Raising the CG

So I've been thinking of adding solar panels and it seems like the most reasonable placement would be on a "rigid" bimini frame over my flybridge. My concern is raising the center of gravity with that weight so high on the boat. Is this an issue? Does one consider adding ballast?

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Thanks,

dvd

need a lot more info to even speculate an answer

Your solar panels will weigh no more than 50 lb, including the additional bimini. As a percentage of total boat weight, it shouldn't be more than .005. I wouldn't worry.

How big and heavy is your boat?

A friend did exactly this, added 3 x 135W panels atop a full canvas bridge enclosure. I don't think he even noticed.

The boat is an Albin 36, 1989, approx 25,000#.

As koliver pointed out the additional weight is tiny although high. Ask yourself if another person, 150-175#, on top of the bridge would materially affect stability.

Of course don't keep adding wee bits and more wee bits.

You can estimate the weight added and decide.

I checked on the weight of the panels, and I think koliver is right. My boat is very similar to the '86 Albin 36 (a Newburyport 37) so it looks do-able without a worrisome change in CG.

Thanks,
dvd

If you do it this way, your main enemy/worry will be chafe wearing holes in the bimini if canvas. A hard-top would be better, but then again heavier, but the constant movement of canvas under a rigid object above is a recipe for holes being worn - personal experience...that's all. I now have my panels down on the aft section of the upper deck, out of harms way and on a rigid surface. If that is not an option, then the frame they are on would have to be well clear of the canvas.

Take a look at my friends installation in the Albin forum

http://albinowners.com/aog/viewtopic.php?f=7&t=3703&p=25048#p25048

Maybe this will help.** A subframe an inch or two above the actual canvas so the canvas isn't abraded.

The guy that did the work is excellent, not fast, but excellent.


-- Edited by C lectric on Friday 16th of December 2011 12:42:14 AM

Hmmm,

My last post with the link to my friends thread showing the panel installation is out of sequence.

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What did I do wrong or is this a glitch with the site?*

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Another HMMMM.** Now it's ok?????????????????? well ok then


-- Edited by C lectric on Friday 16th of December 2011 12:45:48 AM

Isn't it a bummer when you go back to a site you've been accessing so long with a 'remember me", then suddenly they want your user username and password again - and you can't remember which one of several you used...?

C lectric wrote:
Hmmm,

My last post with the link to my friends thread showing the panel installation is out of sequence.

Click to expand...

Don't worry about it.* Those of us who aren't Albin forum members can't see it anyway.

I'm a member. Here you go.

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jleonard wrote:
I'm a member. Here you go.

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Click to expand...

*It looks like he went through the Bimini and screwed the supports in place.* How does one get that Bimini off in a storm prep?

JD wrote:
*It looks like he went through the Bimini and screwed the supports in place.* How does one get that Bimini off in a storm prep?

Click to expand...

*That would be my question as well. Also for winter storage.

jleonard wrote:JD wrote:
*It looks like he went through the Bimini and screwed the supports in place.* How does one get that Bimini off in a storm prep?

Click to expand...

*That would be my question as well. Also for winter storage.

*It needs four pockets and zippered slots*to the sides.* Which is easy to do.* I had one on my last sailboat the Bimini*extended back past the split back stay.* They made two circles that had zipper access from the side.* Then the two circles had a Tee Pee type Sunbrella cloth that was wrapped around the stay and sealed with Velcro at the top.* Never a leaked a drop.* Ingenious design.


-- Edited by JD on Friday 16th of December 2011 09:27:04 AM

In that Albin's pictures, you can see that he is in BC waters, so no issue of getting the panels off for winter storage or for storm prep, as we boat all year long, and our last true Typhoon was in 1962.

That's a very slick installation. Puts the panels out of the way, doesn't interfere with the function of the flying bridge enclosure, doesn't add to windage or muck up the lines of the boat. And as Keith said, many boats in the PNW leave their flying bridge enclosures up all winter. The first three photos look to me like the Anacortes marina although I could very well be wrong as we've only been to Anacortes a few times. But if it is Anacortes I believe the marina there is relatively protected from winter storm winds (as are many of the marinas up here)*so it would probably be safe to leave the canvas and panels up all year.


-- Edited by Marin on Friday 16th of December 2011 06:34:11 PM

For winter storage he uses a full canvas cover made by a fellow in Ladysmith. The cover was made to go over the whole shebang.
B.C., we are two slips apart.

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Sorry about the link.** I didn't try it untill now.* Yup, I am a member so I would have to log in to go further.


-- Edited by C lectric on Saturday 17th of December 2011 11:51:02 PM

Ditto for what Marin says. It's a very nice installation. The CG concerns you have are legit, but most of us are running around with quite a bit up top anyway. I've got solar, Sat. TV, Radar, etc., and I'm going to add another two solar panels, higher mast, and even put the Sat. TV and Radar a bit higher on that new mast. Fortunately, I'm also rebuilding my hardtop, and you can be sure that I'm looking at the latest materials and construction methods to save weight up there. I don't think you've got a problem with what you want to do, but it's great to be mindful of things that challenge the reserve stability of your design. When I've really been in doubt, I've consulted one of the staff Architects at Krogen, as I did when I was considering an extension of my pilothouse. One of the inherent problems with having a boat with "space" is that we tend to fill it, and if it's space above the CG, well, you know.

CG is only a concern if you keep adding more weight up top and eventually* use the boat in rough water as the designer had calculated - oops. Weight up top has an amazing lever and tiping effect once you get in big waves. For sitting at the dock and using in very protected waters (where are these by the way) a feeling on invincibility regarding CG is dangerous - remember the thread of a month or two ago of the DeFever flipping over? This was the classic case of doing what s Healhustler mentioned, "running around with quite a bit up top anyway."

I'm sure a diligent owner can add solar panels and forego the other 500 to 1000*lbs of stuff, but how about the non diligent ownerthat we seem to read about all too often??

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I agree w Tom. A low CG is very important. That's the main thing I have against fly bridges. And everyone here knows my feelings about them. Lots of windage is far from ideal, can heel your boat some and cause trouble when mak'in a landing but a CG that's too high can capsize your boat. The domino effect is how real trouble happens. Wind from the port, seas from the port, slight stbd list from fuel differential in the tanks, 4 people on the FB, one at the stbd helm, one center and two behind the helmsman and the helmsman see's a log slightly to stbd of dead ahead. He turns hard to port in the trough of the wave and the boat swings her stern to stbd on the face of the on-rushing wave. That's a few variables but when they get together bad stuff can happen.