiser is four feet long and quite a handful (or should I say kneeful) to launch and recover. You are quite right to anticipate these issues well in advance.

Colin

[Beagle1831]

In reference to the above... After HMS Porcupine was torpedoed the two halves stayed afloat, these were salvaged and used as 'HMS Pork' and 'HMS Pine'


This should be a great build! Really interesting ship with a great history. The large ships are really awkward at 2m... Very easy to knock bits off as they tend to swing around when transported, so splitting it should be a good solution.

[Netleyned]

Destroyers Zulu and Nubian
became Zubian sticking the
Best bits of each together
after battle damage.


Ned

[ballastanksian]

Seeing the hull yesterday at the show, it did cause a stir, especially as Bob didn't know that Ron 'Mr Mischeif' Dean had brought it with him to show him!

Several of us distracted Bob while Ron brought it down all subtle like. It got it's first pond test and took all of Ron Kingdon's ballast blocks that he uses for his Rodney- namely 32kilos. I hope someone took a few pictures as it is impressive. Taking it out, I found it difficult not to start doing a slapstick performance, it was so big.

[Bob K]

Yes Ballastanksian, Ron Dean certainly pulled a surprise bringing my new Agincourt hull to Wicksteed as a surprise.  Sad that he had to take it away again because we need to arrange a date for me to go up to his workshop for cutting in half so that I can get it home.



To get it to the waterline 16 x 4 lbf lead blocks were inserted. That is 29 kg, a bit less than calculated.

I can't wait 

[ballastanksian]

I am not surprised Bob!

For what it's worth, if you cut 244mm from the middle, you can make a KGV (1911) from the hull. Other mods might need to be made but the basic form is there.

I look forward to seeing the hull cutting photos.

[Bob K]

"You're gonna need a bigger boat !"

https://www.youtube.com/watch?v=oKxsW8DKJQQ

[warspite]

Or more importantly - a bigger car 

[Bob K]

There is story here of course.  I used to have a much larger car.  Hyundai Lantra saloon.  17 years old, 25 mpg, high tax and insurance, plus increasing repair costs to keep getting it through the MOT.  However, no seats folded down and despite a fair sized boot it did not lend itself to being used as a van.

So, when I retired at 67 I invested in a nice little Agila. 1 Litre, £10 tax, cheap insurance and 50 mpg. The width across the back seats was only two inches less than the Lantra.  It should last me the rest of my driving years. 

The car is not the issue.  I simply cannot manhandle a heavy 2.2 metre boat, either from the house to the car, or from the car to the lakeside, especially on my own.

The other issue is weight.  Lifting a 64 lbf ship is out of the question, as is kneeling by the waters edge (at my age and infirmity).  I have already stated that the car park at our lake will not allow trailers, and there is a 2 metre height restriction bar at the car park entrance - so no top box, even if I could heave the boat up there.

The object of this project is to be able to own and sail a mega sized dreadnaught.  I believe it is possible, but only by using ingenuity and improvisation.