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Author Topic: Welman build  (Read 16931 times)

Subculture

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Re: Welman build
« Reply #25 on: November 06, 2012, 08:50:56 pm »

I thought that is what I suggested in reply 20?

Anyway, you don't need aluminium bayonet rings, you can make a radial separation and just have the WTC slide in.

bbdave

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Re: Welman build
« Reply #26 on: November 06, 2012, 09:38:32 pm »

I see so just join the hull with magnets or the like over a wtc could be a plan that

Dave
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NFMike

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Re: Welman build
« Reply #27 on: November 06, 2012, 11:27:45 pm »

I thought that is what I suggested in reply 20?

Sorry, with his reply in #21 I thought it was a radial split in the middle of the hull being considered.

Subculture

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Re: Welman build
« Reply #28 on: November 07, 2012, 12:56:37 pm »

Magnets are an option. Not keen on them personally for this kind of thing, too weak and the two parts might separate, too strong, and you might end up a source of amusment for spectators wrestling with a wet hulled boat- akin to trying to grab a greased pig!

I favour either a machine screw fixing ( one will be adequate) or a simple bayonet locking mechanism. Have a look at a lightbulb fixing or those round tubs blank CD's are supplied in. That should provide you with a bit of inspiration for a simple latching design that you can fabricate inexpensively.

bbdave

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Re: Welman build
« Reply #29 on: November 10, 2012, 02:33:35 pm »

Made some progress this week finished planking the bottom half it has been glassed and taken off the formers both halves sanded and dry fitted not the best join but not the worst i've seen but some side bulges will be added later so by the time it's all joined and filled it should all come good. It needs plenty of resin coats inside and out to make sure the wood is sealed and to give me some sacrificial layers to sand down externally.


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bbdave

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Re: Welman build
« Reply #30 on: November 11, 2012, 04:49:18 pm »

Looking ahead I am toying with the idea of using the Thunder Tiger dive system buying off the chap on ebay the control unit and the pressure switch.


 I presume any 12v roll pump will work and any bladder? or are the TT ones ok i will need a motor for the pump unit i guess


Dave
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Re: Welman build
« Reply #31 on: November 11, 2012, 05:43:17 pm »

Some of the peristaltic pumps are painfully slow, leading to long dive times. The Welman shouldn't need a large dive tank if the conning tower is freeflood, but all the same, I wouldn't go for anything too ponderous.

The Neptune pump has a fairly good flow rate. Not sure about efficiency though mind you- the pump is directly driven, and as I recall relies on slippage of the motor spindle to slow it down.

An alternative is to use the switcher, ballast bag and pressure switch, but use a small geared pump instead. With a bag system the pump is working against very low pressures, which helps the life of the pump. These will give you a good flow rate, but are not self sealing, so you will need to make a pinch valve or fit a solenoid controlled valve. Pinch valve is easy to make and cheap.

bbdave

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Re: Welman build
« Reply #32 on: November 11, 2012, 09:00:44 pm »

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Subculture

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Re: Welman build
« Reply #33 on: November 11, 2012, 09:08:50 pm »

Yes, it's a just a basic relay switcher, with a built in failsafe. Think it also has a water detector, hook-up for the pressure switch and also a voltage checker (for a 12 volt system). Relay contacts are rated for 10A, so more than enough for any pump system you're likely to fit in the Welman.

You can use ordinary ESC's for pump control too.

bbdave

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Re: Welman build
« Reply #34 on: November 22, 2012, 09:44:02 pm »

Tonight has been spent sanding some foam to mould the front dome planning to do this on Saturday as i have to go to work so i'll have use of the workshop.


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bbdave

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Re: Welman build
« Reply #35 on: November 24, 2012, 04:42:37 pm »

Had a busy morning this morning i have joined the two halves using CSM and tissue to make the joint strong i covered my mould in plastic and gave it the same CSM and tissue you can see from the mould how much heat a small amount of resin produces but as it only needed to make one this wasn't a problem i'm happy with the result

While waiting for this to cure i made up a stand.

 


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Re: Welman build
« Reply #36 on: November 24, 2012, 05:11:23 pm »

Are you going to make the detacheable mine for the bow too?

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Re: Welman build
« Reply #37 on: November 24, 2012, 10:55:35 pm »

I will be making it when i've finished the rest of the sub as an add on as it only screws on via a threaded rod.


Dave
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bbdave

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Re: Welman build
« Reply #38 on: December 03, 2012, 09:57:29 pm »

The story so far the shape is getting there plenty of filling and sanding to do to achieve an acceptable finish then i'll be cutting the hatch and making all the side bulges keel rudder etc then the WTC to make

Dave


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Re: Welman build
« Reply #39 on: December 04, 2012, 04:32:26 pm »

Now you need a big tub of filler!

bbdave

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Re: Welman build
« Reply #40 on: December 06, 2012, 09:01:13 pm »

I had a productive afternoon making a mould for vac forming the side blisters which hopefully will get done tomorrow

Dave
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Davy1

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Re: Welman build
« Reply #41 on: December 07, 2012, 12:50:09 pm »

Vacuum forming looks an interesting technique.
What material and thickness can you use it for?
Can you suggest any more information on the method?
 
David
 
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bbdave

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Re: Welman build
« Reply #42 on: December 07, 2012, 04:06:21 pm »

I got the vac form done today which seems to have been successfull we used 2mm sheet i had it done at work and think i'll be finding some more jobs to do on the machine.

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Davy1

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Re: Welman build
« Reply #43 on: December 08, 2012, 03:14:59 pm »

Looks good.
It has to be a useful technique for submarine superstructure - reasonable strength with low displacement.
But not feasible for home construction, I take it?
 
David
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bbdave

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Re: Welman build
« Reply #44 on: December 08, 2012, 04:08:12 pm »

Looks good.
It has to be a useful technique for submarine superstructure - reasonable strength with low displacement.
But not feasible for home construction, I take it?
 
David

Very usefull method for repeat pieces i dare say a simple vac-former can be made and used in the home oven then the vacuum cleaner attached i could use it for the superstructure but there's as much work involved making the mould than to make it from styrene sheet so i'll be doing the later method i think.

Dave
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bbdave

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Re: Welman build
« Reply #45 on: December 16, 2012, 09:16:28 am »

Update so far i have been mostly sanding adding filler and resin and sanding i then gave the hull a spray of yellow primer then wet and dried it all off i have just glued the side tanks on not sure yet if to put a layer of glass tissue over them when the glue has set to make sure they are in place for good.

 The plan is to cut the hull out from behind when the hatch has been made making them free flooding?draining also a possible location for battery packs.

It's not as perfect as it would have been if i had used tube for the hull but it has more of the home made appearance hopefully matt black may work wonders  %)

Dave


 
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Re: Welman build
« Reply #46 on: December 16, 2012, 10:35:29 am »

If you have flaws, just means a little more work with the putty and sandpaper. Don't spoil the boat for hapeth of tar.

Matt black will show every mark. I've only seen a couple of colour pictures of these craft, one was painted black, the other was a mid grey. I thought the latter was more in keeping with these craft, but it's your boat so paint it how you like.

If you glass the vac formed pods from the inside, they should be very strong.

U-33

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Re: Welman build
« Reply #47 on: December 16, 2012, 10:48:19 am »

Last time I saw the one at Gosport it was painted in a sort of sea grey colour.
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Rich

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bbdave

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Re: Welman build
« Reply #48 on: December 16, 2012, 04:03:07 pm »

The finish will be smooth no divets scratches etc it's just not dead flat i.e. if i lay straight edge along it doesn't follow exactly  %) . i've sat pondering this afternoon building up courage to cut the hatch it's all marked up i just need to take the plunge excuse the pun.

Dave
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bbdave

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Re: Welman build
« Reply #49 on: December 18, 2012, 04:52:03 pm »

Last night i bit the bullet and cut the hatch with no problems so my nerves can now settle  :-)

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