Let’s Rig This Boat!

[Chotu]

I want a 70ft mast like a sister ship has. Budget does not allow for a brand new factory mast.

I bought a 59ft used double diamond spreader mast off the same size boat as mine with the help of a reputable local naval architect that specializes in high performance catamarans. It’s a little beefier than what’s required for my boat. Moments are higher.

The gooseneck on this 59ft mast is 3ft from the base. VERY LOW!

I need the boom to clear the deckhouse and deckhouse roof equipment at a height of 6ft from the mast base. (It’s currently NOT clearing at 2.5 ft or so due to the diameter of the boom section)

I had some ideas on how I wanted to proceed but I’m going to keep them to myself to see if better ideas come up.

What would you do with this mast to meet the following conditions as best you can but also easily and not wasting too much time?

1) get the boom clearance to 6ft off the mast step.
2) get 70ft of mast length
3) make the modification as easy as possible (note, I’m comfortable with splicing the mast)

Looking forward to ideas!

Thank you!

Note: pics will be taken when complete like the other threads I have going.

Absolutely no naysayers please. It’s a constructive thread. Please don’t bring a “can’t do” attitude in. Ie: don’t answer with “hire a rigger”

[ThereAndBack]

If you have plans for the ICW at all, I would suggest evaluating if you can live with a mast under 65ft. You're right on the line.

[Chotu]

Originally Posted by ThereAndBack

If you have plans for the ICW at all, I would suggest evaluating if you can live with a mast under 65ft. You're right on the line.

Priority is performance. Not too interested in motoring in the icw.

This boat should be able to get in close to 300 mile days. No need for icw.

If going inland, or deciding to motor the ICW, I’ll get a crane and pull the mast so I don’t have to deal with any bridges at all.

Even a 60ft mast sucks in the ICW. Better to pull it and go non stop in my experience.

[tkeithlu]

Chotu, it's fun to think about a challenge like this, but it really belongs in the hands of your naval architect. I wouldn't verture an idea in any case, but those who might don't know a thing about your boat, the mast, or your rigging. We can't even use "50' catamaran" as a comparison, because you are talking about high performance, AKA "Cut the margins kinda fine."

[Chotu]

Originally Posted by tkeithlu

Chotu, it's fun to think about a challenge like this, but it really belongs in the hands of your naval architect. I wouldn't verture an idea in any case, but those who might don't know a thing about your boat, the mast, or your rigging. We can't even use "50' catamaran" as a comparison, because you are talking about high performance, AKA "Cut the margins kinda fine."

Oh come ON!!!

The very first post is a “can’t do” attitude???

In what way exactly, does my naval architect have anything to do with me lengthening this Mast, which I bought a little too short?? Come on!

I’m copying the sister ship that has the 70ft version.

All the details will come out in the thread like they always do.

I’d like to run into all the problems here, before I go and start cutting things. Thinking of all the little details. Making sure I didn’t miss anything.

I didn’t ask you to specify a rig. I have a rig.

I just need to lengthen it. It’s a little too short. I definitely included all of the relevant information. None of this has anything to do with my actual boat. We are talking about an aluminum tube that needs to be extended. It has fittings on it. The only thing about my boat that is necessary to know is the 6 foot height I need on the boom.

You don’t need to know anything else about my boat to participate in this. Just that it’s a catamaran. All the measurements are in my initial post. Those are the things of concern.

[Cheechako]

Originally Posted by Chotu

I want a 70ft mast like a sister ship has. Budget does not allow for a brand new factory mast.

I bought a 59ft used double diamond spreader mast off the same size boat as mine with the help of a reputable local naval architect that specializes in high performance catamarans. It’s a little beefier than what’s required for my boat. Moments are higher.

The gooseneck on this 59ft mast is 3ft from the base. VERY LOW!

I need the boom to clear the deckhouse and deckhouse roof equipment at a height of 6ft from the mast base. (It’s currently NOT clearing at 2.5 ft or so due to the diameter of the boom section)

I had some ideas on how I wanted to proceed but I’m going to keep them to myself to see if better ideas come up.

What would you do with this mast to meet the following conditions as best you can but also easily and not wasting too much time?

1) get the boom clearance to 6ft off the mast step.
2) get 70ft of mast length
3) make the modification as easy as possible (note, I’m comfortable with splicing the mast)

Looking forward to ideas!

Thank you!

Note: pics will be taken when complete like the other threads I have going.

Absolutely no naysayers please. It’s a constructive thread. Please don’t bring a “can’t do” attitude in. Ie: don’t answer with “hire a rigger”

1) What boom fitting is on it? Buy a boom fitting or weld one where you want it. What's the issue?
2) Would deck stepping the mast work to get you enough height? You wont get 70 ft but you'd get close maybe. Many boats are deck stepped with a support post under..
3) well, if you are comfortable, then splice the mast as needed. Good luck finding a matching extrusion though. I guess you could add maybe 7 ft to the bottom and have the joint where it goes through the deck. That gets you to 66 ft.
Where are you? maybe you should be considering 65 ft off the water due to bridges?

[Chotu]

Originally Posted by Cheechako

1) What boom fitting is on it? Buy a boom fitting or weld one where you want it. What's the issue?

1/2” thick welded tabs are the boom fitting. If I raise the boom fitting, I think I would then need to move all the spreaders and everything and add an extension to the tip of the mast. Yes?

2) Would deck stepping the mast work to get you enough height? You wont get 70 ft but you'd get close maybe. Many boats are deck stepped with a support post under..

Boat is a catamaran. By definition all masts are deck stepped. Mast is 59ft currently. No support post needed. Mast rests on the main forward structural beam by design.

3) well, if you are comfortable, then splice the mast as needed. Good luck finding a matching extrusion though. I guess you could add maybe 7 ft to the bottom and have the joint where it goes through the deck. That gets you to 66 ft.
Where are you? maybe you should be considering 65 ft off the water due to bridges?

That is my thought too. I didn’t want to put it out there in case somebody had a better thought. I didn’t want to steer the conversation. In that area.

However, adding 7ft to the bottom puts the current gooseneck fitting 10ft above the deck. I need 6. So, I’d have to move the gooseneck fitting down. BUT... I’d have to move the gooseneck into the splice area. Almost precisely onto the splice point. Is that ok?

I haven’t been able to determine if the splice is weaker than the rest of the mast or is actually stronger given it has a sleeve inside.

[rslifkin]

I'd think you could build an external plate to hold the gooseneck that also acts as a partial external splice and spreads the load. That should eliminate any concerns about the gooseneck being right at the splice.

[Chotu]

Hang on, hang on!!

Important update:

I’ve been off the project for a year since having a heart attack. Sorry. Missed a detail.

70ft was the approximate total air draft of the sistership. NOT the mast length.

Sistership mast length is: 64 feet.


So!!! I think boosting the base of the mast up by adding a 4ft extension will get me there. That will put the boom over the cabin top and put my mast length at 63ft which is close enough to the sistership to be workable.

[Chotu]

Originally Posted by rslifkin

I'd think you could build an external plate to hold the gooseneck that also acts as a partial external splice and spreads the load. That should eliminate any concerns about the gooseneck being right at the splice.

See?????

Now that’s a response! Very creative!

If I had my numbers right from the start, this would probably have been perfect.

Now, with the update of only needing a 4ft splice at the bottom, I think I can just use the current gooseneck.

[Chotu]

There will be a lot more coming in this thread.

Shrouds, forestay. Tang angles, running rigging, sail control table.

[Manateeman]

Up 6’ ...splice 10’ ...cut 3’ off the top but taper TIG it ...Let’s NOT rig this boat.
The potential rig configurations are endless. Yikes.
Let’s just buy the book...Principles of Yacht Design. Put in the numbers for what you DO have and post on Boatdesign.net.
You keep stating “performance” is the overriding rule...not seaworthiness...not costs.. not strength...OK .IF and it’s a big IF, you need “performance” ...well, be prepared for a spar failure....because...you want a lower cost rig but have the need to ride the extreme edge. Your goals are incompatible.
We are sorry, but amateur yacht designers and builders often fail to fully understand the complex engineering involved in being at the very cutting edge, or simply lack the enormous funds. This is not a personal criticism. Why can’t you be satisfied with what you have....seriously... You have a pretty good spar. We think there are several ways to accomplish the modifications...perfect??? Heck no. But good enough to look good and to work well. Anyone with enough money can go buy a Chris White but YOU BUILT your boat and for THAT alone...my manatee crew tips their hats and wishes you...
A Very Wonderful Christmas
Captain Mark

[Chotu]

Deleted like 3 posts in response to my good friend above. Or is that my mother posting? Hard to tell with all the passive aggressive BS.

[sandy stone]

Originally Posted by Chotu

I bought a 59ft used double diamond spreader mast off the same size boat as mine with the help of a reputable local naval architect that specializes in high performance catamarans.

And you're asking random strangers on the internet for advice on how to rig your high performance catamaran? What am I missing here? Won't the NA at least give you some pointers?

[Chotu]

Originally Posted by sandy stone

And you're asking random strangers on the internet for advice on how to rig your high performance catamaran? What am I missing here? Won't the NA at least give you some pointers?

Pointers for what, exactly?

Tell me what specific questions to ask him.

Or do you not understand the question enough to even make a relevant comment?

No more mercy for the dopes that post in this thread. None.

If the good people on the forum are off and busy for the holiday, I’ll hold the fort down fending off all the nervous nellies and others with a “can’t do” attitude.

I ignored one. Probably should have added him to my ignore list. I’m not ignoring them all.

You have been warned.

Stupid, non constructive posts like these will be met with thread enforcement in the form of a snarky attitude and ridicule. So don’t even try.

I’m trying to stick to the subject here. Just because YOU are incapable of doing anything for yourself doesn’t mean everyone else is.

The goal of this thread is to find any problems with the rigging design and errors, omissions, things that just won’t work. To brainstorm to create the ideal rig given the resources and constraints available. To keep track of the running rigging to optimize it. To lead it all to the sail control table and make things easy to control