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morgan3 · 12-02-2012, 13:39

Hi guys -

i have a kettenburg 43, and i'm about to start building a bimini to hold two 135 watt kyocera solar panels and provide a little shade over the helm. The bimini will be completely behind my boom, with one "bow" on either side of the backstay.

I'd like a little advice on engineering the bimini. Here's what i am thinking - it's a simple design.

~ Two "bows" (arches) of 1" SS tubing that i'll have bent at the local metal shop.
~ Four 60 degree stanchion bases. The $16 variety from defender marine.
~ Two T fittings which will connect the bows across the top

Questions i have:
~ Some input on what kind of additional structure i could use to make it more sturdy.
~ Thoughts on how to best connect the solar panels to the bimini bows.
~ Should i angle the panels fore or aft?
~ What about where the Bows cross one another? What sort of connector should be there? Maybe just a bolt?

I'm trying to keep it as simple and inexpensive as possible. As usual i'm doing all the work myself.

Thanks for your time

~morgan

**SaucySailoress** · 13-02-2012, 05:02

There are a number of threads on this topic, old and new - it would be worth you doing a serch - use the google custom search, a lot of members thin k it's the better option! Also, it's worth searching for 'solar' as well as 'bimini'!

To start you of, here's a couple:
Photos of Bimini Solar Panel Mounts
Best Solar Panels for the Buck
Solar Experiences

Bets of luck

**idpnd** · 13-02-2012, 05:07

Pretty boat, good luck with your project..

mbianka · 13-02-2012, 06:18

You might want to take at my solar bimini/ideas which have evolved over the years.
THE BIANKA LOG BLOG: SOLAR BIMINI: PART ONE: Plan A!
THE BIANKA LOG BLOG: SOLAR BIMINI: PART TWO: Plan B!
THE BIANKA LOG BLOG: SOLAR BIMINI PART THREE: A plan comes together!
THE BIANKA LOG BLOG: SOLAR BIMINI PART FOUR: Locating and trimming the rear frame
THE BIANKA LOG BLOG: SOLAR BIMINI PART FIVE: Useful stuff: Filament Tape
THE BIANKA LOG BLOG: SOLAR BIMINI PART SIX: DECK WORK
THE BIANKA LOG BLOG: SOLAR BIMINI PART SEVEN: PANELS INSTALLED

Finally I used 1/4 inch aluminum bars to connect the rear bimini arch to the existing dodger frame held on with ss straps and U clamps. I then attached the panels to these bars. Since you don't have an existing dodger frame like I had. You might want to attach some struts to the cabin top for support forward. I found the rear arch provided good side support. Anyway something to think about.

**Cotemar** · 13-02-2012, 06:50

Here are the solar panels connectors.
You can buy all these from Defender.

Photos of Bimini Solar Panel Mounts

**osirissail** · 13-02-2012, 07:08

My opinion - if you are intending to mount rigid solar panels on your "bimini" then do not use standard bimini "bows." They are too flexible, especially when underway and the solar panel mounts or the panels themselves will be damaged.

Instead build a rigid welded stern "arch" to hold the panels and the aft end of the bimini and then you can use a flexible bimini bow for the front of the bimini. Or better yet, build a rigid "dodger" for the forward end of the cockpit and an attachment for the forward end of the bimini top.

You can do the design by studying and copying other boat's arches and stuff and then drawing up your own design. Put in all the measurements and requirements for stuff like solar mounting pads, etc. Then take it to a welding shop that has marine grade metal and experience and have it welded up.

You can as I did, do it in stages. Have the basic arch build/welded and then take it back to your boat for positioning. Put the "pads" for attaching to the hull in place, align the arch and then temporarily bolt or fix the two together and take it back to the welder so he can weld everything together permanently. He can take out the temporary bolts and fill the holes. The idea is that you will be doing the brain work and fitting and measuring and all you need to pay for is the metal and welding which he does "in-shop."

morgan3 · 14-02-2012, 09:33

Thanks for the info my friends

i did do some searches before i posted and found most of those links already.

I can't afford the time or $$ to do a "welded arch". I need to figure out a way to make 1 inch SS tubing strong enough. I don't see the need for 3 bows instead of 2 (which i see out there sometimes). It seems this is used to keep the fabric from sagging, which is not a problem with solar panels. I'm not going to use any fabric at all.

If i want to improve the rigidity/strength, what is the easiest most effective structure to add? Beyond basically two bows crossing one another with 60 degree bases, and attached via T-joints across the top.

morgan3 · 14-02-2012, 09:36

@Mbianka - thank you for putting that together, it has helped a lot. I'm going to use your suggestion for mounting the panels to the bimini.

I cannot add struts to the front of the bimini. It's quite a distance from my cabin top to the forward end of the bimini.

**Bash** · 14-02-2012, 12:00

I built mine of 1.5" SS tubing, and am glad I did. Had everything welded, including the "feet." Mine holds two 135 watt panels, with a lexan panel between them so I can see the masthead from the helm.

Cost around $1,200 USD for everything, including labor. It's extraordinarily sturdy, which is good because people always use it for a handhold when they're going down to the swim ladder.

Sulaire · 14-02-2012, 12:25

Hi

I am in the middle of a similar project.... All i would add is stand on the dock, look at the area where the panels will be and imagine you are sailing into 40kts with 4m waves , then imagine trying to hold a piece of plywood the size of you panels your head in those conditions. The windage and shock impacts are what your frame will have to withstand for its lifetime. (ever tried to hang onto a sheet of ply in a gale ?)

I looked at this idea and have decided to rethink the location of heavier panels ( above 5kgs), have not got a solution yet, but looking at perhaps lighter flexible panels on the dodger top, ( i already have 3-32 watt flexible panels on the bimini that weigh 2kgs each, BUT i would like more wattage!

Charlie.

morgan3 · 14-02-2012, 14:43

@Bash - got any photos?

The plywood is not so tough to hold - as long as it stays flat ;p

morgan3 · 14-02-2012, 16:18

ok - so i'm starting to see the light here. I understand why two arches are not going to cut it. There have to be 3 bases on each side, one arch goes all the way to the deck and the second arch T's off the first. Then there is one support arm for each arch.....or such is the classic arrangement (such as on The Bianka Log).

With this classic arrangement - how are the bases angeled? Should they all be 60 degree bases?

i also really like the aluminum bar/eye strap mounting method - going to use that method for sure.....thanks Mike

i'm pricing out the 1", 1.25", and 1.5" tubing. All of it seems to be 1/8 inch wall thickness and of type 304. Once we go thicker than that, or move to 316, i've been told that the price rises quite a lot.....but i'm not sure how much.

What sort of wall thickness and type (304 or 316) are you all using?

downunder · 14-02-2012, 16:53

You can probably build the bimini such that you could add addittional panels/other gear in the future. Future proof it and only do it once.

Cheers

mbianka · 14-02-2012, 17:57

Quote:

Originally Posted by morgan3

ok - so i'm starting to see the light here. I understand why two arches are not going to cut it. There have to be 3 bases on each side, one arch goes all the way to the deck and the second arch T's off the first. Then there is one support arm for each arch.....or such is the classic arrangement (such as on The Bianka Log).

With this classic arrangement - how are the bases angeled? Should they all be 60 degree bases?

i also really like the aluminum bar/eye strap mounting method - going to use that method for sure.....thanks Mike

i'm pricing out the 1", 1.25", and 1.5" tubing. All of it seems to be 1/8 inch wall thickness and of type 304. Once we go thicker than that, or move to 316, i've been told that the price rises quite a lot.....but i'm not sure how much.

What sort of wall thickness and type (304 or 316) are you all using?

Glad you like the bar and eye strap idea. It really tightened all the frames up nicely when they were connected added quite a bit of rigidity to the setup and made mounting the solar panels easier. It also lowered them behind the frame tubing for less windage.

The rear 1" frame kit I got from Sailrite is 304 and has a wall thickness of .049 according to their specs. The forward original dodger frame that it connects to is 7/8" tubing but, I don't know what the thickness is.

Also remember you could add some adjustable nylon strapping (or lines) and associated attachment points for when you expect to be in a blow for some added support and security.

ka4wja · 15-02-2012, 07:33

Morgan,
I installed my own above-bimini solar array in 2006....
It is now over 5 years old with ~10,000 miles offshore....including two Atlantic crossings with associated heavy weather (including 3 days/400 miles thru TS Olga), and multiple gales and severe T-Storms elsewhere....

I used thick wall 1" SS tubing (can't remember the exact thickness right now).....and some alum bar stock for coupling the pairs of panels together....

I've only had one screw come a little loose....and never had any other troubles at all...
I love it!!!

While it is larger than your design, I hope these photos will help...
Solar Panels
Bimini

Fair winds...

John
s/v Annie Laurie