Originally Posted by Panope
Does this look like a workable set up?
Legs have been discussed a few times on CF before, so worth a search.
I hesitate to chip in with any comments as despite living in a tidal area where legs are common (and have owned boats with legs in the past) nonetheless plenty of scope
for things to go badly wrong
- so please do not take anything I say here as "gospel"
Ok, disclaimer out of the way.........
You look like you are in the ballpark
. One leg is a bit outside my own comfort zone, but I can see the logic and no reason why it cannot work
- just increases the risk of murphys law applying.....but given that you appear to have already beached (careened) her already on a beach without any issue then have a bit more scope
to survive the unplanned.
I dunno which area you are in and what the tides are like but my first choice would have been to lay her against a harbour wall - or even a post. The price
of that likely would have been the need to turn her around to do the other side because of the lack of easy access.....but you have built the leg now. (and just to say that if you or someone else moors against a wall never put the leg down on the inside - even when you have 2 of them! - the risk is that the leg hooks on the wall or forces the boat too far over so wayyy too much weight on the outboard
leg as the seabed next to the seawall tends to be higher than even 6 foot out).
As I am sure you know already, don't park the boat on any seabed you have not already seen with own eyes when dry (same applies even on a boat with no legs - odds are will be ok, but only takes the one time to be a disaster).
Over here no one parks a boat on a beach with legs as simply too exposed to sea conditions (and other people in boats zooming past at the wrong time), might be fine when parking - but 12 hours later you don't get to pick the conditions. Not to say that it can't be done, but risk goes up a lot - and certainly I would want to be onboard (and awake!) when she settles and when she refloats. Of course over here plenty of options available (for free!) so a beaching with legs not actually neccessary.
The risk is that the boat snaps a leg (actually not that common) or the more common leg folds under the boat. Leg likely still straight but the power of leverage on the through hull fixing (and fore and aft ropes) is enourmous with the weight of the boat on the leg if it digs in as the boat heels and moves sideways - that happens if the tide / wind
is playing silly buggers! particularly from any swell (including that created from boats zooming past)......the time of risk is just when the boat is settling, boat is bumping on the bottom (that happens even in ideal conditions) lifts a few inches (or a few feet if things are bad!) and comes down at an angle - with full weight on the leg
.....it don't matter how strong the leg is as it's all about the leverage...........and that happens even in protected harbours, including on boats with far shorter legs than yours. That often enough not a great problem until the boat settles on the leg as afterwards you have at best a hole in the hull around the fixing or worse a hole in the hull caused by the leg itself - which don't matter greatly immediately, just when the tide comes back in
..........not to say that everytime a leg falls off or folds under is a complete disaster, but less than ideal!...........anyway, forewarned is forearmed.......so my "advice" is to do the beaching somewhere protected, ideally in a harbour.
My own boat has triple keels (main keel kinda like yours - with slightly shorter "bilge" keels each side that do the same job as legs, except less of a PITA
)....she also often balances on her main keel, but she will rock onto her bilge
keels depending on what I am doing onboard - in your case with only the one leg I would make damned sure she was not balanced! - for that all you need is some weight on the leg sidedecks, plenty of it for safety
(buckets and containers of water
- I would say also the anchor and chain, but you will need those elsewhere!) and even then I would hesitate to have anyone onboard wandering around just in case she overbalances the other way
. In regard to anchoring
her you want to avoid her broaching / slewing broadside as the tide recedes / comes back in.....so at least a stern anchor, and then your guess as good as mine!, but personally I would have no faith in also having an anchor amidships to keep her leaned onto the leg due to the inability to guarantee that would always have enough tension / the right angle of pull.
In regard to your leg itself, you are spot on with only a few inches shorter than the keel (the leg is a prop not to bear the weight of the boat) and if that angle (in the pic with the leg leaned against a sheet of plywood) is the same as when on the boat then looks about right. A mighty sized bolt on the top!, my concern would be around what that is fixed through inside the boat as whilst pretty much nothing will cope with the leverage of the full boat nonetheless the hull sides should be able to cope with a fair bit of that before giving up. In regard to the foot size, bigger than I would have done by a few inches, but I don't think
it matters.....my main concern is about the bracing being on the underside. Unless you are parking the boat on concrete then the keel will sink into the seabed at least a few inches and so will the leg (as long as the seabed pretty much the same of course)......and you want the leg to do that to match the keel....therefore I would have put the bracing on top as my expectation would be that the bracing as is will slice into the seabed (so the leg measurement I would be working with is down to the foot plate only and not the extra 3(?) inches of bracing), but no guarantee that it will be the case if the leg bracing hits a rock or large stone under the surface - that don't matter so much if you have a leg on the other side! but could tip her over or simply put too much weight on the leg. Basically what I am saying is that it brings in an uncertainty on the leg measurement
.....and in addition a bit more uncertainty on whether the leg will snag / trip on the seabed as she settles rather than a smooth foot being able to glide / move a few inches as she settles.....those things not bad enough for me to say you need to get the angle grinder out, but nonetheless would make me a tad less comfortable.
Anyway, the above a bit longer and a bit more rambly than I had intended!, and whilst I think you are in the ballpark nonetheless the results very much down to you...aka don't blame me
Pics of the result would be nice.