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Catalina/Capri 25/250 Sailor's Forums

General Sailing Forum

The Standing A Frame

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Arlyn Stewart
Master Marine Consultant

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USA
2980 Posts

Initially Posted - 03/16/2004 : 08:34:10

I've noted the current discussions on the C25 side about mast raising as well as its often a discussion on other forums. While I don't have a lot to offer, I've done my share of mast raising over the years as all my sailing has been trailer sailing. The evolution of mast raising systems over the years has been interesting. We have seen many various techniques all of them helpful. The Huntington, mono gin pole, articulating A frame, trailer pole and most recently the standing A frame.

The latest design, the [url="http://www.stewartfam.net/arlyn/mrs.html"]Standing A Frame[/url] looks to be a great system perhaps superior to all others, in part because it is simpler. Its virtues seem to be;

* it avoids the need for articulating joints
* is easily constructed from common 2x4 s or pipe
* doesn't require baby stays
* can use either the boats sheet winches or if single handing, a small trailer winch
* the length of the frame is not critical
* it avoids the need to mount / dismount the boat to deal with hung shrouds
* it puts the single handed operator in an ideal position to handle the furler while cranking the winch
* raising can be stopped / started easily at any time
* the operator is in an ideal position facing the shrouds to monitor for any hangups
* it is inexpensive
* its attached to the boat easily and quickly

Has any one used this system yet? Any comments?

Arlyn C-250 W/B #224

N/E Texas and Great Lakes
Arlyn's Sailing Site

Edited by - Arlyn Stewart on 03/16/2004 08:44:41

JimB517
Past Commodore

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USA
3285 Posts

Response Posted - 03/16/2004 : 14:18:14

I really like the design and if I make something to lower my mast in the slip in order to replace the spreader sockets, I'll make this - especially the B variant using the cockpit winches.

I think we could modify an existing rotating A frame to be a standing A frame with little or no effort ( a block and a couple of lines).

The problem with a rotating A frame in the slip is that there is no handy trailer winch to use.

Edited by - JimB517 on 03/16/2004 14:19:40

Arlyn Stewart
Master Marine Consultant

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USA
2980 Posts

Response Posted - 03/19/2004 : 18:55:52

Jim, The B variant will work fine but lacks some pluses of the A.

The A variant keeps the operator out of harms way should something go wrong. It also puts the operator in a great place for single handed raising if furler equipped because the operator can hand the furler at the same time as operating the winch.

A small $15 trailer winch bolted to one of the legs is all that is required.

Edited by - on

lcharlot
Master Marine Consultant

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Antigua and Barbuda
1301 Posts

Response Posted - 03/19/2004 : 23:10:51

Arlyn -
Your A-frame looks really interesting! I think I will give it a try the next time I move the boat, which will be in a month or so. I used to use a rotating A-frame on my Catalina 22, but this non-rotating version looks simpler and easier to rig. I don't think I would use the "B" version however, I don't like the idea of being in the cockpit with the risk of the mast falling back on me if something went wrong. My current system is a home made single-spar gin pole and Huntington Rig, and while it works well enough, it uses 4 separate baby stays and bracing lines to stabilize the Gin pole and shroud jumpers, and it takes a long time to set up and adjust everything. My new boat is a Tall Rig 25, which I am told uses almost the same mast as the standard rig C-27. The one mast up/down cycle I have completed, when I bought the boat last September, seemed to be slightly more difficult and required more lifting power than my old boat's mast did, so I have been considering different mast-up systems.

Edited by - on

tmhansen
Captain

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USA
397 Posts

Response Posted - 03/24/2004 : 01:51:41

Arlyn, that is an interesting variation on the A frame. One of the things I like about my A frame is that it is so minimal. Two pieces of conduit loosly bolted at the top and pined to the chainplates with a shackle. I trailer it on the boat in place ready to go. At the ramp I attach it to the roof of the truck while we are out. One difference for me is my boat is equiped with a winch on the mast. I use this to raise the mast. It does put a slight twist on the mast as it is coming up but it does not seem too much for the mast step. I don't think I would like to use a cockpit winch. I won't let anyone stand back there while I am raising the mast.

By the way the weather is getting nice but I still have not had the boat in the water to report back on the new steering. I have some trailer work to complete before I can hit the road again.

Edited by - on

Mark Loyacano
Navigator

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USA
247 Posts

Response Posted - 04/01/2004 : 17:39:04

Arlyn is right about this system. I recently saw several boats in Holland that had this system. They used it to get under the many bridges in and near Amsterdam. If I decide to trailer to other lakes, it will be the system to use...
Thanks Arlyn.

Edited by - on

John V.
Admiral

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USA
559 Posts

Response Posted - 04/02/2004 : 08:13:42

This is very interesting Arlyn. The only concern I would have is using the stanchion. torque could be shifted to the base and could break the caulk seal and lead to leakage. The chain plates are designed to take a beating but I don't know about the stanchions.
Just my observation. Have you noticed any leakage or has that not been a problem. Still hoping to link up in the North Channel this July. I'll be going into Lake superior in late June early July but after that I'll be at Neebish Isle. for the remainder of the summer.
We are trying to bring the whole family, sisters nieces nephews etc. to scatter a small portion of my mom's ashes in the St mary's. I'll probably be taking a few spoonfuls to some of my parents favorite anchorages in the NC. She'd been cruising the NC since the 1930's.

Edited by - on

aeckhart
Master Marine Consultant

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USA
1709 Posts

Response Posted - 04/02/2004 : 12:01:08

John, Where/when are you sailing in Lake Superior this summer. I'm from Houghton ("the Keweenaw"), in the nortern UP. I'll be cruising around Munising and the Pictured Rocks area in the middle to late June time frame.

Al Eckahrt
GALLIVANT #5801

Edited by - on

John V.
Admiral

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USA
559 Posts

Response Posted - 04/02/2004 : 12:32:20

I'm going to trailer around to Grand Portage and sail out to Isle Royal for a week or so. Hoping to write an article about the trip and see where it will sell. I had so much fun with John G.'s request for an article for Mainsheet I thought I'd try writing again.

I have been doing some research for the trip and found the Isle Royal Boaters Association web site. There seems to be some controversy about the new use plan for the park. Living up there year round do you have any insight as to where the park administration stands re. boating in and around the Island?

Edited by - on

Arlyn Stewart
Master Marine Consultant

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USA
2980 Posts

Response Posted - 04/06/2004 : 19:08:47

John,

I don't think the standing A frame will put much torque on the stanchion bases. More than likely the legs will stand on top of part of the base plates and simply be lashed at the base. Or they could overhang the rail and be supported by lines.

I'm not sure how the stanchions are secured on the C25. The 250 have large fender washers on all stanchion bolts.

My work schedule is not such that I can easily predict my summer cruise time. Will have to finsish whaterver job site is in progress prior to leaving. A job site has about a three week cycle.

Will know more when it gets closer.

Edited by - on

deastburn
Captain

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USA
334 Posts

Response Posted - 04/06/2004 : 22:09:37

Arlyn:

Last year I built the pivoting A-frame system and really like it. Your system uses a fixed A-frame, and it seems to me (I am no engineer) that the bending forces on your A-frame increase as the mast approaches vertical. The A-frame which pivots on the forward lower stay chainplates remains at the same distance from the mast all the way through its arc from horizontal to vertical and vice-versa. (It uses the jib halyard from the top of the mast, tied off to a carabiner at the top of the A-frame, and then a line run from there through a snatch block at the bow and back to one of the genoa winches.) That, it seems to me, would impose lower stresses and decreased bending forces. Disadvantage: the skipper raising the mast is in the cockpit and hence in the line of fire should anything go wrong.

Also, I increased the mast crutch height to ten or twelve feet, and that sets the mast at a resting angle which is already well beyond horizontal, further decreasing bending forces at the most extreme angle.

All this is surmise and conjecture. As I say, I am no engineer.

Edited by - on

Arlyn Stewart
Master Marine Consultant

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USA
2980 Posts

Response Posted - 04/06/2004 : 23:39:19

Dave,

No engineer here either. I'm thinking the bending loads for both systems would decrease as the mast comes up as more of the weight of the mast is born by the mast step.

To stay out of harms way, one option would be to U-bolt a small trailer winch on one leg of the pivoting A frame. With a furler, it would put lthe single handed person in a much better place to handle the furler as he winches. The only difference is to shackle the winch line to the stem or eye in the anchor locker and have a block at the apex of the A frame.

Edited by - on

atgep
Master Marine Consultant

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1009 Posts

Response Posted - 04/15/2004 : 22:16:17

WOW! What a great system. I used one today to drop the rig and was completely in control. I used 2-10 ft 2x4's and a large fence hinge at the apex. I securly lashed the bottoms to the stancions fwd of the mast.
I attached a block to the fwd support line at the hinge and used a genoa sheet wrapped around the mast, through the block, down to the jenny car(all the way fwd) and to the main winch. The only thing I forgot is to hold the rope up the mast with a halyard. As the mast started laying down the rope started sliding down towards the base(not a good thing) I realize there are 2 things to improve on.

1. the 2x4 need a bracket that "lock or pin to the stancion base"
2. Add a trailer winch to the a-frame and stay on the safe side of the action. When I work out a few more bugs I will post a few photos.
Thanks Arlyn. Tom.

Edited by - on

Ellis Bloomfield
1st Mate

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USA
85 Posts

Response Posted - 04/16/2004 : 01:49:31

Arlyn,

I like your system. I've been using an "A" frame built out of aircraft thinwall tubing and the main winches. The trouble has been keeping the shrouds and turnbuckles lined up while cranking. Your system would seem to make it easier to keep everything in check while raising, especially as tension is put on the shrouds. I don't loosen the mid and rear shrouds.

Ellis

Edited by - on

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 04/16/2004 : 01:59:04

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Ellis Bloomfield
 ...I've been using an "A" frame built out of aircraft thinwall tubing and the main winches. The trouble has been keeping the shrouds and turnbuckles lined up while cranking...<hr height="1" noshade id="quote"></blockquote id="quote">

To prevent the turnbuckles from twisting as you raise the mast, tie the shrouds to the lifelines using rubber bands. This will keep the turnbuckles in the proper orientation and as the shrouds tension up the rubber bands will break releasing the shroud.

Edited by - on

Steve Milby
Past Commodore

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USA
5902 Posts

Response Posted - 04/16/2004 : 15:21:49

<blockquote id="quote">quote:<hr height="1" noshade id="quote">I don't loosen the mid and rear shrouds.<hr height="1" noshade id="quote"></blockquote id="quote"> For years I did the same thing, but recently learned that the lower (mid) shrouds should always be loosened slightly when raising or lowering the mast. The base of the mast is cut off flat, so that, when the mast starts to lean aft, the tension on the lowers increases until the mast tilts back and starts to come down. This puts an enormous load on the chainplates and the deck itself. You don't have to loosen them a lot, but they should be loosened.

Edited by - on

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