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Author Topic: Welman build  (Read 17994 times)

bbdave

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Welman build
« on: October 21, 2012, 03:30:16 pm »

After lots of thinking and brain storming pawing over John Lamberts i have made a start. I have decided to build in two halves top and bottom using 1/16 balsa which will then be filled sanded then clad in glass and cloth i'm not 100% on the dive system yet but as this will be all inside a WTC tube it isn't a huge problem whilst building the hull.

I have enlarged the plan by around 1.5 giving a final hull of L 813mm x W 127mm i think/hope {:-{.

The top half frames have been layed and lined up not all are integral some are dummies which cross fingers will remain on the board when the hull is removed the permanent frames are the cut out ones from 6mm ply.














Dave
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Re: Welman build
« Reply #1 on: October 21, 2012, 03:49:26 pm »

Great stuff. Action man scale!

bbdave

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Re: Welman build
« Reply #2 on: October 21, 2012, 09:38:42 pm »

Will have to dig eagle eyes out of the loft  %) I need to get some FG ordered not sure what to get as yet but the balsa planking will be quite fragile till i get it glassed.

Dave
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Re: Welman build
« Reply #3 on: October 21, 2012, 10:12:36 pm »

Are you making a mould, or will the wooden hull be part of the finished boat. If the former, polyester or epoxy will do the job depending on your preference and depth of pocket.

If the latter I would use epoxy resin, it tends to soak into wood better I find, possibly becuase it tends to be thinner. You can thin polyester with a small amount of styrene, but it weakens it a bit. Cloth is easier to fill than CSM, with epoxy you can use the small sponge rollers you use for decorating to get a really nice finish. Order some colloidal silica to thicken the resin, which will make it easier to sand and will fill the weave quicker.

I highly recommend Reactive resins for epoxy, and CFS fibreglass supplies for polyester (they sell epoxy too, but it's West Systems, so a bit pricey).

Davy1

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Re: Welman build
« Reply #4 on: October 22, 2012, 12:05:55 pm »

Looking good and it's so nice to see someone actually do some scratch building!

You are still at the stage where you can do a one off or use it as a plug for a female mould.  (I can't help feeing that you are best making a female mould but I have seen the glass coated hulls being used very successfully at Barrow.)

Regarding the final mould finish have a look at the Nigel's builds on the AMS forum. (He has used aluminium Duct tape or tinplate.)

Glasplies in Southport are a good, reliable supplier (call in or mail order), certainly for polyester.

David
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bbdave

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Re: Welman build
« Reply #5 on: October 22, 2012, 03:58:28 pm »

I think i will go the polyester route mainly due to cost and just build the one for now i have a contact who makes boats so may ask him at a later date about making a mould if this works ok


Dave
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Re: Welman build
« Reply #6 on: October 22, 2012, 06:27:47 pm »

If you make a mould, you can crank out a few more hulls. Even if you only make one extra hull, and sell that, you'll most likely recoup the material cost of producing the boat.

Epoxy resin works out about three times the cost, but do bear in mind that if you are making tools, you will need to purchase both laminating and gelcoat resins, and as the minimum quanity you can purchase these in is usually 1kg, you will find that the overall cost works out about the same if you're only going to produce one hull. With epoxy resin you use the same resin for laminating and gelcoat, you just add a filler into the resin (colloidal silica) to thicken it for gelcoating.

bbdave

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Re: Welman build
« Reply #7 on: October 22, 2012, 09:35:12 pm »

At the moment poly will only cost me around 25 resin and cloth so not a major outlay if it all goes wrong


Dave
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Re: Welman build
« Reply #8 on: October 23, 2012, 10:56:56 am »

Have you done any GRP work before?

bbdave

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Re: Welman build
« Reply #9 on: October 23, 2012, 06:34:51 pm »

I have done some boat repairs built an outboard well etc. with west systems unfortunately non left or it would have been done in that. I've not used polyester rein before but i guess not much difference in use or am i wrong? i do have plenty of colloidal silica left.

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Re: Welman build
« Reply #10 on: October 23, 2012, 06:52:07 pm »

Not a great deal of difference, apart from the pong of the styrene. I find polyester tends to give you less time to work than epoxy, however you do have adequate time to complete the lay-up.

If you're just laying glass over wood, you don't really need gelcoat. Chopped strand matt is easier to work with than cloth, but will result in a heavier laminate. CSM does produce stiffer laminates though, which I think is an advantage for submarines. Apparently laminators often mix a layer of CSM in with cloth lay-ups to add a bit of extra stiffness. If using CSM with epoxy it must be powder bound, which tends to be more expensive than styrene bound. Polyester can use either powder or styrene bound, with most people using the latter, because it's the cheapest. I use 300gram matt and usually use two layers with tissue. If just lining a wooden hull, one layer of 300gram is sufficient. A layer of tissue will improve the surface finish, but you will still have to sand back and fill a bit if you're going with a lined hull.

bbdave

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Re: Welman build
« Reply #11 on: October 23, 2012, 07:38:24 pm »

Basically what i was planning was to coat the wood with resin lay CSM adding colloidal silica to the resin when cured add second coat i can add around 1mm maybe 2mm depending on sanding back to the wood to keep scale but we'll see how that turns out. I willl add a layer to the inside when off the board.


Dave
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Re: Welman build
« Reply #12 on: October 23, 2012, 08:22:43 pm »

The approach I would take is this- Give the wood a coat of rein, thinned 10% with styrene. This should help the resin penetrate the grain of the wood. Let that dry off for a few hours until tacky, then apply a a layer of CSM with normal unthinned resin, and no colloidal silica. Lay one layer of glass tissue over the matt, and ensure then ensure the matt and tissue is fully consolidated with the resin (I like to use a washer roller). Let that dry off overnight, then carefully sand back, taking care not to break through the thin coating. Fill any dips with polyester filler, and work until it is smooth.

Then you can prime and stopper the hull until you have your desired finish.

bbdave

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Re: Welman build
« Reply #13 on: October 23, 2012, 09:52:36 pm »

Ok makes more sense i presume the CSM and tissue are applied on the same  application of resin?

Planking so far not pretty so no close ups. This is the first time i've used gorilla glue so it's a learning curve but as it's 100% waterproof i thought a better option than PVA








Dave
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Re: Welman build
« Reply #14 on: October 23, 2012, 10:01:25 pm »

That's the way I apply it.

bbdave

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Re: Welman build
« Reply #15 on: October 26, 2012, 04:39:52 pm »

Planking on the top done ready for filling sanding and glassing. Not sure yet if i'll joint the top and bottom then cut the access or to have the break through the equator.
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bbdave

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Re: Welman build
« Reply #16 on: November 04, 2012, 07:43:12 pm »

Progress so far i have now glassed the top half and removed it from the dummy frames ready for the next set of frames for the lower half which hopefully will get planked up this week and glassed next weekend


Dave
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salmon

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Re: Welman build
« Reply #17 on: November 05, 2012, 04:15:18 am »

Very nice. Looks like it came out well.
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Re: Welman build
« Reply #18 on: November 05, 2012, 10:04:27 am »

Coming along. Something I should have mentioned before, but it slipped my mind at the time. It's not a bad idea to add a bit of tint (something dark) to the resin. This helps show up any areas you may have missed- especially important when using wood in a submarine.

bbdave

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Re: Welman build
« Reply #19 on: November 05, 2012, 05:54:28 pm »

I have made sure the outside had a good coating plus i'm planning to do extra resin coats inside and out to make sure it's fully encased the balsa.

I still havn't decided if to cut a hatch or continue  with it splitting on the equator line, but plenty to think about on that and other bits i'm just trying to get the dirty work done first.

Dave
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Re: Welman build
« Reply #20 on: November 06, 2012, 10:18:39 am »

Have you considered glassing the two halves together and splitting it radially?

All the controls on a Welman are mounted aft, so you need no access forward of that. Will keep the hull nice and taught too.

bbdave

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Re: Welman build
« Reply #21 on: November 06, 2012, 03:23:08 pm »

I had thought of that but not sure how to achieve it and maintain access to linkages etc. i did it with a bayonet ring on my u47 but the removable deck allowed access. Any ideas?


Dave
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Re: Welman build
« Reply #22 on: November 06, 2012, 06:51:07 pm »

The usual solution is to cut in a small access hatch somewhere near where the linkages hook-up.

bbdave

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Re: Welman build
« Reply #23 on: November 06, 2012, 07:50:14 pm »

I see Norbert does different size bayonet rings so i will seriously consider it as i had no problems with my u47 it worked faultlessly. I'll get the main hull made then decide whats best there are some complicated linkages so i'll have to sort what access i need.

Dave
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NFMike

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Re: Welman build
« Reply #24 on: November 06, 2012, 08:10:15 pm »

Just a thought from someone who knows nothing about this boat. From what has been said all the gear is near the stern - prop, rudder, planes, yes? Why not split the hull radially just forward of, say, the planes with a tray for the motors, etc running forward from and attached to that stern-most section? The linkages should then be reachable - perhaps  {:-{
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