DaveH6
Windshield ruminations
The mahogany center section was an easy fabrication in regards to mental gymnastics. This section as pictured is temporarily clamped into place on two plywood supports that rake the windshield aft. A rather straight forward frame fabrication.
Next came the patterns for the port and starboard frames and the great headache began. When I fabricated the torsion box foredeck I was nonchalant about the swept back angle of the solid wood landing strips for the side windshield frames. This is the angle where these frames meet the athwartship solid wood landing point for the center frame section. Last week I positioned the side frame plywood patterns onto the solid wood landing point marks on the foredeck. Alas, I discovered the frames swept back way too much. An ugly sight indeed.
Using a page from my Bluejacket 24 plans that preceded my upgrade to BJ 25.5 plans, I found the specifications that established the prescribed angle. I ended up with an angle of 164 degrees which was scribed on the foredeck both port and starboard.
After tedious emergency surgery cutting a 3 1/2" wide strip through the foredeck's 6mm top sheet, I carved out the styrofoam and installed solid wood (two layers of 9 mm plywood) and covered same with a strip of 6mm plywood. I now had solid wood under the proper angle of 164 degrees. My history of learning lessons the hard way caulks up an additional event.
After much fussing with the patterns, they are now near identical in all dimensions and the frame bases hit their marks of 9" from their respective sheer lines. When establishing the edge of the vertical frame section near the sheer, a plumb bob is your best friend as you account for cabin side tilt in at the point the sides join the windshield frame. I calculated that the top of the frame tilts in by 1 1/4" from it's base. The plumb vertical rise at the sheer frame edge is 26".
With varnished mahogany being my windshield frame material of choice, few remedies exist to correct fabrication errors in the frames without unsightly consequences. Consequently, I have strived to ensure that the 1/2 " thick plywood patterns are realistic representations of the frame perimeters including thickening to 1 1/4" the edge that joins to the 1 1/4" thick center frame. This allowed me to determine and test the proper angle to cut for the joint. Milling of mahogany for the side frames is completed and frame glue up is underway. In spite of my care, I accept the reality that additional "stuff" is going to happen thus windshield frame fabrication problem solving is far from over.
Windshield frame fabrication led me to paralysis through analysis before I generated any sawdust. With the various angles, frame tilt, curves to scribe to, cabin side tilt, etc., this is one task that begs for the builder to stop thinking and simply mock up the critter with patterns. Ann frequently reminds me, "If you have to swallow a frog, don't stare at it too long". "If you have to swallow two frogs, swallow the big one first".
Windshield ruminations
The mahogany center section was an easy fabrication in regards to mental gymnastics. This section as pictured is temporarily clamped into place on two plywood supports that rake the windshield aft. A rather straight forward frame fabrication.
Next came the patterns for the port and starboard frames and the great headache began. When I fabricated the torsion box foredeck I was nonchalant about the swept back angle of the solid wood landing strips for the side windshield frames. This is the angle where these frames meet the athwartship solid wood landing point for the center frame section. Last week I positioned the side frame plywood patterns onto the solid wood landing point marks on the foredeck. Alas, I discovered the frames swept back way too much. An ugly sight indeed.
Using a page from my Bluejacket 24 plans that preceded my upgrade to BJ 25.5 plans, I found the specifications that established the prescribed angle. I ended up with an angle of 164 degrees which was scribed on the foredeck both port and starboard.
After tedious emergency surgery cutting a 3 1/2" wide strip through the foredeck's 6mm top sheet, I carved out the styrofoam and installed solid wood (two layers of 9 mm plywood) and covered same with a strip of 6mm plywood. I now had solid wood under the proper angle of 164 degrees. My history of learning lessons the hard way caulks up an additional event.
After much fussing with the patterns, they are now near identical in all dimensions and the frame bases hit their marks of 9" from their respective sheer lines. When establishing the edge of the vertical frame section near the sheer, a plumb bob is your best friend as you account for cabin side tilt in at the point the sides join the windshield frame. I calculated that the top of the frame tilts in by 1 1/4" from it's base. The plumb vertical rise at the sheer frame edge is 26".
With varnished mahogany being my windshield frame material of choice, few remedies exist to correct fabrication errors in the frames without unsightly consequences. Consequently, I have strived to ensure that the 1/2 " thick plywood patterns are realistic representations of the frame perimeters including thickening to 1 1/4" the edge that joins to the 1 1/4" thick center frame. This allowed me to determine and test the proper angle to cut for the joint. Milling of mahogany for the side frames is completed and frame glue up is underway. In spite of my care, I accept the reality that additional "stuff" is going to happen thus windshield frame fabrication problem solving is far from over.
Windshield frame fabrication led me to paralysis through analysis before I generated any sawdust. With the various angles, frame tilt, curves to scribe to, cabin side tilt, etc., this is one task that begs for the builder to stop thinking and simply mock up the critter with patterns. Ann frequently reminds me, "If you have to swallow a frog, don't stare at it too long". "If you have to swallow two frogs, swallow the big one first".