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Mast Raising A-Frame questions?

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StSimon
Captain

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USA
298 Posts

Initially Posted - 03/13/2004 : 19:12:44

This is directed at anyone who has built one. I am attempting to build the a-frame from bears abode specifications. I took my nipples (both of them) down to the boat to get the correct angles to drill the holes. What I found was the deck plate that secures my forward shrouds had holes smaller than 3/16". I had to go back to Lowes for a smaller size... no big deal.

The question really is what do you do about the two screws in the deck plate? They prevent the nipple from sitting flat on the top. Anyone have a simple solution? I'll tell you the nipples are tough stuff. I bought a drill press just to drill an accurate hole. I did one with my handheld drill and by the time I got through the second side, the first hole was larger from the sides of the bit.

My next question is what is the best (easiest) way to flatten the ends of the conduit. I think I read someone heated it and pounded it flat with a mallet or some other B.F.H. Did I also read of putting a dowel inside to prevent excess flattening?

I'm trying not to reinvent the wheel and any help is appreciated.

Thanks,

StSimon

Fair winds,

Andy, Breakin' Wind, 1984 C25 SK SR

Edited by - on

John V.
Admiral

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USA
559 Posts

Response Posted - 03/13/2004 : 20:05:45

Hi Andy, I use mine all the time, and it works great. don't worry about the bottoms not laying flat the screw heads will not get in the way. as for flattening the ends I just used a blowtorch to heat the ends and beat them with a sledge hammer. they also need to be bent a bit so they will spread properly. I also found it helpful to over drill the hole that joins the two legs so that there is some play.
When I tried it the first time it was so tight I couldn't get it to work, but loose it handles just fine.
Raising the mast this way still requires some strength. I use the mainsheet tackle which gives me a three to one mechanical advantage.
there is a safety feature in doing it this way. If you run the tail through the cam cleat, it acts as a brake should you slip or let go. in that case the mast will stay where it is until you can get situated again.
hope this helps

Edited by - on

ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 03/13/2004 : 20:15:29

"what is the best (easiest) way to flatten the ends of the conduit."

A decent vise will do it... or a press... or a BFH. In my experience, heating is not very effective on aluminum.

Edited by - on

Captain B
1st Mate

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USA
88 Posts

Response Posted - 03/13/2004 : 20:17:06

Dito to John's comments. Although I just used a bigger hammer to flatten the ends of my conduit instead of heating them. The "A" frame works great. Just take your time and use block and tackle for a mechanical advantage when lowering or raising the mast. It's also useful to tape halyards and shrouds to the mast so they don't get tangled. A crutch on the stern rail is also highly recommended so the angle of the mast in the down position doesn't get near the 90 degree mark. Take your time and have FUN.
Cheers,

Edited by - on

204013391
Deckhand

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7 Posts

Response Posted - 03/13/2004 : 22:43:57

Interesting to see this topic now - I just dropped my mast for the first time today using a variation on the a-frame. Though I'm a bit of a rookie at the sailing thing, those who lent me a hand seemed to think it a novel concept and was interested in borrowing it after seeing it in action.

I didn't quite go all the way like the diagram. If it is of interest, here is the steps I took and how I used it. The third step is the real variation and speaks a bit to the topic here.

I started with a ~6" 2x4 and two pieces of conduit. Using a hammer, I dented the conduit about 6" from the edge to weaken it a bit. I put it in a vice up to the indention and used the remaining length as lever to bend it. I was careful not to kink it bad, but for the 15-20 degrees or so, this worked fine. Simple enough, so far.

I drilled two holes through each conduit and the short distance of the 2x4 and used a 4 1/2 carriage bold to assemble the frame. I used two eye lag bolts (offset) into the thick direction of the 2x4 - one which I tied to the fore-stay and one to a 25' line I passed through the jib tack bracket.

Here's where I cut it short a little. I did nothing to the other ends of the conduit. I left the outer shrouds in place (to help with lateral stability if necessary), placed towels at the foot of the outer shroud brackets and set the foot on the towel against the bracket. Being my first time to drop it, I had three others help me - two made sure the feet of the frame did not slide off thier bases and was there to help with lateral stability if necessary. Slippage did not appear to be a problem, though I would probably do something a little different if I didn't have all that help (see note below).

With one person letting line out through the jib tack bracket - lowering the mast - and me keeping it straight and catching it was all it took. Since the mast is back heavy, it did help to have extra hands unscrew the step screw and keep some weight on the lower (forward) portion of the mast until it could be slid inboard.

It could probably be single handed, but a catch tree would certainly be necessary. Also, it seemed ok laterally, but it just didn't look like the most trustable thing. I really appreciated the help.

The mod note: One thing I'm considering for the feet of the frame is 2 pieces of 2x4, ~4" long. I keep the outer shrouds on during the process, but my brackets have two holes each. So, I would use the second to screw a lag bolt into the 2x4, in which I would chisle out a 1" slot into the center, forward, top edge of the 2x4. This would be the place to hold the foot in place. By stepping it (--__) 1/2" (upper) to 3/4" (lower) deep would provide both a place to push against at first, but would also let it rotate up the step, still pushing down in the grove but without the risk of the aft edge of the conduit cutting agaist the back of the grove and possibly caucing the conduit to climb and slip out.

Sorry for the length, but sometimes it's the little details that make the difference in these things. Hope it helps or is at least of interest.

Troy
www.troyandcheryl.com

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MattL
Admiral

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USA
990 Posts

Response Posted - 03/14/2004 : 00:13:13

In regards to flattening the ends of the conduit. Forget the heat, too dangerous for something unnecessary. I used a small maul, bigger than a hammer smaller than a sledg, and it worked great. Kind of fun acutally, I like hitting things with a BFH. That's friendly.

Edited by - on

John V.
Admiral

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USA
559 Posts

Response Posted - 03/14/2004 : 09:01:06

OK I need to clear up a few things about the A frame.

Any tubing you can flatten in a vice or by hand will be too light to handle mast raising. I don't reccomend anything less than heavy steel. The compression forces that act on the A frame are extreme during the first 20 degrees of arc. The tubes are 9 feet long and over that length you will need a very stiff seemless tube. Light conduit or aluminum will begin to bow when you have the mast five or six feet off your mast raiser (or stern crutch) If the A frame fails at that point the mast will come down hard and may injure you or your crew.

Take care in making this device and be sure you use a heavy materials.

Edited by - John V. on 03/14/2004 09:07:56

StSimon
Captain

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USA
298 Posts

Response Posted - 03/14/2004 : 10:57:56

I built my crutch with a 1" square aluminum rod. I put a 16 1/2" piece of angle aluminum across the bottom to fit into the rear of the cockpit. I put a 12" piece of angle aluminum at the top to catch the mast. I have another 5' section of angle aluminum I plan to attach once I get to the boat. It will be placed across the handrails and permanently attached to the upright aluminum square rod at the proper height. I also got some double sided, outdoor (wet weather) carpet tape and some rugged rubber carpet and put a 1" piece across the top and bottom and on the ends of the 5' section. I have no illusions that the mast will slide across this instrument but only plan for it to aid in dropping or stepping the mast.

As far as the a-frame, I got as far as flattening the lower ends with my BFH last night before the admiral told (yelled) me I was making too much noise and had to quit. Maybe she'll go shopping today and I can finish.

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PZell
Admiral

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USA
548 Posts

Response Posted - 03/14/2004 : 12:38:15

Heed John V.'s advise about sturdiness of material. A few years ago
I built the A frame, but did not feel safe with it because one side
would begin to bow if the mast got a wee bit off center. I could not
feel safe with it after that even if I did it in heavier material. Once it goes you've had it. Since then I've been using a system that has control lines attached to the forward shrouds (lower to stern).
These lines pass through the imaginary pivot point of the mast so
give total control of sideways movement. They are led back through
my deck organizers. Those lines along with the control lines for the gin pole off the front of mast (use the boom for that) that keep it perpendicular to the mast and the tackle for lowering the mast all come back to the cockpit. Easily singlehand lowering the mast into crutch.

Edited by - on

John J.
Navigator

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USA
157 Posts

Response Posted - 03/14/2004 : 17:06:25

So, when one is raising the mast with a A-Frame, am I to assume that a helper is at the bow where a line has been attached to the top of the mast, and this person is pulling on this line? Obviously I've never seen one of these work!

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John V.
Admiral

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USA
559 Posts

Response Posted - 03/14/2004 : 18:55:33

John,
If you want to see an A frame in action take a look at this web site

http://www.swartsart.com/Mast-UP/index.html

You don't need someone on the bow. The mast goes up with the jib halyard on one end and the mainsheet tackle on the other. the A frame goes in between and transfers the lifting force to an angle that allows the mast to go up. All you need to do is pull in the the sheet (with some oomph and perhaps the winch) and up she goes. you really don't need to do a lot of stabilization since the A frame dampens any side to side motion. BTW to avoid a lot of stability problems raise the mast on the hard and then launch. If you try to raise the stick after launch......well..... All it takes is one bozo in a stink pot not observing the no wake zone and all your careful preparations are shot.

Edited by - John V. on 03/15/2004 10:28:58

frich
Captain

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USA
418 Posts

Response Posted - 03/15/2004 : 16:43:49

Andy
To get the correct angles for the bolts to attach to the Conduit i did the following.
I disconnected the shroud (1) at a time slipped the nipple over the deck plate. Then I just used a magic marker to mark the point where the bolt would penetrate the nipple. Re-installed the shroud, and mesured from the deck plate up to the centerline of the bolt. This is where I drilled straight through. Did this for each side. Unit works fine, hope this helps

Frank R
84 C25 SK

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