Howto un/step keel-stepped mast without crane ?

[lw395]

BOO2, don't be put off by people frustrated not understanding your problem.
In my list of crackpot solutions, I left out 'build tabernacle and convert mast to deck stepped'.
Just because a boat is built keel stepped, it is not impossible to change, it might involve changing the rigging some or maybe stiffening the mast. And obviously supporting the deck!
Plenty of fair sized boats have been built able to independently lower their masts....

 

[fisherman]

Get your friendly local fisherman to come alongside and lift it out with his landing derrick. Mine is only good for about 200kg, and about 16-18 ft off the water, but others will be bigger. Might want to consider insurance issues first though.....

 

[Alfie168]

Perhaps you could dig out the specification and give Boo some sort of idea if would be suitable for his mast?
Vertical lift / spreader height is the critical one I would say.

The only stamp on it is the S.W.L which, as others have already said, is 120kg. It is adjustable, and I use it on its lowest setting. I'l see what else I can find about lift height. Its deep in my shed and I'm not dragging it out and assembling it just to measure.

As others have also inferred.this thread has got "use a crane with a pro inside it " written all over it.

Tim

 

[doug748]

I'l see what else I can find about lift height. Its deep in my shed and I'm not dragging it out and assembling it just to measure.
Tim

I wouldn't bother see post 40.

 

[BlueLancer]

There are several pages on stepping a mast without a crane in the book by John Scarllet, called Wooden Boats Restoration & Maintenance Manual,he is talking about wooden masts so considerably heavier than ally.

 

[Quandary]

Wood v Alloy

More caution from me, handling alloy tube masts with relatively thin walls can be riskier than timber, a very small kink in the skin writes them off. Alloy masts particularly those where the designer has opted to step on the keel, can be very long and flexible, that is why they need multiple spreaders to keep them straight.
I don't mind Boo asking these questions, the debate is interesting and informative for all of us. MY advice to Boo is if he is going for a boat to do serious trips, those with keel stepped masts will be among the ones with the best rigs. The handling will need a crane or travel hoist jib, but so in most cases so will a deck stepped mast on most 35' boats, unless he is wanting to take some of the risks described above.

 

[Quandary]

Boo2 Your choice of mooring need not be restricted by mast handling. It is not unusual to have to motor to a suitable location un step and put the mast over the deck on small wooden trestles and then motor to the boatyard or slip. I once had to motor across the North Channel to Ireland with the mast tied over the deck because it was too windy to step it at Cairnryan using a big dockyard crane there without punching a hole through the deck.

 

[fishermantwo]

I'm also with Quandary here.The problem with a keel stepped mast is that it has to remain perfectly vertical when being withdrawn from the cabin.Any small deviation and there's big trouble.A crane is the safe way of obtaining a straight pull.I had a boat with a tall keel stepped mast before and know that it's much more delicate to unstep such a mast than a deck stepped one.

Ok this is the bit I don't get. How does the crane keep the mast more vertical than the derrick. I have never seen a crane lift a mast from the top of the mast, always a strop under spreaders, exactly the same as the derrick method. The only difference is with the derrick the legs are exactly the same length so if the boat is level and the derrick is set up correctly fore and aft its more accurate than any crane driver.

 

[Tranona]

Followed this thread with interest. Have little to offer on magic ways of taking 15m keel stepped masts out without the proper equipment. I just make sure I have my rosary with me when we unstep my beautiful 10m long hollow Douglas Fir mast with the yacht club derrick. Worked so far for 30 years!

Seriously, though, it amazes me that such an issue becomes relevant to choice of boat or mooring. If you are choosing to buy a racing boat with a keel stepped mast, independent of whether it is suitable for your intended use, - one thing is certain. You need access to a crane to remove said mast - just goes with the territory. Of course if you get stuck in a situation where no crane is available and your mast needs taking out you may have to improvise. However, the very nature of improvisation means you cannot predict what you might do in advance.

So it is a non-issue!

 

[Tranona]

Further to my post above, I think this problem is being tackled from the wrong end.

The question is not whether you can remove a keel stepped mast without a crane. The answer to that is obvious - only with difficulty and possible danger.

The real question is choosing a boat for the use you wish to put it to. If the objective is long distance cruising to undeveloped places (and single handed) is a keel stepped mast suitable? The answer to that is probably no. It introduces constraints that you can avoid by having a boat with a deck stepped mast. The loss in performance (due to the stepping of the mast) is probably irrelevant, but the gain in the ability to be independent of sophisticated equipment is probably very valuable.

This might explain (in part) why most cruising boats have deck stepped masts. Recognising that any loss in performance (whatever that may be) is more than made up by the simplicity, lack of leaks and easier removal of the mast if needed.

The inconvenience of stepping and unstepping the mast might be one of the reasons why, for example, a UFO 34 is not valued in the market (along with not being designed for short handed crusing, suffering from wayward handling downwind, variable finish, shortage of features for cruising such as anchor handling equipment etc that all leads to asking prices up to 50% lower than similar size boats more suited to cruising).

 

[fishermantwo]

The inconvenience of stepping and unstepping the mast might be one of the reasons why, for example, a UFO 34 is not valued in the market (along with not being designed for short handed crusing, suffering from wayward handling downwind, variable finish, shortage of features for cruising such as anchor handling equipment etc that all leads to asking prices up to 50% lower than similar size boats more suited to cruising).

Depends on where you live. UFO 34's in Perth WA are expensive and highly respected. Several for sale at the moment. Its interesting that these and a lot of other quality cruiser racers in Perth such as SS34's, have tabernacles so that the masts can be lowered daily to clear bridges on the way to the race course.

 

[William_H]

Keel stepped masts

BOO2, don't be put off by people frustrated not understanding your problem.
In my list of crackpot solutions, I left out 'build tabernacle and convert mast to deck stepped'.
Just because a boat is built keel stepped, it is not impossible to change, it might involve changing the rigging some or maybe stiffening the mast. And obviously supporting the deck!
Plenty of fair sized boats have been built able to independently lower their masts....

Quite a few boats at our club have keel stepped masts but all must be able to lower for bridges. The answer is to fit a hinge into the mast itself. So mast remains deck stepped with the same flexibility etc.
The mast (just above the deck) is cut at 45 degree angle higher at the front low at the back. Flat plates of Al are welded onto both cut ends (with a hole for halyards. Lugs are welded onto the aft side of the mast and stump that match to make a hinge. The front edges of the plates are extended forward enough to allow 2 bolts to be fitted to clamp the whole lot together to make the mast one piece in stiffness.

Once installed the mast is lowered on oples etc like any deck stepped mast with hinge.
One boat a Farr 40 has a 250Kg mast about 70 ft long and is lowered this way for bridges while under way. Yes it is still a worry but so far without problem. Of course that is to lower the mast you would still need crane or derricks to remove it from the boat.

Re posting. yes i admit I like to seem like an expert and have people possibly listen (read) my advice. Yes it is all an ego trip (definitely needed in retirement). However not only the op reads these things and I for one get a lot of useful ideas from posts on all sorts of subjects. (or at least an appreciation of other peoples problems and solutions) olewill

 

[Quandary]

Ok this is the bit I don't get. How does the crane keep the mast more vertical than the derrick. I have never seen a crane lift a mast from the top of the mast, always a strop under spreaders, exactly the same as the derrick method. The only difference is with the derrick the legs are exactly the same length so if the boat is level and the derrick is set up correctly fore and aft its more accurate than any crane driver.

I don't believe that, last week in 20 kt. winds the crane driver we use, was able to drop my mast straight through the deck ring which has about 8mm. clearance for the wedges and guide it on to the step car without me needing to move the car at all. (set up for about 400mm. of rake) Not a scratch on the anodising and all the cables emerging from the right slots. Took about 5 min.
This guy who normally does construction work but does our lift every year can place the mast to within 3-4 mm or less horizontally and vertically even in windy conditions. Of course he is helped by having a very hi-tech modern tubular jib crane and gets plenty of practice erecting steelwork. Being vertical is not nearly as important as precise control.

 

[Boo2]

Quite a few boats at our club have keel stepped masts but all must be able to lower for bridges. The answer is to fit a hinge into the mast itself. So mast remains deck stepped with the same flexibility etc.
The mast (just above the deck) is cut at 45 degree angle higher at the front low at the back. Flat plates of Al are welded onto both cut ends (with a hole for halyards. Lugs are welded onto the aft side of the mast and stump that match to make a hinge. The front edges of the plates are extended forward enough to allow 2 bolts to be fitted to clamp the whole lot together to make the mast one piece in stiffness.

You wouldn't have any pix available would you ? I can sort of see what you are saying but a couple of photos would make it much easier to understand.

Thanks,

Boo2

 

[William_H]

Mast Hinge photos

A short walk to the club and photgraphed 5 different boats, 2 here. One on a 27fter the other on a 39fter. Sorry not quite as simple as in my description with extra structure aft of the mast for the pivot.
As with all mast pivots you must ensure the mast stays on c/l in its traverse down to a crutch. This is where most people come unstuck especially if large boats go past when you are lowering or raising.http://www.ybw.com/forums/attachmen...ment.php?attachmentid=4512&stc=1&d=1270354317

olewill

 

[davidej]

Doesn't this mod negate the point of keel-stepping?

IMHO you might as well terminate the mast in a conventional taberncle and install a sampson post.

Or am I thinking back to my racing dinghy days when we controlled mast bending with a ram at deck level.

 

[Boo2]

A short walk to the club and photgraphed 5 different boats, 2 here. One on a 27fter the other on a 39fter. Sorry not quite as simple as in my description with extra structure aft of the mast for the pivot.

Thanks, that maks it much clearer. I see much welding involved to the alloy masts, I take it from the fact it's widely done in your region that this can be done without ill effects ?

As with all mast pivots you must ensure the mast stays on c/l in its traverse down to a crutch. This is where most people come unstuck especially if large boats go past when you are lowering or raising.
olewill

Ho do you do that ? Is it just a question of taking a couple of halyards down through blocks on the forward quarters and then back to winches or tackles ? Or do you use special setups ?

Boo2

 

[Boo2]

Doesn't this mod negate the point of keel-stepping?

IMHO you might as well terminate the mast in a conventional taberncle and install a sampson post.

But I guess that the internal structure might need to be altered to cope with a deck mount, whereas the hinged mast will have the identical loading on the deck structure that the original mast did ?

Or am I thinking back to my racing dinghy days when we controlled mast bending with a ram at deck level.

With the 45 degree plates and a big bolt at the front I suppose that the mast is probably stiffer in the region of the hinge than it was before, but I may be wrong.

Boo

 

[fishermantwo]

A short walk to the club and photgraphed 5 different boats, 2 here. One on a 27fter the other on a 39fter. Sorry not quite as simple as in my description with extra structure aft of the mast for the pivot.
As with all mast pivots you must ensure the mast stays on c/l in its traverse down to a crutch. This is where most people come unstuck especially if large boats go past when you are lowering or raising.
olewill

What William did not mention is that yachts in Perth and plenty around Australia that originated in Perth, ones with tabernacles or the pivoting mast section also have solid shroud attachments that reach up from the deck the same height as the mast pivot point. This keeps sideways tension on the mast as its lowered/raised. UFO's, SS34's etc and plenty of larger yachts.

 

[William_H]

Mast hinge

The force of pushing the mast forward when lowering seems to be easily taken up by chocks if any at the deck level or simply by the deck itself. I don't have this system myself but have not heard of any concerns.
Yes this joint does provide a hard section in the mast over a small distance but essentially the mast when bolted together acts as a keel stepped mast in terms of mast bend from the keel to the top. I don't know much about the bend characteristics of keel stepped versus deck stepped masts but essentially the hinge does not change anything.
Re solid shroud attachments this is applicable to all mast lowering, tabernacle or hinge. If the shrouds have chain plates abeam the mast then a solid bar can be fitted in the shroud up to a point exactly in line with the pivot of the mast ie about 800mm this bar is stayed so it always remains vertical Now when the mast is lowered the shrouds remain in tension so hold the mast on centreline in its traverse down. This is very desirable when lowering under way with a lot of wash from other boats. If the mast swings to one side it will wreck the hinge or taberrnacle because the leverage is so big.
I use a couple of cable clamps on the shrouds at about the line of the hinge. Ropes are taken from these clamps forward to a turning block on the deck and back to the cockpit. These ropes when tensioned pull the shroud tight as the mast traverses down so stops sideways swing.
This latter method is one of the few ways of controlling the mast when you have a fractional rig with shrouds set well aft of abeam the mast. You have to tighten the ropes as it comes down to keep tension.

Another completely different method used by some involves a car which runs up the main sail track. Attached to this are 2 spinnacker (or similar) poles which attach to purpose fitted rings near the gunwhales and about J distance aft of the mast (ie a few metres) the car is controlled by down haul and halyard so that as the mast leans back (coming down) the car slides up the track. If the downhaul on the car is tied off, the mast will come to rest on the spin poles a bit like a crutch. The solid poles stop any movement sideways. They say you can raise the mast again by pulling on the down haul but I think I would rather use a tackle on the forestay as well probably with more poles to improve pull angle.

It is all very interesting and on a really big mast quite fraught to say the least but at least one big boat 70ft does this most weekends for ocean racing when going under bridges.

As said these lowering methods mean that you can do much mast top maintenance from a step ladder on a high wharf but to actually move the mast to the ground requires a lot of helpers and muscle power.
good luck olewill

PS one real danger of mast lowering I found many years ago. It is easy to drop the mast for a bridge and pull it up again for stability and tidiness. Unfortunately power authorities think that if there are low bridges it must be ok to have low power lines. Not seen until it is too late.