Re: Gel batteries, solar panels and inverter - an experience
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I’m curious if anyone has had huge breaking waves across the stern of an Amel that would be high enough to get at the panels on an arch. I’ve been out in some (for me at least) boisterous conditions in the North Atlantic but nothing that even remotely looked like it would come aboard despite following seas higher than the arch and the boat surfing down the steep waves under minimal sails. I’ve seen the bow and the cockpit take breaking waves a few times but never the stern. That said I’m a complete Newb so I certainly don’t look at my extremely limited experience as indicative.
It seems to me that you’d have to have massive breaking waves over the stern to do real damage assuming that the arch design can handle the wind loads (the forces do go up with the square of the wind velocity though so the difference between 45 knots which I’ve seen and 90 knots Is 400% more force). I wouldn’t trivialize the forces involved as we know of at least one Amel that looks to have been lost in part because their “arch” setup came apart in the very high winds and the panel(s) became vertical (which weather cocked the boat so it became unmanageable in severe conditions - there were other contributing issues but as I’ve learned from my flying days, these things quickly add up and can overwhelm the crew and result in tragedy).
The other scenario where it comes to mind that the boat could take breaking waves would be when using a Jordan Series Drogue. I know that Eric has had good experience with using these in survival conditions (I also know that Kimberlite doesn’t have an arch!) but don’t know if it results in the stern getting submerged by breaking waves or not so I guess we should factor that scenario in as well.
Wouldn’t the enclosed cockpit also be an issue in those conditions? I seem to remember Eric saying that he had his full enclosure up when Kimberlite was swamped. I know how wonderful it is to be “inside” in boisterous conditions so would be very reluctant to take it down as long as I could safely be at the helm.
Danny, I know you have your solar panels mounted on the lifeline rails. Wouldn’t they also take as much or even more of a load too (assuming that you don’t take them down before hand of course)? I guess they have quite a bit less surface area than panels on an arch but they are lower so I’d think more likely to get dunked. I’d be interested in knowing if your panels have ever been an issue as I know that you have faced some very significant conditions. Do you leave them in perpendicular position as long as they are up? I certainly like the look of the boat without an arch better.
I also see a lot of Amel’s out there with Paddleboards, wind surfers, engines, fuel and scuba tanks (and life rafts) mounted on the rails. Those would seem to me to be even more risky as they are lower down and perpendicular to the forces involved (surface area is directly proportional to the forces - double the surface area and double the forces). An arch has the panels mostly parallel to the potential forces so the horizontally mounted solar panels would have MUCH less drag than say a paddle board).
Force is 1/2 times Density of the fluid (air can be considered to be such) times Surface Area times Co-efficient of Drag times Velocity squared. You can adjust the surface area by adjusting the orientation of the object but everything else is more or less constant except of course for the wind velocity so it behoves us to keep this in mind as we add stuff to the outside of our boats. (The Cd is different for a paddle board on edge versus on the perpendicular but for a solar panel, it would be considered as 1 in either case as they aren’t really aerodynamic in any specific orientation).
Another factor to consider is the weight out at the ends of the boat (this isn’t just an arch issue). Adding weight whether on decks or in the lockers will change the design handling of the boat.
Perhaps a good compromise would be to have an easy way to quickly disconnect the panels and put them below in severe conditions. That would obviously entail foreknowledge of upcoming conditions as you wouldn’t be able to remove them in much more than mild breezes but I suspect that lifeline mounted panels would face the same problem (although to be fair, I’d much rather be standing on deck than climbing an arch at sea!). I’m sure a tilting/sliding rail mounted system could be devised so that the panels could be easily disconnected at deck level as well with a bit of forethought.
I’m not second guessing ANYONE about their decisions here - sailboats are a compromise by their very nature but I’m genuinely curious about the pros and cons so that I can make my own risk/reward evaluation when the time comes. I know that most of us would never plan to be out there in those sorts of conditions but as Forest Gump says “$h.t happens!” I like Amel’s new hardtops with solar panels.
On Oct 21, 2021, 5:22 AM -0400, Scott SV Tengah <Scott.nguyen@...>, wrote:
Your setup sounds perfect for your intended use! I agree with your prioritization, too.
Future Amel Owner & Amel Owner Registry Moderator
Oro-Medonte, Ontario, Canada