Greetings to Ebb and the group,
A friend suggested I take a look at Ebb's photo gallery thread which led me into some other threads here. Great information here and I'll have to borrow some ideas for my next refit.

I stumbled on the last post of the rudder thread below and pulled it over here. Thanks, Ebb, for the kind words and the interest in the dry-out legs. That sailnet article is not specific with dimensions or details according to the editors request . When I get some time I plan to pull the rest of the sailnet article links and put more detailed articles on my own site pages. Meanwhile, hope I can help with your questions here.

To start with, I've added a page with larger sized photos of the legs. Looking at these along with the article you should be able to see how it works. (Links below)

http://atomvoyages.com/projects/Legs.htm

http://atomvoyages.com/images/Legs02kb336.jpg

http://atomvoyages.com/images/Legs03kb298.jpg

http://atomvoyages.com/images/Legs04kb340.jpg

http://www.sailnet.com/forums/showthread.php?t=20077

I recall taking Atom several miles up a narrow mangrove creek in Madagascar on the rising tide to visit a village where we could provision cheaply with mangoes and cashew nuts and fill the tanks at the freshwater well. Tide range was about 5' that day. Once we got to the village at high tide we had only about 6' of water in the deepest bend of the river. I would have like to stay at that village overnight if possible, but within an hour we had to rush out with the tide to avoid being laid over in soft mud all night. In some places with nicely sloping and protected hard sand beaches I would careen, but on that river and many other places it wasn't an option. That's where I decided to come up with some system to hold the boat up.

I'm sure the design can be much improved because I just cobbled together what was at hand in Richard's Bay South Africa. There was a metal scrap yard there that supplied all the stainless steel and I had use of a drill press, grinder, and crappy DC Arc welder and not much else.

As to your questions:

Aluminum could be used, however there is corrosion issues underwater in contact with various stainless fittings and fasteners. If the legs are take-apart instead of one piece then there is the coupling system that might corrode. I was lucky to find heavy duty stainless pipes with couplings that were piled up in the scrap yard. A sleeved and pinned stainless pipe system may be easier to source materials for.

Connecting the legs to the aft lower shroud chainplates (after temporarily removing the aft lowers) worked well and prevents the bow from dropping. My east coast Triton with internal ballast annoyingly insists on dropping her nose over a foot when laid with bow unsupported against a wall for careening due to the center of gravity being close to the point of the cutaway forefoot. I could use the upper shroud chainplates if I wanted, but they hold up the mast in case the boat were to topple over. The embarassment of tipping over would become a disaster if the hard landing bent the mast at the spreaders. And since there's no reason to use them, I don't. Still, it could be done if a new design warranted it.

Choosing a safe place is key. Depending on conditions, the boat can look precarious balancing high and dry on its legs. Don't use them in a tight location where if the boat fell over the mast or hull might strike something hard. At the link below I see the Alberg 30 sits nicely level on her keel. Maybe the Ariel does as well? A little pressure down on the legs is not a problem - make sure you make them extra strong for that and many other unexpected loadings. I wondered why the Alberg at the link below is heeled away from the wall instead of against the wall, which is the only way I've done it or seen it done.

http://www.alberg30.org/maintenance/...zed/careening/

What happens when a wake from a fat powerboat comes by or some other unforseen event cause the boat to flop over toward the wall when the tide is only down a foot or so? Remember this is a 12 hour event. While you're asleep or doing something ashore some wharf rat could cast off a couple lines for a good laugh. Unlikely I know, still...

The feet pivot fore and aft because you generally have a nearly flat bottom or are bow on to a sloping beach. I have yet to see the need for a universal-type joint. Just make the feet connectors extra strong. I try to keep things simple as possible.

As for extra lashings of the top of the leg to the shroud? As hinted at in the article, the top of the legs are held a few degrees inboard by a line or tackle between the two legs. They are fixed at one point to the chainplates. The feet are held tight fore and aft by two lines and pulled slightly inboard to oppose the outward pull of the line connecting the tops of the legs. A high desity foam block around the leg protects the hull. I don't see a need to add lashings to the shrouds. Actually, I'm not able to picture it this way since they've been disconnected at the bottom pin of the chainplate toggle.

In the photo of the legs dissassembled you'll see the turnbuckle/sleeve/shackles assmbly allows adjustment of the boats angle of heel, at least during the first few inches of tide drop once aground. An improved design of this assmbly should be possible with a little more thought.

I hope to bring Atom next to our shop in our backyard in Brunswick, GA this winter for another refit and by that time I'll try to get better photos and dimensions on the updated article, particularly the legs to chainplate connection which might be baffling you. Meanwhile, you may come up with a refined design of your own.

This is a great forum and though I can't come aboard too often because of limited internet access and so many jobs to do, I'll check in when I can.

James
Triton #384 Atom

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Baldwin's Give Your Boat Some Legs
(this could be a new thread - but it still is apropos access to the rudder)

Jim Baldwin's Sailnet article now comes up using the address in the previous post.
If whisker and spinaker poles don't have a place on your cruising A/C then this invention of Jim's is fantastic. He uses s.s. pipe/tube. Relatively common 6061T6 aluminum might work as well.

The article is not complete in that there are no closeups of the fittings. Most important is the method of attachment of a leg to the chainplate. I believe Jim temporaryly removes the aft lowers, using that plate.*

Some exploration of 'Some Legs' for the Commander or Ariel should probably be done on the hard. I have trouble 'seeing' the legs at the top 'attached' to a single point on top of the chain plate, obviously by a bolt or pin. Couldn't the leg be lashed in some fashion right to the upper shroud, which is almost vertical? In other words I would rather have a two point tie to the upper shroud in order to have a stiffer leg. One lashing at deck level, another a couple feet higher. What am I missing here?

Another thought is that if the center shroud is used, the fore and aft lowers on either side could be employed to position and steady the legs, again by lashing. Maybe - like the feet below - a plywood devise that clamps to the shrouds with a couple clamps for the leg poles could be designed. Ariels with inboard shrouds might benefit with a gizmo that clamped to the shrouds but standoff the proper distance outboard for the legs to be at a optimal angle. Seems to me that an optimal angle would be slightly knock-kneed, wider at the bottom than the top.

Another 'exploration' is necessary to articulate the footpads. Seems to me the pad to pole joint has to be a universal type - able to lay flat at whatever angle the boat is to the surface. How?

Another problem is whether the legs can or ought to be adjusted IF the boat decides to lean and a foot starts sinking?

Another issue is that the flat part of the keel is aft of the shrouds. Is there any tendancy of the A/C to nose forward or downward? An inclined beach would counter that problem if the boat is bow in. Yet most of the Ariel's sitting surface is under the companionway - the keel starts upward from a point between the two big windows in the cabin - that might put "unintended" pressure on the legs at the shrouds.

That means there is less than 6' of horizontal keel surface (in the 25' length of an A/C). And all of that is concentrated in the rear half. If you wanted to remove the rudder, it would be dicey to say the least, even tied to side of a quay.
Has anybody done this - tied off at dock side and have the tide go out to work on the bottom?
A THIRD LEG MAY BE NEEDED AT THE BOW. (just being difficult - and voluminous as somebody once said! )
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Anybody carrying oars (see appropriate archives) might find that they could be adapted to leg duty. Blade up with slip on footpad over the handle, and a clever, simple attachment of the blade end to the shrouds...

Last edited by ebb : 08-17-2007 at 12:05 PM.