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June 23, 2002
Time to make the cross member that supports the back of the seat boxes.
Again, I started with a aluminum sheet sheared to size. The templates
used
to trim the seat boxes combined with the remnants of the original part
provided a good template. I trimmed this with hand shears and fitted it
to
the hull. A few light trim cuts provided a perfect fit. I left about
1/16"
on both side when the part was correctly situated. This spacing was
provided
with a thin chunk of cardboard. I do not want a floppy sheet of aluminum
buzzing against the hull under power. The seat boxes were used to
establish
the location of the walkthrough cutout. The exact location was mostly
guesswork. this cutout was done with a jig saw and a fine pitch metal
cutting blade.
This left a sharp metal edge. The original part had a nice thick trim
strip
to stiffen the part and provide a safer edge. I have not been able to
find
this material at the local marine dealers. So I made some. I started
with a
2" x 1/8" strap. After two hours of concerted hammer work I
had a nice U
shaped metal channel. This was fitted to the cutout. The part was a
rather
loose fit - I wedged the channel closed on the cross member with some
flat
stock and, you guessed it, some sharp blows with a hammer. several
passes
with a belt sander removed all traces of hammer marks. The formed part
was
trial fitted to the seat boxes to mark the last flange. My good friend
Rob
helped me put in the final bends to form said flange. A quick check to
make
sure that everything would fit together and we were ready to rivet the
part
in place.
Rob did the honors with the rivet gun, I did the bucking bar. Then we
put
rivets through the trim strip to fix it in place. In short order we had
the
part installed.
Mark Browne
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June 18, 2002
The seat attachment points are done; time to make some midship seat
supports. The details of the design came from three sources: the
original
outline left in the zinc chromate on the hull, measurement of the
attachment
tabs, and viewer photos on the retrocrestliner site. (thanks all!)
I started with sheets of 0.07" aluminum. I do not have a break or
shears so
I bought the sheets sheared to size. After marking and cutting notches I
was
ready form the boxes. This is tricky for the home DIY worker. I clamped
a
pair of angle irons at the intended bend lines. This assembly is clamped
in
a vise. A combination of firm pressure and hammer blows will do the
trick. A
heavy wooden block is used to avoid scaring the material. Repeat the
process
for each bend. For best results distribute the hammer blows along the
bend
line. It sounds hokey but it is possible to perform quality work with
this
method.
The next part of fabrication is to trim the boxes to match the curve of
the
hull. A rough cardboard template is placed against the hull. The exact
shape
of the hull is captured by laying the body of a felt tipped marker
against
the hull. The marker point closely traces every seam and rivet head.
This
template is transferred to the seat box. All height measurements are
referenced to the upper seat mounting points. You can run a beam from
side
to side am measure the height with an adjustable square. After marking
the
seats were trimmed with a hand shears. The final step is to mark
and trim
the notches to match the ribs on the floor.
Proudly inspect a pair of finished seat supports.
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June 2, 2002
This weekend I replaced all the iffy rivets in the hull.I started with
the heads that were most deformed / worn or thinned out.
I ground off the heads, then I center punched them to drill them out.
Many popped out when they were punched.
This is a pretty good indication that they were loose in the hole.
Then were put in new rivets.
After the first wave we took another inspection pass.
Some that had looked good in comparison to the bad ones looked very bad
in
comparison to the new rivets.
The head popped of one rivet when we center punched the one next to it.
We continued in waves this this way until all the rivets were solid when
we
punched them.
Two of the bad main seam rivets came up INSIDE the ends of the interior
ribs.
This makes it impossible to buck the rivet.
We drilled all the way through the rib from the outside.
Then we drilled through the rib with a much larger bit from the inside.
That provided enough room to buck the rivet with a heavy drift punch
backed
with a 5 pound hammer.
I mentioned a similar problem with a rivet in the port seat support.
Unlike the interior ribs, I did not want to drill through the strake.
The good folks at Fasenal make a closed end draw rivet.
This is an all aluminum part (won't cause galvanic corrosion) that is
claimed to be water proof.
I am not sure if I am ready to believe them, but it *is* above the
waterline.
The order number is AB6-2ACLD for the 0.063"-0.125" grip
range.
They are about 20 cents each.
The standard order quantity is 500 parts but the local store sold me
five
loose rivets.
They did not have any of these on the shelf so I used the
0.251"-0.375"
parts with a doubler.
This is part number AB6-6ACLD. About the same price.
You can put these parts in with an ordinary pop rivet gun.
Every home DIY boat builder should have some of these in the tool box.
When all the hull rivets were to my liking I spent several hours
grinding
off all the carpet glue with a cup wire brush.
It was a horrible grubby job.
The glue turned into a stringy mess with the consistency of sticky cotton
candy.
A dust mask is a must-have item with this junk.
I had the stuff in my hair, clothes, stuck to my glasses, everywhere.
I expect a scrub with paint thinner and scotch bright will remove the
last
traces from the hull.
But not tonight.
Its time to get ready for my son's graduation.
Mark Browne
Osseo, Minnesota. |
