Windshield frame fabrication

Pictured plywood panels in background were temporarily installed to establish approximate sizing of the windshield frames thus provide perspective.

 

Aft pilothouse bulkheads braced to keep them plumb.

 

Reviewing the issues on fabricating a three section windshield frame:

 

- the plans prescibe that the top of the center section tilts aft about 24 degrees which establishes tilt of outer sections

 

- each section will be about 28" wide

 

- the port and starboard window sections will end 9" from their respective sheer lines and the outer vertical pieces of these sections must be angled to match the tilted pilothouse sides.

 

- the center window section will open via a hinge at the top of the frame

 

- the bottom edges of the frames must be scribed to match the curvature of the foredeck

 

- the top edge of the frames must be scribed and trimmed to fit the interior curvature of the torsion box pilot house roof

 

The last requirement of the windshield frame/roof arc meeting is the one that creates a challenge. I suppose that an application of intellect beyond my abilities and use of a laser could render a simpler solution than mine.

 

My solution:

 

Using the template that was used to create the plywood forms for the laminating jig for the transom, foredeck and eventually the pilothouse roof, I created the two pictured curved plywood forms.

 

The laminating jig will be used to fabricate the pilothouse roof. Consequently, I needed to increase the radius of the pictured plywood forms to match the radius of the laminating jig that has 2X2s on top of the plywood forms.

 

Based on a string depicting the keel centerline, I positioned the crown or center of these two plywood forms so that the forms are in the same alignment in regards to being directly above the keel line and later will be in harmony with the fore and aft centerline of the yet to be fabricated pilothouse roof. Of course the bottom of the plywood forms are level. The pole spanning the forms is also level. When the pole is positioned directly above the keel line, the pole's bottom edge is 76" above the pilothouse sole.

 

Every six inches I indexed the plywood forms so the pole can be positioned along the arc of these forms and always kept parallel with the keel line.

 

The pole can now be slid forward until it touches the window frame and a line can be scribed to cut the frame. The top edge of the frames must be trimmed level to match the pilothouse attachment point thus a major challenge as none of these frames are plumb. Better yet, I can fabricate a router attachment point at the end of the pole so the frames can be trimed via a router thus very accurately and level. That is the theory and this event will bear watching as moderate potential for disaster including putting a spinning router bit into the top of my head.

 

Mistakes in frame fabrication especially in the the scribing and trimming in the frame top edges can easily be corrected/hidden in a frame to be painted. However, and it is a big however, I am building my frame out of dimensional mahogany which will be varnished inside and out thus much more difficult to hide a mistake.

 

In regards to a brightwork windshield frame, one voice said, Dave you are looking for trouble and unleashing a major time sink with all the angles, necessity for clean tight joints and too much other stuff going on in the frame fabrication. And then the Devil came on the scene and said, "Dave it is all easy and go ahead and spend much money on the mahogany."

 

The Devil's brother-in-law owns our local fine lumber store.

 

Done