I Found a Rig

[Chotu]

Someone on the forum directed me to an aluminum rig for sale near my boat.

The rig is older, needs a paint job, but it comes with everything. Even a couple winches and chain plates thrown in.

The rig is about 1/6 the price of new.

It also comes off a similar size catamaran that has circumnavigated. May need new standing rigging, but comes with that too.

PROBLEMS:

It’s 5ft shorter than a sistership’s mast which is 64ft. So what can I do here? Add 5ft to the top with a taper? Get an extra extra huge roach and keep same sail area as taller mast, but keep it down low? This will affect the height of jibs and screechers and everything too. Is it ok or will my boat suffer tremendously?

It looks kinda gross. Needs a repaint.

I have no idea what the manufacturer or the xx and yy values are. How can I be sure it’ll work? Is it enough that the boat it came off is the same size as mine?
It’s 11 inches in a fore and aft sense.

Should I pick this rig up? I’d be buying it this weekend

Why or why not?

[Spot]

What would be the difference in the main sail without the 5 feet of mast, guessing at boom length?
What sort of back stay arrangement? Topping lift or hard vang?
Any advantages in a smaller rig for ICW bridges?

I am not a big boat or cat guy, just following along with the folks at home...

[Chotu]

Originally Posted by Spot

What would be the difference in the main sail without the 5 feet of mast, guessing at boom length?
What sort of back stay arrangement? Topping lift or hard vang?
Any advantages in a smaller rig for ICW bridges?

I am not a big boat or cat guy, just following along with the folks at home...

Boom length!! Damn. I forgot to check that one.

I saw it was a double diamond spreader setup like the mast in my plans. It’s also a standard catamaran fractional rig with 3 stays total, like you see on most all cats.

I don’t know what it’s got for topping lift/boom vang.

No advantage in the ICW for 5ft smaller rig since the total air draft will still be 66ft plus antennas.

I haven’t seen the rig in person yet. Just in pictures. I’ll see it this weekend.

[Nicholson58]

Add to the bottom with heavily bolted splice plates. This is common.

[Chotu]

Originally Posted by Nicholson58

Add to the bottom with heavily bolted splice plates. This is common.

Oh!!! Ok! That’s how it’s usually done? At the base?

[contrail]

Originally Posted by Chotu

Oh!!! Ok! That’s how it’s usually done? At the base?

Yes. Another thing that would be interesting is what your displacement and the displacement of the boat the rig came from are. Comparable? One much lighter or heavier? I am thinking of sail area here. What do you plan for the sail area of your main, ideally? And, where will you be sailing, most? Light or heavy wind? How long is your boat, again? (For some reason, 50 feet sticks in my mind).

[smj]

Originally Posted by Chotu

Oh!!! Ok! That’s how it’s usually done? At the base?

That sounds like a good idea but then the standing rigging it comes with is worthless, if good to begin with. The boom would have to be lowered so the included sails would be worthless. At that point your looking at a mast and some winches for the price. Is it worth it?
Playing devils advocate.[emoji16]

[chris95040]

After all this work I can’t fathom why you’d shoot from the hip for your rig. No, I don’t think you should buy a rig that’s too short and with unknown ixx iyy !!!

Maybe its stiffer and significantly heavier than your designed rig. Maybe it’s less stiff and it’s gonna buckle and kill someone.

Aren’t you building a performance cat? And you wanna live with all those compromises but castrate your mast?

Deep breath time, a bird in the hand is not worth two in the bush.

[smj]

Originally Posted by chris95040

After all this work I can’t fathom why you’d shoot from the hip for your rig. No, I don’t think you should buy a rig that’s too short and with unknown ixx iyy !!!



Maybe its stiffer and significantly heavier than your designed rig. Maybe it’s less stiff and it’s gonna buckle and kill someone.



Aren’t you building a performance cat? And you wanna live with all those compromises but castrate your mast?



Deep breath time, a bird in the hand is not worth two in the bush.

So if he took the used mast and rigging, used the original sails that came with it and kept the same basic geometry for the shrouds and stays and their attachment points then he would basically be replicating the rig as it was on the original cat, so no problems.
If he were to ad 5’ to the base of the mast the entire geometry of the rig would change and there may be a problem.
If he were to add 5’ to the top of the mast the geometry of the rig would be the same except that last 5’ and that would have the extra stress of an additional 5’ of mainsail.
So which would be stronger, the original mast height with a square top main and large roach or the mast extended 5’ with a pinhead main?

[wingssail]

Originally Posted by Chotu

Oh!!! Ok! That’s how it’s usually done? At the base?

In Seattle Larry Christensen with the tri Invictus, among his other crazy projects, welded a section of an aluminum light pole to the top of his mast to make it taller.

Of course he wanted it to be oval not round, (but it had a nice taper) so he "squashed" it with a few hydraulic jacks inside of an I-beam he found in an industrial yard. But of course the I-Beam opened a little and all of a sudden it was raining hydraulic jacks. But a second try worked.

So then, after a little welding, Larry could set a Santa Cruz mainsail on his older tri and it was faster.

Larry finished his project, as was his fashion, the night before his next race, the Jack and Jill race. He hurried down to the Sloop Tav and found a Jill.

(Larry said his wife wouldn't sail with him because she didn't like the boat. He said she thought that "Damnboat" was one word.)

[Chotu]

Originally Posted by chris95040

After all this work I can’t fathom why you’d shoot from the hip for your rig. No, I don’t think you should buy a rig that’s too short and with unknown ixx iyy !!!

Maybe its stiffer and significantly heavier than your designed rig. Maybe it’s less stiff and it’s gonna buckle and kill someone.

Aren’t you building a performance cat? And you wanna live with all those compromises but castrate your mast?

Deep breath time, a bird in the hand is not worth two in the bush.

I was looking forward to some posts like this.

Can you tell me how to buy a used mast then?

No one knows the ixx, iyy or weight of a used mast. Yet all the time people are buying them, selling them, putting them on and off different boats.

So how’s it done?

If you can’t trust a mast of a nearly identical size cat, how do you go about finding a used mast?

I’ve been struggling with this a long time.



I don’t see how if it’s stiffer, there can be a problem. I also don’t see how if it’s less stiff there can be a problem when it’s already circumnavigated on the same size catamaran.

But I’m here to learn. I know next to nothing about rigs.

Please elaborate on how this can go wrong.

[Chotu]

Originally Posted by smj

That sounds like a good idea but then the standing rigging it comes with is worthless, if good to begin with. The boom would have to be lowered so the included sails would be worthless. At that point your looking at a mast and some winches for the price. Is it worth it?
Playing devils advocate.[emoji16]

I need all the devil’s advocates I can get on this one.

Definitely looking to avoid the $60,000+ bill for the rig if bought new.

I just don’t get how people buy used masts if something like this doesn’t work either. It’s the closest thing I’ve ever found.

If the beam is slightly different, the spreaders will not work as the angle of the shrouds will be different.

[fourlyons]

Yes, if this mast came off a boat of the same size (length and width), weight, and sail area, basically the same righting moment, it should work fine. If the other boat was heavier or had more sail area it would still work, it would just be heavier than you need.
Further having a different beam doesn't mean the spreader angle is wrong. Spreaders are used to ensure the proper (minimum) angle at the top of the mast, and of course to support the spar to keep it in column under load. But if the spar section were stiff enough and the beam wide enough, you could dispense with the spreaders all together, as some boats do.
If you measure the fore and aft and side to side dimensions, wall thickness, and taper and contact a spar manufacturer, they should be able to give you the numbers you need.

[geoleo]

Originally Posted by Chotu

Oh!!! Ok! That’s how it’s usually done? At the base?

Righto! Find the mast section at rig right --then find a 5ft oiece and splice itusing interal plates inside mast from same piece of mast hint get a piece 8 ft long and fab the inside plates then use 3/8 FH machine screws tapping only the plates so its drawn tight a possible. Mast has slightly larger holes.

[fourlyons]

Some masts are shipped in two pieces, then joined with an internal sleeve, with everything riveted.