Designs of telescopic legs, can anyone help?

[matnoo]

Being in the wash and not having much experience is good because it forces you to toutch up on your navigation skills, and also that you can only possibly hit sand!

The bad bit is that you (or I) tend to hit sand more often than id like and then get stuck...

In addition to practising my dislodging skills I have decided to build two legs for my boat. On the topsides there are already two large reenforced holes (adjacent to a bulkhead) with two 12mm stainless steel bolts through them which when removed are for fitting legs onto.

Any suggestions? Obviously then need to have a 12mm bolt as a fixing, but it would be good if they were adjustable. Im fine with wood, and plastic (I prototype products in both all the time for my job), but not metal as i cant weld, so metal tube isnt possible.

Before I start drafting my own ideas, are there any simple methods that you know of?

Shes only a little thing, 23ft fin keel so doesnt need tree trunks.

ta

Mat

 

[Sixpence]

If memory serves there was an article in PBO not long ago about someone that did something like that , may be worth a bit of research in that direction

 

[William_H]

From one who has no experience but loves to speculate.

I can understand from a post some time back that to be caught on sand in the open sea can be quite dangerous. The boat lays on its side when dry and can be filled with water when the tide with waves comes in.

So you need legs that are long enough to keep the boat reasonably vertical while sitting on its keel. You might as well use them as props when the boat is wintering on the hard. So that will help you figure what length you need.
However if they are too long then you may have troubel getting them attached when the keel has sunk into the mud a little. On the other hand too short will allow the boat to heel too much. The more heel the more stress on legs etc.

You can have them telescoping to permit adjustable length. (and possibly for storage) or have a choice of attachment holes for the 12mm bolts so that if you can't get the poles down deep enough (cos the keel has sunk) you can still attach the poles.

You will need a foot of some sort to stop the poles sinking. An elegant solution is to join the front pole to the back pole by a cross member at the foot which will add to stability but make it necessary to attach the poles in pairs, so much more tricky.
If your attachment points are sufficiently far foreward and aft of the fin keel then a joining of the poles across from port to starboard would be even better as it may allow some splaying of the poles for more stability. The best is to join the bottom of the 4 poles both fore and aft and across the ship but this could be impossible to fit while in the water.
Brainstorm.... You could make fore and aft members that attach near the top with a loop of steel around each leg such that they can be dropped(slid) as far down as possible to fix the legs relative to one another.
You will be leaning over the gunwhale trying to locate and attach the poles in possibly rough conditions.(practice would be essential)

I imagine 4 poles will be necessary for fore and aft stability.

Somehow just thinking about it all, it may be just too hard to make and carry legs that will support the boat vertical while on the bottom in rough water. My 21 fter is very light and has a fin keel. Actually vertically retracting but I do not retract when I run aground.

The rules are to know which way you want to go to escape the shallows. Have a suitable pole that can be used from the bow to rotate the boat to point in the direction of escape. Try to choose your escape direction with a beam wind. keep all sails up and sheeted tightly then using crew weight heel the boat over to lift the keel off the bottom. I think the trick is to plan actions before you hit the mud so you and the crew are not to surprised and know what to do. Speed of escape is essential. of course an engine canb help a lot.

Anyway good luck and don't take my speculations too seriously. olewill

 

[Sixpence]

A much more helpful and concise suggestion than I could have given , thankfully Miss Ellie and Trevera will happily sit on the sand upright

 

[Bajansailor]

One could facetiously say sell the boat and buy a bilge keeler, but I have seen the photos of your Breda, and she is lovely. And definitely not worth trading in for a twin keel job.

I know you want to make your own legs, and you claim to be not too hot with metal (but I doubt it), but you could perhaps get some good ideas from the telescoping legs made by these folk at :
http://www.yachtlegs.co.uk/products/yachtlegs_adjust.php

 

[Niander]

I imagine 4 poles will be necessary for fore and aft stability.

Normaly there are just 2 legs with ropes to the bow and stern from each leg.

 

[aitchw]

How about using Ali scaffold tube that uses standard fittings like foot plates and using a half a scaffold clamp fixed to the gunwhales with the tube allowed to slide up and down in it and clamped solid at the appropriate length for the situation you find yourself in. No metal working skills required, cheap and versatile. On the hard you can use more tube and fittings to brace the legs diagonally and athwart.

 

[mtb]

12mm ? I'd not risk that
A decent plate to carry the load, remember at any time the whole load may be on one side if for example you get one leg hit some thing harder than the other also the boat will settle over a few hours
That brings out a thought straight away if you make legs that have feet think about suction re sinking into sand

I built legs for my trawler that was 65ft 34 tons ofcouse they were steel and I had 4" inner legs and used to have holes through wich I'd put pins.

Your toy wont need heavy stuff but I think thats good because you can use for example jocky wheel type things at the top so you can adjust each leg

As for running aground in the wash !!! come on get an uptodate chart lol freeman channel is well marked its only up through boston deep where you have to be careful re long sand
do you keep your boat at fosdyke ?

cheers
Mick

 

[pappaecho]

The obvious things for legs are Acrows, preferably with a larger base plate welded on. I have a 6 tonner with two such legs, and found the acrows in the DIY section of the local paper

 

[Blueboatman]

I suppose you should post a pic or give design links to the profile of your boat-there are fin keels and then there are fin keels..
Also you do not say whether you intend to lug these telescopic legs around as deck gear each time you go sailing?
In principle and only if the boat is realistically going to be stable fore and aft when sitting on its keel,use alloy tubing say 70mm with inner ally tubing and a series of holes for an adjustment pin,12mm bolt throught the topsides,alloy plates 200x200 welded on the feet(get someone to weld em)and eyebolts at the base so that you lead guywires to bow and stern on each side....seems like a lot of work though..
Another alternative if you haver a permanent drying berth on the foreshore:Have you thought about building a scaffold pole cradle in which the boat sits securely as the tide goes down?

 

[matnoo]

Thankyou very much to everyone, especially william. I will take all into consideration!


I was asked for a photo of the keel, which is very heavy, abot (4-6inches wide!)

http://www.faceparty.com/gallery/view.as...&pos=1#view

Cheers!

Mat