Portable frame for mast lift/drop suggestions welcome..

[Vega1447]

Hi,
I'm planning to bring my boat to sea this summer - I need to drop the
mast before passing down river (bridges) and raise it again once I am
downstream of the bridges.

As craneage charges are exorbitant I plan to make up a simple frame
which can be assembled on deck with the boat tied alongside in a dockyard.

The best suggestion I've heard so far:

- a tripod/wigwam formed from 3 (prob stainless steel) pipe sections (of
sufficient metal thickness and diameter to do the job)
- the 3 pipe sections secured together at the top (lashed or a custom
fitting??)
- the feet of the 3 pipe sections shod in rubber and secured via
welded-on eye fittings to the deck - probably at the chainplates on side
decks and to the foredeck fitting.
- the height of the apex above deck obviously needs to be above the
centre of gravity of the mast
- probably easier to do the lift/drop if the apex is above the spreaders?

I'm thinking of a simple pulley block system with (say) 3-1 ratio
secured to the apex of the "wigwam"

Is this all hopelessly naive - I Am Not An Engineer!

Thanks for any advice/suggestions.

John V1447 Breakaway--
John A. Kinsella Ph: +353-61-202148 (Direct)
+353-61-333644 x 2148 (Switch)
Mathematics Dept. e-mail: John.Kinsella@...
University of Limerick FAX: +353-61-334927
IRELAND Web: John Kinsella's Website

 

[stevebirch2002]

There is a system used by the Dutch. Works fantastic. Seen someone drop a mast, go under a mast and lift teh mast in 8 minutes!! Uses a fixed tabernacle and a stainless A Frame. Uses the forestay and main sheet as a tackle system.

Steve B

 

[edbawden]

Many years ago I dropped and raised a pine mast on a 28ft Seaking many times. The mast was fitted into a tabernacle. We made a simple "A" frame from cheap pine (I think about 2x3"), that was mounted at the shroud deck fittings and apexed at the forestay fitting. Note all the force on the "A" frame is compressive so huge sections are not required.



As Steve suggests we used the mainsheet and forestay to raise and lower. It was a two man job but once the mast got some way above the horizontal was much easier. The mast was too heavy for one man to lift. Shrouds were fitted loosley before lifting to check port/starboard movement.



For the Vega without a tabanacle, it would need something at the base of the mast to anchor it at the right location and stop the base moving forwards when being raised.



Ed
To: AlbinVega@yahoogroups.com
From: steve@...
Date: Thu, 25 Feb 2010 13:29:55 +0000
Subject: Re: [AlbinVega] Portable frame for mast lift/drop suggestions welcome..


There is a system used by the Dutch. Works fantastic. Seen someone drop a mast, go under a mast and lift teh mast in 8 minutes!! Uses a fixed tabernacle and a stainless A Frame. Uses the forestay and main sheet as a tackle system.

Steve B

 

[rogerefairest]

I have an A frame and drop the mast at least once a season and then put it back up.
Done with confidence is an 8 min Job as Steve says each way (the down side being the fastest part), I use the forward stay, which gets “locked” (by gravity) to the top end (towards the bow) of the A frame (which is stainless steel) but I use a dedicated sheet to pull the line using the windlass as the anchor point and to do the pulling, it works well, if out of the water I would use what solid point is near and the boom block to do the work.
If it stops raining this weekend I will be dropping it, maybe I can take some pictures.
However the key piece is the tabernacle, without it, I would not attempt it. about being a two man job this weekend might be the first time we try it that way, we normally have 3 people, one on the Windlass, another keeping the mast strait (it likes to swing a bit) and another making sure that the rigging is free and gets straitened and cleared as the mast goes up.

 

[pjacobs55]

Hi John,
The most secure and simple one I've seen is on the Alberg 30 website.

Position the A-Frame

Position the A-Frame

tinyurl.com

I built one from sections of galvanized fence rail, about 1 7/8" OD which is probably overkill. I made them in 2 sections that plug together with a short piece of pipe that fits inside.

It's basically an "A" frame that straddles the boat, with the apex about a 18" above the spreaders, and the base of each leg (padded) resting on deck and lashed to a chainplate.

The top ends of the pipe are hammered flat and have a hole drilled through them to connect them together with a bolt and locknut.

Two guy ropes extend from the top of the frame, one to the bow cleat and one to the stern rail, to hold the frame in place.

If memory serves me well, I think I put the frame on the forward face of the mast. A four-part tackle is suspended from the top of the frame. A loose loop of line is tied around the mast and attached to the tackle, then hoisted up tight under the spreaders.

All shrouds and stays are disconnected, then the mast is lifted a few inches out of the step, then slowly lowered while one person holds the base of the mast and walks it forward.

Because the mast is suspended from it's mid balance point it's easily held and walked forward.

I've only used the rig for one down and one up. The down part I had a friend help with the lines, but going back up I was alone (no witnesses!) and managed OK.

It's a bit scary to do for the first time, but once done it seems easy. The most difficult part is erecting the "A" frame ... the rest was easy. Next time I do it I'll make sure I have my camera!

That said, the best way is probably a tabernacle, especially if this is going to be a regular occurrence! The downside of this method, is if you lower the mast forward it protrudes a long way over the bow, and if you lower it aft it only comes part way down because the cabin top is in the way, and it still sticks out quite a way aft.

Using the "A" frame the mast is always over the boat, and only sticks out about 18" at either end when down.

Peter
#1331 'SIn Tacha'

 

[Vega1447]

Hi Roger, Edward, Peter and all.

Roger mentions the necessity of having a tabernacle if the A-frame
method is used.

Without one, what do you think of the "tripod" method.

Advantages:
It uses 3 poles (forward-facing one longest), aft 2 shorter.
Could use scaffolding with inner sleeves to assemble - ss lighter.
Use a double block under apex of tripod and a single block secured to
the spreaders

When raising the mast:
Tie a bowline round the spreaders,
feed line up through first block at apex
down through single block secured to spreaders
back up through second block at apex
down to a turning block secured (somehow) close to base of mast (not
sure about this)
then aft to cockpit winch.

Giving a 3-1 pull which should be enough with winch.

(The block secured to the spreader can be easily retrieved with a ladder
once mast is stayed.)
(Or it could be secured with a slippery hitch the standing part of which
is made off on a cleat at the mast foot??)

Disadvantages:

Does this setup put too much load on spreaders??

I'd like to go with this setup if feasible - any criticisms/comments please?

Thanks

John V1447 Breakaway
Roger Fairest wrote:

 

[bbach1949]

OK, so here's another of my ways of doing things. My wife and I are able to raise and lower the mast ourselves with this rig, and no tabernacle to complicate things. I built a simple A frame from two 20 foot long 2 by 4 inch douglas fir (minimal knots). It's bolted together at the top and and again about a foot down from the top (the lower bolt is where the tackle hangs from). The legs spread (spring at an arc) to attach to the chainplates for the upper shrouds. Just bolt these loosely as a pivot while raising the frame and to keep them located on the deck. I pad these with an old piece of carpet. Guys are attached to the top of the A frame and led both forward and aft. Now you have a "crane" of sorts in the air over the mast step. A 3 or 4 part tackle, I can't remember which at the moment, is attached to the A frame and a short sling is placed around the mast below the spreaders. The mast is raised or lowered with its forward side up. Just have to clear the aft guy while raising. Once up in the air, the butt of the mast is lowered into the step and the shrouds and stays used to stabilize it. The A frame is lowered forward (use a pole like a boat hook as it gets close to the ground, as it gets hard to hold with just the back guy).

Use good lumber (Oregon fir!) and keep it light weight. The sling is a climber's short loop used for rigging pitons - kevlar or aramid, I think.

Bill Bach V 1071

 

[j.hunter9999]

Out of simple curiosity, why would you want to avoid the tabernacle? Is it cost? Difficulty in finding a manufacturer? I only ask because I might one day make the same decision and would love to understand your thought process.

Thanks,
Jack

 

[edbawden]

If you will be lowering the mast frequently then fitting a tabernacle is the way to go. For me the "A" frame is the simplest solution. Easier to control with the base always anchored. But then I have never tried the "tripod" method.



Rgds

Ed
To: AlbinVega@yahoogroups.com
From: j.hunter9999@...
Date: Fri, 26 Feb 2010 01:36:04 +0000
Subject: [AlbinVega] Re: Portable frame for mast lift/drop suggestions welcome..


Out of simple curiosity, why would you want to avoid the tabernacle? Is it cost? Difficulty in finding a manufacturer? I only ask because I might one day make the same decision and would love to understand your thought process.

Thanks,
Jack

 

[bbach1949]

I'm just using this method to raise and lower the mast for haulout. If I were lowering it and raising it for a bridge or something like that, I might consider a tabernacle. Or moving my boat to somewhere downstream of the bridge! For haulout or laying the mast on deck for transport, the tabernacle wouldn't be much help. My method doesn't require the butt of the mast to be fixed in place while raising or lowering, so also easy to take the time to connect wires. It works for me and was cheap and the A-frame stores easily.

 

[pjacobs55]

Bill, apart from our different choice of materials, it sounds like we have the same setup. It's great for seasonal use.

I think there's some confusion here on the term "A" frame. The type used with a tabernacle remains at 90 degrees to the mast (fore-aft) and moves from the horizontal to vertical when lowering the mast, and is pivoted at the gunwale on either side of the mast tabernacle.

It's another version of the Gin Pole method, which is usually attached right to the base of the mast, and uses guy lines, or a helper, to prevent the mast from toppling sideways.

Example video:

Bill and I (and on the Alvberg 30 site) are using an "A" frame fixed in place vertical, against the front of the mast, guyed fore and aft, as an attachment point for a block and tackle setup, like a crane, to lift the mast straight up out of the step, then lower it to horizontal to lay on the bow pulpit and cabin top.

Example video:

John, your suggested method is like ours, but uses an extra pole instead of the fore and aft guys, if I read you correctly. The only problem I can see is that the forward pole will be in the way of the mast as it comes down.

The spreader mounts are pretty strong, so a sling under them should do no harm. I'd put it around the mast rather than the spreaders, and just use the spreder mounts as a 'stop'. It's almost the exact balance point of the 30' Vega mast.

Picture of spreader bracket, with new 'hound' from Steve Birch! (Thanks Steve)

http://www3.telus.net/sailing/spreaders.jpg

Peter
#1331 'Sin Tacha'

 

[Vega1447]

Hi Peter (and the many others who have contributed).

I'm still uncertain which way to go.

The tripod method is simple imo - and easy to assemble.

It also avoids the necessity of retrofitting a tabernacle to the mast foot.
(This is why I prefer the tripod method - if it works)

On the other hand:

As Peter says, the forward pole will be in the way of the mast as it
comes down.
Perhaps this doesn't matter too much provided the mast comes to rest on
the deck aligned (almost) fore&aft?

My picture of the mast lift (with tripod) is:

1. mast initially lying with foot forward and forward face up
(almost) aligned fore&aft
2. as mast is raised the foot of the mast drags aft along the deck
(with helpers controlling it) so mast foot must be wrapped in
cloth to prevent it damaging deck
3. once mast is nearly vertical shrouds and fore/back stays are
loosely attached to chainplates
4. protective cloths are removed from mast foot and foot is
man-handled into position
5. helpers keep mast foot in position as standing rigging is
tightened and pull from block &tackle at apex of tripod is released.
6. The foot of the mast could be guyed port&starboard to control it.
7. perhaps the forward leg of the tripod could be repaced by a
fore&after guy constraining the (now) bipod A frame to remain
vertical.
8. This is (I think) Peter's suggestion?

The main difficulty I see with the tripod (or bipod) method is making a
strongpoint on deck near mast foot to take a turning block so standing
part of halyard can be led to a cockpit winch.

Even with a 3-1 pull imo it would be dangerous not to bring halyard to a
winch and a turning block is needed for this...
My thought on this is to use a steel bar lashed athwarthships to the
port & starboard grab rails??Any specific comments on the above?

Thanks

John

Peter wrote:

 

[pjacobs55]

John,
On the way down, I used a snatch block attached to the mid chainplate as a turning block, and ran the hoist line through it, then through the jib sheet block and back to the winch manned by a helper.

It was overkill, as when I put the mast back up (alone) I had attached a cleat to one of the "A" frame legs and used it to belay the hoist line. With a control line tied to the mast foot (which was at the bow) I hoisted the mast up, belayed the line, and brought the foot down to the deck with the control line.

Also, I used a four part tackle. It takes a little extra line, but the mechanical advantage is worth it. Good quality ball bearing blocks make everything easier, too.

The only fiddley bit of the whole process was stopping now and then to adjust the mast so the spreaders would clear things.

Oh yes, and I tied the boat up at a slip in a vacant area of the marina, well away from other craft ... just in case

Peter
#1331 'Sin Tacha'

 

[dougpol1]

Here is a maybe possible solution as I use it on my 20ft Canoe Yawl and
it works. I have a couple pad eyes attached on the inside of the main
hatch companion way as well as a small cleat. The boat is smaller and so
is the mast. I stand the mizzen saysail mast up in the hatch way and
lace it to the pad eyes and tighten it to the cleat. I use a mizzen yard
as a gin pole and lift the mast in place using the ginpole and a double
block tackle. Works great and in this case I have to carry no extra
poles to do the lifting with they are already there all the time. The
ginpole keeps the mast from wanting to tip over sideways as well. My
mast is not deck stepped but goes down through the deck to a step in the
keel. There are no shrouds but since the mast is held by a lifting line
at about the center of ballance you can guide the foot of the mast
around with one hand and put it in place while the other hand raises and
lowers the gin pole by the tackle line. Of course the mast is lighter
but that is only a matter of how many parts there are to the tackle.
It's a very simple rig.
DougPeter wrote:

 

[Vega1447]

Thanks Peter,
that's very helpful.

All the best

John V1447 Breakaway

Peter wrote:

 

[bbach1949]

Peter is right-don't be too concerned about the strain on the tackle.
The fully rigged mast only weighs a couple hundred pounds so with a 4
to 1 tackle that's only 50 lbs of pull. I don't use the winches but
just haul away! So far so good.