Mahuna

Skipjack Kathryn by Mahuna - 1:32 - Based on HAER Drawings

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Part 8 – Frames, cont’d

 

Framing Kathryn has been continuing – albeit slowly.  There have been a lot of other activities interfering with the modeling work, so there hasn’t been as much progress as I would have liked.

 

It quickly became apparent that the model’s frames are very delicate, and some additional steps were needed to strengthen them.  This resulted in some additional structures that are not in the actual boat, but these structures will be hidden by planking and shouldn’t cause any issues.

 

The first such structure was the addition of a reinforcing plate at the joint between the frame floor and the frame side.  This plate was added after the chine had been shaped and the glued-on drawing removed.  After the glue attaching the plate to the frame had dried, the plate was then sanded to match the curve of the chine.  The following photo shows one of these plates in place.

 

58cdfb85eba1e_66ReinforcingPlate.thumb.jpg.b6c02cc3cc269bb7e19a9a532e56e7b3.jpg

 

The individual frames are only attached to the keelson with a minimal glue joint, so individually these frames are very easy to disturb.  By tying the frames together the frame assembly would be much stronger.  I decided to tie them together by using 1/8 x 1/8 stock, cut to match the distance between frames at the keelson.  Since this distance varies from frame to frame, the braces needed to be measure individually.  They are then installed at approximately the midpoint of the frame floor to join the frames together.

 

The first frame installed – frame 12 – was held perpendicular to the keelson by the c-clamps shown in the following photo, and then the subsequent frames were joined to that frame via the braces.  The c-clamps were left in place until the first 4 frames were joined and the glue set. 

 

58cdfb8ae629a_67Settingthefirstinterframebrace.thumb.jpg.e562ad74619469c50919f3800aa3c589.jpg

 

The first 4 frames were very stable after the glue had cured, and didn’t need to be held in place for installation of bracing for subsequent frames.  It was easier to use the long-nosed spring clamps for this work, rather than the miniature machinist clamps used in the prior photo.

 

58cdfb8e36429_67a7framesinplaceandbraced.thumb.jpg.6ec607b8ab6e4b1583e66c786243cd2c.jpg

 

As described in the prior post, structural bolts would be used to fully secure the frames to the keelson, and pilot holes for these bolts were drilled as part of the construction of the frames.

 

After the installation of the first six square frames (12 through 17) was completed, it was time to insert the first set of structural bolts.  The model was removed from the shipway and placed in an adjustable keel clamp.  This clamp was positioned so that the pilot holes were visible. 

 

58cdfb94c5d66_68DrillingSetup.thumb.jpg.5977f8156279cc95ef58fc195b9e3b61.jpg

 

This allowed drilling through the pilot holes and into the keelson, as in the following photo.  Pieces of 3/64 brass rod were then epoxied into these holes to serve as structural bolts.

 

58cdfb9ea48dc_69Drillingtheboltholes.thumb.jpg.cbf103216fbe97f0a6e2234f4a3f6d9e.jpg

 

While the model was in the clamp, the forward edges of the mortises for the cant frames were angled to allow the cant frames to be properly positioned.  This work was performed with a diamond bit in a rotary tool.

 

58cdfba83317d_70Shapingtheforwardedgeofthecantframemortise.thumb.jpg.be3b7f85e7cbd657ad82077593188247.jpg

 

The middle 8 square frames are now in place.  Since each half of a frame is a separate installation, this is the equivalent of 16 frames having been installed.

 

58cdfbb02d05d_718SquareFramescompleted.thumb.jpg.fdf51464ab02583bddd65f300904aa16.jpg

 

The frames installed so far have not needed any dubbing (shaping) to allow the planks to lay flat against them.  The remaining seven square frames in the rear of the model will need shaping.  In addition, the forward eleven frames are cant frames, which will require a modified installation procedure.  These topics will be covered in the next post.

 

Thanks everyone! 

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Interesting framing, Frank.  I can easily appreciate the strength problems with this design, but you seem to be conquering them.  Nice work.

 

Ed

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The form of construction at this stage is pretty flimsy, so I can see why you need further reinforcement. I'd be nervous about catching those toptimbers! You are doing a very neat job, Frank.

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Catching up after a week away from the forum (trip out of town).  Great progress Frank, and superb work as always.  Sort of surprised you needed to use those reinforcements, I figured your wooden dowel placed through the joint would have been sufficient.

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17 hours ago, albert said:

Your work is very very nice.

Thank you, Albert

 

15 hours ago, Omega1234 said:

Hi Frank

 

Very nice.  Slowly but surely, the hull's taking shape.  Methodical and precise as usual.

 

All the best.

 

Cheers

 

Patrick

 

 

Thanks Patrick - little by little, Kathryn is starting to shape up.  I'll keep plugging away.

 

14 hours ago, EdT said:

Interesting framing, Frank.  I can easily appreciate the strength problems with this design, but you seem to be conquering them.  Nice work.

 

Ed

Thanks, Ed.  I've needed to re-do a couple of frames, and removing them was quite easy - shows how little strength there really is right now.  I'm hoping that once they're sandwiched by internal and external planking the model will  be as strong as it needs to be.  It's a far cry from Dunbrody.

 

13 hours ago, druxey said:

The form of construction at this stage is pretty flimsy, so I can see why you need further reinforcement. I'd be nervous about catching those toptimbers! You are doing a very neat job, Frank.

Druxey - you're absolutely right about being nervous.  Whenever I reach across the model I need to remind myself to keep my arms up!

 

5 hours ago, GuntherMT said:

Catching up after a week away from the forum (trip out of town).  Great progress Frank, and superb work as always.  Sort of surprised you needed to use those reinforcements, I figured your wooden dowel placed through the joint would have been sufficient.

Hi Brian - thanks for the compliments.  The small dowels are really not too strong - I've already disturbed a joint that had one in it.  I don't think I'll be bringing Kathryn to our meeting on Saturday - she's not strong enough to travel!

 

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I thought I'd share a couple of photos of the framing in the actual Kathryn.

 

The first is from the HAER drawings.  The frame pointed to by the number 15 is one of the original frames.  They don't look like the joint was held together by much more than a few bolts, and I would love to know how they built Kathryn.  They must have used a lot of temporary ribbands to hold her together before she was planked.  The mortising of the frames into the keelson also looks very flimsy.

 

58cf4236e0e1b_SkipjackKathryn-Frames.jpg.4e09dadfeb128208b857af463e22ca29.jpg

 

The following photo is from the recent rebuild that was completed in early fall 2015.  As can be seen in the photo there is a fairly complex (and strong) knee arrangement holding the frames to the keelson, and there are knees installed in the joints of the frames.  I don't think ceiling planking was installed during this rebuild, so these knees didn't interfere with anything.  Since I'm building Kathryn as she was originally built, I can't use any similar structures that might interfere with the internal planking.

 

gallery_skills1__3.jpg.cfa357b512345d1c2e15004951f09c17.jpg

 

 

 

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The boat would not have been built free standing on her keel as we do with our models.  If she were build upside down the frames would have been extended to and toenailed to the floor.  If she were built upright the frames would have been extended to the ceiling of the boat shed or possibly an A frame structure.  Each frame would have been squared and well supported on its own.  Only after she were planked would the frame ends be cut free.

 

Bob 

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On 3/20/2017 at 11:39 AM, captainbob said:

The boat would not have been built free standing on her keel as we do with our models.  If she were build upside down the frames would have been extended to and toenailed to the floor.  If she were built upright the frames would have been extended to the ceiling of the boat shed or possibly an A frame structure.  Each frame would have been squared and well supported on its own.  Only after she were planked would the frame ends be cut free.

 

Bob 

Thanks, Bob.  That makes sense.  Given her size I don't think Kathryn would have been built upside down as in other skipjacks - that, and the herringbone bottom planks of the typical skipjack provide some structure to the boat. Since Kathryn's longitudinal bottom planks would probably require that the framing is completed prior to the planking, I think your second alternative is probably the way she was built.

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Part 9 – Frames, cont’d

 

There is no mention of cant frames in the HAER documentation, but in the drawings the forward most 11 frames on Kathryn appear to be canted.  I’ve decided to construct those 11 frames as cant frames.

 

The framing jig for the cant frames is essentially the same as for square frames, except that only one side of the drawing is used at a time, due to the angle the jig must be held at, as in the following photos.

 58d47e143ea81_72cantframejig.thumb.jpg.5bfea63d06c441199a8bde9f54bfb29f.jpg

 

58d47e1c692e1_73cantframejig2.thumb.jpg.fb1921da47fe35af2b229e173e504eeb.jpg

It is also necessary to angle the base of the frame floor timber so that it sits flush against the keelson.  Each of the eleven frames will sit against the keelson at a different angle, so these angles were measured from the half-breadth plan and recorded.  Templates were created so these angles could be accurately created on the frames, as shown in the following photo.

 

58d47e1eaa428_74CantFrameOffsetTemplates.thumb.jpg.5e53a74fe24b2686a664f5b69fdfe7f0.jpg

The following photo shows a template being checked against the drawing on the shipway.

 

58d47e26d1483_75Checkingtheangleagainstthedrawing.thumb.jpg.1f36dab9cf1ce674b2773a1650a871eb.jpg

 

The templates were printed on card stock and are used to adjust the miter gauge on the disk sander to the appropriate angle.

 

58d47e316672c_76adjustingthemitergauge.thumb.jpg.07635e519fb38c079b86e1339e3dbc08.jpg

A temporary batten – held by clamps – is used to double-check the fairness of the frames.

 

58d47e35ce789_77Usingabattentocheckalignment.thumb.jpg.28e0d641e78d87d6a30aa42ee2e0857d.jpg

The cant frames were installed in the same way as the square half-frames.  A stiffening brace was added between frames while the new cant frame was still in the installation jig.

 58d47e3bd9028_78Cantframeinstallationjig.thumb.jpg.11adbd220fe66ec9f48b78b0f9044fdb.jpg

 

58d47e424c080_79cantframescontinuing.thumb.jpg.13afd67f2cbb793b221b62f3815e2338.jpg

The aftmost square frames – 22 through 26 – need to be faired to conform to the rising shape of the keelson in that area.  The drawings for these frames indicate the fairing needed.

 58d47f1a1e9ef_80Frame22.jpg.50492088345ba164c8517c79f0cb5f41.jpg

In this drawing the color and configuration of the lines indicates the shaping required:

·      The red lines indicate the aftmost face of the frame, while the green lines indicate the forward face.

·      The frame is cut out along the solid lines, whether red or green, and then the dashed lines indicate the edge of the frame that that needs to be reduced (the cutting line).

 

Since the drawing is pasted to the front face of the frame, the first task is to draw a line corresponding to the red dashed line on the aft face of the frame.  A compass is used to measure the distance of the dashed line from the edge of the frame, and this compass setting is used to draw a corresponding line on the aft edge of the frame.

 

58d47f273eeb7_81drawingtheaftcuttingline.thumb.jpg.9e020a8a458ba5a719e0dfd53e03cfb1.jpg

 

The frame is then shaped using a stump cutter in a rotary tool.  First, the cutter is used to cut the aft edge of the frame down to the drawn line.  It is then used to flatten the entire outer edge of the frame at the appropriate angle.

 

58d47f3223a21_82shapingwithastumpcutter.thumb.jpg.f3e073755df70716a07c7d92ced112de.jpg

 

The forward face of the frame is shaped by cutting to the green dashed line. 

The braces used for the cant frames and for the aftmost square frames need to be angled to fit securely against the frames they support, as shown in the following photo.

 

58d47f3cc087b_83angledbrace.thumb.jpg.97a0729f14afe68ffc4c10c0b7007931.jpg

Cant frames 7 through 11 have been installed at this point.

 

58d47f4526d47_84cantframes7-11.thumb.jpg.29b79c29078ee9581bedcf6504c8c6fe.jpg

The square frames have been installed to frame 23.

 

58d47f4e7d31b_85aftframesto23.thumb.jpg.c0f65a7d8204d84f9da022df91e47573.jpg

So this leaves 6 cant frames and the aftmost 3 square frames to be installed.  I hope to have these frames completed sometime next week.

 

 58d47f5459056_86currentstatus.thumb.jpg.2b02073d7fc6cba9081768bad451d72e.jpg

There are a couple of frames in the midship area that concern me, and I may need to remove and re-install them.  But I won’t think about that until all of the frames have been installed.

 

Thanks everyone for following, for the ‘LIKES’, and for the encouraging comments.

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5 hours ago, Omega1234 said:

Hi Frank

 

Lovely framing.  This is where the fruits of your labour really starts to take shape.

 

Cheers

 

Patrick

 

Thanks Patrick.  Yes, Kathryn is starting to shape up and pretty soon I'll need to deal with the bow and stern timbers - these have me a little confused and I'll need to study it some more.  Great fun!

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2 hours ago, thibaultron said:

Nice work! Looks like a fine delicate spider web.

 

Thanks Ron.  Delicate is the key word - Kathryn is pretty fragile at this point, and will be until I can get some planking on.

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