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The Solar Bimini Part 4


Fortunately, as a youth of 16, my girlfriend’s father was a mechanic at a Boat store in the Folsom Lake, California, area. I was delivering the Sacramento Union, 623 copies during the week and 712 on Sundays every morning between 4:00 AM when the bundles were dumped in my driveway and before 6:30 when the paper guaranteed it would be on the breakfast table. Brought in about $600.00 a month and really did not need another job. Nevertheless, when girlfriend’s father says boyfriend should work at a ‘real’ job, I spend four days a week learning the art of fiberglass; to include the joy of long sleeved shirts with cuffs and collar taped shut in 120 degree Valley heat and lake and river generated humidity to keep out the annoying byproduct of fiberglass sanding. (Do not try it. The glass is so fine that it works right through the shirt material and sticks to the tape and sands the skin under it. Do something really clever like attaching a shop vac to the sander.)

I covered the Bimini with 8 oz. cloth, adding mat to areas that needed extra strength and proceed to ruin shirts, pants, and shoes with polyester resin while actually getting some of it on the bimini.

There is really not a lot to say about this process. It either goes well with no bubbles or… well that is why they make 50 grit belts for sanders and why I included a shop vac to correct the mistakes I made.

I decided against a gel coat for a simple reason, cost. After completing the glass, filled joints and the few imperfections with fiber filler. A final sanding with 120 grit and then four coats of epoxy.

Before glass, I fitted the Solar panels and drilled and inserted compression bushings. Of course, I glassed and pained over these carefully located holes and had to go back and sand off the paint so I could drill out the resin filled compression bushings.


Level, square, and plumb are relative concepts on a boat. Tide, tidal current, wind, and idiots who think it is fun to blast their 14’ runabout with its massive 60 horse outboard past the marina. Their little two foot wake does not seem much unless you happen to be in a bosons chair at the top of a 60’ mast trying to get a tiny screw in a masthead light that is still six inches above your head.

But, I digress. The solution to level, square, and plumb was to place the Frame used to build the bimini on the boat. The objective is for the bimini to be level, square, and plumb relative to the deck, regardless of the decks relation to G.

The first challenge was to determine the actual Boom position with the main sail set. That lowest position is determined by the leech. (A sail has three sides. The front edge is called the luff, the bottom edge is called the foot, and the back edge is called the leech. The three corners are named head, tack, and clew respectively.) With the head at the masthead, the clew at the end of the boom, the boom angle is set by the length of the cord of the leech.) Do not worry if you did not get all that, that is why it is in parenthesis.

The challenge with determining this lowest point is to find a block of time with no wind long enough to run up the sail, take measurements, reset the topping lift (the line from the masthead to the end of the boom,) and get the sail down and flaked onto the boom. (Did I mention that I am doing this work alone? Am I begging for a bit of sympathy? Nah, but then I get to play the false modesty bit.)

That bit being accomplished, I determined that I could have 8 ½ inches clearance between boom and bimini top and still have 70 inches head room under the bimini. The bimini is 2” thick and the panel rails are 2 ¾ inches high. This leaves me 3 ¾ boom clearance between panel rails (1 ½ above panels,) and boom. Close, and if Patience were set up for racing, too close. However, Patience is a cruising boat. Tacks and gybes are not, as a rule, going to be made in haste. While she is a Tartan and noted for carrying to windward closer than other boats in her class. I am not in a hurry and unless close hauled to make a harbor entrance or clear a point, a low point is about as close hauled as I intend to get. Tacks and gybes will be controlled and stepping the mast across routine. There is no vang , the boom being controlled by an end boom traveler. Gybes have a tendency to lift the boom and as long as the boat does not stall in a tack, the boom remains level, the leech being under constant tension through the maneuver, keeping a lifting force on the boom.

All of that extraneous information is useful consideration for those installing solar in a juxtaposition with something needing to interact dynamically with the dimensional space in which the solar array is placed.

Home owners and RV’ers can generally skip over the above paragraphs. (I thought it was nice of me to tell you that after you spent the time to read it.)

Once the boom position was fixed, the next step was to set the frame at the correct height. That was accomplished with the simple expedient of measuring the frame and adding 4 ½ inches, then subtracting that from the height of the boom from the cockpit deck. Subtracting 4 inches from that sum gave me the length of extensions needed for the frame legs. Of course, the front frame legs sit on the dash at the front of the cockpit and those extensions had to be shorter by the height difference between the cockpit seat and the dash.

Part 4 Pic 1

(f) x,y, z OR screw the math, just put the frame on the deck and it will line up.

It all sounds more complex that it was. The whole process was really more intuitive. I used my handy blind people toy, a click rule, to make the measurements and when it was all in place and the bimini set in place, confirm the clearance. I got lucky or the bathtub was running in the correct direction because when I got the bimini set on the frame the clearance came out to the 6” I planned.

Installing the Panels:

Everything had been pre-fit. Mounting the panels took almost half an hour from placing the first panel to securing the last bolt in the guard rails. I spent 9 weeks at MCRD (Marine Corps Recruit Depot) San Diego, California, 5 weeks at ITR (Infantry Training Regiment) Camp Pendleton, California, 8 weeks in Artillery School (Main Side, Camp Pendleton,) and 4 weeks in Combat School (Camp Pendleton) before reporting to Whisky Battery, 1/11, 1st Marine Division, I Corps, Republic of Viet Nam. Through that entire period my six P’s were pounded into me. Half an hour to mount panels and rails, thank your six Ps’. In fact, in any project you undertake, your six P’s are the key to success.

(Prior Planning Prevents Piss Poor Performance)

Part 4 Pic 2

Aligning the two sections. Critical alignment was the center panels so the guard rails would align.

Centering and aligning was a bit more tedious. A bit of geometry and trig and my handy click rule accomplished this. A 15 oz. fishing weight and a light crab pot line served as a plumb bob to double check the math. It was useful in a general sort of way. I taped a piece of paper to the deck and a sharpie to the plumb and let it trace an orbit assuming roll, yaw, and healing angles would average out over time and confirm a relative center. This is where vision becomes a bit of a bother. It all feels and measures right to me and to those who are actually bothered with having to see everything they look at are either too polite to tell me it is a bit off kilter or it actually is correct. In either case, I’m happy, it is my boat, and everyone else can either offer to fix it or have the decency to not mention it.

Part 4 Pic 3

All 400 watts of solar panels installed and ready for wiring. Support frame finally not bashing me in the shins and head anymore.

Of course, the Cockpit Combing is sloped on the sides and follows a pleasing double arc at the front. No simple measurement and cut struts would do. Kriss, Solar Sphere, thought much of my project out before he spec’d the bits. Included were not only the rails that turned out to be just what was needed for protecting the panels from a crashing boom, the mounts normally used to affix solar panels to a roof or RV were the answer to attaching struts between bimini and cockpit combing. All I needed were some stainless steel ‘L’s, a vice, and a piece of pipe to bend the 90o ‘L’ to the appropriate angle to match between cockpit combing angle and bimini.

Part 4 Pic 4

Not sure how this picture got in her. – Cube Steaks sautéed in olive oil, sea salt, black pepper, covered in pepper jack with steamed vegetables on the side, pears in light syrup and vanilla, 12 grain bread and butter, milk, tea with milk (not shown.)

A second lesson learned in the Corps: The first consideration, in either attack or defense, is to prepare is your fallback position. In preparing this position the main consideration is that it is stronger than your original position. If you need it, it means you are getting your ass kicked and you need the position, rather than the people to take the burn of the enemy action so your people can regroup and retake the field.

I spent careful hours designing and fabricating mounts out of fiberglass. They are really nice with embedded stainless steel bolts and careful planning for correct angles in three dimensions. Problem is, they just do not fit. I was concerned about this when I was at home making them and referring to dimensions I had on a CAD drawing that I could not identify where I had sourced the dimensions.

While I pondered this, I toyed with the mounting bases Kriss had sent me. I tried to visualize how those bases could be made to accommodate a 10o angle in one axis, and a 9o angle in another. That is when I realized that x and y can be combined into (f)x,yD (x,y relative to the angle of the combing) and become a single angle. Then an appropriately bending an ‘L’ bracket makes (f)x,y, z into a simple x,y.

Once I realized this, a bit of modeling to confirm, a trip to the big box hardware store, about $20, and everything fit with some angles cut at the struts to halve the angles and make for smoother transitions.

I cut 2x4 pressure treated yellow pine into 1 ½ square 8’ pieces and fit them to the bimini on the frame on the boat. Now that those are all cut and in place, I can get accurate measurements for the 1’ square (1/8” wall) aluminum tubing that will be the permanent struts.

The base of the ‘T’ shaped bimini went even more smoothly. It had to match in position with the top of the ‘T”. I simply bolted a plate to the rear center to the front part and got a friend from the marina to hold up the back while I affixed a temporary strut to the rear of the base. Two struts that were kind enough to just go straight up were then bolted in place and the front and rear sections bolted together and everything was ready for wiring.

Part 4 Pic 5

5’ 10” of headroom. Note the struts connecting to the base mounts. This is the wood ‘template’ version. The final will be 1” square aluminum tubing with polycarbonate window along the front and clear vymil windows that will snap in on the sides when necessary.

Electrical Installation:

The panels come all nicely wired with about 3 ½ feet of positive and negative cabling. They have these cute little snap-fit connectors all nicely set up for wiring in series (+>->+>-…) Great plan if you want voltage. I do not! I want AMPS! I called Kriss in a panic on this one. Being the calm and easy going sort he is, he said, “Yeah, that’s too bad isn’t it. Just cut them off and make them up with butt splices or whatever is marine friendly.”

To this I calmly emailed back, “Thanks Kriss.” While I thought, ‘well, duh. And I’m not even blond.

I went down to River Supply, the local chandlery in Savannah, and bought a buss bar with two common sides rated at 100 amps, cut the connectors, stripped the cables, affixed solder-less connectors (soldering induces impedance, remember that,) and merrily connected my panels in parallel. To this I attached both the 30 foot cables I ordered and started worming it across the bimini overhead, down a strut, through the cockpit combing (after dousing the open, enclosed area for wasps,) into the boat, along the overhead, and to where I would mount the controller. Linear distance is about 12 feet. I ended up with about 18 inches of the 30 feet slack. (Wonder if I can get a refund for two 18 inch pieces of cable?)

The TriStar Solar Controller is a dream. Six whole wires and everything is clearly marked and it has instructions that actually make sense, with PICTURES! First you cable up the battery (ies,) next comes the pair of ‘sense’ wires (16 AWG) to the positive and negative poles of the batteries, finally the positive and negative from the solar array.

Nope, do not do anything else (unless you are also adding a battery temperature sensor.) (If you are, connect that before you connect the solar array.) Just sit back and watch the sun pump free electrons into your batteries.

Part 4 Pic 6

Please not the green LED telling me that my Solar Array is busily pumping free electrons through the TriStar Controller and into my Ship’s Battery Bank and through my Battery Switch into my Main Engine Start Battery.

I’m telling you folks. Free electricity is simple and easy.

I have the rest of the bits coming tomorrow to connect the large format digital multimeter I will install on my electrical panel. (Cannot read the display on the TriStar even with my adaptive tech stuff.) Then I will have some real answers. Over the two days I have been living on solar, I have not turned on the shore power breakers. Once I get some real numbers for refrigeration, AC, computers, and my book reader, (all AC devices,) I will know if I can drop the $60/month I pay for shore power. If that works, I will also know if I can no longer concern myself with 2 hours a day @ $5 and more an hour for diesel to charge batteries. (Once offshore I have to budget between $7 and $10 a gallon for diesel and hope it is clean. That can be as much as $600/month.)

Just shore Power cost alone that is $60 a month divided into the $2K cost for this project and in 4 months I am $400 ahead of the game.

The final edition is to come in about a month when I have some real empirical data. It will be boring tables and graphs, but it is why you’ve struggled through my somewhat dry cracked sense of humor so stay tuned.

This post first appeared on Blog - Solar Sphere, Inc., please read the originial post: here

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The Solar Bimini Part 4


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