Solar Panel on Davits?

[Ed Schenck]

You guys with davits on narrow-sterned hulls, do you ever need to fold them? Is there any reason, during the in the water season, that the davits might need to be folded in? I am considering a set and then mounting a solar panel across them. I have an idea for a mount that would permit some degree of angle adjusment in both directions. But it would be difficult to also allow easy folding. The dinghy would be ashore most of the time since overnight anchorages are going to be rare.

 

[cbsailor]

Our 33.5 isn't exactly a narrow stern. When I installed the Martek davits I considered making them foldable, but in the interest of time, decided to install them fixed. Thoughts were I could always make them foldable later. (We had heard rumors of being charged for the overhang length, even when the dinghy wasn't hanging from the davits, by many marinas.) We have used the davits a couple of years and have never seen the need to make them foldable. I installed two 85 watt panels in Feb and are very pleased with the setup. A friend with a H40 and the same davits recently installed a single 130 watt panel across the davits.

Docking, of course, takes on a whole new dimension with the davits, dinghy and panels. That's a lot of expensive hardware just waiting for a screwup by the helmsman.

 

[Maine Sail]

You guys with davits on narrow-sterned hulls, do you ever need to fold them? Is there any reason, during the in the water season, that the davits might need to be folded in? I am considering a set and then mounting a solar panel across them. I have an idea for a mount that would permit some degree of angle adjusment in both directions. But it would be difficult to also allow easy folding. The dinghy would be ashore most of the time since overnight anchorages are going to be rare.

No need to fold. You'll want some sort of cross bars to keep them from swinging when the dinghy is in them. These cross bars will hold a solar panel quite well, ours do.

 

[med2463]

Thanks for the pics. Gonna work on (nag) husband for setup like this.

 

[Bill1565]

Ed, we are looking into solar panels also. Guys here with narrow stern boats don't fold the davits, they remove the dingy. I have some pix of a tartan 37 with folders, and I am over due to visit a neighbor with a Catalina 34. Both echo someone's comment that it brings a whole other dimension to docking.

I am serously considering the solar mount sold here on SBO with a motor lift. We have an inflatable floor dingy that I roll up and store under the staysail. Dog does not need to go ashore, but he loves playing frisbee in the surf when we are near beaches free of Crocs and pythons, so we carry a dingy when we anchor out. @#$% outboard is to heavy for me to mess with so I use a Garhauer motor lift, but I could replace that with the official SBO pole and tilt and swivel my solar panel.

 

[Ed Schenck]

Thanks guys. And for the pictures. Am I right, CB and Maine, that your panels are fixed? Do I need to make them adjustable? I think the SBO pole is adjustable. But I already have a Garhauer radar pole and do not want to add another unless I forgo the davits. And I do know that a bowsprit would add to boat length so I had better check on the marina rules regarding davits. Lots to think about.

 

[Maine Sail]

Am I right, CB and Maine, that your panels are fixed?

Ours is not fixed it simply rotates around one of the 1" SS cross bars with two friction adjustable clamps. This level of adjustment works well in getting the most amps in based on where the sun is in the sky. I'll try and find some pics of the clamps..

 

[cbsailor]

Thanks guys. And for the pictures. Am I right, CB and Maine, that your panels are fixed? Do I need to make them adjustable? I think the SBO pole is adjustable. But I already have a Garhauer radar pole and do not want to add another unless I forgo the davits. And I do know that a bowsprit would add to boat length so I had better check on the marina rules regarding davits. Lots to think about.

Ed, Our installation is "sort of fixed". By loosening two hex cap screws, the panels can be pivoted some. I checked with a bunch of cruisers who had adjustable installations and the consensus was that most used a fixed setting and never bothered to baby sit the panels to optimize charging. Lots of data out there, most of it way over my head, about the optimum angle. I went with the rule of thumb I found which said

May 5th - Set at the same angle as your latitude minus 15 degrees.
August 5th - Set at the same angle as your latitude.
November 5th - Set at the angle of latitude plus 15 degrees.

For my local summer cruising that means an angle of only 23 degrees. Winter cruising to FL it means about 40 degrees. In either case it's enough angle to keep the cat off of them and water from pooling when it rains. I rarely make adjustments. Then again, the backup Honda is always available too.

 

[Bill1565]

Ed, I was thinking about this last night. If you keep your boat in a marina and rarely anchor out, why do you need solar panels?

 

[cbsailor]

Chiming In

I'm Not trying to answer for Ed, but we are in a slip here at home and I prefer to keep the shore power disconnected unless I am on the boat. The solar allows me to do that and walk away without the usual shore power fears... fire, loss of power, stray currents, electrolysis, etc. With solar, the batteries are always topped off and ready to go. As an added bonus, there is usually cold beer in the fridge and no ice to haul.

The solar really proves its worth when we are cruising 6-8 months. One of the best improvements we have made to this boat.

 

[Ed Schenck]

Actually CB that is the answer I would give to Bill. I have always left the shorepower on with some trepidation. And I did so for the same reason, beer and batteries. Beer for obvious reasons and Batteries because of constant bilge water from the keel-stepped mast. Well not constant but you get my drift.

I am beginning to rethink a complicated adjustable mounting of the panel however. When I consider that the boat is either swinging at anchor or facing west in her slip why adjust?

Some of my dockmates have theirs fixed to the bimini top. But I sail with the bimini folded whenever possible. So I think it will be davits.

 

[Bill1565]

Sorry, I was out walking the dog. I have never had a problem leaving the 110 cord connected. I run the A/C during the summer to keep the mold and moldew away.

The admiral has re retired, this time from church music/choir director stuff and we plan on cruising extensively. I have a Honda 2000 and it works just fine, but I am also looking into solar. My current thoughts are to adjust the solar panel, since we will be on the boat at anchor. A friend with flat panels tells me he only gets 1/3 to 1/2 what people with adjusted panels gets.

I made a mistake buying group 31 deep cycle 12 v batts. Always used 6v 4d's didn't know of T-105's. Gonna rectify that soon, maybe before we leave for NewYear's eve at anchor.

Funny how we all use our boats differently, Mine is about 50 feet from my back door, I am on it almost daily and I have forgotten all about making an expedition to the boat yard as we did on Lake Michigan in the baad old days.

 

[Ed Schenck]

And don't you ever for a second take it for granted Bill ! Two important things in life, good health and having your boat close by.

I guess some tilt adjustment makes sense. But at anchor how do you control where the sun is? The problem with my davits idea is when the bimini is in use it will shade the solar panel. Permanently on the bimini frame with some adjustment is probably the best. Or I guess with the SBO pole( http://shop.hunterowners.com/detail.htm?group=1714 ) it could be above the bimini.

 

[Bill1565]

That is my plan. I will remove the Garhauer motor hoist and replace with the SBO pole and optional motor lift. Maybe a 135 watt panel taller than the Bimini.

Will tilt and swivel as the spirit moves me, not gonna spend my days aiming the thing like a laser. Will run the Honda as necessary, shouldn't be to often. Going to 3 pair of T-105's for 700+ amp hours, so solar will delay need for fossil fuel recharge.

Typically even on those occasions when we are able to sail to our next destination, I run the propulsion engine a half hour or so in the morning pulling the hook and getting clear of the boats aroud us and a again at night mtoring around the anchorage and setting the hook. On days we motor 30 or 40 miles my 50 amp alternator running for 5-8 hours is more than adequate.

 

[Mathurin]

Bill, I wouldn't go for 3 pairs of T105, you will have problem topping them off. I don't recall the exact scientific ratio for amp hour vs charging means, but with 6 T105, or 675 amp hour, you will need a lot of power and time to charge your batteries. We have two pairs of T105 (450 amp hour), that we charge via our 75amp charger with our honda 2000 (almost twice a day, computers eat a looooottttttt of amps), and with our 125 amp balmar alternator, and we are finding it difficult to top them off. Equalization with a 450 amp hour bank is a pain, I wouldn't want to equalize a 650 amp hour bank unless I have a very good charger and a lot of gas for my honda.

Oh by the way, just forget about wind generator and stick with solar panel, our wind gen is basically useless (oh except for those two days when the wind blew 55-60 knots and it was charging 25 amps with the dump resistor working full time, next time we won't forget to stop it before the storm) and from what we've seen, people who have 135+ watt solar panel are more than happy. Next time we go for a long trip, we will have at least two 135 watt panels.

 

[Mathurin]

here:

''The main engine alternator should be 25-40% of the rated battery capacity''

so for a 675 amp hour bank, your alternator should be around 170-270 amp, on the low side if you have AGM of Gel batteries and on the more muscular side for lead acid.

Source: http://www.amplepower.com/primer/consider/index.html

 

[Ed Schenck]

So guys, you are online! But where? We haven't heard from you. You are our test vessel for electrical and everything else.

 

[Steve W]

Ed, I installed the Martek davits on my old 1981 H33 along with an 85W solar panel. Talk about "narrow stern"!!! But it worked perfectly. Although I opted to the non-swivel type that was never an issue. If my pictures were posted properly and show up below, you'll see that the installation was simple, only requiring the two transom mounting plates and the two stern-rail "stand-offs". With a friend, the installation only took about 3 hours. I added the cross bar and the two bracing bars at each outboard end for rigidity and that was that.

The only modification to the boat (aside from moving the GPS antenna and Sirius radio antenna) was that I had to purchase another stern light to mount on the crossbar. I realized that after I had the dink up and secured it blocked the existing stern light.

I also installed the Isotherm refrigeration system on the boat and with the input from that 85W panel, I was able to leave the reefer on Monday-Friday while away from the boat and only found the house bank down about 30% when I'd get to the boat on Friday afternoons.

As an FYI, aside from the Garhauer motor lift, the other vertical pole in the picture is the radar mount - also from Garhauer.

Steve

 

[Ed Schenck]

Wow Steve, you had that baby loaded! I recognize the radar pole, also have the Garhauer. You have really answered the question for me. So after all of this dialog I am at a decision point. A nagging question in my feeble mind is why, after ten years of dragging the dinghy, do I want it on davits? I don't like biminis and dodgers because I want to be "free". So do I want a dinghy hanging behind me?

 

[Bill1565]

Bill, I wouldn't go for 3 pairs of T105, you will have problem topping them off. We have two pairs of T105 (450 amp hour), that we charge via our 75amp charger with our honda 2000 (almost twice a day, computers eat a looooottttttt of amps),
Oh by the way, just forget about wind generator and stick with solar panel, our wind gen is basically useless.

Thanks for the advice. My hope in going to 3 pair of T-105's is that I will not have to run my generator even once a day. We use 60-80 AH per day and I should be able to go 3 days without running the Honda. As quiet as the Honda is, I get tired of hearing it so I shut it down hen the charging rate falls to 20-25 amps

As far as topping off, we still live in a house. Boat sits sometimes for a week or more and unlike others, I leave it plugged in with the charger on. Our experience here in SW Florida is that on a cruise, we wind up motoring or motor sailing more than half the time. When we do that, the engine runs six to 8 hours. That is more than enuff time to recharge the batteries even with a 50 amp alternator.

I agree with you about wind generators. When I was into racing,I looked at well over 100 races here on Charlotte Harbor to see if a 155 was necessary. Average wind speed reported was less than 8 knots. WF PHRF uses 8-10 knots as their wind speed and compares itself to Long Island Sound, a notorious light air venue. At those speeds, wind turbines do not seem worth the money.