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[Langsford]

I have nearly finished the bulkheads for my model of the Liverpool Pilot Boat "Edmund Gardner". I have now to decide the planking? I am going to use ply with a final coat of resin and fibre mat but should I double diagnonal plank with .8mm ply os conventional horizontal plank with 1.5mm ply? Any advice please.
Cheers, John

[Bryan Young]

Forgive me asking, but are you bulding the hull with the keel at the bottom or upside down with the keel at the top? Just curious. BY.

[Langsford]

My idea was to follow Bluebirds ideas and construct with the keel on top. However i have found that I get a better idea of what I am doing, particularly regarding the placement of the motor and prop shaft, by setting it up with the keel at the bottom as a temporary measure. I intend to turn it the other way up to do the actual planking.
I am coming round to thinking that I might plank with 1.5mm ply using the horizontal method, but would be interested to hear other views on this.
Cheers, John

[Bryan Young]

Although I always make my hulls out of "fibre-glass" (so the bit you have posted would be a "plug" to me) , I know some folk prefer to build "the right way up". Personally I cannot understand why. But I would love to hear from those that do. If I start building a "plug" then that "plug" stays right where it is until I have completed the mould...and then I may turn it over. Many ways to "skin a cat" (as they say). Bryan.

[Martin13]

My idea was to follow Bluebirds ideas and construct with the keel on top. However i have found that I get a better idea of what I am doing, particularly regarding the placement of the motor and prop shaft, by setting it up with the keel at the bottom as a temporary measure. I intend to turn it the other way up to do the actual planking.
I am coming round to thinking that I might plank with 1.5mm ply using the horizontal method, but would be interested to hear other views on this.
Cheers, John

G'Day John,

Firstly you need to work out your prop shaft location from the plan and build this area into your keel as per Bluebird's Build. Anchor your model with Keel up or you will end up with a nightmare as happened on my hull (since scrapped it). I tried 1.5mm planks and found I could not get the material to follow the curves in the hull.

I ended up using 0.6mm 3 ply double diagonal planking. A lot of work (400 planks) but was amazed by the ease to plank and strength in hull.
if your still undecided, pm Bluebird, he can give expert advice to pro's and con's of what you are trying to achieve...

Hope this has been of some help.. :)

Martin doon under

[Langsford]

Thanks martin, I have emailed bluebird to see if I can get any advice. Cheers mate, John

[Martin13]

G'Day John,

Yes, I tried your method with my first hull, now it lives high up on a shelf. After much advice, used Bluebird's method and am 100% satisfied. I have been getting John's advice ever since - the man is only too pleased to help.

By the way, what scale are you building to - looks big

Martin

[John W E]

hi there one and all

First question I need to ask John is; is the model a single screw or a twin screw?   If it is a single screw, we would, first of all have to split the keel in the correct place and add the propeller shaft.  This makes it a lot easier because it is more difficult to drill through the keel when the hull is finished, i.e. when it is fully planked.    You may possibly find that you will have to add 'cheek pieces' either side of the prop shaft at the keel.    If she is 'twin screw' the position of both prop shafts could be marked out on the appropriate frames.     Where the prop shaft passes through the frames, a hole must be drilled prior to planking.   You must ensure that the holes are a slightly larger diameter than the prop shafts.   This allows for slight re-alignment of prop shafts.    Once you have sorted out the positions of your prop shafts or prop shaft (whichever the case) I would carry on, removing the centres of the frames and then locate the frames onto the building board in the correct manner. 

If you are concerned with regard to the frames and how they look; when on the building board - you can always turn the building board over, with the frames on, and, this puts the hull the correct way up with the keel downmost and allows you to look along the frames through the hull along the sides and gives you a good idea of what the hull shape is going to be like.

Word of caution though - please do not do what I did - turned the hull over on the building board and it fell off the bench   :'( and I had to replace two frames.

Planking the hull - Obviously there are lots of materials which can be used to plank hulls.   Depending on what materials are available for you - also, what material you will be most happy working with.   I know Martin13 has shown he is quite happy working with plywood as planking    and he has made a good job of it - Martin13 used double diagonal planking and what we would class as a two part planking.   Not meaning there is an inner and an outer plank, but, Martin13 planked from the keel to the chine with one length of planking and then from the chine to the deck edge or gunnel with a 2nd plank.

Now, with the hull that you are building - it is a 'rounded' shaped hull.  Where as it would be one plank going from the keel all the way to the deck edge.  This type of planking is what we would class as a single run plank.   Even though we intend to double diagonal plank it - we are still referring to it as a single run plank.

Now then, this type of planking has its own small problems to overcome - one of the problems is - as we work from the centre of the hull to the ends.  The planks need to be narrowed every so often.  This is to stop the plank from buckling and it is a procedure called 'splicing the plank in' it is not a great problem and is quite easy once we understand what we are doing.    If you decide to go for longitudinal planking; you will find, towards the stern of the board, you are going to require a lot of stealer planks - this may be an easier option but it does depend upon how confident you feel about it.

Diagonal planking will give you a 'nicer' finish with less filling to be done.

Planking materials - as I have said Martin13 is quite happy planking with plywood - as are a lot of folk - a lot of people though like to plank with balsa wood.   My preference is - Obechi - and for your size of hull, if it were me - I would plank it in either 6mm strips x 1.5 mm that is if I was to plank longitudinal - if I were to plank diagonal (which is what I would possibly do) I would use 10mm strips x 1.5 mm thick Obechi.

Hope this is of some help.

Aye
John e
bluebird

[boatmadman]

John,

Could you please give us a little more detail of what you call 'splicing the plank in'.

How much would you narrow the planks by? What dictates when you do it? Or is it a 'by feel' process?

Its something I am new to and would appreciate the info as I may be looking at some form of diagonal planking for the next build on my list.

Thanks

Ian

[RipSlider]

Bluebird:

Can I ask a question here as well?

What do you find the benefits of Obichi are?

I used Obichi for fishing things in wood that I want to sink ( like the bottom half of floats ). From my experience it's very dense - close to iron wood - a bit brittle and very heavy. Lovely to lathe, but a pain to wok by hand. I wouldn't have expected it to make a good hull.

However, that's me using lumps of obichi or dowels. Does is act differently when it strips? Is it a ply?

- apologies to original poster for hijaclking thread but I'm very curious about it.

Steve

[Langsford]

Thanks Bluebird, also everyone else taking an interest. The model is a single screw so I don't think the prop will give me a problem and I will split the keel and add cheeks as you mention. When you talk of diagonal or longtitudanal planking with 1.5 mm obech, are you single or double planking. I was thinking of double planking with0.8mm ply.
My idea is to keep the model upright on the baseboard until I have the prop tube finished and to turn it over when I do the actual planking. How does this sound/
I suppose it doesn't matter too much how you approach it, keel up or down, so long as you take a lot of care, it's just that I have a better feel for what I am doing if it looks the right way up. Never thought of turnong the baseboard the other way up and "hanging" it.
Thanks again for all your help Bluebird.
John

[dreadnought72]

Hi Ian, not John here, but...

"Stealers"



This is the aft end of my HMS Dreadnought taken a couple of years ago. I planked with 1.5mm balsa (later glassfibred on the inside and covered in scale cartridge paper plates on the outside - the outside then treated with G4 pond sealer to make a surprisingly solid and tough skin).

The golden rule is to avoid compound curves when planking - those are any curves that try to bend a plank or sheet in two dimensions. If you cut a plank and lay it on the hull, you'll find that it has a natural tendency to bend and fit over the frames - it's harder (and not wise) to also force it "sideways" on a frame, away from where it "wants" to lie.

With the frames mounted firmly upside down on the building board, I planked the bottom of the hull first (and used sheet wherever I could for speed), then planked those strips along the waterline, then filled in the gap at the turn of the bilge. In the foreground, you can see where some of these latter planks had to be cut with triangular ends, and end short of the natural plank-run. These are called stealers. It's a process best done by eye - as long as the ends of the triangles are supported by a frame, and they fit snugly, you'll be ok.

Once all had set, I flipped the hull over, and planked the sides up to the gunwales.

Here's the bow (before the stem block was carved), showing the same process:



Looking at your hull (and is that a chine near the bow?) you'll probably find you'll only need to employ stealers below the waterline at the bow and stern.

Andy

[John W E]

Hi there all

Sorry for the delay in replying about splicing planks.

I have been trying to relocate some photographs to go along with this and I do hope that they are clear enough for everyone to see.  

Whilst we are planking a hull using one run planks, i.e. planks that run from keel to deck edge in one length  :) and are set at 45° to the keel; now we are working on a shape – which, not only does it have a radius from the keel to the deck but also at radius’ from the centre to the bow and also from the centre to the stern slightly – these radius’ depend upon the hull shape we are making.   In other words we are working in 2 plains.

If we begin planking at the centre and working towards our ends – the radius begin to decrease – and what is actually happening as we are gluing and clamping the planks, the first thing is the angle of the plank from the keel which was originally at 45° - starts to increase.   

Along with the radius’ decreasing the plank tends to try and twist – due to the fact that we are compressing one edge of the plank into a smaller radius and stretching the opposite edge of the plank. 

To compensate this, we can taper the planks at the edges every so often.   This method though is only good for those who have the experience of planking diagonally.   

For those new to planking diagonally; they would possibly run into a lot of problems, either taking too much off the edges of a plank or not taking enough off.   So, one possibly option is to what is called ‘Spill the plank’.  This is where we clamp a fresh plank next to the last plank we have laid but allow the new plank to fall naturally over the bends.   Therefore then this plank is lying flat along all the stringers.

There should be a slight gap at the keel end of the plank and a larger gap at the deck edge – now this large gap can be set with the use of a scrap piece of plank – so that now we have a tapered gap between the two planks.

With a scrap piece of plank of the same width as the planks we are using – we score a reference mark on the plank, which we have clamped next to our last glued plank, the distance of the marks parallel to our glued plank.   We then remove the clamped plank and join our reference marks up.   Along this line, we then cut this line to give us a tapered plank which will fit snuggly to our last glued plank but which will give us a true face on the opposite side to which we begin to re-plank again.

This I do hope answers one question.    The next question is for John (Langsford)  ‘After trying to study and work out the length of the hull you are building it looks as though it is somewhere in the region of 40 inches long x approx 10-11 inch beam’.   Now for this type of hull, I would be tempted to use 8mm wide x 1.5 mm thick Obechi – Obechi material is a very light wood with a very close grain.  It is slightly harder than balsa wood – and it easily lends itself to being bent with the aid of soaking in hot water, or steaming, without splitting.

On certain radius as the hull you are building; you would not require to steam or wet this, it would bend quite freely.  The other advantage of it is that it sands quite well.

So, when you have done your first layer of planking, you can ‘rough sand’ it down and fill in any hollows with car bodge filler – ready to take the next layer of planking, which would obviously go in the opposite direction.

After you have finished planking; you could give this a good sanding and finish sanding removing any bumps or hollows & then you would have a choice.   The hull would be sufficiently thick and strong just to apply a coating of epoxy resin over the top.

That is planking diagonal.


If we were to plank this hull longitudinal, I would choose to only plank this single layer – followed by a coating of polyester resin then followed by tissue mat and then two coats of polyester resin over the top - when it has dried – sand and finish with exterior coat of paints.

As a thought to your hull, if you are going to double diagonally plank it, you are going to require at least six stringers per side evenly spaced between the keel and the deck edge plus an extra stringer to take the shape of the knuckle which is at the bow.   Any less stringers than this, will give you a 50 pence shaped hull.

I have attached a couple of photographs to try and explain spilling the planks.

aye, John

[Langsford]

Thanks Bluebird. The hull is 42 inch long so you made a pretty good guess!! Your instructions are very helpful, not only to me but I am sure others are interested too. One question (for the moment anyway.)
I'm not sure where to obtain obeche but 1.5mm ply is available. Why do you not recommend the ply as it should be quite strong?
John

[John W E]

Hello there John, good morning

first of all - you can obtain Obechi from Mantura Models and also from Jotika.

It is not that I do not recommend using plywood - there really is nothing wrong with using it.  Everyone has their preferred materials to use - mine, when I build hulls, is Obechi.   I know a lot of people like using Mahogany, Plasticard and etc., and there have been some superb hulls built with these materials.

In some way they all have their advantages and disadvantages - at the extreme if you wished you can plank using cereal packets - which has been done, you would do that by cutting the cereal packet into strips & gluing them as you would do with wooden strips and then finish off by sealing it with something like resin or whatever you would choose.

What I would suggest to a newcomer, someone who has never planked a model before, is to obtain a variety of materials and sit and try them out - see which you prefer, which one bends the easiest etc. and which you are happy using to obtain the results that you require.   There are no hard and fast rules here.

The only suggestion I would make if you prefer to use plywood or when you use any other materials is to keep the planks as narrow as possible.  To give you an example; many years ago I built, from plans, the Boston Blenheim which is a stern trawler.  It was suggested there that the materials used for diagonal planking there was 1mm plywood - which I did use.  It was 1mm thick by a little over 15mm wide strips.   However, when I cut the plywood with the outside grain going with the overall length of the plank I found, when I bent it around the hull and the stern, apart from it trying to buckle and lift off the stringers - the outside veneer split and tended to split apart from the inner veneers.  So, half way through the build; I narrowed the planks down to something like 10mm and also cut the planks so that the outside grain of the veneer ran across the plank.     With hindsight and many years after - I should have cut all the planks and then stuck them in a hot bath for an hour or two just to ease the bending of them.

I hope that gives you some help, with a bit food for thought, but, I do stress that as soon as you have finished cutting the centres out of your frames and you have cut the notches out for the keel and the gunnel stringers that you begin to assemble these on a building board to keep everything true - because, if you try and cut notches whilst the frames are not on the building board, you will find the notches do not line up and the strings will run all over the place and not be true or parallel.

I have included a photograph - of the Fairmile B hull I built - this has 10mm inner Obechi planking and Mahogany planking of 4mm x 0.5mm thick on the exterior.

My Fairmile is finished with three coats of epoxy resin.

aye
john e
bluebird