Day 261 Radar Arch
We looked at many radar arch designs on the 'net, in books, on TV, everywhere. Some look like they belong, others look like a tee-pee frame on the back of the boat. Some have a lot of windage with solid sides ( mostly on power boats ) which is undesirable on a sailing vessel, and some are made of tubing like ours will be.
Origionally, the arch was going to come up along the coaming, close in to reduce the span and allow one to walk by it without interference. I didn't much like that idea and drafted it up in a 3D program to further convey my envisionment.

A full width arch will be huge and have a large span that would make it weak in the center without support. Gussets made of smaller tubing could be added in but this gives it a cluttered look with too many bars at different angles.
This width means the sides must be angled in towards the center some. I drew up several other designs and the turn just above the stanchion hieght was the nicest, and the most logical.
After that was decided, a sweep back is needed and again several drawings were made over a side photo of the boat to see whick one looked the best. I would recommend doing this part because suttle changes in sweep angle make a huge difference to the appearance. The angles we agreed on didn't really match any other angles on the boat, except maybe the average angle of the aft hull curve average.

I'm a bit of an artist so I understand some of what the eye finds tasteful in curves and angles, but this is still confusing. It would be nice to have modelled after another boat but every boat is different.

The next thing to do was haul the welder up from below for it's first peek at daylight for almost 3 years. This area is far out of reach of the welder while down below.

My little "crane" extension did the trick hauling up the 300 lb thing.
The rest of the arch assembly was making joiners and tacking it all together in place. The hieght is basically 6 feet and the aft sweep comes even with the bottom of the swim platform pretty much.

Getting the side and top bars even and level was a bit tricky. Every time the sweep back was adjusted, the thing would come out of level. Also the "elbow" of the 15 degree angle needed to be readjusted several times by eye. It needs to be pretty close, but there's just no other way of doing it without laying each frame down and measuring. The forward section is raked back more than the aft in sticking with our design. This made the aft sections height more on a flat plane.

Eventually we wiggled and jiggled it into place and added in some cross bars. It's suprisingly rigid already!

This arch must be removable for transit though so tomorrow we'll work out some accomodations for this.

 


Beauty!


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