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Author Topic: Bob's H.M.S. Polyphemus  (Read 208409 times)

essex2visuvesi

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #325 on: June 11, 2013, 07:44:12 pm »

Its sad to see a failure but no one can say you didn't stick with it and explore every avenue


A real shame as I really enjoyed this build.  Please carry on posting updates to the build
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Snowwolflair

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #326 on: June 11, 2013, 07:59:00 pm »

Bob
All I can say is she went down gallantly, and dare I say quite realistically. 
I like the idea of the foam to fill the sides, just add weight to make them neutral bouyent and then use a peristatic pump and a bladder in the flood compartment to change depth.
NB I have probably got a spare pump if you need one to try.
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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #327 on: June 11, 2013, 08:07:03 pm »

Hi Bob k


Sorry to hear about your near sinking, however the model is fantastic example of her period, hope you have her dried out and ready to go again soon. To quote everyone following this build thread, I love the build so far and look forward to seeing her one day in the flesh.
Good luck once again and fingers crossed it was a freak incident. :-))


Nick B
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Bob K

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #328 on: June 11, 2013, 08:50:48 pm »

Bob
All I can say is she went down gallantly, and dare I say quite realistically. 

You did have a ring-side view  :embarrassed: .  Thanks for the pump offer. First I need to get my thinking cap firmly attached.
 
Thanks all for your kind comments. 
She appears to be drying out well, so hopefully no major internal damage. 
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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #329 on: June 11, 2013, 09:36:27 pm »

Thanks, Bob, for posting the bad with the good during this build. It's been a fascinating journey - and it's not over yet.

Regarding the bond between lexan and sikaflex, the sikaflex website states that there shouldn't be a problem with a seal, especially given that there was no obvious UV allowed to damage the sealant.

It might be worth dropping them an email and seeing what they say about the failure of adhesion. I've no doubt they'll be fascinated by your experiments, and may be able to offer clues, an explanation or advice.

Andy
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derekwarner

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #330 on: June 11, 2013, 11:36:08 pm »

Bob K.......I too have read & watched this thread from day 1.........& understand your limited options as noted below & your disappointment
1. without destroying the hull......
2. the only realistic option at this stage is to seal off the ballast tank vent slots......
Having said this ...& as dreadnought72 says......I would also recommend talking with the SIKA people........ Derek
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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #331 on: June 12, 2013, 01:25:10 am »

having built many things twice what about pulling all the internals and starting with a new hull.. converting  to standard running will give you a ship, but not the ship you want!!!! to neat of a project to give up on it...
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steve pickstock

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #332 on: June 12, 2013, 07:03:03 am »

I am gutted for you. To have to make such a compromise at this stage must be heart-breaking. You have my sympathies.
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Shipmate60

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #333 on: June 12, 2013, 10:22:31 am »

Bob,
Please do not fill the gaps with gap filling foam.
This will add another different (far higher) expansion rate.
You must be gutted after all your hard work and development time.


Bob
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essex2visuvesi

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #334 on: June 12, 2013, 10:27:48 am »

Is there nothing on the market to disolve the sikaflex
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Snowwolflair

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #335 on: June 12, 2013, 10:30:04 am »

What about the substance that disolves bath sealant, its the same chemical base.
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Subculture

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #336 on: June 12, 2013, 01:05:21 pm »

Sikaflex is polyurethane based, you'll have to cut it out with a sharp scalpel, although I must say I'm perplexed why the bond is failing this way. I wonder if the prop of the materials is adequate, e.g. thorough degreasing with isopropanol alcohol, key the plastic with first (both the GRP and the lexan).

GRP sheet would be better, I would use polyester resin and chopped glass to join the sheet to the hull. You could make your own sheet up very cheaply by purchasing some 450 gram chopped strand matt, and resin, and laminating onto a waxed board.

Snowwolflair

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #337 on: June 12, 2013, 01:24:52 pm »

Sikaflex is not resistant to organic acids, alcohol, concentrated mineral acids and caustic solutions or solvents.
 What you want is a sealant remover with
Dimethyl Formamide(DMF) as a component, which works for silicone and Polyurethane (fingers, skin, bone, fiberglass, etc, so treat it with care). 
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unbuiltnautilus

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #338 on: June 12, 2013, 02:04:48 pm »

My first thoughts were rip it all out and replace with fibreglass bulkheads built to match what you have already created in lexan, but looking back over the build thread it would take a brave soul indeed to undertake that course of action.
How about an alternative, line your existing ballast tank longitudinal bulkheads with thin fibreglass sheet, bonded to the hull where it touches with a suitable adhesive. The only issue being if you already have a large amount of sikaflex or similar within the ballast tank hull joint, this would cause major issues bonding to the hull. IF you were able to bond to the hull, this would effectively seperate your ballast tanks from the lexan part of the structure, while the lexan bulkheads could carry on flexing when they feel they must, your fibreglass saddle tanks wont move. Difficult and only you know the build well enough but it would be a shame to lose that capability.
Red lines suggest where you could fit the fibreglass bulkheads.
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Shipmate60

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #339 on: June 12, 2013, 02:22:39 pm »

If you removed the ballast tanks you could use plastic bottles of the right size for ballast tanks.
Internal Tanks are terrible to seal for any length of time.


Bob
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Bob K

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Re: H.M.S. Polyphemus (1881), became a submarine
« Reply #340 on: June 12, 2013, 02:49:44 pm »

Thanks for all the ideas. 

Some further info:  Knowing how problematical getting a good seal has been, and the large quantity of sealant plus various adhesives now inside, the only practical way of removing the innards would be with a Rotacraft grinder.  Everything from the under decks downwards.  The sealant has set quite hard.  Bound to go through the hull though.

3 mm Lexan is very rigid, much more so than ply.  It is the hull that is thin, and maybe slightly twistable.  The hull and bulkheads were cleaned as if for painting.  The cut edges at least should have permanently bonded.

I like the idea of lining the ballast tanks with fibreglass sheet, but now the only access to the inside of the tanks is through the vent slots.  Liquid rubber ?  ‘Emergency’ tyre inflator liquid?  Air bladders? (if I can get them inside).

My thought of filling the tanks with sealing foam, before filling in the slots, was just to provide permanent buoyancy.  However, that would end submersibility.
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Bob K

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Re: H.M.S. Polyphemus (1881), not giving up yet
« Reply #341 on: June 13, 2013, 10:52:03 am »

Not giving up yet

I am going to try something before I seal off the ballast tank vent slots and resign to a surface runner.  It will either work, or not.

Looking at a chandlers site I came across “Captain Tolleys Creeping Crack Cure”.
http://www.yachtshop.co.uk/store/product/801/Captain-Tolleys-Creeping-Crack-Cure/?gclid=CKC7lfXK37cCFY3HtAodABUAIA
Designed for ‘real’ boats, to fix leaks in inaccessible spaces. 
ie:  Pour through ballast vent slots, swill all around tanks.
Anyone used this?

Also I am looking into liquid rubber, the kind of stuff used for sealing the primary layer of flat roofs or damp proof membranes.  Supposed to adhere to almost anything, but in any case should set as a continuous rubberised coating. 
Hopefully thin enough to pour rather than brush on.
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rmaddock

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #342 on: June 13, 2013, 10:59:30 am »

What about the stuff the pour into vintage car fuel tanks to seal them?
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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #343 on: June 13, 2013, 11:20:55 am »

or a liquid rubber swirled round to create a balloon inside the tanks?
Grendel
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tghsmith

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #344 on: June 13, 2013, 11:55:46 am »

fuel tank sealer is sold by POR15 over here, adhesion to lex test may be needed, its interesting stuff that reacts with the air, open cans must be used, unused product (waste) is set in water to stop ignition.. I did several motorcycle tanks a few years back with great results.. other products not so great... por15 includes instructions of how to remove and prep after other stuff was used and failed..
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essex2visuvesi

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #345 on: June 13, 2013, 02:54:13 pm »

fuel tank sealer is sold by POR15 over here, adhesion to lex test may be needed, its interesting stuff that reacts with the air, open cans must be used, unused product (waste) is set in water to stop ignition.. I did several motorcycle tanks a few years back with great results.. other products not so great... por15 includes instructions of how to remove and prep after other stuff was used and failed..


Sounds a lot like this stuff
http://www.shop4glue.com/fuel-tank-sealer-for-motorcycle-bike-car-lawnmower-petrol-diesel-alcohol-fuel-leaking-repair-rust-612-p.asp
When we did the zetor tractor restoration (See other thread) we had a small leak from one of the tank seams so used the stuff above... worked perfectly.  Was all very odd, the tank was tested prior to going to paint but then stated to leak when we put it back together. only thing I can think of is that somehow the seam weakened during the painting/baking.
Anyways 4 weeks on and still no leaks
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derekwarner

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #346 on: June 13, 2013, 11:51:43 pm »

Bob & E2V.......the product below has the name coding ..... Product Code: PETSEAL001Brand: StarLoc Hesketh Automotive Isn't Mr Starloc a member on MBM? ....or is this another similar trade name?.......I would be inclined to post an e-mail to the supplier as the data sheet suggests the product is for metal tanks........Derek
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Bob K

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Re: H.M.S. Polyphemus (1881), not intended as a submarine
« Reply #347 on: June 14, 2013, 12:27:36 am »

Thanks Derek and E2V.  I will investigate that.
I am still intrigued by liquid rubber or latex.  A thick balloon liner.
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essex2visuvesi

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #348 on: June 14, 2013, 08:57:57 am »

Bob & E2V.......the product below has the name coding ..... Product Code: PETSEAL001Brand: StarLoc Hesketh Automotive Isn't Mr Starloc a member on MBM? ....or is this another similar trade name?.......I would be inclined to post an e-mail to the supplier as the data sheet suggests the product is for metal tanks........Derek


We have some more in the workshop, If Starloc doesn't notice the thread then I'll do a test with some tupperware type containers next week
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steve pickstock

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Re: H.M.S. Polyphemus (1881), not giving up yet
« Reply #349 on: June 14, 2013, 10:35:35 am »

The poured and swirled latex liner sounds like a good idea but anything that goes by the name of
“Captain Tolleys Creeping Crack Cure”.
has to be in with a shout for the name alone.
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