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Building a Mast Crutch

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fpill
1st Mate

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USA
51 Posts

Initially Posted - 03/14/2009 : 07:50:09

After looking through the forums and finding plans to build an A frame, I would also like to try to build a mast crutch.
I have seen plans and pictures for wooden, aluminum and I think one steel mast crutch.
I would like to know how strong must the mast crutch be?
I guess what I'm really asking is could I build one out of an extending fiberglass painting pole? More importantly will it hold the mast?
A pole like this:
http://www.lowes.com/lowes/lkn?action=productDetail& productId=40158-1199-3212& lpage=none

I really like Jim Sweet's Aluminum mast crutch forum in this thread:
http://www.catalina-capri-25s.org/forum/topic.asp?TOPIC_ID=18608& SearchTerms=crutch

In Jim's picture I see the mast crutch resting on the (thin) traveler rail. If I'm just wrong about the fiberglass can I use thinner pipe for the crutch?
I guess I would like to limit the weight and make transporting it to and from the boat easier.

Thanks in advance for your help,
Frank

Frank
1978 C25 #488
SR/WK
West Islip, NY

Edited by - on

SteveRoberts
1st Mate

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USA
45 Posts

Response Posted - 03/14/2009 : 13:46:01

I don't think the crutch has to be all that strong in compression but based on my experience it will experience lateral loads when you move the mast base forward and aft. In my case, I had the backstay hang up while I was positioning the base back in the step and wound up pushing pretty hard before I figured things out (yes, I can be accused of having a strong back and a weak mind).

I don't think I'd personally use a telescoping pole but you might get away with a fairly lightweight metal pole, maybe like what's used to make an outside clothesline. The trick then would be figuring out how to mount a crutch or roller onto the end of it.

Edited by - on

mlg3733
Navigator

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118 Posts

Response Posted - 03/14/2009 : 15:15:11

You need something which won't bend at all, one inexpensive option is to use galvanized fence tubing (Home depot, of course) which can be attached to the gudgeons, the middle part will be attached to the stern rail and the very top to the cleats as can be seen in Jim Sweet's picture.

Edited by - on

pastmember
Master Marine Consultant

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2402 Posts

Response Posted - 03/14/2009 : 18:58:30

The mast crutch can be and do many different things. The Steel telescoping, gudgeon mount that is called a mast up does more than hold the mast. The telescoping steel square tubing is strong enough to roll a mast up, and actually help in raising the mast. A simple mast crutch that holds a mast while trailering can be pretty much what ever you want; wood, aluminum, serious PVC...
I liked my Mast Up alot... so much I had one up front too.

Edited by - pastmember on 03/14/2009 18:59:40

Happy D
Admiral

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921 Posts

Response Posted - 03/14/2009 : 20:28:39

Hey Frank,
Was that mast up round stock or square material?

Edited by - Happy D on 03/14/2009 20:29:23

pastmember
Master Marine Consultant

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2402 Posts

Response Posted - 03/14/2009 : 21:26:55

square

Edited by - on

fpill
1st Mate

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USA
51 Posts

Response Posted - 03/15/2009 : 09:48:08

My Catalina didn't come with a trailer, but in the future I may have some questions about that.
(I'll try not to ask if my truck is a good towing vehicle, but I probably will.)
I would like to be able to roll the mast onto the crutch and then hook up the A frame to step the mast.
I would also like for it to (softly) catch the mast when unstepping.
I guess I didn't think about the forces acting on the crutch while rolling it up.
From Frank's other posts it seems like the Mast Up is a great solution, but I was hoping to same some money for all my other projects.

Not to beat a dead horse, but looking for the A frame tubing 1" EMT is not sturdy enough and I NEED to buy 1" Rigid?

Thanks for all your help,
Frank

Edited by - on

pastmember
Master Marine Consultant

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2402 Posts

Response Posted - 03/15/2009 : 13:48:26

Make sure to tie it off to the primary winches and cleats to help it handle the forces when you roll the mast back on it.

... and your welcome.

Edited by - on

fpill
1st Mate

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USA
51 Posts

Response Posted - 03/15/2009 : 17:45:50

Frank,
In your picture I don't see your mast up tied off.
Am I just missing the lines? Or do you mean with a home brew mast crutch?
By the way you had a post on another thread about cleaning and polishing the topsides(?).
(the area on the hull above the waterline) Do you remember what thread that was?
Frank

Edited by - on

dreddick
Navigator

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117 Posts

Response Posted - 03/15/2009 : 21:29:19

The telescoping mast crutch I assembled last year has worked very well so far. The details are here...

http://evenstar.mysailboatblog.com/tech-page/

Edited by - on

skrenz
Captain

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USA
351 Posts

Response Posted - 03/18/2009 : 17:49:50

One thing that I have found that any match crutch will help is in lowering the mast. I don't have any problems lowering the mast using the typical A frame until I get to the very bottom. At this point I need to remove the bottom pin holding the mast to the mast step. But the mast is also sitting on the top edge of the sliding hatchway causing it to lever against the mast step pin. So I have to hold up the mast - heavy - while the admiral removes the pin. A real pain - removing the pin I mean :-) Also, this isn't so hot for the front edge of the hatch. So any mast crutch will be a blessing. Once the mast step pin is removed its easy enough to move the mast forward to the pulpit mount but it would be nice if the mast crutch didn't fall over in the process. So if or when I make a mast crutch, it needs to be tall enough to allow it to not rest on the hatch cover while removing the pin.

Edited by - on

fpill
1st Mate

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USA
51 Posts

Response Posted - 03/19/2009 : 18:36:06

dreddick,

That's the one. I'm going to give it a try.
I had a difficult time finding those perf tubes here on Long Island.
I finally found a supplier that shipped for free.
Thanks,
Frank

Edited by - on

Prospector
Master Marine Consultant

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Canada
3159 Posts

Response Posted - 03/19/2009 : 19:42:39

I am also looking at mast raising options for next year. We need something that will secure the mast high enough to open the pop top while we motor down the Trent Canal, then work to raise the mast while on the water possibly at a dock, possibly not once we are out of the canal.

I just sketched this in ACAD as my latest idea - I welcome any other thoughts (for starters, I'd likely switch to a 60 deg spread rather than the 90 shown). This is a quick sketch, and very changeable.

Edited by - Prospector on 03/19/2009 19:53:31

JohnP
Master Marine Consultant

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1520 Posts

Response Posted - 03/20/2009 : 14:01:54

It looks so "mechanical" and interesting, but I don't get what it is, or what scale it has.

Could you explain what your diagram represents?

Edited by - on

Prospector
Master Marine Consultant

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Canada
3159 Posts

Response Posted - 03/20/2009 : 15:06:47

Sorry John...

Basically, the legs of th emast crutch (vertical members open at a pin hinge at the top, converting it from a mast crutch to an A-frame. The quick release pin would allow teh "feet to move from an outward "inverted T" to an inward truss shape by flipping the part around, and sliding up to the next hole. The drawing is to scale, I just don't know what scale ;) I used a 4ft height for the mast crutch, and a 2 ft base, but in real life I would have to work with the cockpit dimensions. I suspect it would be much smaller.

I see the routine going like this...

With mast supported in crutch, set bolt in mast step.
Support mast on the coachhouse using 4X4 that normally holds mast clear of pop-top (we keep a 4X4 in the mast step to hold mast up high enough to raise/lower pop top.)
Convert mast crutch to A-Frame
Set A-frame up on foredeck,
Hoist away.

Edited by - on

JimB517
Past Commodore

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USA
3285 Posts

Response Posted - 03/20/2009 : 15:41:21

I built my crutch out of 2 inch PVC. It is not strong enough. I reinforced it by sliding a thin walled pipe inside the upright.

Works OK.

My aframe is built out of 3/4 inch steel conduit from Home Depot. Bent, cut, and shaped by hand. Works good. Don't use the pulpit for hoisting!

Both together cost about $10 but I had the thin walled pipe laying around.

PS. I have no trailer but it's really helpful to be able to drop the mast in the slip.

Edited by - on

dreddick
Navigator

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117 Posts

Response Posted - 03/23/2009 : 09:00:14

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by fpill
 I had a difficult time finding those perf tubes here on Long Island. I finally found a supplier that shipped for free.
<hr height="1" noshade id="quote"></blockquote id="quote">
Yeah, locally we have Home Depot, Lowes, and Menards for home improvement stores. Menards was the only one that had those. Good that you found them with free shipping as they probably wouldn't be cheap to ship.

Edited by - on

delliottg
Former Mainsheet C250 Tech Editor

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USA
4479 Posts

Response Posted - 03/23/2009 : 10:14:13

Chris,
I haven't done any math on this, so take it with a grain of salt.

If I understand you correctly, your A-frame would only be 4' high? I'd think you'd want that dimension to be more like 8'+ to give you sufficient leverage when first raising the mast away from near-horizontal, or dropping it into that position. Probably more so when dropping it since the length of your lever arm determines the vector loads on the A-frame, control lines, & mast. The longer the lever arm (length of A-frame), the more control you have when the mast approaches horizontal.

I like the idea of the dual A-frame/mast crutch because it's clever, but it seems cumbersome in practice. You have to move it out from underneath the mast, yet leave the mast supported, then attach it to the deck & rig it while the mast is on a jury support. If it were me, I think I'd want the mast supported by a crutch dedicated to that purpose while I was rigging the A-frame.

My $0.02.

Edited by - on

dmpilc
Master Marine Consultant

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USA
4593 Posts

Response Posted - 05/20/2011 : 12:47:33

From another thread, I made this and will be testing it soon:

Edited by - dmpilc on 05/20/2011 12:49:23

Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 05/20/2011 : 18:14:32

I had a gudgeon mounted 2x4 that was notched to hook over the stern pulpit and 4 lines to cleats. It broke last winter when I was rolling the mast out (no damage to the mast). I then bought a 2x4x8' and cut a piece off the end that just fit the footwell width and added a strap hinge to attach it to the upright (easier stowage. I still run lines to the cleats and now I do a quick lashing to the pulpit - still less of a PIA than removing and reinstalling the rudder IMHO. For a high storage support that let me comfortably work under the tarp, I notched 2 2x2's and lashed them to the stern cleats and through bolted where they crossed to catch the mast in the "V" and make them easily collapsed for summer storage

Edited by - on

OJ
Master Marine Consultant

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USA
4382 Posts

Response Posted - 05/21/2011 : 02:40:12

Having a tall-rig, we face a slightly different challenge. When moving the mast backwards using a boom crutch it becomes almost unruly because of its added length and weight. We're going to try the gin pole route - supporting the mast just high enough so it doesn't touch the sliding hatch when the bottom is inserted into the tabernacle. Using a gin pole that telescopes to 10' (the distance between the tabernacle and stemhead) for leverage.

Edited by - OJ on 05/21/2011 02:50:40

aeckhart
Master Marine Consultant

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USA
1709 Posts

Response Posted - 05/21/2011 : 09:44:51

OJ,

I have a tall rig and have used both the gin pole and most recently, an A-frame. I have found the A-frame to be easier to rig than the gin pole. Both do the job adequately but I am sticking to the A-frame.

Edited by - on

dmpilc
Master Marine Consultant

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USA
4593 Posts

Response Posted - 05/21/2011 : 11:35:39

One of the best mast crutches I've ever seen in a homemade rig is one by a C-22 owner in our fleet, a new owner at that. He purchased one of the late model wing keel C-22's. His crutch is made out of a metal post like ones you would mount a road sign to. It has a channel that will hold a square nut like ones used on old wooden bedposts. Using plywood, he made 2 pieces to hold the mast, one up high for raising/lowering the mast and one lower down for trailering. I'll try to remember to get pics next trip to the lake.

Edited by - on

GaryB
Master Marine Consultant

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USA
4303 Posts

Response Posted - 05/21/2011 : 12:12:09

My mast crutch is made up of a perforated metal post that telescopes out to whatever length you need. Insert a pin through the holes when you reach the desired height and your ready to go.

It looks very similar to the crutch in Franks photo above except it's made out of the perforated post.

I've got a keel roller mounted on a square piece of metal that snaps into place at the top of the crutch. Once the mast is resting on the keel roller I carefully pull the pin and lower the mast crutch down to the desired height.

Edited by - on

OJ
Master Marine Consultant

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USA
4382 Posts

Response Posted - 05/21/2011 : 17:01:52

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by aeckhart
 OJ,

I have a tall rig and have used both the gin pole and most recently, an A-frame. I have found the A-frame to be easier to rig than the gin pole. Both do the job adequately but I am sticking to the A-frame.
<hr height="1" noshade id="quote"></blockquote id="quote">Thanks Al - I appreciate you sharing that info. I have a design for a gin pole that I will share when completed. Hopefully I won't regret taking your advice . . .

Edited by - on

islander
Master Marine Consultant

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USA
4023 Posts

Response Posted - 05/21/2011 : 17:43:32

Sure do have some engineers on this, I dropped my mast and simply screwed some 2x4's together. A simple T, Say 5ft high with a 2ft cross screwed to the top and a 1ft cross at the bottom. I duck taped it to the stern rail on the inside so the bottom sat on the cockpit floor. Put a little scrap of carpet on the top cross and your done. It did what it had to do. Of course this is not for those who drop their mast on a regular basis but for the Once every few years its fine.

Edited by - on

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