Ways to Add 6ft to the BOTTOM of a mast?

[Chotu]

Originally Posted by stubones99

Is your current mast keel stepped or deck stepped?

If it is keel stepped, simply have a NA design a compression post to convert it from keel stepped to Deck Stepped, and there would be about 6' of extra height.

If I were doing an extension to a mast, I would hire a good welder, use an excess section of the new mast to build an inner splice to fit down inside the new and old mast tubes, and slot weld it to the old mast, and a weld around the junction and it should be as strong as the rest of the mast.

[sigh]. Ok, Yeah. It’s keel stepped. Goes right down to the keel. 15,000lbs of ballast sitting right below it on the bridgedeck.

Is anyone else getting annoyed at the lack of reading or is it just me?

I tend to read threads before I respond. Guess at least 50% of the people don’t. They just read the title of the thread.

Maybe it’s time to turn off notifications on this thread.

[krid2000]

Originally Posted by Chotu

In fact, this thread is closed. Done. Solved. It’s already been figured out.

I for one would much appreciate if you could keep us posted on the actual solution you've implemented, with quotes along the way. I have a similar problem (corroded mast base) and am contemplating my options and budget. Learned a lot in this thread!

Thanks
- Dirk

[Tonali99]

Originally Posted by Lake-Effect

I've seen repaired masts, with a very carefully made internal splice, and precision riveting... but I suspect that for the cost of extending, it would be the same or cheaper to find a used mast of the desired height.

Nothing like comparason-shopping after the fact.
Frankly, I doubt I'd have a lot of faith in a slpiced mast. Holes equal weakness.
Maybe an internal splice with an external one to compliment it from the base up and past the splice?

[Benz]

Originally Posted by Tonali99

Nothing like comparason-shopping after the fact.
Frankly, I doubt I'd have a lot of faith in a slpiced mast. Holes equal weakness.
Maybe an internal splice with an external one to compliment it from the base up and past the splice?

At the place where the splice would be there is zero bending force. None. It is purely in compression. There simply isn't enough distance from the step to the gooseneck to generate a force that would strain a well-done splice. And no reasonable amount of holes, if filled with fasteners, will affect compression.

[Chotu]

Listen to the post above this. We are hearing what a professional rigger thinks here.

[Buzzman]

I added 2' to the bottom of my I-14 mast after it snapped below the partners.

Got local sheet-metal workers to roll/fold a piece of same thickness ally around the existing mast, overlapping for 20% length of extension, and cut verticla slits on four cardinal points (i.e. fore aft port starb) and weld outer to inner.

This got away from the problem of weaking the ally at the point of the join by welding right around at join.

It worked, and cost less than the ally for a new spar on it's own, never mind fitting and rigging the tube.

[AKA-None]

I believe the problem to be solved and the solution were identified above.
Deck stepped mast, no change in the boom fittings just 6 ft taller unless I missed something somewhere.

I’m going to really like seeing some production shots if you wish to share them.

[Tonali99]

Originally Posted by Benz

At the place where the splice would be there is zero bending force. None. It is purely in compression. There simply isn't enough distance from the step to the gooseneck to generate a force that would strain a well-done splice. And no reasonable amount of holes, if filled with fasteners, will affect compression.

True enough. I was just thinking of a good way to to do it. Even considered any possibility of torque, but the mainsheet would handle that too.

[Icarus]

Originally Posted by Chotu

I haven’t got a rigger involved yet, but does anyone know or have experience adding 6ft to the bottom of a mast?

My used mast has a very low gooseneck and is 6ft short of the proper height for this boat.

Since the gooseneck is about 6ft too low and the mast needs another 6ft anyway, I want to add that 6ft at base.

What are some ways to do this? Is there a best way?

The naval architect talked about stepping it on a 2ft box. That’s not enough.

What about a sort of sleeve as strong as the mast itself? What about a splice? The naval architect mentioned the base is a tricky spot to do this stuff because it has a lot of force acting on it.

I would sleeve the mast with an identical mast profile section on top and move the spreaders and boom.
How tall is the mast?
A lot of mast are sleeved for transport.

[Icarus]

Usually if one is going to sleeve a mast one uses the same mast profile for the extension and hold it together with an internal sleeve. Riveted together.
absolutely nothing wrong with that.

[Chotu]

Originally Posted by AKA-None

I believe the problem to be solved and the solution were identified above.
Deck stepped mast, no change in the boom fittings just 6 ft taller unless I missed something somewhere.

I’m going to really like seeing some production shots if you wish to share them.

No problem. Happy to share the process and end result when I get there.

Plate is pretty full at the moment. How we went from good boat building weather to starting to get hot in Florida already is beyond me. I have a little race against that to get my air conditioning in and get a bunch of stuff done that needs doing before that. So it’ll be a bit of a lag on the rigging side. But I’ll be sure to post.

[Chotu]

Resurrecting this thread.

I am unable to find the piece of the mast I need. Places that have masts have very few of them and even sailorman has absolutely none.

What do you all think about getting an aluminum fabricator to bend something around in the proper shape?

Would it be technically possible for them to bend it around so that it takes the same oval shape that the rest of the Mast has? And they could make it out of 3/16 aluminum just like the rest of the mast?

Then the standard splicing process outlined in this thread and maybe others, could be used with an inside space? Making it look like one piece of a nice mast?

Does anyone have some experience with aluminum fabricators? Could they use a type of metal bending brake to do this? I have the right pattern. The mast is sitting right here.

[Tupaia]

Mast sections are extruded so stresses are to some extent relieved during the process. Bending a flat piece to match and extrusion IMHO will result in a severely compromised section with a very high possibility of micro cracks or even visible cracking on the outer surface. Never seen anything like this done so probably it either can't be done or won't work.

Assuming the mast section is anodized and the bent plate won't it will probably look a mess too.
Sorry.

[Chotu]

Originally Posted by Tupaia

Mast sections are extruded so stresses are to some extent relieved during the process. Bending a flat piece to match and extrusion IMHO will result in a severely compromised section with a very high possibility of micro cracks or even visible cracking on the outer surface. Never seen anything like this done so probably it either can't be done or won't work.

Assuming the mast section is anodized and the bent plate won't it will probably look a mess too.
Sorry.

The mast is painted and some other section would be too.

Where can I go from here? I need something to look like the last 6ft of the mast and be able to be spliced to it.

I recall reading somewhere aluminum bends fine if heated. Just a vague thought I picked up online. Any merit to that?

I need to get SOMETHING to work with this part.

What about any random mast section larger than the main mast, then vertical bulkheads inside it in a “+” pattern to take the load? Then a plate at the top of that to settle the mast into?

[Tupaia]

Do you know the origin of the mast section? Posting a detailed drawing of the profile might come up with someone recognising it or even having a piece.