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Old 29-06-2020, 04:44   #1
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How Do You Buy a Used Mast?

I was told I needed to know quite a bit of information to select a used mast.

Namely, length, diameters and wall thickness, PLUS Ix, Iy, Wx, Wy.

When looking for a used mast, youíre lucky if the seller even knows the length usually.

How does one go about finding the right used mast for their boat?
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Old 29-06-2020, 05:42   #2
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Re: How Do You Buy a Used Mast?

I know the length, the diameters and wall thickness needed.

Then what?

I was told those other values are crucial.
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Old 29-06-2020, 06:35   #3
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Re: How Do You Buy a Used Mast?

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Originally Posted by Chotu View Post
I know the length, the diameters and wall thickness needed.

Then what?

I was told those other values are crucial.
You need to know the righting moment of the boat before you can calculate compression loads and propose rigging geometry

You have a cat ?

I have no idea how you would calculate compression loading , righting moment on a cat

Surely your design came with a proposed mast ?

You might be better to get a quote from a mast builder , then work backwards to see if you can find any suitable mast sections on the used market

Rigging geometry is important

Once a mast gets a bunch of holes cut and rigging attached itís not so easy to change without compromising the section
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Old 29-06-2020, 06:40   #4
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Re: How Do You Buy a Used Mast?

If you have a valuable boat ? a naval architect would be worth paying for the correct calculations (assuming you cant get them from the manufacturer)
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Old 29-06-2020, 06:51   #5
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Re: How Do You Buy a Used Mast?

Call Mac sails in FL, I was informed they have some masts from changing boats over to in mast furlers.
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Old 29-06-2020, 08:20   #6
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Re: How Do You Buy a Used Mast?

I’m a little baffled. A lot of people on this forum have talked about getting a used mast. Other times when I’ve complained about the $70,000 cost of rigging my boat being too expensive, people have come out to say I could just get a used mast and sails and rig it for under $20k

I have a mast in my plans. I also have the information that a 60’ Selden 304 mast section works. All the data for a Selden 304 is in the Selden catalog so I have the numbers.

However, given that very exact information, how do I then go shopping for used masts?

I see ads like “55ft sailboat mast — $5000”

Or

“Amel SuperMaramu mast $6000”

How will I ever know if a mast I find is going to be right given nobody selling the used mast knows these other numbers?

It’s a catamaran so the moments are a little different. Then again, the probably doesn’t matter since I know a Selden 304 is the right mast and the numbers for that section are available online. Does this belong in the multihull section?

I’m really lost.
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Old 29-06-2020, 08:32   #7
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Re: How Do You Buy a Used Mast?

From what I have seen masts are selected from a few available extrusions, not custom usually. The chances that a mast off a 40 ft boat will work fine for your 40 ft boat are great I would think if they are close to the same length.
On a 31 ft boat I built many years ago, I had a selection of two extrusions, one seemed marginally small, the other seemed a bit big. I went with the big one as that was my mindset on building that boat, but later I kinda wished I had went with the smaller extrusion. It seemed every boat my size I compared with, and even a bit bigger boats, had smaller lighter spars.
On the same boat I hired a well know marine architect to help me with my rig design. I designed it and then had him evaluate it. One question I had was spreader location and length. it seemed they could be a few feet up or down and not really change much as far as the rig calc's go. The rigging wire angles dont change much up or down.
Based on all this, I think it's as much an art as a science. Sure there are numbers you can crunch. But there are many possible outcomes that work fine. Limited options to use prevail. If you design a mast only for hurricanes you are going to have a pretty ugly and heavy rig.
What may be more important is the rigging, that's what holds the mast up and you can use a thin bendy mast if you have the right rigging, or multiple spreaders. Compression loads are such that the aluminum is not going to crush like a bellows, they just don't get high enough. But "slenderness ratio" can be a factor if the rigging is not right and then compression load comes into effect. Any un straightness in the mast can cause it to fail.
If you look around and measure the mast sections of boats your size, I bet you'll find they are all quite similar for cruising boats.
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Old 29-06-2020, 08:37   #8
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Re: How Do You Buy a Used Mast?

As far as finding a used one. I would ask boatyards if they have any around. Seems some of the old ones have a rack of masts that appear unused for years.
You can sometimes rent a trailer from a rigger to go get a mast.
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Old 29-06-2020, 09:44   #9
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Re: How Do You Buy a Used Mast?

People get way too technical on everything.. if you talk to a rigger there are only a handful of mast profiles that are available at any one given time. If you were to buy a brand new mast section you'd only have 6 different profiles choose from. They don't go out and extrude a mast just for you, unless it is composite

So in looking for a used mast, I think you need to try to get close. Close is enough.
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Old 29-06-2020, 10:07   #10
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Re: How Do You Buy a Used Mast?

Quote:
Originally Posted by Chotu View Post
Iím a little baffled. A lot of people on this forum have talked about getting a used mast. Other times when Iíve complained about the $70,000 cost of rigging my boat being too expensive, people have come out to say I could just get a used mast and sails and rig it for under $20k

I have a mast in my plans. I also have the information that a 60í Selden 304 mast section works. All the data for a Selden 304 is in the Selden catalog so I have the numbers.

However, given that very exact information, how do I then go shopping for used masts?

I see ads like ď55ft sailboat mast ó $5000Ē

Or

ďAmel SuperMaramu mast $6000Ē

How will I ever know if a mast I find is going to be right given nobody selling the used mast knows these other numbers?

Itís a catamaran so the moments are a little different. Then again, the probably doesnít matter since I know a Selden 304 is the right mast and the numbers for that section are available online. Does this belong in the multihull section?

Iím really lost.
A lot of people on this site arenít experts, and just are giving you their opinions. For something as critical and technical as a mast, I would use a high quality boat yard or rigger. Mack Sails, in Stuart, FL , as someone recommended, would be a good option. They have two digit - a sailmaker and a boat yard/service company. Just my opinion.
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Old 29-06-2020, 10:10   #11
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Re: How Do You Buy a Used Mast?

The last few posts are what I had heard before.

I had never heard you had to be so precise.

Really good point about measuring what’s on similar boats.

I know a 12” x 6” section with a 1/4” wall thickness and 60’ long works because it’s on a sistership.

I prob have to do those specs or slightly greater I’m thinking. Never smaller?

When I mentioned the specs I have for section diameter, wall thickness and length elsewhere, they said I needed a ton of other technical information. To me, those numbers define a complete extrusion.
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Old 29-06-2020, 10:23   #12
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Re: How Do You Buy a Used Mast?

Quote:
Originally Posted by rhpike View Post
A lot of people on this site arenít experts, and just are giving you their opinions. For something as critical and technical as a mast, I would use a high quality boat yard or rigger. Mack Sails, in Stuart, FL , as someone recommended, would be a good option. They have two digit - a sailmaker and a boat yard/service company. Just my opinion.
Mack is $70,000. My budget is a little bit less and a lot more DIY.
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Old 29-06-2020, 10:50   #13
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Re: How Do You Buy a Used Mast?

The mast section is only 1 of dozens of variables that affect the proper design of the rig. "Proper" is also only in the eyes of the designer, because there is more than one way to skin the cat, depending on service and performance.
Spreader location/length for example could drive a designer to select one nominal section over the other, or force selection of a particular section, due to characteristics, by playing with the location/size of spreaders and mast fittings.
No one learns how to perform this analysis overnight or by asking questions on forums. For many, it's not something that's worth their time or within their capacity to understand, which is true among many subjects to which people opine about sailing.
Although riggers are not naval architects, you should be able to find plenty of qualified ones that have the capacity to guide you through the decision process of selecting a used mast serviceable for your intended function.
You may see that many options beyond "original design" will be feasible, but the original design likely provided a good compromise and a balanced rig. For example, as the spectrum between cruising performance and racing performance is navigated by the designer, the rig tension is proportional to mast flexibility. You can support a noodle, or you can support a tree trunk, it doesn't matter. It's all in the way you do it and the excepted outcomes. That's why people pay people who do that analysis for a living. You are correct to assume that you don't know what you don't know.
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Old 29-06-2020, 10:52   #14
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I bought a used stern rail at Mass Marine Parts, and it was excellent and affordable ~$400 . They have a whole yard full of sailboat parts including lots of masts and booms.

Masts - Mass Marine Parts
617-719-8232 and ask for Jon

They are in Quincy south of Boston and are worth a trip if its's not too far for you
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Old 29-06-2020, 11:03   #15
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Re: How Do You Buy a Used Mast?

Folks are correctly mentioning that there are a lot of variables that go into *designing* a rig - stay/shroud locations on the mast, chainplate locations on the boat, spreader configuration, hull's righting moment...

But you aren't *designing* a rig - you already have plans which include the mast design. You already know the answer. Now just stick to the plan, use roughly the same mast section specified in the plans and the same rigging configuration. That's all you need to proceed.

The hurdle is just going to be the impracticality of used rig shopping and getting accurate measures of the mast they are selling. Also, if the section you find is a little bit different than what the plans state, an hour of an experienced rigger's time should be able to figure out if the mast you found is similar Ixx Iyy as your plans call for.

Note that you'll likely be adding new shroud tangs, spreaders, etc per *your* plan, not per the plans from whatever boat the used mast came off of.
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