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#21

Main Message Board / Re: Where can I get 9" bolts f...

Last post by KWKloeber ‘84 C-30 #3573 - September 11, 2025, 01:25:30 AM

It seems to me you'd get a better purchase mounting them as far outboard as possible.

Kevin

I'm going to go a little outside my immediate knowledge of the 34 traveler/riser/deck sections here, so I may not be 100% right on. 
Forgive me Stu!

You have to drill down (ugggh) into the links in the Critical Upgrade.  To get enough length to use the outside holes, John's Plan B was to use all-thread from McMaster, and countersink the Acorn nut into the traveler.


This part is in my wheelhouse.
We know the force is greatest on the fastener when the load acts verically directly above it (the vertical component of the stress is virtually 100% - no horizontal component.)  ie, the boom/mainsheet blocks and car are positioned directly above the bolt, and nearly all (say 90%) of load is be transferred to that fastener. 

If the boom moves left or right of that car position the vertical component on the fastener decreases and (not an issue) the horizontal increases.

That's if all things are equal in all positions on the traveller at all points of sail. Of course sail pressure and load on the car don't work that way.

So very theoretically, the optimum thru bolt location is when you'd expect the hardest mainsheet (low horizontal load, high vertical load) and the car imparting that load as equally as practical onto both fasteners.

So I tend to agree that the optimal is where the two bolts are furthest apart.  Then, the stress is more equally shared between them as the vertical load is anywhere except maximum outboard.

The highest load is going to be beating with the car inboard (greater sail pressure, harder sheet so greater vertical component — the perfect storm.) 

And the further apart the fasteners, the more equally will the load be shared between them.

BUT that is theory.  If one fastener is way stronger than the load it could ever see, then taking 100% of  the load alone makes no nevermind anyway.

It's like I say about the Sherwood pump - yes, it pumps more but if you don't need that additional capacity why put up with a crappily designed pump?

That said my propensity to over-do (and sometimes regret it) I'd probably thru-drill for two on each side and to hell with relying on the embedded plate (because it's an unknown quantity.)

(Notice - ignoring my own rule about "excess capacity"  )

#22

Main Message Board / Re: Where can I get 9" bolts f...

Last post by KWKloeber ‘84 C-30 #3573 - September 10, 2025, 10:30:53 PM

IIRC, it's in CRITICAL UPGRADES

Oops!  Defo. I lost my CRS mind.

#23

Main Message Board / Re: Where can I get 9" bolts f...

Last post by Stu Jackson - September 10, 2025, 08:15:13 PM

Ken, and Stu,

>>>>>>>>>>>>>

In any case I've got the bolts necessary to do the upgrade but what I find counter-intuitive is the recommendation that the thru bolts be mounted as close to center as possible. It seems to me you'd get a better purchase mounting them as far outboard as possible.

Kevin,

It would be helpful for you to click on the Critical Upgrade link I provided and please read the two links in that first thread.  The reason is that the pictures I provided show that the long bolts that I installed on my boat came through holes in the traveller track inboard of the machine screws into the plate.  They also show the mistake I made of having one four holes in and the other three holes in.  Turns out that didn't matter much because the one further inboard on the starboard side just got an acorn nut stuck on the inside, while the other one just barely made it deep enough to be able to put a fender washer and nut on it!

If you put the 9 inch bolts further outboard they won't be long enough.

If you get longer ones, I can't tell you enough of the geometry of the curved headliner vs. the flat traveller fiberglass to tell you if it'd work.

That's why we recommend following what has worked for others.

As far as support, no, it wouldn't make any difference, because its still the two machine screws plus the two through bolts - over that short a distance it doesn't matter what order and that thick and stiff track.

#24

Main Message Board / Re: Where can I get 9" bolts f...

Last post by scgunner - September 10, 2025, 06:25:02 PM

Ken, and Stu,

I wandered the labyrinth that is the McMaster website and while I'm sure those bolts are in there somewhere if you can find them you're a better man than me.

In any case I've got the bolts necessary to do the upgrade but what I find counter-intuitive is the recommendation that the thru bolts be mounted as close to center as possible. It seems to me you'd get a better purchase mounting them as far outboard as possible.

#25

Main Message Board / Re: Spinnaker staysail and spi...

Last post by Gary Brockman - September 10, 2025, 10:39:32 AM

Pete,

A tall boy is a tall narrow staysail that is set in the slot between the spinnaker and the mast. It is usually tacked midway between the mast and the headstay, on either a u-bold (shackle) or a block with the line lend back to the cockpit. It is normally set on a jib halyard and sheeted to a snatch block on the leeward rail. On a deep run, it can also be tacked on the windward rail. I have never seen a tall boy used with a sock. Once set, you only trim the sheet and not the halyard. The spinnaker is set first and then the tall boy. The tall boy only needs one sheet and can be led to any available winch, clutch or cleat.

Hope this helps.

[NOT at McMaster]

#26

Main Message Board / Re: Where can I get 9" bolts f...

Last post by Stu Jackson - September 10, 2025, 10:11:38 AM

• That 9" bolt is a real odd ball.
  

  
  
  NOT at McMaster, which was the source recommended in the original post about doing the 101 Upgrade!  That's why I pointed you toward the 101.
  

IIRC, it's in CRITICAL UPGRADES, not in 101:

https://c34.org/bbs/index.php/topic,5078.0.html

[NOT at McMaster]

#27

Main Message Board / Re: Where can I get 9" bolts f...

Last post by KWKloeber ‘84 C-30 #3573 - September 10, 2025, 09:29:02 AM

That 9" bolt is a real odd ball.

NOT at McMaster, which was the source recommended in the original post about doing the Critical Ugrade 101 Upgrade!  That's why I pointed you toward the 101. [correction, Critical Upgrade] 

#28

Main Message Board / Re: New Furling Main

Last post by scgunner - September 10, 2025, 06:02:23 AM

That's a pretty good price, I paid $3,500 for a fairly plain vanilla 135 jib last year.

#29

Main Message Board / Re: New Furling Main

Last post by Noah - September 09, 2025, 01:35:44 PM

Probably no help, as mine is  non-furling. I have traditional, "Cruising Dacron", loose-footed fully-battened mainsail from North Sails and I really like it. BTW- North now owns Doyle sailmakers and Quantum sailmakers.

#30

Main Message Board / New Furling Main

Last post by krafty81 - September 09, 2025, 11:10:29 AM

Got a quote from Doyle for new furling main sail. Includes three vertical battens which I want to keep a better shape. $2700. Any other recommendations for new main from other vendors?