Double planking a hull: pros and cons

[bruce d]

I hope the forum will provide some last minute advice. I am about ready to start cutting wood for my first wooden ship scratchbuild, a P.O.B. schooner in 1/40 scale. 

This will be my first attempt at planking a hull. I have read logs and how-to guides looking for a clear statement (and reason) from a modern source on why one or the other technique would be best for a particular project. No luck. 

If it sways opinion one way or another, the finished hull will be painted and coppered. The planks (outermost if double planked) will be holly. 

Any comments?

Thanks in advance. 

Bruce 

[Gregory]

Have you seen these articles, here at MSW:

 

Ship Model Framing and Planking

[bruce d]

Hello Gregory

Yes, and maybe I am assuming too much but I imagine some experienced builders have clear opinions on the subject. I suppose it is yet another sign of hesitancy on my part, I know there is no rule to break or planking police to enforce it, but I have drawn my plans and after a year of anticipation this one point can still be adjusted.

I am concious of being an inexperienced builder and wonder if one technique is more forgiving than the other, or one is more suited to the subject (P.O.B. schooner at 1/40th)? There is a whole bunch of unanswered questions that I am looking forward to tackling myself as the build progresses but this seemed like the best time to sort out this particular point.

 

Thanks,

Bruce

Edited July 27, 2019 by bruce d

[Beef Wellington]

My suggestion, based on personal experience,, would be to start with a double planked hull.  That will give you a chance to get a feel for the process (twice in fact!), as understanding how planks need to be shaped comes with the experience of doing.  Its possible to plank a hull with any kit supplied strip, but it will not be planked in authentic fashion.  If you will be painting and coppering, I would say this is a lesser concern as this will not be very visible.  For a beginner (and I put myself in that category as I've only planked 2 hulls), its nice knowing that the shape of the hull can be figured out with a first planking, sanded and filled as necessary to give a really nice surface for the second planking.

 

Single planking will require more time and expertise in shaping planks (spiling) and also using other techniques, drop planking.  Not that I don't think it could be learned as a start, but I would suggest you might reach a point of frustration and stop. 

 

There are some kits available now that seem to provide pre-cut shaped planks out of the box (Master Korabel "Tender Avos" comes to mind) although it is still double planked. 

 

[kurtvd19]

Double planking is done to provide a fair base for the final planking - usually because the bulkheads are widely spaced and the planks stretching between the bulkheads tend to flatten out rather than keeping the fair curve that closely spaced bulkheads would provide.  The area that are not fair can be sanded down or filler added as needed to provide the fair surface.  Same as planking a solid carved hull.

If your bulkheads are close together double planking isn't needed.

Kurt

 

[bruce d]

OK, this helped.

7 hours ago, kurtvd19 said:

Double planking is done to provide a fair base for the final planking -

... and ...

7 hours ago, Beef Wellington said:

... start with a double planked hull.  That will give you a chance to get a feel for the process (twice in fact!), as understanding how planks need to be shaped comes with the experience of doing. 

Jason, I will do a double planked hull. This was my Plan A but I needed to be told that I wasn't missing a trick.

Kurt, your comment on spacing was a bulls-eye because this was what alerted me that I was 'out of step' with other builds: my schooner will have plenty of bulkheads and the great majority of builds I had looked at with similar construction were single planked.

Many thanks for the input. You may even see a build log before long!

Bruce

 

 

Edited July 27, 2019 by bruce d
Finger trouble

[kurtvd19]

Bruce:

I meant to include this drawing inmy previous reply.  It was made to illustrate a single planked hull and how to check for fairness and the need to possibly shim some areas or sand others to get a fair run of the planks.  But it shows how the planks can run straight between bulkheads.  The kit this drawing was referring to had plenty of bulkheads for single planking - a rare kit - but the idea works to illustrate my point from earlier.

Good luck on your build and please do a build log.

Kurt

[bruce d]

Many thanks, Kurt. 

I am glad MSW is here for pooling iinformation. Before cutting a single piece of wood for my retirement project ship-build I have had the benefit of advice from experienced builders.

Having spent time researching and drawing, digging and digesting, it is good to know that I have served a 'mini-apprenticeship' and enjoyed doing it. 

[Roger Pellett]

I agree with Kurt’s posts above.  The reason for the double planking is economic.  It allows kit manufacturers to provide more widely spaced bulkheads, reducing material and shipping costs.  It also provides a marketing bonus- “you get to build the model just like the real thing” which of course is untrue.

 

Since you you are building from scratch a better system would be to fill in the spaces between the bulkheads with easily carved wood blocks.  The hull is then carved in the usual manner.  You now have a solid, fair base for planking.

 

Ed Tosti demonstrates this method in his build log for Young America.  He actually built two hulls, a plank on bulkhead one and a plank on frame one.  

 

Roger

[bruce d]

9 minutes ago, Roger Pellett said:

Ed Tosti demonstrates this method in his build log for Young America.  He actually built two hulls, a plank on bulkhead one and a plank on frame one.

Thank you Roger, I will look at that log. I still have time to adapt.

[barkeater]

I double plank. Besides allowing you to even out any imperfections it also gives you more strength to the hull. While this may not be as important on a schooner, with models having bulwarks above the deck cannon ports, hawser holes or any other perforation in the hull it is a big benefit.

[Roger Pellett]

Bruce,

 

I checked Ed’s post and was unable to find his description of building his POB hull.

 

As an alternative check Backer’ series of posts for building Golden Hinde.  He uses the same technique with excellent results.

 

Roger

[mtdoramike]

To me, there is no con's to double planked hulls except the extra time involved. The pro's of a double planked hull are, you don't have to worry to much about fit and finish on the first layer, just get it laid, smoothed out and fill in any cracks. The second or finished layer of planking shouldn't have putty and all seams need to be tight and have the best fit possible if you want a great looking hull upon completion. That is unless you intend to paint the hull then you can slap putty on until the cows come home. But why would you go through the expense of Holly wood if you intend to paint it, if that is the case, use some cheap wood strips, scrap wood or what ever you can find for the hull planking.

 

 

mike     

[bruce d]

58 minutes ago, mtdoramike said:

why would you go through the expense of Holly wood if you intend to paint it

I am cheating. The holly is from my garden, brought down by high winds in December 2013 and stashed in anticipation of this project. The first layer will be something else, perhaps beech or Sapele, both are available.

Actually, I suppose that since I have a free hand the priority should be something easy to shape and sand for the first layer. 

Now that I have seen the responses I have started adjusting the frame drawings to allow for the two layers.

Thanks Mike.

 

Bruce 

[bruce d]

1 hour ago, Roger Pellett said:

… check Backer’ series of posts for building Golden Hinde.

Thanks Roger, it is now on my to-do list for tomorrow after the Grand Prix.

 

Bruce

[wefalck]

As Kurt noted above, the technical reason for using double-planking is that the bulkheads on kits are spaced too far in order to prevent the planking from sagging. Letting aside the aspect of gaining experience (which is not so important, if you plan ahead and work carefully), there is another and probably faster way around this: (partially) filling the spaces between the bulkheads with scrap pieces of wood. The wood should have more or less the same hardness as the bulkheads. One colours the edges of the bulkheads and then glues pieces of wood between them that are just a tad proud of them, creating a sort of thick shell. You then sand the pieces down until you touch the coloured bulkheads. During the fairing you will bevel the forward and after bulkhead until only a thin coloured line is left. Depending on how the waterlines look like, in the midship section not much fairing may need to be done. In any case, you will end up with a hollow, faired hull that is ready for planking.

[Jaager]

I guess I must be missing something about double planking a series of POB moulds.

The outer layer is done in a way that covers whatever is under it?

Unless the hull is intended to actually float ( and POB is a poor choice for this) why bother with a filler for the first layer? It will not be seen anyway if longitudinal gaps between planks is what is being "fixed".  If the run has hollows, a wooden scab is probably a better fix.

 

Bruce,

Have you milled your Holly logs yet?  If you did not immediately get the logs into a kiln,  unless Blue Mold is restricted to this side of the Pond, it is likely to have invaded your lumber.  If so, the bad news is that the wood will not be white,  rather grey or light blue.  The good news, the integrity of the wood is not compromised.  It is just as hard, bends just as well - really an excellent species for our needs.  It accepts aniline dyes well.  The fungus does not affect that - except for the final shade..  I am thinking that infected Holly may yield a more realistic deck than a marquetry white stock.

 

[wefalck]

I gather it is a question of the relationship between the stiffness of the material used for planking and the distance between the bulkheads. You want a spline, rather than a chord. Also fairing the bulkheads is difficult, when they are too far apart.

[bruce d]

58 minutes ago, Jaager said:

the wood will not be white,  rather grey or light blue. 

Jaager, I have had good results from the holly I have cut so far. I sealed the ends soon after cutting and because the tree came down in winter (so I have been told) the odds are better. I think the blue mould is less of a problem over here but it definately can happen.

The deck is the area where I want to stick close to the pale white holly colour so, if some of it shows discolouration, I will use the best for the deck and the duff stuff for the hull planking which will be painted/stained and coppered.

I have about six of lengths as in the photo which is enough for my modelling needs, I expect, and more wood is seasoning from a cull last year. It is beautiful wood.

Bruce

[Pete Jaquith]

Bruce,

 

I prefer to single plank.  That said, with single planking it is important to carefully fair the hull and ensure adequate support for planks in areas of significant curvature.  As Kurt noted, the number of bulkheads is a key factor.  The following pictures from my "Fair American" build show how I filled in between bow and stern bulkheads to help fair this hull and provide more planking support.

Pete

[bruce d]

Pete, that is nice work. I think I looked at those pictures some time ago when I was cogitating and can see the advantages: it is almost like a solid hull.

[mtdoramike]

Boy that Holly is sure going to be pretty once it's applied and sealed

[Jaager]

Bruce,

It looks like you have beautiful, clear stock.  It does not get much better than Holly.  Fortune turned her smile onto you there.

 

I don't know what your building material is over there,  but here, the most common construction lumber is 2"x4" x 8' Pine or Fir.  It is not expensive as far as wood goes.  If you can mill it, it works well as fill stock between the moulds.  Do an inside curve, rather than solid to the "keel centerline piece" to save wood and weight.  It can be a several lamination. 

If an additional throw away layer that is the thickness of the plywood moulds is added, two adjacent mould patterns layered in a drawing program with locator guides added - bamboo skewers - straight from the package make good dowels - if you have a drill bit that diameter and a drill press to make sure the holes are perpendicular.  Only need to manipulate the pattern for one side - flip horizontal is a big time saver and assures lateral symmetry.

Most of the scroll cutting,, layer assembly, shaping to near final curves - done off the hull. - paper or cardboard shims if there is play between the moulds.

Do this all the way and it is like having a solid hull.  One layer of planking is enough.  The planks have about as good a glue support as possible.

[Doug from Kiowa]

I was wondering if you should overlap the seams on the 2nd layer. After reading this thread, I haven't seen any reason to do that. I am building an RC model with double planking and thought that it was for strength, but that would be the best reason to do that. The hull will be painted with Gelcoat, (same as a full size boat would be). 

[Gregory]

Overlapping the seams sounds like clinker planking, and is actual practice on some ships and boats.

 

[wefalck]

I think what was meant was, that the longitudinal seams between the planks in the second layer should be in the middle of the planks of the first layer, not overlapping within a layer.

 

Personally, I think that POB construction where the spaces between the bulkheads are filled in makes for much easier and successful fairing. Any fairing errors not corrected before a first layer of planks will transmitted to the second layer, so that there is no real advantage.

 

Of course, when you are working from a pre-cut kit, where the dimensions of the bulkheads assume two layers of planking, you cannot avoid this extra work. When the bulkheads have not been cut already, you could add the thickness of the layer by drawing a parallel line and saw to this line.

Edited August 29 by wefalck

[Doug from Kiowa]

I think what I'm hearing is you should fair the hull between the first and second planking. I was going to do that anyway and would also use caulking to fill any gaps and smooth the first layer out. That should alleviate the need to split the gap with the 2nd planking. 

[CiscoH]

Doug- that is exactly what i did on my last build.  faired the bulkheads, added the first layer of planking, and realized this was an opportunity.  i both practiced my plank layout, practiced bending and twisting the planks into place (with heat and a little water), and treated it as a chance to re-fair my hull.  the second layer i made no attempt to overlap seams although it happened a lot by chance.  having a solid wood base made the thinner second layer adhere so well i dont think staggering the seams would have made a significant structural difference

[Doug from Kiowa]

Thanks, that really solidifies my thoughts also. Although the model I'm working on is plank on frame, I think the idea is sound