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Author Topic: Bob's H.M.S. Polyphemus  (Read 208408 times)

Ian K

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #350 on: June 14, 2013, 12:34:44 pm »

Hi Bob,
 
You can get Por 15 tank sealer from frost.co.uk
 
Regards
 
Ian
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Bob K

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Re: H.M.S. Polyphemus (1881), now a submarine
« Reply #351 on: June 14, 2013, 01:09:16 pm »

Thanks for the link Ian. 
However their blurb on POR 15 tank sealant says "Not Suitable for Plastic and Fibreglass Tanks."
Maybe try the Captain Tolleys first, then find a latex rubber to coat the tank innards with
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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #352 on: June 15, 2013, 12:24:22 pm »

Did you use a Sika primer on the lexan before applying the Sikaflex?

Bob K

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #353 on: June 15, 2013, 12:53:44 pm »

Did you use a Sika primer on the lexan before applying the Sikaflex?

No.  Interesting.  I cleaned and prepared both the Lexan and fibreglass hull as if for painting primer, then followed the instructions supplied with the Sikaflex 221 cartridge.  There was no mention of a special Silka primer, or that it may be required.
 
Looking at the online info for that one-part primer now the primer is for porous or high moisture content surfaces and for ease of brush application.  The later is odd as the sealant is a nozzle cartridge.  221 is an "adhesive and sealant", the spec making no mention of a special primer.
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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #354 on: June 15, 2013, 09:00:35 pm »

I depends on the use, Bob. If it's underwater then they advise the use of a primer. they also advise the use of a cleaner before application of any sealant. I expect this to remove any possible contaminants, especially grease, isopropyl alcohol usually works for me, but if you have any doubts it's probably best to use their cleaner.

http://usa.sika.com/dms/getdocument.get/34823a6c-1669-3622-a3f4-eafbcb59173c/pds-cpd-SikaflexSealAdhPrimers-us.pdf

It's like many things e.g. a normal model boat made from wood, resined and painted will stay pristine for years. Try the same technique in a model sub, and you'll see problems occurring very quickly, because the coating is having to withstand complete submergence, higher expansion and contraction rates, and hydrostatic water pressure.

Bob K

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #355 on: June 15, 2013, 10:12:20 pm »

The data sheet for 221, which I found ealier today, quotes "Resistent to fresh water", although its general sales description extols its waterproofing qualities with no mention of primer.  The max depth of the tanks are no more than the almost horizontal prop shaft outers, fitted in the usual way for model boats, without problems.  The last sailing was well over an hour before it suddenly failed.
Pressure should be no more than in a normal deep draft hull, until it sinks.
 
My error was in not going for 3 mm fibreglass sheet, bonded with matting reinforced resin across all joints.  In the end it would have been much stronger and lighter.  I used almost 2 cartridges of 221, so added a lot of weight whilst coving much of the clear Lexan and losing my aim of visability.
 
That's now water over the Bridge (and wheelhouse).  My aim now is to seal the tanks via the only access remaining, the vent slots.
 
Has anyone used Captain Tolleys Creeping Crack sealant, from marine chandlers?
 
 
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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #356 on: June 19, 2013, 11:13:54 am »

Bob,


Was perusing some old model boats magazines looking for an article and found another model of HMS Polyphemus in 1:60th scale.  Won the C2 class gold medal at the 1988 Model Engineering Exhbition.  There's a couple of Photos and a very brief desription.  It's in the April 88 issue, not sure if you have a stash of old mags but if not drop me a PM and we can work something out
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Bob K

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Re: H.M.S. Polyphemus (1881), in for refit
« Reply #357 on: June 19, 2013, 12:40:03 pm »

In for refit

E2V:  That is the original model from which this hull is taken from.  Amazing build.

Everything is disassembled and drying out, waiting to see what permanent damage done to the electrics etc, and for the Captain Tolleys Creeping Crack Cure to arrive.
Worth trying.  A chandlers solution.
See demo movie http://www.captaintolley.com/movie/movie.html

As said before, I have had three fair length lake runs with minimal ingress before the failure at Black Park. 
Hopefully this fix will be effective.  If not then try liquid rubber.

Photos from successful one hour run at Alfold event, with thanks to Guy Bagley.


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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #358 on: June 19, 2013, 08:24:38 pm »

Have to say its a stunning model even tho the pictures in the magazine were only black and white
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Bob K

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #359 on: June 19, 2013, 09:37:02 pm »

Front cover picture of that magazine feature in colour.

The model by Jon Hollis was indeed amazing, and won several awards. 
If I can finish mine a tenth as good I will be well pleased.
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Re: H.M.S. Polyphemus (1881), autopsy
« Reply #360 on: June 26, 2013, 06:46:18 pm »

post sinking damage

After the surprise sinking in 6 feet of water two weeks ago I carefully rinsed innards with tap water and allowed two weeks to thoroughly dry out.

The 40 MHz Rx, ACTion P94, servos and 5V SLA appear to have survived. 
However, the motors, 2 x 12V battery packs, 12V air pump, solenoid, plus control switches (that were solidly waterproofed but only from the outside) are all ex parrots.   >:-o
 
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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #361 on: June 26, 2013, 08:50:19 pm »

post sinking damage

After the surprise sinking in 6 feet of water two weeks ago I carefully rinsed innards with tap water and allowed two weeks to thoroughly dry out.

The 40 MHz Rx, ACTion P94, servos and 5V SLA appear to have survived. 
However, the motors, 2 x 12V battery packs, 12V air pump, solenoid, plus control switches (that were solidly waterproofed but only from the outside) are all ex parrots.   >:-o
 


I feel for you Bob, loosing batteries and motors like that is more than annoying. A few years back we had an motor fire in our springer tug submarine, the water cooling tube wrapped around the motor got blocked and the motor seized. Luckily the fuse blew before it took out the ESC but the first thing we knew about it was a puff of smoke coming from the periscope! We got it back in and lifted the lid to see the entire inside go up in smoke! The only thing salvageable were the batteries and the ESC! We repaired it with a new motor and rx equipment but she preceded to do it again luckily only taking the motor this time. She is now retired!
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Re: H.M.S. Polyphemus (1881), the Glug Glug Box
« Reply #362 on: June 26, 2013, 11:31:14 pm »

Thanks Nick  %)   Luckily I am sufficently determined (or pig headed) to persist in getting this working, eventually, so apologies that this thread may go on for a while.
 
Perhaps I should buy replacement bits for those that failed in sets of three, just in case the Captain Tolleys does not cut the mustard.  If all else fails I can always fill in the ballast tank slots, but I have had nearly three hours charging around semi submerged in the water to start enjoying the possibilities of a deep draft racing raft.   :D
 
See http://www.hitrecord.org/records/313435
 
 
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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #363 on: June 28, 2013, 02:05:48 pm »

I can rebuild the airpump if you send it to me.

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #364 on: June 28, 2013, 03:01:58 pm »

Deep thanks for the offer Andy.  That pump came all the way from the States.  At present the 12V side of the electrics look to be "Pining for the Fjords", even the swiches and connectors are corroded.  I need to unwire the pump and connect it to a good 12V source to be sure. 
Fingers crossed.
 
Retrospectively it would have been far more sensible to scratch build a USS Kalamazoo twin turret monitor.  Only one solid watertight hatch needed. 
1100 x 180 mm at 1/96, twin shafts, almost zero freeboard but a fixed draft and therfore very simple controls and minimal joints to leak.
 
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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #365 on: June 28, 2013, 03:17:46 pm »

In all fairness, Bob, I'd have gone about the project in a different way. You treated it as a surface ship with the hatches bolted down. I'd have treated it like a submarine which didn't have to fully submerge.

Put all the equipment in a watertight cylinder of sufficient displacement, streamline the power system down to one battery pack, and use a single, centrally placed ballast tank (nuke the saddle tanks). Holes could be let into the bottom of the hull to make it free-flooding.

This would be much lighter to cart around, easier to service, as the cylinder can be made removable and much easier to keep watertight. Also should you get rammed by another boat, your boat will remain afloat, as the outer hull is just a shell.

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #366 on: June 28, 2013, 07:03:07 pm »

Already been through this…..

At the start I did try the 100 mm tube module from my Engel 212A but that was too deep to fit the hull, and nowhere near large enough volume to contain the equipment.  About a third of the hull volume is drainable water.  Weight is more a function of internal equipment and depth of draft.  .

Prior to the materials/adhesives failure it has been a successful build, and worked well until the bulkhead joints failed.  The design requires three voltages.  Slow turning large props, an effective large pump, plus funnel 'smoke'.
 
Remedial solutions would be greatly appreciated.  When I can overcome the materials failure I should be back in business.
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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #367 on: June 28, 2013, 07:24:52 pm »

I know, but I keep pushing because I think your design is flawed. Sorry.
 
I've had a good look at most of the boat in the pictures, and the equipment you're using, and I reckon you can get everything you need in a fairly small tube. 70-80mm diameter is sufficient- I'm sure that will fit- no?

For a start, you don't need very big servos for this model. 9 or 10 gram servos would be quite sufficient to actuate the rudders. The cheapest models from hobbyking are little beauts and cost a couple quid a piece. I use these in model aeroplanes of up to four foot wing span, and they work great. http://www.hobbyking.com/hobbyking/store/__16257__HK15178_Analog_Servo_10g_1_4kg_0_09s.html

Also if you use some controllers with modern surface mount components, they take up a lot less real estate.

Lead acid batteries can go in the drink.

All the different voltages can be largely harmonized, by careful selection of motors. The mister unit is the elephant in the room, but I did recommend a boost converter for that. If you're worried about noise from the unit whack it in an earthed steel box.

The mister unit could be placed inside the ballast tank or in the free flood area, and get shot of that heavy bulky box it comes in- try and make items do two jobs.

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #368 on: June 28, 2013, 10:25:20 pm »

Bob,
I must agree with Subculture.
I have known several good modellers try and fit internal ballast tanks and the majority have leaked after a fairly short length of time.
I put this down to several factors:
The different materials all have different coefficients of expansion.
The different materials each have their own individual strengths.


These two factors seem to combine to cause small leaks after a while.


The sucessful ballast systems that I know of are made outside of the model and fitted as a seperate unit(s).
This is for pumped and free flooding.


Bob
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Bob K

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #369 on: September 04, 2013, 01:48:24 pm »

Yes, it would have been a lot easier to build a high freeboard tug.

However

After assessing the water damage from 6ft deep I have been getting replacement electrics for parts damaged.  Mental note to get quality servos in future, esp those that have seals on the shafts. 

Next onto the Captain Tolleys Creeping Crack Cure.  This stuff is like a cross between a multi-material CA and penetrating fluid.  Quite thin, intended for cracks rather than gaps.  I used a 4mm silicone tube to access inside the hull voids.

Hull right way up, went in without apparent dripping through.  OK.

Hull inverted, using the ballast vent slots, several places where the fluid dripped through.  Drained off surplus.  It thus appears that the slightly sprung joints are between the top bulkhead edges and the sealed under deck.  So now at least I know where the problems are. These are joints 15mm above the deep-draught waterline so not pressure bearing.

Leave 24 hours then reapply.  If nothing drips through I have two coats of a strong adhesive seal.

Design

Had I make the bulkheads from f/glass and not used that duff mastic I would not have the problems.  Far too much equipment to fit into a 70mm tube, even if I dumped the sound system and mister. 
I was looking at the internals of a large Engel sub at the weekend.  Similar compartments and screw down acrylic hatches. Engel have used f/glass for the compartments though.

This ship had had three one hour sailing sessions before the accident, and performed very well.
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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #370 on: September 04, 2013, 10:22:25 pm »

Bob now you have gone this far would it be worth considering a bag inside the tank.
Belt and braces!!
Use what the sub boys use and should be sorted.


Bob
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Bob K

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #371 on: September 05, 2013, 01:10:51 pm »

Good idea Bob, unfortunately the only access to those compartments now is through the 5 mm vent slots.  In any case I am going to have seal those compartment joints.
 
The three stage plan is:
1)    Use Captain Tolley's penetrating sealant.
2)    Coat the inside of the tanks with liquid rubber.
3)    If all else fails, f/glass in the vent slots for a fixed waterline hulled 'surface runner'.
 
Step 1, then 2, lastly if I have to go to 3 I will still have a working vessel, albeit without variable depth trim.
If I have to lose the vent slots the hull reverts to 'standard' with only prop shafts and rudders penetrating.
The hatch covers are gasketed screw-down, same as the big Engel's.
 
Fingers crossed  :-))    Polyphemus will be sailing, hopefully in variable depth mode.
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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #372 on: September 05, 2013, 04:09:20 pm »

I should mention re my earlier post that none of the three steps involve scrapping the model and starting again.  I should have used f/glass bulkheads with reinforced f/glass for the joints, but you live and learn.
 
The joint leaks now identified are hairline, anything larger and she would not have sailed over an hour before the low freeboard bouyancy became affected.  I am being positive and optimistic.  This is a major R&D project.
 
 
 
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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #373 on: September 07, 2013, 10:34:14 am »

Second internal application of penetrating sealant, swilling around, syphoning out surplus after 1/2 hour.  This time nothing coming through.  Brush coated sealant into compartment side of joints.  Wait 24 hours to cure off.
Tomorrow I will fill the inverted-hull ballast tanks with water and leave to stand overnight.
 
Whilst the original mastic recommended is flexible and secures the parts, it does not bond with Lexan hence the hairline leaks. The Tolley's should penetrate these fine gaps and bonds to "Perspex, fibreglass," etc etc.
 
New servo for the forward rudders now operational.  Next repairing the control panel, replacement switches arrived.
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Re: H.M.S. Polyphemus (1881), hull rework
« Reply #374 on: October 02, 2013, 04:23:32 pm »

To try to avoid flak I am only posting successful stages in the repair / rework stages.
These are taking time as I am being careful and running trial tests before each stage.

  Captain Tolley’s

After two applications of Captain Tolley’s Creeping Crack Cure the hull appears leak free.  Flooding the inverted ballast tanks via the inlet slots, the tanks hold water without the level dropping over a long period.  Subsequent examination showed no sign of internal ingress. 
Aye aye for Captain Tolley !

  Liquid Rubber Lining

Just to make absolutely sure I then coated Plastidip “Liquid Tape” around all the inside surfaces of the tanks.  An adhesive air-drying synthetic rubber insulator, lining the tanks.  When it came I found it was slightly too thick to pour, so after contacting them I ordered 1/2 litre of their special thinners.  It didn’t need much to achieve an ideal just-runs viscosity that could be slowly swilled building up layers of rubber.



  Bilges Alarm System

Because of the ultra low freeboard, and being trebly cautious, I sought the advice of Hunter Systems having had excellent results with their bilge control systems.  It turns out that their controller sensors are effectively on / off and can be multiple connected.  Six sensors, one in each dry compartment, connected to a single controller.  Instead of a pump bright flashing LED’s are activated if any of the six bilge sensors detect water.

All rudder tubes end above the waterline and lubed as per the prop shafts.  No problems there. 
Screwed down 3 mm thick hatches are seated on neoprene gaskets with silicone grease, similar to the big Engel subs.
 
After further tests I will then rework the internal electrics, including fitting a much better solenoid valve to vent air from the tanks.
 
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