Bulkhead beveling - lots of questions

[W4LKR]

I’m currently building the MSW Bluenose.  This is my first wooden ship model.  Thus far I have assembled the keel, created the rabbet below the bearding line, and installed all bulkheads.

 

For some reason I’m very intimidated by the process of fairing or beveling the bulkheads.  I’ve read and reread the instructions as well as the sections on bulkhead fairing in the LSS practicum by Bob Hunt.  It all makes sense on paper but in practice I don’t think I understand the technique well enough to start.  I am especially hesitant because many of my bulkheads do not extend all the way down to the bearding line even though they are perfectly flush with the keel at the top.  As I look at all of the installed bulkheads I have three types of issues:

 

1. Bulkheads that do not touch the bearding line at all.  They stop above it by as much as 1/8 inch.

2. Bulkheads whose aft edge only touches the bearding line, but the forward edge does not.  This is happening with some bulkheads that are between the midpoint of the keel and the stern.

3. Bulkheads whose forward edge hangs below the bearding line while the aft edge touches it.  This is happening with some bulkheads that are between the midpoint of the keel and the bow.  This situation seems like an expected challenge and is really the only one that is addressed in my reading.  Beveling these bulkheads correctly will shape them to match the curve of the bearding line.

 

There seem to be lots of tutorials, guides and videos on planking, but I’ve not found much on the topic of preparing the bulkheads to receive the planking.  I could not find a single video on youtube or elsewhere demonstrating the actual sanding of bevels into the outside edges of the bulkheads.  So I wanted to ask some questions here.

 

What sanding tools/aids are recommended for sanding across the the parts of the bulkheads that are well above the bearding line, away from the keel?  I would appreciate specific recommendations for after market sanding blocks, jigs, etc.  I did wrap a scrap piece of 1x2 in some 100 grit sandpaper and took some light passes.  This strikes me as a poor technique though.  The sandpaper isn’t adhered the block and tends to bow outward away from the hard surface even though it’s creased at the edges.  Maybe I need sticky backed sand paper attached to a smaller block?

 

How does one sand a bevel into the bottom “tips” of the bulkheads where they touch the bearding line?  This seems difficult using the same tools that are well suited for higher up regions of the bulkheads.  A sanding block won’t fit unless its too small to hold.  I’m curious what works for experienced modelers.

 

How many bulkheads should my sanding ‘thing’ touch at the same time?  2?  3?  I’ve considered using an emory board, those tongue depresser sized sanding boards.  One would probably contact at least 3 bulkheads on my Bluenose.

 

The instructions and the LSS practicum both recommend laying a plank along the bulkheads frequently while fairing to detect gaps.  What I’m confused about his how many bulkheads the plank needs to contact when doing this.  The location and size of gaps change depending on how many bulkheads are contacted.

 

How do you know when to stop sanding?

 

Lastly, with issue number 1 I listed above, I’m assuming the only thing to do is add shim material along the entire bulkhead edge?

 

Thanks.

[Jaager]

OK, let's see if we can get you some traffic for this:

 

First off, I have never built a POB hull.  I would never entertain any ambition to do so.  With my prejudice against POB,  I probably should not be discussing it. However,  I have framed hulls from a pilot schooner to a 118 gun first rate.   I can try to help you with the concepts needed to finish your project.

 

On nomenclature, there are two misleading terms that apply only as POB jargon.   What is called a keel is actually a spine.  A little bit of it is where the keel is, but it is otherwise nothing like a real keel.  What are called bulkheads are actually mounds to define and support the hull planking.  If western wooden ships actually had water tight bulkheads, there would have been fewer sinkings.  It would have also  been much more difficult to store cargo and manage guns.  If you read anything about real ship building, the difference in what the terms mean could cause some confusion.

 

Your moulds:
For support at the garboard, and what/where it should be,, lay a plank at the rabbet.  If there is no support from the moulds at the position wanted, add veneer to the mould to flesh it out.  

 

The moulds are either plywood  or MDF?  MDF is beyond the pale.  Plywood is just terrible about the working characteristics of the edge faces. End grain is bad.  It might be stronger if  yellow PVA is infused into the open end grain.  Let it dry for a couple or three days.  Doing this will not make sanding more difficult.  Probably stronger still, would be to infuse two part epoxy. But that probably would make it difficult to sand and planking glue may not like it.

 

The mould plans represent the shape of each mould at the face closest to the midline.  Except at the midline- the deadflat - the actual shape is a knife edge on that face. The rest is beveled to match the curved run of the planking.  The bevel curve has a continuously changing slope.  The slope increases as it approaches the bow or stern.  If you cut the bevel such that a batten is a straight shot to the next mould, too much has been removed.  The planking is not a series of facets. It is a smooth curve.

 

A batten is laid across several moulds. The cut of the bevels should be what is needed to support a sweet run.  Sand, test, sand, test, there are no shortcuts here.

 

The way plywood is, if it is cut or abraded with a tool or material that is too course, it may peel or split out on the downhill face.

If you have sandpaper with a simple paper or cloth backing,  a sanding stick or batten can be used to support it.  Just coat both faces with Elmer's or Best Test rubber cement, let it dry and press the two faces together.  The Norton  3X or 10X no-skid backing hates rubber cement.

 

You could try doing this:
Buy a pack of Midwest Basswood sheets,  1/4" x 2" x 24"  @ Blick ~$ 25.00
Glue on a pattern for each side of each mould on the sheet. The inside shape can be as deep or shallow and as ugly as you wish as long as it has some depth.
If you do not have scroll saw, a hand fret saw will do well enough to free the shape from a 1/4" Basswood sheet.
Glue the appropriate Basswood section to the fore side of the bow moulds and the after side of the stern moulds.
If the moulds are not attached to the spine already, the patterns can drawn so that there are guide holes that match up the Basswood with the mould.  Bamboo skewers from a grocery store make excellent locator dowels and provide additional hold.
This provides a wider land for planking and a real hold for certain types of clamps.

There could be an identical 1/4" support on the midline side of each mould, but the shape of the next larger mould would be needed and the beveling there would be much more interesting to do.

 

If you use your imagination, you should see that the entire gap between each mould can be filled with a continuous series of these 1/4" layers.  With this sort of support, only a single layer of planking is needed.  But, this pretty much needs a power scroll cutter ( scroll saw or 9" bandsaw ) and a disk sander or drum sander to perform that much work.

[vaddoc]

I ve never built a kit or POB but I think I could contribute a couple of things

Rabet and bearding line are two different things. As the plank meets the keel (or stem or sternpost) at an angle, the meeting point of outer surface of the plank with the keel is the rabet line. The meeting point of the inner surface of the plank with the keel is the bearding line. Now, the rabet line will be visible so needs to be straight or really fair with no big gaps. The bearding line is less important. Now, the frames should stop exactly at the bearding line so that the plank will be supported in all its width.

 

For tight areas, especially dealing with plywood, a very scary sharp chisel or knife is a good tool. But plywood is terrible. I am using this for permanent frames in my fishing boat-regretted it very much.

 

You need to keep one of the edges of the frame untouched but sand the other to the appropriate angle. You could maybe paint the edge of the frame so that you know how mush is taken off. Again, I have found that chisels work well for this. But really is a hard job-sand, test with a baten, sand again. In all honesty I ve never done it as I cut the bevels before installing the frames but occasionally I need to touch some frame here and there-same process.

 

Lay the baten across the whole hull if you like. As you sand all frames, little by little the baten will reach the frames. Or do three at a time to start with, so that the bulk of the excess material is taken off and then do more frames to ensure fairness. It is indeed a ton of work.

 

I think your questions show you are on the proper path, the hard one...

 

Regards

Vaddoc

[allanyed]

I agree that plywood is not a good material for bulkheads/moulds and I prefer to use unlaminated material including poplar which is cheap and easy to work IF it is not going to be visible on the finished model.    But I think that most, if not all, POB kits still use plywood so a challenge in getting the beveling done correctly.   If you have a rotary tool such as a Dremel or other brand, you can use sanding drums to do the rough beveling then go to sanding sticks that you can make by the dozen for the finish work.  The drums make quick work of it, so you need to go lightly.

 

As your plywood bulkheads are not sitting correctly, these should be adjusted.  If you could post some photos it may help get you some suggestions.  I am surprised that current kits would have this kind of issue what with the laser cutting and all, so not sure how you came across a problem like this.  I have seen a recent post or two with the same kind of problem, but don't recall which kit.   

Allan

[W4LKR]

33 minutes ago, allanyed said:

If you could post some photos it may help get you some suggestions.

 

Here are some examples.

[W4LKR]

Here are the two bulkheads where the gaps exists.  I'm trying hard to hold the plank across multiple bulkheads either side of the gap.  Maybe this will close naturally as the bulkheads either side are beveled down, but even if it does, this bulkhead will only touch the plank on an edge.  I don't know what else to do but shim it and then bevel afterward.

[W4LKR]

8 hours ago, Jaager said:

The moulds are either plywood  or MDF?  MDF is beyond the pale.  Plywood is just terrible about the working characteristics of the edge faces. End grain is bad.

 

Yes the bulkheads are plywood.  It's pretty dense stuff to my eyes.  I've worked with all kinds of plywood in furniture making and construction projects.  This material is very dense, thin ply stuff.  Maybe there is just as much glue as wood in it.  I don't expect to love sanding it.  I don't love sanding anything.

 

Quote

If you use your imagination, you should see that the entire gap between each mould can be filled with a continuous series of these 1/4" layers.  With this sort of support, only a single layer of planking is needed.  But, this pretty much needs a power scroll cutter ( scroll saw or 9" bandsaw ) and a disk sander or drum sander to perform that much work.

 

This does make sense and is effectively what will be done behind the last (or aft-most, is that a word?) bulkhead.  A solid block goes between it and the transom, fully filling that void.  Looking at build logs and videos of POF models I definitely appreciate the advantages of that approach.  More frames, more coverage of the hulls contours, smaller gaps.  A POB kit is what I am working with so I would like to persevere and enjoy the kit.

[W4LKR]

6 hours ago, vaddoc said:

You could maybe paint the edge of the frame so that you know how mush is taken off.

 

I've seen people do that with POF.  In my case the laser cutting process left a uniformly darkened edge face to every piece.  I plan to sand most of it off and use that as my indicator.  But with a few of the bulkheads I'll have to shim them and will probably mark those with ink as you've suggested.

 

Quote

I think your questions show you are on the proper path, the hard one...

 

Thanks, and I don't expect it to be easy.  If it were then I wouldn't enjoy it as much.  There's just a lot of ambiguity with this beveling process.

[Jim Rogers]

[vaddoc]

I bought this pen sander and tried to make it work sanding the bevels. It did not. 

 

I would not worry too much. Do your sanding and bring the bevels where they should be. If you need to glue a bit of wood then do it. Bit of sanding, bit of shimming. 

 

I ve used in the past plain folded paper to shim temporary frames which were later replaced with bent frames. When the planks go on, the whole thing will be solid as a rock.

 

 

[allanyed]

It may be easier and give a better result if you can lower the offending bulkhead.  Not sure this would align it with the adjacent bulkheads, but looks like it may solve the problem.   If the top is then a tad too low to align with the others it would be easier to add a shim on top then on the sides.   I wonder if others with this kit have had the same problem.  Could be a manufacturing glitch.

Allan

[GuntherMT]

From your pictures, if the bulkheads are set properly at the top, your easy solution is shimming.  The basswood strips to be found in all MS kits for planking work perfectly for this.

 

Rather than trying to explain in detail, I'll refer you to my build log where I ran into pretty much the exact same issue (although on a different kit) where I was able to fix everything with simply adding more wood to the outside of the bulkheads and then sanding them down during the fairing.

 

Here is the post where you can see the extra shims added - https://modelshipworld.com/topic/8085-armed-virginia-sloop-by-gunthermt-finished-model-shipways-scale-148/?tab=comments#comment-241424

 

 

If you scroll up a few posts in that same log you can see my pictures where the bulkheads didn't extend down far enough, just like yours.  This 'fix' also works perfectly for your picture where the bulkhead isn't far enough 'out' to make your planking lay properly, just shim that entire bulkhead out and sand it back to match the plank-line.

Good luck!

 

[Jaager]

What I would do is:

Check each mould against the pattern on the plans.

If they match, see if these patterns are presented as a true Body Plan.  Is there something wrong there?

If there is no true Body Plan. scan the patterns,

[adjust the scale distortion of the scan, a factor with every scanner, how much is unique to each machine, but for any single machine, it is internally consistent.]

Align the layers to make a Body Plan and check the shape.

 

Bluenose was a greyhound, a thoroughbred.  Fine, sleek lines with no hollows in her run.  But then, no ship had hollows.

Once you determine which moulds are incorrect - are some too fat or others too lean? - fix that.  Thin built up layers of hardwood veneer used as scabs if it is lean.

 

Looking at these moulds and POB moulds in general, and how much support surface is present and how unforgiving it is,  I still echo the plea of Lt. Orr "You really ought to fly with me."

[Thunder]

out of the 9 kits i have built only one has not had some issue like you are experiencing. to be right the forward bulkheads should overlap the bearding at their front side and the rear bulkheads at their rear edge. then once you have faired them they will be reduced back. The bulkhead you are showing with the gap looks to be far to small, I have one such as this on my present build, Diana. I am going to fair them all then pad out the gaps and do them afterwards. It really is down to experience and i still struggle with it now. However, don't worry, wood is forgiving and more can be glued back on to let you sand it again.

[Don Case]

I'm new at this so this is more of a question. Is the bulkhead offset. ie is it too big on the other side of the ship?

[Roger Pellett]

I have never built a POB kit and don’t intend to do so.  My models are carved from solid blocks, laminated lifts, or POF.  Having read many posts from modelers struggling with POB kits I offer the following:

 

Most POB kits do not provide enough bulkheads to ensure an accurately shaped hull.  Unless a fixture is built to restrain it the spine bulkhead combination lacks necessary rigidity leading to difficulty fairing  and planking.   In an effort to make up for widely spaced bulkheads, kit manufacturers have adopted two layers of planking where areas in the first layer can be faired before adding the final layer.

 

My suggestion would be to completely fill in the areas between the bulkheads with wooden blocks.  By using the bulkheads as a guide these blocks can be easily cut to the required profile with a coping saw.  With blocks glued between the bulkheads the hull can be accurately shaped.  Since the hull is now a continuous wooden surface, the “first planking” is now unnecessary, and the modeler can now apply the “second planking, or if kit dimensions require two layers the solid substrate will provide a firm foundation.

 

Roger

 

 

[W4LKR]

20 hours ago, Don Case said:

I'm new at this so this is more of a question. Is the bulkhead offset. ie is it too big on the other side of the ship?

 

No it's pretty much identical on both sides.  The bulkheads are all symmetrical and the notch for the keel is perfectly centered.  Almost all of them slipped into the notches in the keel such that when they bottomed out in the notch the top of the bulkhead was even with the top of the keel.  These aspects of the laser cutting seem to be spot on.  I think several of them just come up short in their height.

 

If I was more experienced with model building and was more concerned with minute accuracy than I currently am, I would probably make my own bulkheads from solid wood using the plans.  But that's not really my goal with this model.  It's my first build and I'm just enjoying myself.  I can overlook the imperfections and inaccuracies.

[wefalck]

Follow Roger's suggestion of filling up the spaces between the 'bulkheads' with some scrap wood that is a tad softer than the plywood. Many kit-builders do this and make life a lot easier ...

[No Idea]

I agree that shimming will solve the problem. However just double check that the correct frames are in the correct slots first 👍. I made this error once and it took me a few days to realise what I had done 😂

[ERS Rich]

Have built quite a few plank on bulkhead and solid hulls.  True POB is “harder” or has more problems than a solid hull. However they can be overcome.  In my experience bulkheads have had fit problems.  The beauty of wood is, if wood is missing, it’s easy to add, and if there is too much, sand it away.
 

As GuntherMT explains above, the bulkhead problem is solvable.
 

In my experience with POB, letting the planks lay easy across the bulkheads is important.  Realize the board can be bent to fit the frames and it can be twisted, but it can’t be bent along the edge very much.  A minute amount of edge bending to set against a neighboring plank is Ok.  Edge bending to close a big gap deforms the board.

 

So there will be stealers to fill gaps and planks will be tapered.  Failure to taper means the plank will need to be edge bent to fit.  So if you find you are edge bending it’s time to taper.

 

Avoid hollows by edge glueing the board to it’s neighbor during installation.  Install a board by applying wood glue to the plank edge, then placing dots of CA on each bulkhead.  Start say left to right, left end on bulkhead, then moving right apply light pressure to push the board against it’s neighbor, at next bulkhead press board into CA, apply pressure, etc.  Fix the board to each bulkhead one at a time.  Left to right.

 

Enjoy your first kit!  
 

Note I’ve noticed that once the model is finished and on it’s stand, underside hull or planking imperfections are less noticeable.  The viewer is looking in from the side and down.  

 

 

[W4LKR]

1 hour ago, No Idea said:

I agree that shimming will solve the problem. However just double check that the correct frames are in the correct slots first 👍. I made this error once and it took me a few days to realise what I had done 😂

 

That would certainly cause some issues!  I have double-checked and they are in the right sequence.  One of the first things I did after removing each bulkhead from the part board was to label them with ink.  As long as I don't forget my ABC's, I'll be ok.

[W4LKR]

47 minutes ago, ERS Rich said:

Have built quite a few plank on bulkhead and solid hulls.  True POB is “harder” or has more problems than a solid hull. However they can be overcome.  In my experience bulkheads have had fit problems.  The beauty of wood is, if wood is missing, it’s easy to add, and if there is too much, sand it away.
 

As GuntherMT explains above, the bulkhead problem is solvable.
 

In my experience with POB, letting the planks lay easy across the bulkheads is important.  Realize the board can be bent to fit the frames and it can be twisted, but it can’t be bent along the edge very much.  A minute amount of edge bending to set against a neighboring plank is Ok.  Edge bending to close a big gap deforms the board.

 

So there will be stealers to fill gaps and planks will be tapered.  Failure to taper means the plank will need to be edge bent to fit.  So if you find you are edge bending it’s time to taper.

 

Avoid hollows by edge glueing the board to it’s neighbor during installation.  Install a board by applying wood glue to the plank edge, then placing dots of CA on each bulkhead.  Start say left to right, left end on bulkhead, then moving right apply light pressure to push the board against it’s neighbor, at next bulkhead press board into CA, apply pressure, etc.  Fix the board to each bulkhead one at a time.  Left to right.

 

Enjoy your first kit!  

 

 

 

Thanks for the reminders about tapering.  There is so much to getting this right.  I appreciate the way you've explained it.

 

Maybe I'm opening a can of worms but I'm going to ask anyway - is there any benefit to using CA vs wood glue?  In my mind the wood glue gives you plenty of time to position the piece before it sets compared with CA, but they make some slow drying CA (relatively speaking).  I'm thinking of the gels I've seen over the years that take up to a minute to set compared with the instant glues that set in 3 seconds or less.  So far I've only used wood glue on this kit but I'm tempted to try a slower drying CA when affixing the planks to the bulkheads.  The process you describe above sounds good to me.  A dot of CA on the bulkhead, press and hold, wait a minute, move on to the next bulkhead....

 

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Note I’ve noticed that once the model is finished and on it’s stand, underside hull or planking imperfections are less noticeable.  The viewer is looking in from the side and down.  

 

Especially true with this kit as the hull is painted   

[ERS Rich]

Hello, about the glue....let’s take advantage of their properties.  As you say CA is a fast, but it’s a brittle, bond.  So the CA means no need to clamp or hold the plank.  

 

If you make a mistake, the plank can be popped of the bulkhead, pry with a knife, and removed before the glue on the edge dried.  Start over by sanding off the residue on the bulkhead.

 

Mistakes always happen!

 

Read about the glue procedure somewhere, check out Ship Modeling Simplified by Mastini.  There are ways to check that the bulkheads are book matched around the centerline vertical axis.

Dealing with problems is part of the experience, and becomes easier with experience, eventually you’ll be able to tackle any problem.

 

 

 

[GuntherMT]

I personally avoid CA.  I dislike the fumes, it will stain the wood if you accidentally get it on a visible surface, and of course I always end up gluing my fingers together.

I try to stick to just wood glue as much as possible.

 

I know a lot of people here on MSW use CA all the time for their planking (I believe even Chuck uses CA and he has beautiful clean planking), so it is definitely a viable option for some.

[JerryC]

I think you may have installed some of the bulkheads backwards, such as the intende forward side to the rear. Some kits advise having the forward bulkheads with the numbers on the face of the bulkhead facing forward and the bulkhead letters facing rearward. Doesn’t help with your difficulties at this point, but your getting great advice from others here.

[W4LKR]

4 hours ago, JerryC said:

I think you may have installed some of the bulkheads backwards, such as the intende forward side to the rear. Some kits advise having the forward bulkheads with the numbers on the face of the bulkhead facing forward and the bulkhead letters facing rearward. Doesn’t help with your difficulties at this point, but your getting great advice from others here.

 

I was afraid I'd swap them accidentally so I did label them all.  Fortunately with this kit each bulkhead was engraved with the letter.  I took it another step by coloring in the engraved letters with ink.  Since they are uniform thickness I don't think it matters which face of each bulkhead is forward vs aft.  This photo shows how the profile of the rear bulkheads are markedly different than those forward.  I'm pretty sure they are all in the right locations.

 

[wefalck]

Laser-cutting results in a slight kerf, but this doesn't account for the observed gaps here. Due to the kerf, forward bulkheads should face forward with the side that that was down during the cutting process and vice versa for the rear bulkheads.