1/72 Victoria Class Submarine

[Slats]

Every day is a school day.

Andy, between you, Joel Stadnick, and Merriman - we're spoiled for choice.

Thanks again.

J

[Subculture]

Every day is a school day.

[Slats]

Carbon fibre is also a superb radio shield, meaning you will have to run an external aerial. Have it moulded in glass, the weight difference will be marginal. Only use carbon for aeroplanes, where the high strength is beneficial, complete overkill for a sub IMO.

Amazed at the shrinkage you report. I've never seen serious movement on any of my glasswork, and I use mostly polyester resin- high shrinkage. But I do strap or peg the mouldings. I'm assuming John used epoxy resin. Haven't done much work with this type of resin, but what I have done suggested bugger all movement once cured.

Wow - learned something Andy- had no idea about the Radio shield. - Many thanks
I think he is heading back to GRP.

Cheers

J

[Subculture]

Carbon fibre is also a superb radio shield, meaning you will have to run an external aerial. Have it moulded in glass, the weight difference will be marginal. Only use carbon for aeroplanes, where the high strength is beneficial, complete overkill for a sub IMO.

Amazed at the shrinkage you report. I've never seen serious movement on any of my glasswork, and I use mostly polyester resin- high shrinkage. But I do strap or peg the mouldings. I'm assuming John used epoxy resin. Haven't done much work with this type of resin, but what I have done suggested bugger all movement once cured.

[Slats]

By my Dead Reckoning, a U class boat(Victoria) was 230.5 ft. long. At 1/72 scale that puts her at around 38" long. Very Nice indeed. I find my envious eye studying the pictures. When will you get it did you say???

just to give you boys an update on this.

There are a few problems Jon is ironing out with the hull.
Boat No.1 which I received bowed outwards significantly from her beam in both upper and lower hulls - this meant she shrunk length wise. The upper and lower beams moved outwards at different rates too.

As this boat is Carbon fibre all my skills of heating to get her back into her shape failed. Carbon fibre for all its strength benefits, IMHO, has some big drawbacks, and as Jon told me you need a lot of heat (oven temperatures) to get her back in shape - way way beyond my skill base boys. I can also tell you working with Carbon fibre (cutting and sanding) is the biggest PITA too.

The boat is back with Jon in Canada, whom might redo it in GRP, or use some other molding methods.

All up - its a great first attempt - the detail is stunning, but the boat needs some structural improvements, which I'm sure Jon will achieve.

Best

John

[greenman407]

By my Dead Reckoning, a U class boat(Victoria) was 230.5 ft. long. At 1/72 scale that puts her at around 38" long. Very Nice indeed. I find my envious eye studying the pictures. When will you get it did you say???

[alad61]

I'll be there for sure as I have booked our accommodation and paid the fees to Triple S. I know what else doesn't help with the spelling and grammar and that is using the virtual keyboard on my HTC phone...BLUSHER

I've been checking its class on the web. I like its look and I am impressed about the amount of free board. It must have rolled some in anything but calm seas? Can't wait to see what you do with yours.

[Slats]

Struth I reckon I actually understood all that!! By the way John that is a damn fine looking hull. The modeler in me would love to detail n weather that kit. Not to mention assemble and play with the finished article. You sir are a luck man.

Your grammar sucks too Alec, but that is coming from a "luck man" as you put it, whom fights dyslexia daily!
Glad you understand Alec - that is about as technical as I can get. Still electrically challenged.

I do hope to see you at the Central Coast Regatta in October.

Best

John

[alad61]

Struth I reckon I actually understood all that!! By the way John that is a damn fine looking hull. The modeler in me would love to detail n weather that kit. Not to mention assemble and play with the finished article. You sir are a luck man.

[Slats]

Yeah he does nice work.

Dan - no problems - I like good technical discussion.
I have to agree with David however. It is so simple to start trimming submerged.
It's also far better to work out the diameter of the SD before you start buying gear. In my early days, the required WTC size - was what I could buy to fit inside the boat. My early boats were too darn heavy. A lot of that weight had to do with not only dealing with a Ballast tank that was too big and buoyant (read, lead required at surfaced to make her stable), but the diameter of the buoyant tube above the surfaced water line and also that diameter down low added to more stability issues and more lead required.

Matt Thor I owe my early education too in regards to mass momentum in the water. Matt's message - the more weight, more momentum in a straight track, the harder it is to turn.

In summary, the more your WTC diameter fills the inside diameter of your boat, the more your boat behaves like a dry hulled submarine, thus loosing a fair bit of the weight / maneuverability advantage/s that the wet hull approach offers.
If your WTC extends down too low you have a buoyant area down low that causes stability issues requiring lead. Up top if you have a the WTC venturing over the surfaced waterline, you have a buoyant area requiring the Ballast tank to overcome this buoyancy as well as the sub material itself above the surfaced WL.

In conclusion - from the plans I have seen of the surfaced WL in respect to the centre axis of the boat around the prop shaft line. A 3" SD will venture some 8mm above the surfaced WL. A 2.5" will be 4mm below it.

David the 2.5" will be the go for the Victoria Class.
I just need to try and work out the ballast tank size.

J

[bcliffe]

John A,

John E has been keeping me up to date on this project over the course of time. The detail he has put into the boat is incredible. I believe these images are of the hull enroute to you. Enjoy. Look forward to seeing your project come together.

[He Who Shall Not Be Named]

Dan,

Most appropriate to this thread, if John agrees, that is. His thread.

You're methodology works fine. However. If you start the trimming process submerged, the only thing you have to change, once you empty the ballast tank, is the vertical location of some or all of the foam to achieve designed waterline. All that providing your ballast tank is either of the correct volume, or is bigger in volume than what you need.

Agreed: a slightly bigger than needed ballast tank is a good thing. Just a bit more energy is required (and wasted) to empty it completely, that's all. And, of course, you have the extra real-estate in there to accommodate it.

We now rejoin John's VICTORIA project ... now in progress.

David

[roedj]

If the thing has a high freeboard then we want a narrower SD so we don't put any ballast tank sticking up into the air where it becomes part of the problem, not the solution.

David

David,

I hope I'm not hijacking a thread here but your statement raises an issue I've had bouncing around in my head for some time now and why I believe larger-than-needed ballast tanks are really OK. - even if they're above the surface water line.

Here's how I trim a boat:

Part A
Put the complete (complete as in everything - batteries, electronics -everything) boat in water. Make sure ballast tank is completely empty. There are three possible outcomes:
1) Boat sits exactly at surface water line - you're really lucky (or a great planner) - proceed to Part B
2) Boat sits high - add weights as down low as possible until boat sits at surface water line - proceed to Part B
3) Boat sits low - add flotation (usually closed cell foam) below surface water line until boat sits at surface water line - proceed to Part B

Part B
Completely flood ballast tank. There are four possible outcomes:
1) Boat sinks to slight positive buoyancy - just a tip of sail out of water - if this is what you want, proceed to Part C
2) Boat sinks to just below water line - let's call that neutral buoyancy - if this is what you want, proceed to Part C
3) Boat sinks but there's still a lot of boat out of the water. Two choices:
a) Leave it like that. You've created a sort of dynamic diver - run it full throttle - dive planes set to dive - proceed to Part C, or
b) This not what you intended - add more weight as low down as possible until just a tip of sail is out of water - you'll have a lower than desired surface water line - but it will work - proceed to Part C
4) Boat sinks like a rock. Two choices:
a) Remove all the internal works - paint nicely - place on mantle - all done - Do NOT proceed to Part C, or
b) Add more flotation above the surface water line until boat is slightly positively buoyant - just a tip of sail out of water - proceed to Part C

Part C
Go run boat - have fun.

Actually I prefer situation Part B, 4), b) - boat sinks like rock. That way I can, by adding foam above surface water line, raise the center of buoyancy above the center of mass for a more stable boat when submerged. In this regard, I like bigger-than-needed- ballast tanks.

How crazy or wrong am I?

Dan (loins girded)

[Slats]

If the thing has a high freeboard then we want a narrower SD so we don't put any ballast tank sticking up into the air where it becomes part of the problem, not the solution.

David

Exactly which is why I'm thinking 2.5" for the Victoria. I'll have the boat soon and get to work.

J

[He Who Shall Not Be Named]

If the thing has a high freeboard then we want a narrower SD so we don't put any ballast tank sticking up into the air where it becomes part of the problem, not the solution.

David