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

[smj]

Pretty sure Richard is still selling plans and still has his consulting business.

[Chotu]

Originally Posted by smj

Pretty sure Richard is still selling plans and still has his consulting business.

That’s weird. A few years back he was leaving. Maybe it was a sabbatical and I got confused.

[Knotical]

Originally Posted by Chotu

Yes. I see the same possible drawback too. A very rigid upper mast step at the top of the pedestal, then a free floating mast above that.

It sounds like it could be a problem.

But when I continue thinking about it, I have to ask myself, how would that be any different from taking the same mast and setting it on a lower mast step?

If both mast steps don’t move, wouldn’t a mast that is already designed and proven work just as well on a higher mast step as it would on a lower?

I mean as an extreme example, imagine your own mast (or any deck stepped mast) complete with stays and the entire setup that’s currently working on any boat.

Now take this entire rig and install it at the top of the Empire State Building. Will it behave any differently? I don’t think so.

All that would matter is the upper mast step doesn’t move.

And that brings me to another interesting thought.

If a standard mast step works on this rig (this rig is from a catamaran like mine) why would I need to do any splicing and burying of the mast at all? If I just provide the mast step to the rig at a higher point, assuming the mast step is stationary, there is no need for any of the extra work you’d do with a splice or to bury the mast into the pedestal.. It’s just a higher mast step.

Anyone see anything off about that thought?

I see your point, somehow it just seems that the stress on the joint will be greater with the raised pedestal than if the mast was deck stepped - something to do with the geometry of the whole rig including stays etc. I am not saying that the joint cannot be stiffened or that it will break, just that you may have to consider those additional forces that the joint will be exposed to.

I will be curious what you come up with and how it holds up.

Good luck.

[Chotu]

Ok, if none of the retired engineers or amateur engineers see an issue with making a pedestal to create a higher mast step (which will be surrounded by bent sheet aluminum or a mast section for looks), I’ll proceed.

All good?

[AKA-None]

Originally Posted by Chotu

Ok, if none of the retired engineers or amateur engineers see an issue with making a pedestal to create a higher mast step (which will be surrounded by bent sheet aluminum or a mast section for looks), I’ll proceed.

All good?

I don’t know but with the bracing and such it just seems mmmm inelegant

[Chotu]

Originally Posted by AKA-None

I don’t know but with the bracing and such it just seems mmmm inelegant

Agreed.

There would be no bracing.

I have steps where the bracing was suggested.

In the drawing you can see massive through bolts and a backing doubler would go there too. A bit more oomph than a backing plate.

So any side loading would be dealt with in cantilever fashion.

[Chotu]

Originally Posted by carlosproa

Have you tried passing this idea to a multihull designer like Richard Woods or Berndt Khoeler? Their designs are practical and do not relay on fancy materials. Maybe they can give you a pointer.
I still think you can fit a sleeve on it from a different mast with cut outs to form inside and out

Comments have completely dropped off. I don’t get it.

So you think I could grab a similar mast section and sleeve it rather than do a pedestal? Not using an insert and splice, but an outer sleeve?

[Sos]

I think the pedestal idea should work since it is the same as raising the cabin roof or where ever the mast will sit. However you will have to make the pedestal very rigid and this is where I think it gets tricky. I would not want to weld a base plate to the bottom of the aluminium pedestal so it would need a bolted and sleeved shoe. This would also apply to the base of the mast.
You could of course make the pedestal from stainless steel (316L) which would be fine to weld and offer a lot more options at the base and the join to the mast at the top. Do the best technical drawings you can and run it past people with experience. Good drawings will also save you time, money and mistakes!

Ali mast base fixing:-

[Chotu]

Originally Posted by Sos

I think the pedestal idea should work since it is the same as raising the cabin roof or where ever the mast will sit. However you will have to make the pedestal very rigid and this is where I think it gets tricky. I would not want to weld a base plate to the bottom of the aluminium pedestal so it would need a bolted and sleeved shoe. This would also apply to the base of the mast.
You could of course make the pedestal from stainless steel (316L) which would be fine to weld and offer a lot more options at the base and the join to the mast at the top. Do the best technical drawings you can and run it past people with experience. Good drawings will also save you time, money and mistakes!

Ali mast base fixing:-

Yes, I was picturing this type of normal shoe/base plate would work at the top level where the original mast contacts the very rigid pedestal. Same as stepping it on a coach roof.

Question about welding (since no one wants to get back to me locally that works with aluminum):

My tangs are welded to the mast. My gooseneck is welded to the mast. I don’t know anything about welding. Why would it be bad to weld the base plate to the bulkheads inside pedestal, assuming it’s all aluminum?

[Sos]

Originally Posted by Chotu

Yes, I was picturing this type of normal shoe/base plate would work at the top level where the original mast contacts the very rigid pedestal. Same as stepping it on a coach roof.

Question about welding (since no one wants to get back to me locally that works with aluminum):

My tangs are welded to the mast. My gooseneck is welded to the mast. I don’t know anything about welding. Why would it be bad to weld the base plate to the bulkheads inside pedestal, assuming it’s all aluminum?

It is of course possible to weld aluminium but it has to be designed & done correctly. Have a read of this
Get it wrong and you won't know until it's too late. Personally, I would put my trust in mechanical fasteners or use stainless.

[Chotu]

Originally Posted by Sos

It is of course possible to weld aluminium but it has to be designed & done correctly. Have a read of this
Get it wrong and you won't know until it's too late. Personally, I would put my trust in mechanical fasteners or use stainless.

Whew!! Really glad I don’t know anything about this topic.

After reading this link, it’s clear this MUST be left to extremely skilled welders and fabricators.

I can’t use stainless because it’ll weigh too much. So it’ll have to be aluminum or worst case, composite maybe. But probably aluminum.

[Chotu]

Random question since it’s proving very difficult to find aluminum fabricators that will take on the work. Apparently, they are so busy, they don’t want the job. I’ve tried 8 so far.

Fiberglass stinks in compression, right?

There’s no way I could make the pedestal out of glass is there?


I have a great mold (the mast itself) and could put bulkheads inside the section.

[Tupaia]

For the effort, money and uncertainty of extending your mast would it not be better to buy a new extrusion of the right length and transfer the components, foot, head, spreaders etc from the one you have. Or cut your losses flog the mast you have and buy another new or second hand.

The reason you are finding it so hard is that nobody does it this way and unless you can do it yourself nobody will take responsibility for doing it for you.

[Chotu]

Originally Posted by Tupaia

For the effort, money and uncertainty of extending your mast would it not be better to buy a new extrusion of the right length and transfer the components, foot, head, spreaders etc from the one you have. Or cut your losses flog the mast you have and buy another new or second hand.

The reason you are finding it so hard is that nobody does it this way and unless you can do it yourself nobody will take responsibility for doing it for you.

No, that’s Insanely expensive and time consuming. A rig quote for my boat is $60,000. I have the right mast that’s a few feet short to clear the deckhouse with the boom and the same few feet short of the designed length.

The catamaran it came off had a very low deckhouse and elevated foredeck. So they hacked off the base area most masts have below the boom.

Much easier to add a piece at the bottom or a pedestal for it to sit on. I just need to find someone who has time to weld (they have weeks and months of waiting lists if they answer the phone at all) or do it in glass if possible.

If I had been able to find a piece of this mast profile, I’d already be done splicing it and onto something else.

So I’m wondering. Can this be done in glass?

[Searles]

Have been thinking this through, you will external help for this but it’s simple enough, as follows use the lower section of the mast to make a mold of the section you require ,lay up an epoxy carbon new section that will be a perfect replica of the mast ,sleave and fasten ,as you cannot use epoxy you will require sone help ,the new section can be as long and as strong as you wish .⛵️⚓️