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Advice on how to straighten a 23' mast ( pic included )

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Oct 18, 2010
58
Anon Anon Anon
A sidestay let go while the boat was on mooring.. The mast came down and now it has a crook about 3' up from the bottom.

Facts:
I will not pay for a new mast and I am determined to fix this myself. I have dealt with other bent booms and spars in the past and have straightened them by bending them back straight. A dimple or crease in the Alum does not bother me.

My main question is this: Where in nature or my city surroundings can I find a 2 point brace situation where I can lever the mast against itself and torque it back straight? An old style steel jungle gym in the city park would have been great, but they removed all those in the 80's..

I was also thinking, what about two 8" blocks and a small ramp on the bent area.. Slowly drive my car on it?

Offer up any idea's you may have to straighten out this dilemma. Please do not talk to me about how the integrity of the mast is no-good now b/c I don't care..
 

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Sep 25, 2008
2,288
C30 Event Horizon Port Aransas
Re: Advice on how to straighten a 23' mast ( pic included

This is how I would do it. Get some 2"x4" and 2"x6" lumber.
Build supports about 2' long that are C shaped channels that fit snugly on the mast. space those 4' apart centered on the bend. Clamp them on with big hose clamps.
Make another 2' C channel and hose clamp it on the bend on the opposite side of the mast right on the bend. You may be able to put the mast under your trailer crossways to use it to support the two C channels, and then put a small hydraulic jack under the middle C channel and start jacking.
Have the trailer hooked up to the truck of course to keep it from being pushed up with out bending the mast back.
If you have a table saw, you can rip the lumber so that it just fits overt the mast so the C channels fit snugly. Screw them together. Then hose clamp them on. The hose clamps are just to keep the braces in place, it will make the job easier. Use the softest lumber you can find that way it will crush against the mast and conform to it's shape a little better. With the hydraulic jack you will be able to control the bending much better than any other way.
If the mast set up won't fit under the trailer, put it under two truck trailer hitches, just make sure that the two parts touching the truck are the wood clamped areas.
Get as long of a straight edge as you can to check your progress in bending and take it slow. You may be able to look into the end of the mast with a flash light to see when you are getting close to straight.
I know you didn't want to talk about it, but where the repair is will be under mainly a compressive load. It doubt very seriously if it will be a problem anyway on a 23' mast. But I don't know how thick the aluminum is you are dealing with.
 
Nov 9, 2008
1,338
Pearson-O'Day 290 Portland Maine
Re: Advice on how to straighten a 23' mast ( pic included

I was going to say gin pole and a come-along but Scott's method has more control. Be sure to over bend it slightly since it will want to spring back some.
 

Ross

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Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
Re: Advice on how to straighten a 23' mast ( pic included

The blocking that Hermit discribes will help to prevent point contact crushing of the tube. trees are an option if you can find some in the right places. You just need to have complete control of the load that you apply as you watch your progress. Another posibility is a hole in the ground and a pull on the top.
 
Jun 4, 2009
13
Ocean Yachts Islands 20 Paradise Cove
annealing aluminum

I agree with Lee. Don't forget the heat. A propane torch does a good job of annealing without any worry about melting. Do a google search for "annealing aluminum" to see why it's done.

Thanks,
Ray
 
Oct 2, 2006
1,517
Jboat J24 commack
Re: Advice on how to straighten a 23' mast ( pic included

Heat in this case is BAD as it may affect the Aluminiums temper

I would use a chain hoist and put the mast between the fixed points you find and use a tape measure to see how much travel is required to start

If you pull to much you can bend it to far so work into it slow
 
Jun 6, 2006
6,982
Hunter 40.5 Harrington Harbor North, MD
Use two cars

park the cars close together and at the right stager to apply the loads with the wheels then use a come-along to pull on the end.
You guys make things too hard. Must be manly men. I am just a girlly guy and ........
 

Ross

.
Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
I agree with Lee. Don't forget the heat. A propane torch does a good job of annealing without any worry about melting. Do a google search for "annealing aluminum" to see why it's done.

Thanks,
Ray
Unless you know the alloy you are completely helpless trying any kind of heat treatment on aluminum. The different alloys require very different methods such as time at temperature, method of quenching, temperature of the post hardening tempering, Some alloys require soaking at temperature for hours to allow the alloying metals to stabilize.
I would avoid playing with any heat on the minor bend.
The biggest concern that I would have is making certain that I didn't collapse the tube where I applied the forces.
 
Oct 18, 2010
58
Anon Anon Anon
Thanks for all the replys..
Its done and its relatively straight.

I put an 8" concrete block under my truck right below my hitch. I then put the mast bottom in the block holes and then shimmed it with small wood block in there to keep it straight. Next I set up three 8" concrete block under the bend point with wood on top. ( about 4 feet up from the bottom ) I then put the mast under my arm and against my body and worked my way to the top ( about 20' out ) and putting my weight on it I flexed it.. And, boy did it flex.. It took more than several times and I got it a little straighter each time I was really close and everything was going good.. I went to check and it collapsed about 1/2".. My friend was suppose to show up to help, but never showed.. Had he been there, I would have known I was applying to much force.. I will still use it and be happy with it.. This is def a 2 person job...

Also, I was going to use heat, but figured it was overkill and maybe would have caused the mast to collapse more so. Plenty of force when your torqueing something 20' out on the end..
 
Jan 19, 2010
7,231
Hunter 26 Lake Martin AL
Re: Advice on how to straighten a 23' mast ( pic included

Johan

I have a very close friend (Adam) who wants to part out his Macgregor V21 and turn his boat into a motor day-camper type boat. You might be able to buy his mast from him for the cost of the parts you will need to straighten this one out.

Let me know off list if you are interested and I'll put you in contact with Adam.

r
 

Ross

.
Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
Re: Advice on how to straighten a 23' mast ( pic included

A 160 pound people on a 20 foot lever can exert 3200 pounds of force. Enough to lift the front end of most cars or light trucks.

edit to correct a misstatement.
 
Oct 6, 2007
103
Catalina 387 Panama City, FL
Re: Advice on how to straighten a 23' mast ( pic included

Take the mast to a large machine shop with a large "press".
The pressure will controlled much better, they can do a little at a time and you can watch the results, to determine just when enough is enough.

Bill
 

Ross

.
Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
Re: Advice on how to straighten a 23' mast ( pic included

Consider using sand bags to support the mast while it is laying horizontal and another sandbag on the top at the high point of the bend to cushion the mast from a strong lever. This should provide the best protection from crushing the tube.
 
Jul 1, 1998
3,005
Hunter Legend 35 Poulsbo/Semiahmoo WA
Elastic Limit Exceeded

From the picture it is obvious the Elastic Limit has been exceeded.

Facts:
I will not pay for a new mast and I am determined to fix this myself. I have dealt with other bent booms and spars in the past and have straightened them by bending them back straight. A dimple or crease in the Alum does not bother me.
Please do not talk to me about how the integrity of the mast is no-good now b/c I don't care..
Okay, I won't talk to you about how the integrity of the mast is no-good, but instead, I will tell others. The Elastic Limit has been exceeded [read: "deformed"] and, additionally, it did so near a pretty bad location which is right near the gooseneck.

If one doesn't believe this is a bad location, just look at the bracing on some Hunter masts where the braces go from the deck to the area near the gooseneck. This is telling because that's an area of maximum stress. Once the Elastic Limit has been exceeded the material is substantially weaker.

It might not bother the owner of this boat but it would sure as heck would bother me.

Block and tackle, trees, cars, etc., won't "fix" this one.
 

Ross

.
Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
Re: Elastic Limit Exceeded

We must define some terms here. John has stated correctly that the elastic limit of the mast was exceeded. The evidence of this is a permanent bend that was the result of plastic deformation. Now the real question is has this plastic working of the metal resulted in sufficient work hardening that it will not be possible to straighten the bend? many metals have very wide limits of plastic deformation, lead is one of the most common examples. Aluminum is very notch sensitive and a sharp edged nick on the surface can propagate a crack. That is why pop top beverage cans work. There are many considerations involved in an effort to straighten any structrual component. However to state that once bent no repair is possible is too broad a statement to have merit.
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
Re: Advice on how to straighten a 23' mast ( pic included

I am with you John. I would believe that this is a safety issue and may result in someone death, but to each his own.

My suggestion would be to go to a salvage yard and find a mast with similar dimensions to replace what you have.

No one will know what may happen until it fails. (if it does).
 
Oct 18, 2010
58
Anon Anon Anon
A 160 pound people on a 20 foot lever can exert 3200 pounds of force. Enough to lift the front end of most cars or light trucks.

edit to correct a misstatement.
yes, this is true, Ross.. But, one must take into account that the mast is flexible and will flex and bend thereby canceling out certains aspects of the lever action.

It lifted the truck to a point, but then as the mast flexed, the mast gave in before the weight of the truck..

Rgranger:
I would probably buy a new mast if I was a serious cruiser, but I'm not.. I spend most of my time drinking beer at the mooring and banging my GF.. I sail in 15 MPH winds max for about an hour here and there..

John Nantz:
I would be willing to bet that mast lasts another 30 years.. The boat has upper and lower shrouds which basically supports the top and middle of the mast.. The tabernacle supports the base.. Look, If it didnt break with close to 3000# of torquing force unsupported.. What makes you think it will break with small 20 MPH wind loads all the while being supported.. And, the boat will give from the wind because its in water moving or shall I say sailing..
 
Sep 25, 2008
2,288
C30 Event Horizon Port Aransas
Thanks for all the replys..
Its done and its relatively straight.

I put an 8" concrete block under my truck right below my hitch. I then put the mast bottom in the block holes and then shimmed it with small wood block in there to keep it straight. Next I set up three 8" concrete block under the bend point with wood on top. ( about 4 feet up from the bottom ) I then put the mast under my arm and against my body and worked my way to the top ( about 20' out ) and putting my weight on it I flexed it.. And, boy did it flex.. It took more than several times and I got it a little straighter each time I was really close and everything was going good.. I went to check and it collapsed about 1/2".. My friend was suppose to show up to help, but never showed.. Had he been there, I would have known I was applying to much force.. I will still use it and be happy with it.. This is def a 2 person job...

Also, I was going to use heat, but figured it was overkill and maybe would have caused the mast to collapse more so. Plenty of force when your torqueing something 20' out on the end..
The problem with hanging on the end to straighten a bend somewhere in the middle is this.
The bend causes work hardening. So when you try to bend it, it will bend BY the bend not AT the bend. Then you have an S shaped mast instead. It will be straighter, on average, and probably more usable. The blocking with wood was the most important part of my plan. If you ever bend pipe, there is two common ways to do it. Both involve tight dies around the outside, one way (drawn over mandrel) involves a support piece inside the pipe to keep it from collapsing. You didn't need a mandrel because the bend was so slight(just a few degrees) but you definitely needed outside support because of the nature of bending pipe and the work hardening that had already been done at the accidental bend. I guess it doesn't matter now. what's done is done. So this will be for the next guy who searches how to straighten a bent mast.
 
Jan 22, 2008
53
Macgregor 21 MN
Re: Advice on how to straighten a 23' mast ( pic included

When I hooked my mast on a tree branch one time pulling my venture 21 out of the water and put a nice curve in it, I stopped at a friend's house who had a few ten-twelve inch oak trees growing in a group - some pretty close together - I stuck the mast in between two of them and judiciously bent the mast the other way. It pretty well straightened it. I did some fine tuning by laying the mast on a couple of blocks and standing on it. It's been just fine since (20 yrs.)
 
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