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A-Frame help

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stampeder
Master Marine Consultant

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1608 Posts

Initially Posted - 03/15/2005 : 01:27:59

I'm about to build an A-Frame for my 81 SR/SK. I've looked at Bear's Abode tech drawing and I've visited JimB's website and I've read all the posts I could find.
Does anyone have more exacting specs for the A-Frame? (or am I being more analytical than I need to be?

I am wondering if the Apex of the A-Frame has to be built so that there is no movement - the tech drawing shows a bolt with two bull rings - with no specs on the bolt. Seems to me that maybe this should be welded or bolted so that it's rigid.
What degree are the bends - they look to be 45?
Thank you

Edited by - on

atgep
Master Marine Consultant

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1009 Posts

Response Posted - 03/15/2005 : 04:33:50

I used 2x4's 10 ft long. They are connected at top with a big gate hinge. Folds up nice when in the garage for the other 364 days not being used in a year.

One RULE you need top follow regardless of which variation you use is to secure your attachment to the mast with a halyard holding it UP! If not, when the angle becomes greater than 45 deg, the rope will slip towards the base and the mast WILL come crashing down! This is particulary true with the standing A frame.

Tom.

Edited by - on

Gloss
Master Marine Consultant

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USA
1916 Posts

Response Posted - 03/15/2005 : 08:29:00

I used pressure treated 2 x 4's 12 footlong. Too heavy. I just picked up some cedar 2 x 4's to lose some weight, and may make them about 13 or 14 foot long. I just drilled holes in the bottom and looped a short length of line through it and tie it off to the base of the rail stanchion. I also rounded off the base of the 2 x 4 with a sabre saw. The top is an eyebolt to which I loop another line, and then clip on my jib halyard, tighten it up, and clip the end of an old boom vang with about 80 feet of cheap line let through the cabin top rope clutch and then to the cabin top winch. I can raise my tall rig solo. If anything hangs up, and it will, I just clutch the rope down, unhang whatever, and continue to raise the mast. I let out all the slack in my adjustable backstay. I also installed quick releases on my front lowers. Once the quick releases are attached to the deck eye, and they are dogged down I then can release the jib halyard, the mast will not fall down, remove the A-frame and then attach my Schaeffer CF-700 furler to the bow. All of this can be solo, but it helps to have someone with you.

Edited by - on

Buzz Maring
Master Marine Consultant

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USA
1772 Posts

Response Posted - 03/15/2005 : 10:42:51

Hi Mike,

We've had many discussions of the A-frame and mast raising, so, in case you missed these two, here are two threads that have quite a bit of info: [url="http://www.catalina25-250.org/forum/topic.asp?TOPIC_ID=3633&SearchTerms=mast"]Mast raising 1[/url] and [url="http://www.catalina25-250.org/forum/topic.asp?TOPIC_ID=7738&SearchTerms=mast"]Mast raising 2[/url]

'Hope that helps. You won't regret building an A-frame ... it works great ... good luck!

Edited by - on

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 03/15/2005 : 13:19:53

Mike,

Thanks for bringing up this rather timely topic, because I, too, am planning to build an A-frame of some type.

Tom,

I'm guessing that you are using a standing A-frame to lower your mast...Is this correct?

I'm also planning on dropping my mast soon, but I'm looking into building a stationary frame. I would like to go stationary because I want to avoid swinging my mast out and over the boats that are shoehorned in around me.

Does anyone have any experience with a stationary A-frame system and if so, any helpful hints?

Thanks

Edited by - on

stampeder
Master Marine Consultant

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1608 Posts

Response Posted - 03/15/2005 : 14:37:38

Thank you for the info - I missed mast raising one thread in my searches. I'm a 12 hour drive away from the boat - so I'm trying to be exact in all the things I need to do when I get to the boat. Us accounting type guys can't always make the leaps of construction logic that some guys can - details and pictures are valued and appreciated. For this to all 'click' in my brain - it took looking at and connecting all the pictures - especially the closeups as well as the drawing. I envy you guys that can get to your boat and make your own measurements and work on your projects when you have the time.
The mast must come down, haul the boat 7 hours closer for the summer, replace keel raising parts, paint bottom, raise mast and enjoy the summer.

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atgep
Master Marine Consultant

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1009 Posts

Response Posted - 03/15/2005 : 22:48:30

I us and prefer the standing a-frame. I use the mainsheet Block and tackle as the lifting device. I was using a winch in the cockpit but got nervous looking up at the rig

. I use regular studs which are still plenty heavy but non marring to the deck. I also use a line around the legs and tie off to the stantions fwd of the mast. I would not recommend doing it by yourself for the first time. But with practice comes the confidence you need to disconnect the rig and lower away. I did it last month on the water to fish in a new halyard.

And...When using a standing a-frame the rope NEEDS to be held up with a halyard or......It will come down at 32 FPS squared! TRUST ME!

Mine slipped with only a few feet left and scared the bejesus out of me.

Tom.

Edited by - on

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 03/16/2005 : 10:51:46

Tom,

What is the height of your standing A-frame in relation to the spreaders?

I'm thinking that the frame needs to be slightly higher to lift the mast at the spreaders, which is about the balance point of the mast.

As for securing the lifting rope so it doesn't slide down the mast, I'm planning on using my spinnaker bridle in conjunction with the main halyard to secure the lifting rope to the mast at the spreaders.

Any thoughts???

Thanks.

Edited by - on

atgep
Master Marine Consultant

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1009 Posts

Response Posted - 03/16/2005 : 19:08:05

My A-frame is 10 feet. It gives an effective arm of about 8 feet because of the spreading and the coachtop. Taller would be better but heavier and more difficult to store. I estimate it takes about a 200lb pull tget things moving from the down position. I hook on to the mast about 9 feet from the tabernacle.

This year I made a higher position for my mast crutch. It is about head height while standing on the cockpit seats. It makes a it a lot easier to get things moving. Once the mast is at about 30deg the pull gets very easy.

Which ever system you design, You need to test it with a helper to work out bugs and to gain the confidence to do it alone. It is pretty scary to watch that much hardware moving. I now KNOW my system works and know what not to do.

I tilt the a-frame toward the bow a few feet to allow for rope stretch and to allow the whole thing to remain in tension while I start connecting the shrouds.

I also use 1/2 inch low stretch rope for all the lifting lines.

Perhaps a couple people should compose videos as it would be worth a thousand words.

Tom.

Edited by - on

stampeder
Master Marine Consultant

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1608 Posts

Response Posted - 03/16/2005 : 23:46:40

Please confirm - you guys are talking about building <font color="blue">standing &/or stationary A-Frames</font id="blue">...the A-Frame I propose to build is like JimB's, which I gather is unlike a <font color="blue">standing/stationary A-Frame</font id="blue">.
As I read your comments for the 25th time, I uncomfortably assume ATGEP's cautions about the rope don't apply to the JimB/Bear's Abode A frame.

thanx

Edited by - on

atgep
Master Marine Consultant

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1009 Posts

Response Posted - 03/17/2005 : 04:44:14

You are correct. A rotating a-frame attaches to the forestay and cannot slip. I have used both types and prefer the standing version as I feel it provides the best leverage at the beginning of the lifting cycle.

The rotating a-frame has the advantage of keeping the furler straight and out of the way, and as it passes 45 deg, the a-frame weight actually helps raise the mast.

You can never ask too many questions.

Tom.

Edited by - atgep on 03/17/2005 04:46:34

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