Demasting yacht

[Conrad]

Hi has anyone any tips on taking down an 8m approx 30ft mast without a crane.

Is it doable for instance or a foolhardy task?

The boat is currently out of the water on chocks to make it more interesting.

 

[deep denial]

yes, definitely doable, presumably a deck-stepped mast. Does it have a pivot point at the step? In which case you attach a tackle to the end of the forestay secured to a strong point at the stem, and a stout length of wood or a pole etc attached also at the end of the forestay and to the bottom of the mast to act as a fulcrum, and have a couple of blokes to hold the shrouds as it goes down to stop it rocking from side to side. (do it on a still day). RElease the shrouds, and lower the mast backwards under control with the tackle, with the fulcrum pivoting back as the mast goes down. Should be easy with 8m mast.

 

[Conrad]

It does have a pivot point at the step, I'll give it a go.

 

[Shanty]

As Kevin_Mac says 8mtr deck stepped mast with a bolt at the foot that can act as a pivot - its doable. However, remove any of these elements, and it becomes a lot less doable:

is your mast 8mtr or 30ft (a tad over 9mtr)? the extra metre will make the job that bit harder

deck stepped or keel stepped? If keel stepped, you will need some means of lifting the mast, such as sheer legs

if deck stepped, does it have a suitable pivot bolt? If not, you have the additional problem of restraining the heel of the mast.

If you don't want the expense of a crane, have you considered using a lorry mounted Hiab?

 

[Searush]

as it comes down, the forestay will become much less efficient as it reaches 30deg or so from horizontal. At that point it will be useful to have someone actually get under the mast to take the weight. They are not that heavy, but are awkward to manouvre. One can hold it, but better for two to carry so that you don't hit stuff or lose the balance.

Similarly, for erecting, connect at the heel pivot & have a man lift & push it up initially until the forestay can take the weight at 35-40deg. Use shrouds to minimise sideways movement, but remember that if they fasten aft of the mast they will quickly slacken. Forward shrouds MUST be disconnected as they will prevent the mast lowering. Just give it some thought before you do it!

 

[deep denial]

[ QUOTE ]
as it comes down, the forestay will become much less efficient as it reaches 30deg or so from horizontal.

[/ QUOTE ]
....that's why you use the fulcrum pole as described, to stop that happening, rather like a spreader holds the shroud away from the mast.

 

[Graham66]

Leave the mains attached, just loosen, detach lowers and add length so as they can be controlled from the ground and have them held by assistants. however if mast base is cast alloy think long and hard about lowering yourself as a new base doesnt come cheap (thats if you can get one!) a minimal swing either way will snap the lugs off before you can say------ as the leverage and the weight can be VERY deceptive.

 

[blackbeard]

[ QUOTE ]
Leave the mains attached, just loosen, detach lowers and add length so as they can be controlled from the ground and have them held by assistants. however if mast base is cast alloy think long and hard about lowering yourself as a new base doesnt come cheap (thats if you can get one!) a minimal swing either way will snap the lugs off before you can say------ as the leverage and the weight can be VERY deceptive.

[/ QUOTE ]
Yes I found this too. ....
Helps if the fulcrum mentioned above is an "A" frame.
Also helps to have something to lower the mast onto.

I think I know how to do it now.

 

[theoldplucker]

Have used both methods. Using sheerlegs is the easiest. You haven't got all that leverage as the pivot point is at cross trees, not the base of mast. 2 or 3 persons will get it down in twenty minutes.

 

[William_H]

I have never used the shear legs method of lifting the mast bodily from near the centre. You would need very long shear legs. ie 20 ft or so that are well braced fore and aft.

Around here every one uses the pivoting base method because of low bridges in access to the ocean. Some masts much more than twice your size are lowered while under way.

As stated you must be careful of sideways swing as this will destroy your pivoting base.

I suggest you get 2 pieces of wood about 10 ft long with a bolt between the two near the top to act as a crutch. Lash it to the stern rail, legs apart so that the mast can sit into the vee at the top when down.
As the mast comes down the load on the lowering tackle gets greater beyond about 45 degrees. The crutch should be as high as possible consistent with your being able to reach the crutch to lift the mast down. Once the mast is down into the crutch you will want to lower it to the deck. This is best done by removing the pivot pin and sliding the base of the mast forward to the bow rail. The mast will have to be lifted to slide it in the crutch. From the position of base of mast at the bow you need a lower crutch or just lower the mast down on a rope from the crutch to the level you want.

The post at the base of the mast (previously incorrectly called a fulcrum)(I think) is there to improve the angle of pull of the forestay.
It comes into effect as the mast gets beyond 45degrees. If you didn't use this post as the mast gets lower the forestay will be approaching parallel to the mast and the trigonometry means the load on the forestay becomes much greater. It is much more obvious when the mast is down and you want to get it up.

People around here myself included use 2 spinacker poles that pivot on purpose built rings in the deck abeam the mast. 2 poles means you don't have to worry about supporting or guying the single post.
But for infrequent use one pole is OK.

For the tackle to the bottom of the forestay you will need a 4 purchase ie 2 double blocks and the rope must be long enough to reach a winch. Make sure you have enough rope. My guess is you will need about 90 ft of rope. Don't leave it till the mast is nearly down to find you don't have enough rope.

Many people actually use a spinacker or jib halyard, well cleated on the mast, instead of the forestay. Although I don't like the load on the halyard it does mean that the forestay is free and easy to detatch and reatttach to the bow. This especially so if you have a roller reefing drum close to the deck so you can't get room under it for a tackle.

good luck and be carefull. olewill

 

[Conrad]

Many thanks again definitely a few ideas to play with.

 

[john_morris_uk]

[ QUOTE ]
....that's why you use the fulcrum pole as described, to stop that happening, rather like a spreader holds the shroud away from the mast.



[/ QUOTE ] Just to be completely anorak about this, the 'fulcrum pole' is called a 'gin pole' when erecting radio masts.

 

[kds]

"attach a tackle to the end of the forestay"

Much easier to use a doubled sheet round the mast at the spreaders. Doubles the angle to the mast and significantly lowers force needed on pulleys.


"a couple of blokes to hold the shrouds as it goes down to stop it rocking from side to side."

This could cost you a new heel fitting. Lash a long timber across boat in front of mast foot and put temporary shrouds up to spreaders from each end. Any movement at all is to be avoided.

"on chocks"

Are you happy having 4 blokes clambering about on a boat supported by chocks ? Have an ambulance on stand-by !
ken

 

[DavidNB]

Just a daft question while we are on the subject of masts ....is it possible to step any mast/boat, if not, why not?