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Old 17-12-2018, 15:33   #31
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Re: Arches, Biminis, Dodgers and Stability

I put a stainless steel structure on the back of my S&S 30 to support 2*130 watt solar panels and provide some shade. I hadn't noticed it affecting stability but recently I lowered it by 6 inches to give it a bit more rigidity and get rid of excessive head room. I've also added sail cloths to the top and bottom of it to provide more shade. I've yet to see how these perform in the ocean. I can't really fit a dodger because I have a relatively low boom. I recently hired a Bavaria 37 in Thailand and was impressed by the shade offered and the need for shade in the cockpit hence my modifications.
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Old 17-12-2018, 22:27   #32
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Re: Arches, Biminis, Dodgers and Stability

As a pilot, I experience all-direction gusts approaching and during a landing. Progressing toward touch-down, I am occasionally constantly correcting. During some landings, I can be port-wingtip nearly dragging the dirt, instantly followed by the strbd-wingtip nearly dragging. Over and over... including during taxi. Talk about sweat! YeeHaw!

For vessels, first the Naval Architects establish stability curves prior to tank-testing before the build. Builders usually aim for self-recovery from a roll. Realistically, some vessels are unable to recover from a knock-down.

Second, every surface catches moving air, aka 'wind'. How does wind under a dinghy or horizontal photovoltaic panels affect directional stability? Gusts are invisibly unpredictable.

I may have some experience in the matter.

Would we de-rate our stability by adding weight aloft? Before I could feel comfortable, that would require additional tank-testing by more than one accredited Naval Architect. Preferably ocean-going NAs. With decades of green-water experience.

Irregardless of my affection for spokes-model Mike Rowe of Dirty Jobs on televisionprogramming, this is one time his "Safety Third" slogan may be less-applicable.
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Old 17-12-2018, 22:40   #33
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Re: Arches, Biminis, Dodgers and Stability

Wingssail But I will say that when I meet the most experienced offshore sailors they almost always have the same preferences: Clear decks, no on-deck stowage (no jerry cans or kayaks), no arch, no davits, solar panels down low, and an easily removable bimini.

Lol - birds of a feather must flock together. Your boat buddies with clean decks.....rounding Cape of Good Hope last December, amongst a shifting group of about 10 cruisers wed known mostly since Australia, all had dodgers, most had biminis we sailed with, most had davits, and I cant think of one that didnt have a couple jerries on deck.
Agree the davits were all empty on passages - everyone aside from the odd cat carried their dinghy rolled up inside, or on the foredeck.
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Old 18-12-2018, 01:01   #34
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Re: Arches, Biminis, Dodgers and Stability

Quote:
Originally Posted by nofacey View Post
Wingssail But I will say that when I meet the most experienced offshore sailors they almost always have the same preferences: Clear decks, no on-deck stowage (no jerry cans or kayaks), no arch, no davits, solar panels down low, and an easily removable bimini.

Lol - birds of a feather must flock together. Your boat buddies with clean decks.....rounding Cape of Good Hope last December, amongst a shifting group of about 10 cruisers wed known mostly since Australia, all had dodgers, most had biminis we sailed with, most had davits, and I cant think of one that didnt have a couple jerries on deck.
Agree the davits were all empty on passages - everyone aside from the odd cat carried their dinghy rolled up inside, or on the foredeck.
Couldn't agree more Norm, your actually out here doing it, I'm just behind, currently in South Africa. It always amuses me when I read stuff like what Wingsail says, he must knock around with different "experienced cruisers" than you and me.

Nearly every boat out here has a bimini, dodger, davits and solar panels or a combination, they have all crossed at least one ocean if not three, I would call them experienced.
Is Wingsails way incorrect? Nope it's just his way.
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Old 18-12-2018, 04:01   #35
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Re: Arches, Biminis, Dodgers and Stability

Hi,

For what its worth:

We added a very large solid bimini and gantry for sun and rain protection, solar panels and 2 windgenerators, the negative affects were considered before we ordered these items and we considered them acceptable because live on board 24/7.
(The boat is an old HR49 with an assumed ex factory STIX value of 60, this is higher than most. The minimum for an ocean going yacht is either 32 or 34)
The above is mentioned because if our boat had a minimum STIX value, we would not have made these changes.

All the same:
- Before we cross an ocean we plan to have a naval architect asses how the changes we made affect the stability of the boat.
- If needed we are prepared to add weight to the bottom of the keel, remove the 15mm teak deck and 10mm ply underlay which in itself may save 750kg.

We expect the gantry will make the boat skittish when sailing downwind above certain wind strengths and expect to have to counter that as follows:
- Use a drag devise a lot earlier than more normal configured boats.
- Deploy the JSD (Jordan Series Drogue) a lot earlier than we would have before the gantry and bimini were added.

You now have many opinions, good luck with the decision.

Pete
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Old 18-12-2018, 06:16   #36
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Re: Arches, Biminis, Dodgers and Stability

Well, happy boats are not airplanes (yet), water is a more densed media to support the body and our speeds are somewhat lower... (at optimal conditions I can get to ~11+ kts... ). Indeed, any added weight and surfaces on board or above has an impact. It is all a balance between the need for comfort, safety and performance.

Cruising boat designs are way more forgiving on that, unlike racers that consider way more aerospce and hydrodynamics concepts.

Ive seen cruisers with ridiculous high arches loaded with solar panels etc. maybe good for a lazy mooring while keeping self sufficiency. On my cruising boat I use smaller flexible solar panels over the bimini and aft deck - not as efficient as the large solid framed panels, but doing the job plus I plan to add few more flexible panels I can add during longer mooring and stow under while sailing. Davits are good as an easy way to hang the dinghy while docking and in very short easy passages - while the dinghy is lowered and tightly secured to the aft deck or transom.

There is also the aspect of aesthetics - I like very clean boats - by all means.


QUOTE=LargeMarge;2783460]As a pilot, I experience all-direction gusts approaching and during a landing. Progressing toward touch-down, I am occasionally constantly correcting. During some landings, I can be port-wingtip nearly dragging the dirt, instantly followed by the strbd-wingtip nearly dragging. Over and over... including during taxi. Talk about sweat! YeeHaw!

For vessels, first the Naval Architects establish stability curves prior to tank-testing before the build. Builders usually aim for self-recovery from a roll. Realistically, some vessels are unable to recover from a knock-down.

Second, every surface catches moving air, aka 'wind'. How does wind under a dinghy or horizontal photovoltaic panels affect directional stability? Gusts are invisibly unpredictable.

I may have some experience in the matter.

Would we de-rate our stability by adding weight aloft? Before I could feel comfortable, that would require additional tank-testing by more than one accredited Naval Architect. Preferably ocean-going NAs. With decades of green-water experience.

Irregardless of my affection for spokes-model Mike Rowe of Dirty Jobs on televisionprogramming, this is one time his "Safety Third" slogan may be less-applicable.[/QUOTE]
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Old 18-12-2018, 06:30   #37
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Re: Arches, Biminis, Dodgers and Stability



Awesome! Hard to get to the quay, but with this big wing aft she can probably fly. Also not so heavy on the bow.
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Old 19-12-2018, 12:02   #38
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Re: Arches, Biminis, Dodgers and Stability

Quote:
Originally Posted by Peter Fidder View Post
Hi,

For what its worth:

We added a very large solid bimini and gantry for sun and rain protection, solar panels and 2 windgenerators, the negative affects were considered before we ordered these items and we considered them acceptable because live on board 24/7.
(The boat is an old HR49 with an assumed ex factory STIX value of 60, this is higher than most. The minimum for an ocean going yacht is either 32 or 34)
The above is mentioned because if our boat had a minimum STIX value, we would not have made these changes.

All the same:
- Before we cross an ocean we plan to have a naval architect asses how the changes we made affect the stability of the boat.
- If needed we are prepared to add weight to the bottom of the keel, remove the 15mm teak deck and 10mm ply underlay which in itself may save 750kg.

We expect the gantry will make the boat skittish when sailing downwind above certain wind strengths and expect to have to counter that as follows:
- Use a drag devise a lot earlier than more normal configured boats.
- Deploy the JSD (Jordan Series Drogue) a lot earlier than we would have before the gantry and bimini were added.

You now have many opinions, good luck with the decision.

Pete
Hey Pete - all you have to do is a inclination test on your boat at the dock = real life data, then measure it against the original factory provided inclination curve. results would be interesting. i'd predict no changes required.
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Old 11-05-2019, 07:48   #39
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Re: Arches, Biminis, Dodgers and Stability

Quote:
Originally Posted by nofacey View Post
Wingssail But I will say that when I meet the most experienced offshore sailors they almost always have the same preferences: Clear decks, no on-deck stowage (no jerry cans or kayaks), no arch, no davits, solar panels down low, and an easily removable bimini.

Lol - birds of a feather must flock together. Your boat buddies with clean decks.....rounding Cape of Good Hope last December, amongst a shifting group of about 10 cruisers wed known mostly since Australia, all had dodgers, most had biminis we sailed with, most had davits, and I cant think of one that didnt have a couple jerries on deck.
Agree the davits were all empty on passages - everyone aside from the odd cat carried their dinghy rolled up inside, or on the foredeck.
It's all a matter of preference. We have made sailing characteristics and safety at sea a priority. When sailing in heavy weather with high winds and waves sweeping the deck we'd rather be focused on boat and sail handling than being forward dealing with deck items which the sea is trying to claim.

We live aboard, cruise oceans, cruise coastal water, race heavily, and have done so for 33 years including a circumnavigation. This works for us. People with other priorities have different approaches. It's all good. At least with us marking out one extreme on the scale the rest of you are able to see where the middle ground is.

We don't hang out with any particular group, but we meet a lot of sailors. We hear all the opinions. The people I meet who seem the most knowledgeable to me, who seem to be the best and most experienced sailors, are most often people who have a similar approach to safety and sailing performance and usually they agree with the safety aspect, totally, plus they love sailing and don't want to destroy the sailing performance, even a little bit. Most others just don't care about that part or discount it.

PS, Davits? Australia? Yes, that's where I first saw this. Most with tinny's hanging on them.
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Old 12-05-2019, 07:25   #40
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Re: Arches, Biminis, Dodgers and Stability

CT 47 12,000 miles open ocean...

Installed some custom davits, I can turn them around if they start charging me for actually being 51 feet long. Davits should only be loaded in harbor or for itty bitty coastal jaunts where weather is assured. Aft davits allow for dinghy stabilization directly below the aft ladder. New acquaintances being brought aboard might appreciate this.

Designed, built and installed permanent small hard dodger. Absolutely essential that it be in place at sea, the worse the weather the more it is needed. The solar panel is semi permanently attached to the dodger. You can remove it or cant it with a bit of screw turning.

The small bimini overlaps the dodger, if you stand up at the helm you see over the dodger and under the bimini. This viewpoint pretty important in close quarters or near docks. We leave the bimini up, but I suppose if the weather was bad enough we could/should put it down. We have also put it down just for the pleasure of steering (while lying down) by the stars.


The boom passes over both the dodger and the bimini. I cannot imagine enough windage impairment to cause significant performance loss here.


I realize that I had the advantage of building/adding on exactly what I wanted and needed (over a period of time, and after some considerable experience), but if you look about, you will see quite a few open ocean boats outfitted pretty close to this two piece system.


As for arches, they do make a good place to mount electronics....
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