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[Glen Howard]

Hi all - I am about to buy hull planking for my ketch. I am planning to double plank the hull, and was therefore going to use 1mm thick planking. I'd be interested in anyone's views on whether this thickness is appropriate, or whether should consider a thicker one. Plus, if anyone has any other general advice for someone new to planking, it would be most welcome.

[sinjon]

Glen,

Go to Beginners start here (bluebird), click Advanced beginners plan, scroll down to the planking, Its all there.
I would also purchase a miniature pin pusher from Squires + 7mm brass pins (pages 72 & 73) they make life a lot easier.

Colin

[barryfoote]

As a starter though...1mm is fine but only if youe are going to doulble plank... having said that it is only my opinion..

Barry

[barriew]

I'm just planking a Mantua Trotamares hull - see thread in My Builds. The first planking was in 1.5mm balsa, and the second is 1mm mahogany (I think). An alternative to the balsa was 1.5mm lime which I wished I had used. The advantage of 1.5mm over 1mm for the first planking is it gives more  to sand away to get a smooth finish for the final layer. I am certainly glad I had 1.5mm to go at - almost through in a couple of places as it is.

Barrie

[dougal99]

I used 1.5mm obechi on my Brittay trawler but finished off with fibreglass tissue and resin. No problems in 5 years or so. (I was goimg to double plank but the first layer was enough for me at the time.  My first effort at planking. )

Cheers

Doug

[Glen Howard]

Thanks all. That's a good tip to make the first planking in 1.5mm to allow for sanding smooth, thanks Barrie. Is lime as fexible as balsa? Is it stronger?

Re the brass pins, Colin, I was intending to glue and pin temporarily, then fill the pin holes. Pinning sounds like a lot of work, is it really necessary? My other boats have held together without pins. I'd welcome your thoughts.

BTW speaking of Balsa, let me just note here a very useful tip that I came across on bending balsa. A good soaking with Windex (Australian brand - but I believe any commercial window cleaner will do) softens up the balsa to the point where it's about as malleable as wet cardboard. The balsa won't glue while it's wet, but if you bend to the desired shape and clamp, pin or tape it in place until it dries, you'll find it holds the desired shape for a very straightforward gluing. I have managed some incredible bends using this technique.


Anyway, will scroll through the recommended forum notes, thanks again.

[sinjon]

Glen,

Probably not a lot in it, pins or pins!
The pin pusher can put the pin just below the surface, leaving a tiny hole, perhaps the advantage is, that there is nothing on the surface to get in the way of the next plank, and it certainly pulls the plank tight onto the frame.

Colin

[barriew]

I normally pin the first layer, but remove the pins - for re-use as I'm a Yorkshireman . That was one of the problems with the Balsa - the pins didn't hold unless pushed all the way home.

1.5mm Lime will probably require soaking to bend, but it is harder than Balsa.

Barrie

[John W E]

Hi there Glen

The choice is yours - as they say - but, also, the major factor is:

the size of hull you are building; and which way you are going to plank it - are you going to plank it longitudinal (planks running from bow to stern)  or double diagonal (planks running from the keel at 45 degrees to the deck) or, are you going to use a combination of the two - longitudinal for your first layer of planks; and double diagonal for your last, outer layer

the other thing is - are your outer layer of planks going to be shown - i.e. you are going to varnish over the top of them - to show the finish of the timber?

the other thing to consider is - you are going to build a Ketch and this hull does have a lot of curves in it - the more curves in a hull and the tighter the radius of the curves - the thinner the planks have to be

and ..... last but not least - when you are talking about pinning and nailing; I take it you are not going to use stringers in the build?   (Stringers) they are normally lengths of timber which run from bow to stern and are notched into frames.  The more you have, the easier the curves are to follow in a hull.   If you do have these stringers built in; there is very little need to pin your planking - as you will be able to clamp you planking to them.

I have been approached to see if I would put a 3rd build on; to go along with the other 2 builds I have done on construction - this would consist of double diagonal. 

Aye
John E
bluebird

[Martin13]

I have been approached to see if I would put a 3rd build on; to go along with the other 2 builds I have done on construction - this would consist of double diagonal. 

Aye
John E
bluebird

Oh! yes please John :) :) :) :)

Martin doon under

[Glen Howard]

Right then, lots of good ideas there, thanks very much everyone, especially John E, for your interest.

In response:
- the hull is around 800 mm in length, and I am planking longitudinally (though it never occurred to me to anything else - what is the advantage of diagonal planking?)
- the planking will be sealed and painted, so it's timber performance I'm interested in, rather than appearance. With that in mind, is lime a good choice?
- yes, I am going to use stringers - I find they add to stability of the structure, both during and after construction, but especially when the frame is vulnerable early on. And, as you say, they give you something to 'cling onto'.
- I am planning to use 4mm planks - which would be qabout a 6 inch plank in full scale. Do you think these will be thin enough to give me flexibility?
- I'm now leaning toward not using permanent pins. I always intended to pin temporarily, it was this business of pinning permanently I was interested in, and thanks for all your thoughts.  If she starts springing boards in the middle of the pond, you'll all be able to say 'I told you so!'.

If you are interested, I have posted photos of the plan elsewhere on the forum - go to 'Scale sail / Newbie attempting a gaff rigged ketch'.

[andrewh]

Glen, probably far tooooooo late

You have probably got it finished - http://www.rcgroups.com/forums/showthread.php?t=822317&page=2

My suggestion to "line " the edge of each frame with thinnest ply may still bear fruit for you  (unless your'e done)
andrew

[Glen Howard]

actually Andrew, you've got me right in the nick of time. I've just got my upside-down build board done, and am ready to plank her up. I like your idea - do you think using 1mm balsa for that task will compromise the strenght of the job? I am using sopmething called Sapelli for the planking (it was the best fit I could find at the model shop). My plan is to single plank, smooth and fill with body filler, sand, and line the inside with fibreglass and resin for strength. Sound like a plan?

[andrewh]

Glen,

Thats a card-carrying plan!

The sapeli (or sapele) you have found is a nice decorative hardwood (Sapele, Sapelli or Aboudikro (Entandrophragma cylindricum)) and a bit like mahogany - if you have planks of this 6mm wide or less it will make a beautiful layer on top of a 1mm balsa layer.  If you are doing two plankings you could consider putting a thin glass cloth or non-woven polyester tissue (such as horticultiral fleece or tumble dry-sheets) between the layers  - this bonds the whole shebang together but isn't essential.

By the time you have the first layer in place and the glue dry the whole hull will be stiff, strong and happy.  Do a light sand, fill any large gaps with slivers (balsa cement works well and sands beautifully) sand again and lay on a top layer of sapele.

Good news - you will know from the first layer where the planks run easily, and where you need to lose some width, and where you have to add a plank (stealer). 

Guessing  - I would think that your hulls would need twist and a little fitting of the edges at the bow, and certainly some stealers in the last 1/4 towards the stern.  None of these will be a problem in any thin wood strips. 
Your frames are wide enough to join planks easily on a frame where this is required

enjoy,
andrew

[andrewh]

Sorry - should have said:

If you are doing the outer layer with sapele, you might like to do the wales (thick planks round the waterline) with a wood that is thicker and contrasts with the sapele - say birch ply or something like that. 
It can really look the biz! - or you could do the whole hull and lay a double of thin ply (1/32nd) over the top as a wale - same effect!
andrew