NEW ROTATING MAST STEP

SailingTips.Ca

Feigns Knowledge
790
342
Victoria, BC
solid metal, right?  Non-compressible for all intents and purposes.  
Typically yes. Although there was another thread in the FCT forum of a rotating mast ball failing, perhaps a manufacturing defect?

image.png

Either way, important not to underestimate the compression loads while sailing. 

 
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MultiThom

Super Anarchist
1,745
392
Benicia, CA
Typically yes. Although there was another thread in the FCT forum of a rotating mast ball failing, perhaps a manufacturing defect?
That or shear loads failure.  Lotsa shear load when raising the mast.  Depending on the geometry, could get shear loads while sailing if rig is canting (or just loose).  

 

Rasputin22

Rasputin22
13,907
3,459
Can Colligo CNC mill the F-39 ball? Is the ball for the F-39 the same as the 44 cat that Farrier designed? Anyone have a source for a cnc or lathe guy who understands what is needed for a rotating mast ball and socket? I can not find a 3" off the shelf road trailer ball in 316 to save my life.  70,000 lbs mast compression on a 50' day charter 49 passenger CG inspected cat.

 

Hunky

Member
56
5
NW Alaska
My tow ball SS is 750 grames while Ti is over a pound (475 grames) Thas not even the weight of a can o beer. Bending stiffness pre and post fatigue with such weight is also pointless for pourposses.
Old thread but I'm finally trying to get my boat launched within a year. Amgpuma: where did you source your ball? I'm looking for a stainless trailer ball hitch in the 1-7/8" size..  I'm thinking of using Kurt Hughes's design, which is water-catcher mode.. maybe not the best but he likes it so since I have no experience will do as my designer says. Similar to this (second image is different boat than first image, but same idea):

mastbase.jpg

maststep.jpg

 
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Rasputin22

Rasputin22
13,907
3,459
Did you consider how many rotating masts have been with the ball pointing up compared to Kurt's ass backwards way of doing it?

 

KONeill

Member
147
75
Thanks KONeill, I had seen those and figured they were 304 stainless rather than 316L since they don't say the grade. How is it holding up for you?
It's fine. I'm sure it is 304. The boat is dry-sailed and washed off after every sail, and the ball is ridiculously over-spec for the application, corrosion on a 304 part is the least of my worries to be honest. The ball and cup with cutout has worked flawlessly in raising and lowering the mast with no extra hardware needed at the mast base, so that's a nice clutter reduction.

Good luck with your project!

 

Groucho Marx

Anarchist
842
221
auckland, nz
How about just too simple wood and glass ball and socket; never wears out, mast rotates freely, costs matbe a few of dollars for materials. Complexity is not intellgence.

757U0019.JPG

 

DDW

Super Anarchist
6,549
1,108
Can Colligo CNC mill the F-39 ball? Is the ball for the F-39 the same as the 44 cat that Farrier designed? Anyone have a source for a cnc or lathe guy who understands what is needed for a rotating mast ball and socket? I can not find a 3" off the shelf road trailer ball in 316 to save my life.  70,000 lbs mast compression on a 50' day charter 49 passenger CG inspected cat.
How hard can it be? You got a drawing?

 

DDW

Super Anarchist
6,549
1,108
Sure send a drawing. Can't promise anything as time is getting short before the summer cruise but I can't imagine this is a huge job. Tried to PM you but you're not accepting. But I think you have my email. 

 
How about just too simple wood and glass ball and socket; never wears out, mast rotates freely, costs matbe a few of dollars for materials. Complexity is not intellgence.

View attachment 490795
Hi Groucho,

I am looking for a solution similar to what you suggest.
I got a mast from the SuperCat 20 for my Sardine 23 trimaran project and need to build a mast step that will fit. The trailer hitch solution seems a little overengineered and heavy.

Can you show your fiberglass mast step, that seems like a good approach.

How did you achieve a halfway smooth ball shape? what female mold did you use?

Greetings from California

 

Groucho Marx

Anarchist
842
221
auckland, nz
Difficult to see but you can get the idea. I roughly shape a wooden base then sand to make a semi-circular shape for the male bearing, then glass coat. The female bearing takes a bit longer because you're having to cut and grind to make a hollow cup. Glass that too. You can then mate the two with sandpaper between the two to get a smooth surface. And then a thin layer of lubricant. On the male bearing you cut away some of the lower area of the base - so that when lifting mast the female cup can sit on the male bearing edge. Once the liting compression loads go up it will slot into position.

JacquesGroucho - Copy.jpg

 

basketcase

Fuck you second amendment
4,048
1,032
a long way from home
Hi Groucho,

I am looking for a solution similar to what you suggest.
I got a mast from the SuperCat 20 for my Sardine 23 trimaran project and need to build a mast step that will fit. The trailer hitch solution seems a little overengineered and heavy.

Can you show your fiberglass mast step, that seems like a good approach.

How did you achieve a halfway smooth ball shape? what female mold did you use?

Greetings from California
You could just call up Aquarius Sails and get a Supercat 20 mast base.....

 
Difficult to see but you can get the idea. I roughly shape a wooden base then sand to make a semi-circular shape for the male bearing, then glass coat. The female bearing takes a bit longer because you're having to cut and grind to make a hollow cup. Glass that too. You can then mate the two with sandpaper between the two to get a smooth surface. And then a thin layer of lubricant. On the male bearing you cut away some of the lower area of the base - so that when lifting mast the female cup can sit on the male bearing edge. Once the liting compression loads go up it will slot into position.

View attachment 499619
Thank Groucho for the comments on making the ball joint.

Nice picture btw :)

I have been looking for years see your fleet on youtube, but I was never successful seeing your awesome boats in action.

Is there any footage?

 




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