Almost-A-SCAMP Progress Report #3-3 . . . .

[Charles Brennan]

It's Bimini top week; a vital accessory to my boating environment.
(Mostly!)    Keeps off the rain, provides shade, staves off any (new!) skin melanomas, and provides a platform to support a solar array panel.
I love the idea that energy is oozing back into my electric motor fuel tank (the batteries), as I sail along. 
(Is gas seeping back into YOUR engine fuel tank,    after you leave the ramp?!?)     
But there are a lotta things I have to fix, before all that happens.

First Problem: Length Dimensions.
The Bimini tops mostly come in 4, 6, and 8 foot lengths, and I needed 5 feet. (Story of my Life.) 
6 feet, would prevent me from adjusting the out haul, aft, and for having enough room for reefing the main sail, up forward.
4 feet doesn't really cover a companion and me good enough, for protection from sun in the early morning and late afternoon, or from rain. 
This trial-fit pic from last November, shows the front of the Bimini top over-lapping the cabin roof.
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Second Problem: Width dimensions.
The minimum width frame they supply, is 67" - 72" and I need 64" - 66".
That's not so bad as regards fabric, since these tops are rarely wide enough across the top, so an inch or so of extra fabric on the edges will be nice, for a change.
But excess frame width is a non-starter.
Well, Charles, isn't that a lot of effort, for a mere two or three inches? 
You'd be right, if I didn't have to install a tent over the frame, at a later date.
With the top wider than the hull, water will drip inwards and with the top narrower than the hull, water will drip outwards.
(Details matter.)
This trial-fit pic shows the frame-too-wide issue more clearly; it also shows the not-enough fabric-width-on-frame problem.
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The closest top I could get for my requirements (which included: a favorable price!) was a 6 foot long, two-bow system for a jon-boat and I really needed a 3-bow system to properly support the solar array panel and all the available 3 bow systems are universally, way too big.
Forced me to get a used third bow from a marine salvage store and even then, I could only find  ⁷/₈" instead of 1" tubing.
Ah, well. I'm not THAT fussy!! 

Third Problem: Fasteners.
I dislike the stainless steel snap hooks, that they always provide with the Bimini top straps.
The spring tension is too stiff,  they barely clear the eye-straps they attach to and I inevitably split a thumbnail, when removing or installing them. 
Clearly, they weren't designed to be taken on and off, repeatedly. 
Plus, you have to stretch the strap enough, to get enough clearance to turn and unsnap the snap hook, thus requiring both hands.
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I much prefer bronze, swivel trigger snap hooks.  Easier to deploy, straps pivot to un-twist easily and they can be attached/detached, with one hand. 
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I found on-line, bronze trigger snaps with a built-in strap holder, Very Cool. 

Wonder where that idea came from? 
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On Urchin, I simply clipped the crummy snaps, onto bronze trigger snaps, but with this new type, I don't have to deal with crummy snaps, at all. 

Frame modification was the first order of business.
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2 inches cut out of the center, with a tubing cutter and will need a smaller splice tube installed.

The frame came with 1 inch aluminum tubing and I'd bought a  salvaged ⁷/₈" frame tube. 
I had taken a 1" sample of the Bimini frame with me to the salvage store and when I checked with a tape measure, the I.D. looked to be ⁷/₈"
Cool.    The new bow had a single support tube still attached to the bow, which I could cut up and use to splice all  my one-inch frame cuts.
Back in the car port, got ready to push the splice in . . . . . . . annnnndddd . . . . . . it didn't fit. 
Turns out, dial caliper micrometers are wayyyy more accurate than tape measures. 
And the micrometer said the 1" big tube I.D. was  0.850" and the ⁷/₈" tube O.D. was 0.865"
DOHHH!!! 
Heyyyyy!!!    Waitaminnit!!    ⁷/₈" is 0.875" NOT 0.865"!!!    I WAS GYPPED, OUTTA 10 thousandths of an inch!! 
GEEZE!!    Ya pay Good Money for something, you'd think they would give you everything you paid for! 
Which actually, would have been an even worse fit, I guess. 
While I was thinking dark thoughts and  pondering the impossibility of the task before me,    it suddenly occurred to me:
Hey!    I'm off by just 15 thousandths of an inch!  I ONLY need to remove seven and a half thousandths of an inch of aluminum, off the outside walls of the tube and it'll FIT!!! 
Suddenly missed the 5-axis milling machine, where I used to work. 
Took a busted well-used 80-grit sanding belt from the belt sander and holding the belt ends, started rubbing back and forth on the tube (that was now clamped in a vise) like I was some kind of a demented Shoe-shine Boy. 
Every few minutes or so, I'd stop and measure it: Down by 2 thousandths, 3 thousandths, OK, good, but a long way from 15 thousandths.
Hmmm . . . . . 
Under the Don't-Force-It-Get-A-Bigger-Hammer, School of Thought,    I decided to break out the Big Guns and cut open a 40-grit sanding belt.
THAT worked!!    In no time at all, (comparatively!) I had a splicing tube ready to go!! 
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Fits good!! 
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(Ignore the thumb carnage;    40-grit don' play.)

And just like that, half of the frame was spliced.
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Followed by the other half.
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And I added an eye strap on the bottom side.
I do this to hang small items (VHF, GPS, lanterns, sunglasses case, etc.) under the  Bimini top and I also use it with lines and snaps, to secure the solar array panel to the Bimini top. 
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So now I have three bows, 2) 1-inch and 1) ⁷/₈-inch.
The ⁷/₈-inch. tube, (blessedly!)    had a ½-inch I.D. which was easily spliced with standard ½-inch aluminum tube stock.
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The rear frame has to get done first. It's critical, because all other measurements are based on it and all other tubes attach to it.
It needed to be 38" above the bench seats, to have enough head room under the top.
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And it needed to be a foot in front of the stern, to allow access to the main sail out haul and also, have adequate main sheet/traveler clearance.
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Since the Bimini top is going to be nominally 5 feet long, the middle bow needed to be 30" from the rear bow.
I started conventionally enough, by trying to measure and figure out angles, hypotenuses, lengths, etc., until I gave myself a blinding headache. 
Then I simply lashed the two bows together, (so it would fold properly) then took a spare tie-down strap and adjusted it, until the bows were 30 inches apart.
After that, it was a simple matter to find the pivot point, that would also place the middle bow 38" above the bench seat. 
TOLD that 9th grade geometry teacher, I was never gonna use that stuff!!    So, HAH!! 
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I had drilled out the pop rivets holding the fitting in the tubes, when I shortened the tubes to the required length.
Figured replacement pop rivets would be too loose to be reliable, so I fell back on a 10-24 barrel bolt and truss head screw, to hold the fitting securely.
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After some more tube-trimming, I got the front bow and all the frame geometry, right where I wanted it.
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Verified all the measurements (38 inches, from the frame to the bench seat on both sides, on all three bows) and used a wooden batten to ensure the frame was level and all frame members were exactly the same height.
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Temporarily fitted the Bimini cover on the frame to double-check my anticipated modification measurements.
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While I had hit all my intended marks; in actual usage, the forward top/cabin edge ergonomics felt like they needed about another two inches of space.
(Or maybe, I need to lose about two inches of girth!) 
Good thing to know, BEFORE I start sewing things together!! 
That's when I realized, I had never ordered the thread that matched the Bimini top fabric!! 
DOHHHH!!! 
Oh, well.  Lots of other things I can find to do, until Sailrite gets around to shipping me, my thread.

When you KNOW you're getting close to the end of a project, you start concentrating a little more on random details that were previously, too minor to worry about.
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Used a ³/₄-inch Forstner bit, to enlarge the goal post access holes.

So I could install some ³/₄-inch grommets, for a better appearance. 
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Slid two lengths of heat shrink up the mast, until their final resting place could be determined, then bolted on the mast partner.
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Also threaded on the halyard, flag halyard, and lazy jack halyards.

All that had to be done before I could install the mast base.
Annnnnddddd . . . . . .  it didn't fit. 
DOHHHH!!!! 
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Check out the internal mast cross-piece, relative to the mast base flange, at bottom.

Never underestimate a guy with a Sawzall,    that WANTS to go SAILING!! 
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Hey!! It fits, NOW!! 
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No  problems, putting a boom fitting on one end of the boom.
All that hardware at left, is off a 60's era Luger Seabreeze 16 foot sailboat; it has been re-purposed for the main sail's clew and out haul hardware.
(Came with the mast and boom I was gifted, 19 months ago.)
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The SCAMP plans show both single-part and double-part out haul options. 
35 years ago, I might have opted for a single-part block but at this age, using a two-part block wasn't even up for discussion. 

Lashed the peak of the sail, to the end of the yard.
Somewhere or the other, I read where a Surgeon's knot could be modified for use in tying off Dyneema lashings.
(Dyneema is a very slippery line, that needs special considerations for lashings.)
A Surgeon's knot is like a square knot with an extra cross-over to start, then a single cross-over to finish.
In the Dyneema version, you make two cross-overs to start and then make two cross-overs, to finish. 
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It purportedly even works on differing line diameters, so I put that theory to the test.
We'll see how it holds up. 

And lashed the throat of the sail to the other end of the yard, including the Dyneema line extension I recently made, for the halyard.
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And lashed all the rest of the grommets along the length of the yard.
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I was strongly tempted to step the mast and hoist up the sail to see how it looked, but the winds were far too brisk    for a guy without any lazy jacks . . . . . .
Or a down haul  . . . . .
Or a bleater . . . . .
Or reefing lines . . . . .
Yeah, lots more rigging to do, but that's OK.
I'm FINALLY getting to do all the FUN STUFF!!! 

Charles Brennan

[Doug SC]

After the photo of your thumb, I think your yellow Danger Sign should be rephased to "Men Boat Building"!

[Travis Chapman]

Saw this the other day and felt it appropriate. Practically enough to be kin now, eh?

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Thank you for walking through the bimini fit up. I have the fabric for Panda Paws but still need to find bow material I like. Seeing the process is helpful!