Freestanding

Trying to make a wooden, freestanding rig. Most things I read online are negative.

 

Welcome to the forum.

I'm not sure what you're reading, but freestanding rigs have been around for many centuries and have worked very well. With the advent of modern materials, they can be lighter stronger and much better performing than some of the notions you might have read.

How are you calculating the loading, hence the scantlings, on this wooden mast of yours?

 

One way to find threads on the subject is to search.
A recent one (might be a little larger than you want but the principles....):
http://forum.woodenboat.com/showthread.php?187954-Birdsmouth-mast-howto&highlight=birdsmouth

PAR will have lots of useful insight if you give him enough info.

 

Trying to post a picture.

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This is my little plywood boat. The design is an AD-14, by Jacques Mertens.

 

The Adelie 14 has a stayed, Bermudian cat or a hybrid junk rig, with full battens and a huge roach as a result. What about the stock rig don't you like? A single headstay and lowers are all the standing rig is, though it certainly can be made into a free standing stick if desired, some re-engineering will be necessary to cope with load transmission, placing appropriate centers and spar scantlings.



This isn't something you can take a guess at and requires a fair bit of calculation to get it right. Call Jacques and see what he thinks.

 

Well, I did just take a guess at it. (I read your advice) And honestly, I think it's going to be just what I wanted. The designer doesn't like the idea either. His rig is probably great as drawn. I should start from the beginning...

 

Okay. First of all, I don't know what I'm talking about. And in no way do I consider myself somehow more clever than the next guy or any designer.
A long time ago I bought a partly finished sharpie hull from a friends brother. I was maybe 21 years old so I didn't know s from shinola. Me and my friend built two hollow freestanding box masts from 16' lengths of cvg Doug. fir. The masts finished about 26' long, a little heavy (took two of us to step). The sharpie was 30' long and the masts couldn't have worked better. Fast like you only think you know.

 

I'm taking to long to make my point so I will just post some pictures. When I get this site figured out I will get back to it. I basically built a mast similar to Par's advice.

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I live in Seattle. I called around town to see who might be able to source the materials. I was able to find "spar-grade" Sitka spruce sticks locally but they were 20'. My mast needed to be 20'-10", I wanted to make my mast about 22' long. I wanted to make mine longer than plan because a freestanding rig can carry more sail area than its stayed counterpart. So...the next week they picked up three long sticks for me and I was in business. No scarphing needed. The spruce for the mast and the boom cost $360.

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Can you share with us your plan for reinforcing the deck and keel for the mast loads?

Where did you ever get the idea that freestanding can take more load than stayed?

You really need help with some engineering.

 

Back to it. I read somewhere online (so it must be true) some notes from a boatyard back in the day saying the best spruce for the lightest spars would have between 9-12 grains per inch. Our source volunteered that as low as 6 grains per inch was considered "spar grade". The sticks I received were 15-18 grains per inch. I've never worked with spruce before, I must say that at 23+ feet long These were amazingly straight grained pieces of wood. Though it did strike me that it wasn't that much lighter than Doug fir. Working with spruce was great.

 

Bouncing around here. I was originally thinking I would build a birds-mouth mast. I thought it would give the boat some "wooden boat" cred. But a couple things changed my mind. I read that square shaped beam sections are 15-20% stronger for the same size than round beam sections. I read square is better at dampening oscillations than round. And I want to raise a foresail from my mast so I thought I could customize the shape of a box mast to assist. (I carried my fore and aft shape higher up the mast/relative to the sides).
Aesthetically I thought the boxy hull befit a box mast more than a round one. And finally, I couldn't figure out how to taper staves in the thickness for a birds mouth mast.

 

Hi Upchurchmr. I am new to this site and I am stumbling a bit. I just noticed you wrote something and will be happy to answer when I get a chance. But I can say that I don't believe it's rocket science. Besides, you will see, right or miserably wrong I did try to think it through.

Okay, I don't know what you mean regarding the keel. The frame and partners are ready for a freestanding load.
I have already built a mast, I have not tried it yet. First, let me show everybody what I built.

Why do I think a freestanding rig carries more area? Okay, take two identical boats, except for the rigs. One mast is stayed, one is freestanding. The owner of the freestanding rig will put more sail on his mainsail. When the wind is light, the extra sail area helps him. When the wind is strong or gusts the freestanding rig twists-off or flattens off power...now I'm not saying you would choose the unstayed rig, I'm saying if you found yourself the owner of the freestanding boat, would you look to take advantage of that? a freestanding sail will change shape/relative to wind power. It can't be avoided so you have to take advantage of it.

 

"The owner of the freestanding rig will put more sail on his mainsail."

This is the statement I don't believe has any basis in fact.

I hope everything works out, you certainly should do what you want.
When there are statements that seem to be the basis for your decision that I don't understand I'm going to ask a question.

Having been the owner of a stayed catamaran (beach cat) when there is a strong gust I would let out the mainsheet and the sail twists off, dropping power.
Of course with a freestanding mast the reduced power is somewhat automatic - you don't get a choice. That is not desirable to me. As you said, you can't avoid it. With a stayed mast I can avoid it.

What do you mean by the frame? The picture I saw had an empty cabin. If you have a free standing mast you have to have two points of support. One is the cabin top. The other is???

Last but not least. A square mast will reduce the power going to windward. That is the most difficult, slowest point of sail. Why would you penalize yourself in that direction?

Can we see the installed mast?

 

Surprisingly, round masts are worse to windward. Francis Herreshoff is, arguably, the inventor of square box masts. He originally made them for economy, but found out they performed better than the round ones.