Gooseneck design question

[memelet]

As part of my rig rebuild, I had my gooseneck bracket (which was originally welded on the mast) removed and a bracket built. While I did not exactly specify the bracket (my bad) I was expecting something like:

http://picasaweb.google.com/lh/photo...eat=directlink

What I got was:

http://picasaweb.google.com/lh/photo...eat=directlink
http://picasaweb.google.com/lh/photo...eat=directlink
http://picasaweb.google.com/lh/photo...eat=directlink

Here's how it was attached originally:

http://picasaweb.google.com/lh/photo...eat=directlink

The two main differences I'm concerned about are: 1) That the mounting plate does not fully wrap around to the sides of the mast, allowing the plate take the side loads instead of the bolts, and 2) That the mounting plate is so small that only three bolts can be used on each side.

The yard that did the work insists that:
- their design "was built to never fail"
- that "its strong enough"
- that there "is a negative to making the fitting bigger and adding holes"

At my request they have agreed to rebuild the bracket and split the cost, but also stipulated that they would not be "responsible for cracks that could develop in the mast by drilling more holes"

So my question here is two fold:
1) Is the bracket as currently built adequate?
2) Could adding more holes -- similar to the first picture but maybe not as many -- cause the mast to develop cracks. (That picture comes from a Dashew Sundeer)?
*) ... add the questions I should be asking here ...

The boat is a 1985 Passport 42 cutter. The spar was made by Hall, is keel stepped, and very very strong. The boom is only 12 feet.

thanks!!
-barry

[Robbie.g]

Fitting looks pretty suitable. Excepting for something very unusual, it should last the rest of the boats natural born days. 8 machine screws, i think would be more than ok for this.

Selden in many cases uses 6 or 8 1/4 rivets onto a fitting with a way smaller footprint.
See here :
http://www.seldenmast.com/ebrochures/ENG/index.cfm Page 80 - 81

Cheers, just me 2 cents....

[memelet]

Yes, I see that some of the seldon brackets are similar in design to mine, but others do wrap around (p42 I think).

It just smells to me to have a custom bracket made that for a very minor change (wrap around vs just catch the corner) would be an order of magnitude stronger. Well, at least that's my theory. I really wish I would get some more feedback on this, although I do appreciate and yours Robbie!

[Douglas]

Gosh , I am making a similar gooseneck base out of a solid aluminum block, and plan to attach it to the mast with 8 ea FH 1/4" SS machine screws. These spaced at least 7 diameters apart, or more.

I am hoping to counter-act side loads, by machining a verticle rib that fits into the sail track

Was it Nigel Calder's book that says welding structural fittings to a mast distroy's the temper of the mast and welded parts in that area ?

He commented about welding on spreader bases, with the welds going half way around the mast wall on each side .

So with this in mind, I have fabricated a complete mast and it's fittings , without welding anywhere , and mostly because competent welders in my area, are too expensive or not available.

Douglas , Singapore

[Brion Toss]

Hi,
That fitting looks pretty skookum. True, it would be moreso if it wrapped around, but not, I think to a degree corresponding to the difficulty of fabrication. The highest loads on the gooseneck would likely be when the boom is well inboard, because that's when the sail is loaded highest, so wraparoundness wouldn't seem to be as important as good fit, and firm attachment with a suitable number of large screws.
We see gooseneck weldments fail, and pins, and sometimes the clevis pins wear through the tongues, but not bolts pulling or shearing often, though we do see that sort of things with vangs, which put a lot more tension and shear load on things.
Fair leads,
Brion Toss