Bulkhead Support Struts

Day 15.

To stiffen the bulkheads, some modelers like to add to support struts between the bulkheads on POB builds.  This isn’t absolutely necessary – the Model Shipways Bluenose kit instructions list it as optional.

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This is what I’m adding – supports between the bulkheads.

I’m gonna do it.

I decided to go with 1″ x 1/4″ basswood for the supports.  I had a few long strips of this in my scrap wood pile.

In theory, all the bulkheads will be evenly spaced.  However, there is some natural variation in the thickness of the wood and I’m sure not every bulkhead is absolutely evenly spaced.  I think it would be a good idea to measure each space and cut a dedicated piece based on that dimension.

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Each bulkhead space gets measured with the caliper.

I used my digital caliper to measure the distance between each bulkhead.  I decided to use millimeters because I was going to be dealing with precise dimensions.  Really, everything should go metric, but that’s a debate for a different day.

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Measurements were noted and recorded.  There was slight variation, but some math seemed to indicate that the variation wasn’t too bad.

All the measurements were recorded on a simple drawing of the ship. This ensured that I could keep all the numbers straight.

On a side note, I noticed that there was some variation in the numbers.  I dropped all the numbers into a spreadsheet and did some assorted math.  The variation isn’t too bad.  The overall variation from the mean is about 1%, which isn’t awful.  I’d prefer that these numbers lined up better, but as long as the bulkheads end up at 90 degree angles to the hull, I’ll be happy.

The pieces were all cut on my table saw.  My saw lets me dial in the size with a digital gauge, so I was able to get really close on every cut.

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Each piece was cut on a small table saw to the specific size for that piece.

Each piece was labeled (“A-B”, “G-H”, etc) as it came off the saw.

I did one side of the ship at a time.  The entire port side was cut and installed, then the starboard side was cut and installed.

Pieces were dry-fitted, sanded as necessary, then glued into place.  I started in the middle, then did the front and back, then did the spaces in between.  This pattern was driven by the need to leave space for clamping more than anything else.

There was also a need to vary the vertical positioning of the pieces.  Supports in the middle of the ship are positioned about halfway down.  Towards the front and back, they are shifted up towards the deck because the bulkheads are shorter.  A few supports had to be narrowed so they would fit within the profile of the bulkhead.

Overall, it took about 3 days to measure, cut, and install all the supports.

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A few pieces installed.  The vertical placement varies because the bulkhead size and mast hole locations.

After everything was installed, I did a final check on all the angles and alignments.

Oops.

It looks like I managed to create a bend in the keel.  The supports on one side (the first one I did) were a little too long towards the front.  This caused the front of the keel to curve towards the other side.  Since I did one side at a time, I didn’t notice this earlier, and the supports on the other side were simply trimmed shorter.

The bend wasn’t horrible, but it was definitely a bend.  I could leave it and it probably wouldn’t cause any big problems, bit it is always better to fix this sort of thing.

After staring at it for a while, I decided to fix it by cutting the support struts on both sides that seemed to be causing the bend.  A saw blade has a thickness – so the simple act of cutting through the strut was going to remove some wood.  I don’t need to remove much – so maybe simply cutting would remove enough.

I cut a couple supports on each side.  Then I used some big clamps to ‘pull’ the keel back into shape.  This collapsed the cuts on one side, while expanding the cuts on the other side.

I then glued the struts back together.  On the side that was opened up, I added a shim in the opening, glued it in, and spread some wood putty over it.

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To correct the bend, slices were cut in the 4 center support pieces.  This released the tension, and let me glue one side back together to hold the keel straight.

That worked.  After everything dried and the camps were removed, I used a long straight edge and checked the keel – it was straight.

The struts are now pretty ugly, but as soon as the hull and deck and planked, those won’t be visible.  I’ll still know they are there though, so I may add some more putty and do some sanding.

Next step – fair the hull.

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