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Author Topic: Oleg Strashnov hull moulding  (Read 5289 times)

nmbrook

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Oleg Strashnov hull moulding
« on: June 14, 2016, 08:21:28 AM »

Currently in the planning stage is a fully functional model of the crane vessel Oleg Strashnov.I plan on producing a pattern then mould and then producing a fibreglass hull.I have experience with composites but am sat on the fence as to which is better,Polyester or epoxy resins?I know epoxy is easier to bond to(not planning on using isopon p40 everywhere) but I have been told epoxy can be brittle.I would have thought that would depend on the reinforcement used?Can anyone shed any light on this?


Kind Regards


Nigel
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tweety777

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Re: Oleg Strashnov hull moulding
« Reply #1 on: June 14, 2016, 04:44:04 PM »

Hello Nigel,

Nice project!!!
I've made some welds on the real thing during my intern ship, she's really big, so big actually she almost took the door off the construction site with her into the water during her launch.

Epoxy is more expensive and most be mixed in the correct amounts but is stronger and more durable then polyester and epoxy doesn't smell while hardening.

Have you given any thoughts to the propulsion?
She has 2 azimuth thrusters at the stern and 2 more retractable in the bow to aid the normal tunnel bowthruster.

Greetings Josse
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Brian60

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Re: Oleg Strashnov hull moulding
« Reply #2 on: June 14, 2016, 05:18:11 PM »

I look forward to following this build. Epoxy v Poly hmm. The only advice I can give is poly, I worked with it on various projects on and off for 35 years, its easy to work with if smelly, I have never used epoxy and wouldn't want to begin a large project without trying it on something small and disposable if it goes wrong. I know what I'm doing with poly I don't with epoxy - in a nutshell.

I'll be interested in propulsion as well seeing as my current build has a retractable azimuth prop at the bow, always good to compare!

Check out Pioneering Spirit for a big crane ship. Built from two converted oil tankers joined like a giant catamaran, she's just undergone loadtests, where 2 of the 12 lift beams lifted 7200tonnes :o Plenty of photo's on the net and videos on Youtube.

Umi_Ryuzuki

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Re: Oleg Strashnov hull moulding
« Reply #3 on: June 15, 2016, 04:58:39 AM »

I am given the impression that Polyester resins are better for molding and hull production.
Fiberglass matte has an adhesive that binds the matte as sheets, and the polyester resin
disolves that adhesive and then rebinds all the matting. Epoxy doen't disolve that matte
adhesive, and may adversely affect the finish product.


Mailline Vaargroep had a version that their club members built.
Unfortunately, it was lost when their trailer was stolen last year.  <:(

nmbrook

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Re: Oleg Strashnov hull moulding
« Reply #4 on: June 15, 2016, 08:25:29 AM »

Thank you for the interest everyone :-)


The model will be built to the scale of 1/100 which will make it 1830mm long,470mm wide across the sponsons but only 183mm deep amidships.To this end I am after rigidity without lots of internal bracing and am considering possibly incorparing a kevlar weave into the base.This would provide more rigidity and support for batteries etc,but at the same time keep the weight down.Another alternative is a layer of core mat.I am not sure at the moment as to the compatibility of these two materials with the two resins.One may determine the other %) .


A little more about my plans,I have 4 unused marx schottel drives and extension pieces (ala Seabex one).Two most certainly be used at the stern,but the two retractable thrusters amidships cause a problem.It is my intention that the model will partially submerge as the real vessel using either Engel or homemade tanks.Four of these will be employed to enable full control of the trim.
Because of the much higher waterline in lift position and the need that the top of the Schottle drives must be above waterline the retractable thrusters are not really a viable working option,however I will fully investigate this when I delve deeper.


Work in earnest will not start until My Fairmount build is finished,but I am in contact with Seaway Heavy Lifting and have already received some drawings but am awaiting hopefully some sectional views at frame stations.


Oh and I have seen the video of the door collision at launch :}


Kind Regards


Nigel



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tweety777

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Re: Oleg Strashnov hull moulding
« Reply #5 on: June 15, 2016, 04:24:39 PM »

Hi Nigel,

That will be a huge build!!!

Have you made any calculations at all for how much water you'll need to get her to the lifting waterline?
I say this because I know there is a stretch of hull in the middle, about 5-8m wide, housing all the pumps, all extra hull width is ballast tank top to bottom.
There is a reason for that: when the ship is at normal waterline it has reached maximum waterline surface area, this means that for every meter extra depth you'll need to add more and more weight.
This ship is even worse in this sort of situation because of the overhanging ballast tanks, but this extra width is very needed for extra stability when lifting, along with the added weight of the ballast.

In short, I think it's safe to say that Engel tanks are not going to be enough, not 4, and quite possibly not even when you fill the entire hull with these tanks because of the moving bulkhead mechanism.
Add to this that a hull this size in itself is way to lightweight to reach the waterline so you'll need to have quite a bit of ballast in there for the normal waterline alone.

It would be really great to bring this project to that level but I strongly recommend making some calculations before you start building.
I calculated the weight, both at normal waterline and at lifting waterline, the difference is bizar:
Normal waterline: 22,77kg
Lifting waterline  : 92.89kg
You'll need to be able to pump 70kg's of water in the hull to get her from normal waterline to lifting waterline, adding over 3 times the normal weight to get there.
This calculation is based on fresh water, should you want to sail in seawater you'd need to multiply this numbers by 1,025.

Greetings Josse
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nmbrook

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Re: Oleg Strashnov hull moulding
« Reply #6 on: June 15, 2016, 05:34:28 PM »

Thank you Josse :-)


GOOD POINT!!.The method to reach the end goal does need rethinking.I admit not researching the amount of water that would be required,my plan being to mould the hull than adding measured containers of water to achieve the result giving me the volume of necessary ballast tanks.I know the lifting displacement is 79,000 tons but can't find the cruising displacement.
Possible rethink and incorporation of saddle tanks in the model replicating the full size vessels and the use of pumps.The three compartment structure is not ridiculously hard to mirror in model form.

Kind Regards

Nigel
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nmbrook

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Re: Oleg Strashnov hull moulding
« Reply #7 on: June 26, 2016, 08:59:06 PM »

Still very much pondering the ballast situation and researching other semi submersible builds.I did find a Mighty Servant 3 build by a French chap that made me pause for thought.
My get out of jail card with the ballasting is just to build the ship so she sits down on her sponsons.Most photos on the net,even when she is cruising,show her lower down in the water.This will still mean using water as she will be displacing as much as 80kg.I fear if I made her higher in the water,she would roll when the crane jib was swung outboard.
The Mighty Servant build relied on the fact that all tanks were free flooding but didn't take water onboard unless the vent to the outside was opened.
This leads me to the question,if the inboard tops of my Schottle drives are below the waterline,but the motor and servo etc are within an airtight compartment,would I still get water ingress??


Kind Regards


Nigel
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cos918

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Re: Oleg Strashnov hull moulding
« Reply #8 on: June 26, 2016, 09:23:16 PM »

Hi Nigel
Do you want the crane to be able to lift and if so how much . Then work back from there .
As for the schottle you will get water in .The vertical shafts are not the best quality . On option might be to look at Graupner schottle drives .better quality .


john
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derekwarner

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Re: Oleg Strashnov hull moulding
« Reply #9 on: June 26, 2016, 11:11:21 PM »

Nigel.......most marine heavy lift equipment uses high speed transfer of water [ballast] within the vessel hull to compensate for the progressive off axis moment created when lifting of the load

The original positioning and alignment of the hull is calculated so when the load is lifted, the hull aligns to the predetermined level of 'flatness' back to the surface of the sea

These days this is achieved by sat-nav computer aided systems to control the vertical, fore & aft and athwart physical alignment or positioning of the hull

This would be achievable in model applications, however would be a box of BLACK ART thingies and water control valving

Derek
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nmbrook

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Re: Oleg Strashnov hull moulding
« Reply #10 on: June 27, 2016, 05:53:42 PM »

Thanks Derek and John


I would rather use the Marx Schottels if at all possible as they cost me several years back.The Graupner and now CEM schottles are probably better quality,but the smallest is a tad too large for 1/100 scale and are still not properly watertight.Only ones I have found that are properly sealed are Aeronaut? ones.Fully machined metal but 700 Euros each!!!!!


I plan on doing the heaviest lifts with the crane over the stern(pretty much as the original),it is the weight of a tubular brass jib that causes concern.I realise I am going to need scope to shift water around in the hull,just don't want to have to do it to traverse the crane %)


Kind Regards


Nigel
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cos918

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Re: Oleg Strashnov hull moulding
« Reply #11 on: June 27, 2016, 07:11:17 PM »

Hi Nigel
I know what you mean on the cost of the schottle drives .
On the crane have you though about working in reverse .
Build the crane first to the strength require to do the heaviest life you want to do . Then make a trail hull out of a few old planks and see what is required when you make your hull . You might need to increase the draft etc.


John
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nmbrook

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Re: Oleg Strashnov hull moulding
« Reply #12 on: July 04, 2016, 07:34:22 AM »

Hi John


Been busy with work and in deep thought as well :o I had actually thought about doing the crane first,predominantly to overcome some of the construction challenges.This morning a bit of a eureka moment.rather than worry about ballast transfer to overcome the crane traversing,simply counterweight the crane itself.
The winch room is roughly a one foot cube! so plenty of room the add weight in it's rear.I am also thinking of an alternative to brass for the jib,this will be around 1.2mtrs long,so in brass will be a substantial weight fairly high up even when cruising.I did think ABS tube (the main tubes work out at 8mm diameter)but have thought about carbon fibre tube,even lighter but stronger than ABS.If I spigotted the joins with carbon rod and used epoxy glue,I should imagine this would result in a very stiff structure.
So yes,it looks like crane first is the way to go,the unit can be built entirely including any necessary counterweighting and would give me the all up weight that will in essence be plonked on the stern ok2


Kind Regards


Nigel
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tweety777

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Re: Oleg Strashnov hull moulding
« Reply #13 on: July 06, 2016, 04:50:56 PM »

Hi Nigel,

Sounds like quite a bit of thinking going on, keep that going, you'll need it on a project this size.

For the structure underneath the crane, please do keep in mind that all the mooring gear of this ship is located below decks, also under the crane.
It would be useful to have at least some means of mooring when you want to have yourself a coffee break or so.
That very means to moor the ship might well turn out to be located in one of the necessary frames to keep the cranes forces at bay if you don't look into the location before deciding where the frames should be.
A thick deck will certainly not suffice here, you'll need some real heavy framing in 2 directions to transfer the forces into the hull and they need to extent to the edges of the hull.

Brass may be heavy but it's also far stronger than ABS and therefore much more suitable.
I don't know just how strong carbon is, you could certainly give it a try.
Otherwise I think you'll do fine with a brass crane, the hull is very large and gives lot's of stability on it's own.

Greetings Josse
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Under construction: diving support vessel Well Enhancer scale 1:75, a very big and very ambitious project that keeps on going and going till I finally solve all ambitious things about it and have it working.
A day without learning is a lost day

nmbrook

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Re: Oleg Strashnov hull moulding
« Reply #14 on: July 07, 2016, 06:41:43 AM »

Hi Josse


Yes already thought about the rear section.I propose to run the crane pedestal all the way down to the mooring deck as in the original.This will allow me to beef the structure up underneath the mooring deck.The pedestal itself works out at 280mm diameter even at 1/100 scale!!!!
Racking my brains if it would actually be necessary to be able to remove the crane,or make it so the winch house has a removable panel to allow access for servicing the motors.I am going to replicate the roller system on the original for the traverse.This comprises of feet with rollers that sit on an outer ring with four clamps with inverted rollers that pull on the underside of the ring.Utilising small ballraces for the rollers hopefully will mean smooth turning.


Kind Regards


Nigel
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tweety777

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Re: Oleg Strashnov hull moulding
« Reply #15 on: July 07, 2016, 04:21:00 PM »

Hi Nigel,

I would suggest to add frames under the mooring deck as well, all the way to the bottom actually, because otherwise the forces are forced around very sharp corners.
Imaging forces as if it were water, all material being the waterway.
This would make things much easier.

Greetings Josse
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Brian60

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Re: Oleg Strashnov hull moulding
« Reply #16 on: July 08, 2016, 04:52:46 PM »

Nigel take a look at this facebook page. if you browse the photo's there are plenty of onboard shots, that will help with the close up detail when you need it.....


https://www.facebook.com/permalink.php?story_fbid=943205969134901&id=118879764900863

nmbrook

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Re: Oleg Strashnov hull moulding
« Reply #17 on: July 13, 2016, 07:57:01 AM »

Hi Brian


Yes I have visited this page,quite a good few pictures close up rather than from 500 metres like most on google :}


I am taking a slight detour with my plans after going through all my modelling stash(half of it has been in a storage unit for two years whilst we sold our house)
The schottle units will be going where they belong,in Seabex One.I got disenchanted with the kit several years back and it has sat since.Basically didn't live up to expectations,however the reality of just how much cash I spent on not only the kit but the radio equipment has made me have a long hard think(plus I have doubts that the marx drives have enough umpf to propel a vessel with around 80kg displacement).So this will be my next job after Alpine(that is a bit of a white lie,I have stripped the hull started work on sorting the various issues with it so I can take a mould of it to reproduce in GRP)


Kind Regards


Nigel
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Brian60

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Re: Oleg Strashnov hull moulding
« Reply #18 on: July 13, 2016, 08:46:19 AM »

Nigel I gave two Marx Schottels to Tug Kenny for his Seabex. It's now sailing I believe so you could ask him how powerful they are in use.

Tug-Kenny

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Re: Oleg Strashnov hull moulding
« Reply #19 on: July 13, 2016, 08:53:26 AM »


Funny you should be mentioning mine, as I am working on it as I speak.

She has not been the water so I'm unable to comment on power or manoeuvring capabilities.

She has lived on her stand for fear of damaging those expensive Schottles.

ken
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nmbrook

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Re: Oleg Strashnov hull moulding
« Reply #20 on: July 13, 2016, 03:32:00 PM »

I don't doubt the schottels performance in the Seabex which only displaces around 18kg but the original spec for the unit was motors of a maximum of 50watts.I have heard the original drivetrain is quite capable of producing a large 'bowwave' in the moonpool  {-) I have four 600bb turbos which I purchased as the recommended power units.Running anything bigger to help push the much larger and heavier Oleg will quite possibly result in stripping the gears.
The best plan I feel is to build the Seabex  in the meantime and save up to either buy a lathe or some of the superior drives from Bauer model.


Kind Regards


Nigel
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