Roger Pellett

Murphy's law applies on sea as well as on land, and can be rephrased as "whatever you can get your self caught on you will."  Any fitting unnecessary to the boat's unrigged function that could have been removed would logically have been.  Furthermore, removal of the deadeye would have required the bolt to be extracted, so why put it back into its hole until it was needed to secure the dead eye again.

Roger

No, when the boat was not rigged, the bolt would have been withdrawn.

Roger

John,

Your wife would seem to have a wonderful sense of humor!

Mine claims no mechanical ability and just gets on my case to fix things.  The upside of this is that she stays out of my workshop.

Roger

In the 1700’s bolts were not threaded, but were locked in place with a wedge driven through a slot in the bolt’s end.  The deadeye strap could be easily secured with such a bolt that would appear as a nail on a model.  The bolt and deadeye could be removed by driving the wedge from the bolt.

These boats were built with a heavy strake that would be called a “bend” on a larger vessel.  The bolt passes through this heavier strake.  The drawing of the longboat shown on page 90 of May’s book also shows a heavy short reinforcing timber between the bend and cap rail in way of the deadeyes.

Roger

Durham’s Rock Hard Water Putty

As this Is being written there is a used copy of Barbary Wars, Personnel and Ships’ Data available from Amazon for $9.55.  This book includes a fold out drawing titled Plate IV- Lines of the United States Frigate of Constitution Class (Hank offered to send you a scan of this drawing on November 22).

This book was published by the US Navy’s History Command in 1945, prior to CAD, PDF, JPEG, etc.  The drawing in my copy of the book is clear, EXCEPT some of area from frame 34 to 40 did not print well.  The body plan is quite clear as well as the waterlines and buttocks in the area in question.  What did not print well are the straight “grid” lines in the sheer and plan views.  You should have no problem lofting Constitution’s hull from this drawing.

If it were me, I would buy the book, and use this drawing printed in 1945 as a starting point.

Roger

Did the real thing, built in 1721 actually work?

Roger

There are several ideas that you can adapt from full sized pipe welding technology:

1. Socket welding-  In this technique a smaller diameter pipe is slipped into a larger diameter fitting with the joint secured by a fillet weld between the pipe and fitting.

2. Backing ring- When making a butt joint between two pipes of the same diameter a smaller od ring bridges the gap between the two and acts as a dam to support the liquid weld metal fastening the two pipe ends together.

3. Pre-Deposited weld metal- Here, a ring of weld metal is placed between two pipe ends to be joined.  The ring is then fused and weld metal can be deposited over it to complete the joint.

Aluminum readily forms an oxide film when heated that prevents deposited weld metal from adhering. For this reason, it is usually welded with an inert gas shielded torch.  Therefore, trying to solder it with an ordinary propane or butane torch will not work.  It also needs to be clean.  There is an old story about welding the first aluminum boats.  When welds continued to fail, two pieces of cleaned plate were set up in a clean room and the welder was observed through a window.  He picked up his welding torch, flipped his hood down, and from long habit ran his gloved hand down the weld prep groove to sweep out foreign material, thus contaminating the joint!

Aluminum melts at about 1200F so any soldering material must melt at a temperature below that.

I would mechanically clean the joint to remove anodizing  and oxide film, degrease with acetone and assuming the correct aluminum soldering material solder with an electric iron.  It would also seem important to somehow prevent the material from oxidizing after cleaning and before soldering.

A more promising technique might be to use the backing ring/socket weld technique above and epoxy, since small diameter Aluminum tubing is available in telescoping sizes.  Cut a short piece of the smaller tune, slip it into the larger so it protrudes a short distance, secure with a dab of epoxy, and slip the end of the other piece to be joined over the protrusion, secured with epoxy.  For a “branch weld” drill a hole equal to the diameter of the smaller tube in the side of the run, slip the protruding smaller tube end of the branch end in and secure with epoxy.  I believe that you should be able to easily find Aluminum filled epoxy.  The brand JB weld comes to mind.

Roger

Beautiful work!

Roger

Ok, so the oval member is what American Shipwrights would call a Fashion Piece as its primary function was to protect the end grain of planking from absorbing moisture?

So what actually supports the stern structure other than the topside planking?

Roger

Am I correct that the oval piece surrounding the rudder port, yellow in the 3D rendering is actually a structural member tying the upper and lower hull sections together?

Roger

Woodenboat has Catspaw Dinghy kits in stock- $129 and change.

Unless you are building a ridiculously simple model like a square box, the idea of scaling up individual model parts to build a full sized boat will not work. Suppose that you have a kit that builds  a 1:64 scale model of the prototype boat.  Further assume that the kit is a faithful reproduction of the real thing (highly unlikely).  If when scaling up the parts, your measurement is off by 1/32 in, about the thickness of three sheets of paper, this variance is magnified to 2in on the full sized part.  This means that the full sized hull will have a lot of lumps, bumps and parts that don’t fit.

It is for this reason that boat builders redraw boat plans to full size and then pick the parts off the full sized drawing.  This process is called Lofting, and believe it or not before computers it was done for boats and ships of all sizes from an 8ft Dinghy to a 1000ft aircraft carrier.  Today, in shipyards, ship hulls are drawn on computer screens and part shapes are sent digitally to computer guided plate and structural shape burning machines.

Small boatyards and amateur builders without access to computers with CADD software or printers capable of printing large patterns must still loft plans (full size) to obtain accurate patterns.

If you are serious about building a full sized boat, I suggest that you purchase a subscription to WoodenBoat magazine.

Roger

Isn’t 12.8mm, 1/2in?  Then a blade with a 1/2in arbor hole readily available here in the US should fit.

Roger

Wooden Boat sells plans for a “Catspaw Dinghy,” a beautiful lapstrake full sized boat that has been successfully built by a number of first time boat builders.  They used to sell a Catspaw Dinghy model kit based on the idea that building the kit was a good introduction to building the real thing.

If they still offer the kit or if you can find one on EBay this might work for you.

Attempting to scale a model kit up to a full sized prototype is unlikely tp produce a safe well performing vessel.  When it comes time for you to build a full sized boat, invest in a set of plans drawn by a professional.

Roger

Very Nice!

I’m only suggesting use of rasps for initial shaping.  When you get close to the bulkheads, it’s time to get out the sandpaper.

Mark,

Why can’t you remove most of this wood with a half round wood rasp or one of those cabbage grater type tools?  This would generate much less fine dust

Roger

Kris,

If you are a modeler in the USA, 1:32 is an easy scale to work with as common scalar fractions directly correspond to full sized measurements, ie; 1/32 in corresponds to 1 inch on the full sized vessel.

Roger

The artistic aspect of ship modeling-  Better that they be too thin than too thick!  That’s why I prefer to turn them from brass and finish them with a light coat of paint.

Roger

If you use the system that I suggested above- plank over a form made from temporary moulds taken from lines drawing stations, remove from form and insert permanent frames, you really don’t have to loft the frames.  You can determine the shapes with cardboard patterns inserted into the hull made by the cut and try method.

Roger

There are some but much later-  Brady, mid 1800’s and Luce- 1860’s.  Nothing about rigging specifically.

The thwart supporting the mast on eighteenth Century longboats was fixed-that is secured by knees to the clamps running fore and aft inside the boat.  Furthermore, the mast is secured to the aft side of this fixed thwart.  This scheme would, therefore, not work.

Roger

If the boat were intended to be nested, oars and spars could not be stored on board.  Us Navy small boat specifications even specify that ALL thwarts for boats to be nested be removable,  and that heavy longitudinal clamps be substituted for thwart knees.  Boats were heavy, bulky objects and care was taken to cut down on the height of the boat stack to minimize the effect on the ship’s center of gravity and to reduce wind age.

Roger

Sorry I can’t be of more help.  My Naval Architecture education was in the days before PC computers and the only CAD program that I ever learned was Generic CAD and I much prefer the more tactile experience of drawing lines with splines and ships curves.  The real point is, that you do not need this “diagonal” to construct your lines drawing.  You should draw one or more diagonals check the fairness of your hull shape.

Roger

I believe that the curve from bow to stern and extending outside of the half breadths is one of the two diagonals shown on the body plan.  These diagonals are drawn by Naval Architects by measuring diagonal dimensions along the line plotted on the body plan and then plotting them on the half breadths to prove the fairness of the hull.  You do not need these to draw the hull lines but should plot your own diagonals to ensure that the hull that you have drawn is fair.

I would suggest that the other line is a true view expansion of one of the head rails.

Roger