chouchou
Member
Is it possible to make up a contraption to take down a Sun Odyssey 29.2 mast by hand. I have seen A frame arranagements on Dutch Boats.
MAST UNSTEPPING
- Thread starter chouchou
- Start date
ajt
Well-Known Member
Anything is possible but do you really want to take the risk of all that metal crashing on your deck or worse someone elses.
Mac greggor yachts use a system on there 26 footer I think using the spinnaker pole and the spinnaker halyard personally I would rather pay the money to someone else
Mac greggor yachts use a system on there 26 footer I think using the spinnaker pole and the spinnaker halyard personally I would rather pay the money to someone else
NPMR
Well-Known Member
In the current COMPASS catalogue there is an A frame arrangement called a Mobile Mast derrick that has pics of one person lowering a mast . Max lift height 6.5m and 120kg, it says.
No idea if it works but looks simple.
No idea if it works but looks simple.
grievesie
Well-Known Member
Take a look at the Compass web site (www.compass24.co.uk) and search for "telescopic mast derrick" . I have not seen this A frame device in action but the photos look convincing. I am thinkng of getting one myself.
vyv_cox
Well-Known Member
The method used by Dutch boats well over the size of yours is to extend the chain plates upwards so that the mast and shrouds pivot on the same horizontal line across the boat. The mast can then be lowered without any risk of it falling sideways. The A-frame is connected to a point at about the height of the spinnaker pole uphaul so that the angle between mast and lowering line does not decrease to nothing as the mast reaches the horizontal going down. Dutch boats use this method to shoot bridges without even stopping. Your problem is that it is more complex with a Bermudan rigged boat with the foot of the sail attached to the boom.
sophie4
Well-Known Member
Try here, I intend to try this next week.http://www.westerly-owners.co.uk/html/centaur_mast_raising.html .
moondancer
Well-Known Member
We use the Compass telescopic A frame. It works fairly well on our 10 Mtre masts and has a weight limit of around 120 KG. We use a crane on our 14 M masts though.
Brian
Brian
Blueboatman
Well-Known Member
The short answer is-do it with someone who has done it before,at least the first time.
Its all about trying to save a few quid but you need patience,plenty of rope,a block and tackle and preferably 2 lengths of 4x3 timber the height of half the mast ideally.
It is actually much easier to drop the mast when afloat-go alongside a friends boat and use their spinnaker pole rig to lift and swing your mast out.
You are going to end up just paying for a yard crane,realistically ,this time around,no.? 50 quid well spent!
Its all about trying to save a few quid but you need patience,plenty of rope,a block and tackle and preferably 2 lengths of 4x3 timber the height of half the mast ideally.
It is actually much easier to drop the mast when afloat-go alongside a friends boat and use their spinnaker pole rig to lift and swing your mast out.
You are going to end up just paying for a yard crane,realistically ,this time around,no.? 50 quid well spent!
roger
Well-Known Member
A great deal depends on the weight of your mast. Ours is only about 12 metres long but its old and immensely heavy. Even with a mast crane it takes two stron operators and me to do the job.
Be careful with contraptions. The mast is not difficult to control when its nearly upright but the loads get much much heavier when its near horizontal so you can get suckered into a dangerous situation.
I very nearly got killed a few years ago when a wooden mast was being erected and the owner secured the mast with a bowline that wasnt!. The massed crashed down within 2 feet of me and frightened me severely. It also destroyed the boom gallows as it dropped. The drop was only a few feet but the impact was very considerable.
Be careful with contraptions. The mast is not difficult to control when its nearly upright but the loads get much much heavier when its near horizontal so you can get suckered into a dangerous situation.
I very nearly got killed a few years ago when a wooden mast was being erected and the owner secured the mast with a bowline that wasnt!. The massed crashed down within 2 feet of me and frightened me severely. It also destroyed the boom gallows as it dropped. The drop was only a few feet but the impact was very considerable.
wcarpenter
Member
If you can moor bow on to a quay at low water, use a 2 to 1 block (main sheet of kicker blocks are good) to lower from aft, two people with a ladder holding mast at spreader and one or two people on the quay. I've helped to do this before with a Shipman and it works. Finding a high quay on Lough Derg may be a problem.
William_H
Well-Known Member
Yes you can lower your mast easily but you must be set up properly.
Firstly unless the mast is stepped on the deck with a suitable hinge ie if it is keel stepped you will have to fit a hinge about 1 metre above the deck.
Masts are usually lowered backward but I have seen on cats where the mast is lowered down forwards because step is on forward deck and the cabin is in the way. (It must be impressive charging under a bridge with 50 ft of mast out in front like a jouster)
Lowering a mast is in 2 stages. Firstly to lower it to provide clearace for bridges is easier. It is dropped into a crutch at the transom and the top of the mast may still be several metres above the water. The lower you go the harder it is to raise it again.
Almost all decent sized boats on the Swan river do this while under way to traverse under bridges to get to the open ocean. The largest being in the 70ft class with obviously really big heavy mast. It is a pain but doable often out in the morning and home again in the evening of same day.
The second stage is mast removal. This requires a few helpers. The mast will probably be balanced on the crutch such that on disconnecting the bottom hinge the foot will want to rise. You need to get someone at the foot holding it down while it is disconnected. You then need to get people to lift the mast near the crutch and slide it forward. The foot moves twards the bow. As it moves forward the balance becomes easier. To have a lower crutch makes this part easier. Eventually with the foot forward of the bow you can lift the mast off the crutch and lower onto the cabin top. You can do the work from this position or then remove all stays and lower onto the ground.
Now the essence of mast lowering raiing is that you need a jib to the forestay or halyard that will improve the pulling angle of the forestay. This is most commonly 2 spinnacker poles attached to purpose fitted rings near the gunwhale and aprox. abeam the mast. The other pole ends attach to the bottom of the forestay. Any sort of tube or post will do. A tackle usually 4 part is attached to the bottom of the forestay to the bow. The rope needs to be long at least 6 times the length of the spin poles and able to reach a winch.
So as the mast comes down the poles go to a vertical position so that pulling on the tackle can liift the mast relatively easily.
A single pole can be used attached near the base of the mast but it must be stayed sideways so it remains vertical when the mast is down. 2 poles don't need staying. I prefer to use the forestay but a spin or jib halyard can be used. The advantage being you can take the load before releasing or reattaching the forestay. You can sometimes even use an inner forestay.
Ok now that takes care of lowering the mast but in its traverse the stays go slack and there is no sdeways support of the mast. This is critical if the boat is on the water or under way. For a mast head rig where the cap shrouds are abeam the mast a solid SS frame is built so that the chain plates are extended up to be exactly in line with the hinge of mast. generally this is a solid tube about 2ft long between the chain plate and the bottom of the stay which is in itself stayed forward by a wire or piece of steel. This is an elegant solution as the cap shrouds stay tight from vertical mast to horozontal mast position. You will see the staying of the chain plate extension forward is vital to provide a forward pull on the stay when mast is down.
On a fractional rig it is more difficult. The cap shrouds are usually attached aft of abeam the mast and so immediately go slack as the mast head moves back and down. Some solutions are to use halyards as side stays which are continually tightened as the mast traverses down. I use an extra rope or tackle (one each side) from a point about 2 or 3 ft above the chain plate going forward by about 3 ft to a pulley then back to a winch. A cable clamp allows me to attach this rope to the stay. As the stay becomes loose the tackle is tightened to keep the cap shrouds sufficiently tight.
Another method for supporting the mast sideways is to have 2 more poles. Windfurfer masts seem to be ideal. The length will have to be adjusted. These are attached to pivot points on the gunwhale near the stern. The other end of the two poles is attached to a slider which runs runs up the main sail track.
As the mast is lowered this slider is hauled up the track by the halyard. (better attach a down halyard to the slider as well.) It works like a continuously variable mast crutch. The poles can not be too long as there is point half way down when they may be too long to allow lowering. On the other hand the longer the poles the better the support.
If you are doing it on the water the side support is vital. I have a friend with a 36fter whose mast base was badly damaged when it swung sideways while halfway down and under way. On the other hand if you do it in still water or on land one or two people on the cabin top may be able to control the mast coming down. good luck and don't be detered. It sure beats climbing the mast if you can access the top by step ladder. olewilll
Give me a PM if you want details of a hinge for keel stepped mast.
Firstly unless the mast is stepped on the deck with a suitable hinge ie if it is keel stepped you will have to fit a hinge about 1 metre above the deck.
Masts are usually lowered backward but I have seen on cats where the mast is lowered down forwards because step is on forward deck and the cabin is in the way. (It must be impressive charging under a bridge with 50 ft of mast out in front like a jouster)
Lowering a mast is in 2 stages. Firstly to lower it to provide clearace for bridges is easier. It is dropped into a crutch at the transom and the top of the mast may still be several metres above the water. The lower you go the harder it is to raise it again.
Almost all decent sized boats on the Swan river do this while under way to traverse under bridges to get to the open ocean. The largest being in the 70ft class with obviously really big heavy mast. It is a pain but doable often out in the morning and home again in the evening of same day.
The second stage is mast removal. This requires a few helpers. The mast will probably be balanced on the crutch such that on disconnecting the bottom hinge the foot will want to rise. You need to get someone at the foot holding it down while it is disconnected. You then need to get people to lift the mast near the crutch and slide it forward. The foot moves twards the bow. As it moves forward the balance becomes easier. To have a lower crutch makes this part easier. Eventually with the foot forward of the bow you can lift the mast off the crutch and lower onto the cabin top. You can do the work from this position or then remove all stays and lower onto the ground.
Now the essence of mast lowering raiing is that you need a jib to the forestay or halyard that will improve the pulling angle of the forestay. This is most commonly 2 spinnacker poles attached to purpose fitted rings near the gunwhale and aprox. abeam the mast. The other pole ends attach to the bottom of the forestay. Any sort of tube or post will do. A tackle usually 4 part is attached to the bottom of the forestay to the bow. The rope needs to be long at least 6 times the length of the spin poles and able to reach a winch.
So as the mast comes down the poles go to a vertical position so that pulling on the tackle can liift the mast relatively easily.
A single pole can be used attached near the base of the mast but it must be stayed sideways so it remains vertical when the mast is down. 2 poles don't need staying. I prefer to use the forestay but a spin or jib halyard can be used. The advantage being you can take the load before releasing or reattaching the forestay. You can sometimes even use an inner forestay.
Ok now that takes care of lowering the mast but in its traverse the stays go slack and there is no sdeways support of the mast. This is critical if the boat is on the water or under way. For a mast head rig where the cap shrouds are abeam the mast a solid SS frame is built so that the chain plates are extended up to be exactly in line with the hinge of mast. generally this is a solid tube about 2ft long between the chain plate and the bottom of the stay which is in itself stayed forward by a wire or piece of steel. This is an elegant solution as the cap shrouds stay tight from vertical mast to horozontal mast position. You will see the staying of the chain plate extension forward is vital to provide a forward pull on the stay when mast is down.
On a fractional rig it is more difficult. The cap shrouds are usually attached aft of abeam the mast and so immediately go slack as the mast head moves back and down. Some solutions are to use halyards as side stays which are continually tightened as the mast traverses down. I use an extra rope or tackle (one each side) from a point about 2 or 3 ft above the chain plate going forward by about 3 ft to a pulley then back to a winch. A cable clamp allows me to attach this rope to the stay. As the stay becomes loose the tackle is tightened to keep the cap shrouds sufficiently tight.
Another method for supporting the mast sideways is to have 2 more poles. Windfurfer masts seem to be ideal. The length will have to be adjusted. These are attached to pivot points on the gunwhale near the stern. The other end of the two poles is attached to a slider which runs runs up the main sail track.
As the mast is lowered this slider is hauled up the track by the halyard. (better attach a down halyard to the slider as well.) It works like a continuously variable mast crutch. The poles can not be too long as there is point half way down when they may be too long to allow lowering. On the other hand the longer the poles the better the support.
If you are doing it on the water the side support is vital. I have a friend with a 36fter whose mast base was badly damaged when it swung sideways while halfway down and under way. On the other hand if you do it in still water or on land one or two people on the cabin top may be able to control the mast coming down. good luck and don't be detered. It sure beats climbing the mast if you can access the top by step ladder. olewilll
Give me a PM if you want details of a hinge for keel stepped mast.
damo
Well-Known Member
I have heard of this being done:
Anchor under bridge near HW
Hang block from bridge, tied to mast below cross-trees
As tide drops mast rises from deck
Lower mast to deck
I can see several problems that can arise, but is an elegant solution methinks!
Anchor under bridge near HW
Hang block from bridge, tied to mast below cross-trees
As tide drops mast rises from deck
Lower mast to deck
I can see several problems that can arise, but is an elegant solution methinks!
neil_s
Well-Known Member
It is possible. I have used an A frame on my 28 ft Seal. It takes about 3 hours of blood, sweat and toil. My advise is to pay the money.
Neil
Neil
sighmoon
Well-Known Member
If you can find two friends, with masts higher than the height of where your forestay joins the mast, attach their main halyards to your jib halyard, pull your jib halyard alll the way up, take up the slack on the two friends' main halyards, and then you can let the mast down gently using the two main halyards.
Does that make sense?
Does that make sense?
onenyala
Well-Known Member
Sky hooks !
