pics of new gooseneck

[Fortis]

A while ago I posted about a gentleman who forgot that things work better when the gooseneck is not trying to immitate a frag grenade.

This is the instalation I just did on the boat (same type of boat) of a man that is keen not to be the next object lesson.



It has a few nifty features, some visible and some otherwise.

Firstly, when I was working on mine sites I noticed that some slow revving but very high torque machinery that used universal joints (what a gooseneck is) had a nifty stress releif area in the middle that took pressure off the pins in case things went badly wrong. It also (Becasue of how it was constructed) allowed much better bonding of materials and yielded a better result then if the whole thing had been milled from one billet. Anyway, it takes some extra fiddling about with the cutting and welding it toegtehr end of things...but is honestly well worth it because if how the assembly is a matter of self alignment.

Incidentally, as a bit of a "why not" excercise on this project, if you pull the pins and take the middle segment out and turn it upside down and put it all back together, then the boom will still have full motion upwards, but will have a stop that prevents it dropping more then 2 inches past the horizontal, even with a fair amount of weight piled on it. Not sure where that would ever be a help or an issue...But I noticed the possibility when I was sketching up my patterns and decided to go with it. You never know.

The mast plate is 3mm 316ss, the tang rings are 6mm. The barrel is an 22mm rod that I drilled the centre hole in (14mm). The pivot pin is a hollow thick walled tube (16mm OD, with 2.2mm walls) that has had a Ronstan snap shackle welded in place at the top (both with a top weld and a keyhole weld on the shank which is threaded down the tube), the base of the tube has a 3/8 stainless bolt (Same UNF thread as used throughout the majority of the boat) that is threaded and keyhole welded. I opted for two nuts locking off the system at the base because we may need to put in a washer with a loop welded to it at a later date. This way it just needs to go in between the two nuts.
The centre of the gooseneck is three layers of 6mm with a 12mm solid pin running through it to form the vertical axis. lug loops are again 6mm. They are welded to the 2mm saddle material, but there are two lengths of 6mm ss barstock running acrosswise behind all this (facing inwards inside the boom) in order to prevent flex and stress if this area gets worked.
the saddle itself does not just rivet to the aluminium of the boom. It sits on a rubber skin and there are two matching 1.6mm stainless leaves on the inside of the boom, so that rivets go in through all layers and end up sandwitching the aluminium which is highly reinforced in that area. Getting those to stay in place for the first couple of rivets was a pure joy, I can tell you. Rivets are the largest diameter annodised monel we could get.

I would happily pick this boat up by the gooseneck and shake it all about. I would be happy with it strength profile on a 38 footer instead of this 24...I think it will hold nicely, thank you!

;D

The polish is a five stage sanding and buffing proceedure that takes it up to what I used to call mirror-1 in my armouring days. I am happy with it.

When it stops raining like it really means it I can go down and add the side blocks to the boom saddle (I designed them to keep the look and style of the thing clean) and these will be for the reefing systems. They use the flat face of the saddle as the base and are very low profile and sleek. Best of all, the central bolt that holds the roller and pin in place is  threaded on the end, so the centre of the sheave is also going through the stainless of the saddle, then the aluminium, then the stainless inner leaves...helping to tie and tighten it all together beyond the "mere" rivet job.

Want to see what I come up with if you ask for "bulletproof"?


Alex.

[Leroy - Gulf 29]

Wow!!!!!  Order is in the mail :)  DQ though - why pop rivits instead of machine screws?

[Fortis]

They are monel pop rivets, so they are not prone to work hardening or shear failure like stainless rivets, nor are they as soft as warm butter like aluminium ones. The mast and boom are both over 35 years old and have distict wear in the area that the goosneck fastens to. Thus the backing plates...

The rivets are 35mm long and have the special head that does not just expand them but mushroom them, so they actually catch a much bigger area of aluminium mast then just tapping metric thread into it. I did a pull-apart test using my 12 ton hydraulic press and some scrap materials. I found that the RIGHT rivets held much better then tapped in machine screws. even so...there are 11 rivets holding the plate to the mast itself.

Finally, monel is inert when used with either stainless or aluminium...But cutting threads into aluminium and then running in stainless material sounded liek a bit of a recipe for electrolic corrossion. The gunks they sell that you can squirt into the hole or apply to the threads will not prevent metal to metal contact in that application...

With the addition of the cheeck blocks on the sides of the gooseneck's saddle, there will be two machine screws on either side also holding the whole thing together. Sort of a belt to go with the braces.


Oh, the other thing was that the old saddle was held on with pop rivets that had been factory set 38 odd years ago...they were managnese bronze pop rivets! and they had not loosened at all.


Alex.

[AdriftAtSea]

Umm... I don't see a tack hook for reefing the sail.  Are you going to add one or do you use a one-line/two-line reefing system???

[Fortis]

Correct. That is what the cheeckblocks mentioned are for. They go in this morning.

[Leroy - Gulf 29]

Thanks again - makes sense to me.  Hope y'all had a great T-day

[Fortis]

Sorry for the delay. The cheeckblocks in question. One to each side nice and low profile.
I was going to make them from scratch. I have a nifty jig I built that lets me cut sheaves of any size using a router....But then I was going through my buckets of odd yacht bits and found a bunch of small stainless fiddle blocks. Very high load rating, bearings, set up for 6-8mm rope, very slim lined. A little work with an angle grinder and stuff and the little sheaves went away, leaving the big ones as cheeckblocks. The little sheaves are not wasted though...

They are now the blocks for the spinnaker sheet tweekers.

All in all, rather efficient.

Only workshop work in the next few days as the deck-tread is going down on the boat (not by me, thankfully) and it is getting left alone for 48 hours to "go off" properly.

Then the new windows go in.

Oh yeah...another bit of custoim deck hardware (whihc I did not shrink down a picture of yet, sorry) is also fully up and running...I built a mast coronet. This is a ring that gets bolted to the deck around the mast. Because of how it is fastened down it actually reinforces the deck around the mast-setp and better ties the area together to the bulkhead beneath. The idea of this ring is that it allows you to attach a truly large number of blocks wherever you need them at the foot of the mast. There are commercially available mast plates that do about a quarter as much (side mounting points only) but they need you to unbolt and lift your mast foot and insert them in between. Trying to safely lift and then rebed a 40year old mast foot did not sound like fun...so I came up with something else.


Alex.

[CharlieJ]

ok NOW I'm interested for sure :D

Got any pics of this "nifty jig" for making sheaves? If not, please take some and give us  look at it.

[CapnK]

Alex -

The gooseneck looks like a great piece of work.

Also, appreciate the info on the monel rivets - makes a lot of sense!

[AdriftAtSea]

I would have to question if Monel is really inert in a marine environment, when used with aluminum.  It is probably fairly inert with stainless steel, but far more cathodic than aluminum in a salt water environment.

See here

[Fortis]

hmmm. In teresting. I think that is why the monel rivets are so heavily annodised and claim that they are aluminium-to-stainless safe.

On another note, even if it is a problem, the aluminium at that point is sandwitched between the outer stainless of the styrup and the inner leaves of stainless, both of which are isolated. If the holes around the lauminium "grow" and corrode by half a mm, I do not think anything will move at all.

Alex.

[AdriftAtSea]

Just thought you should know... that's one reason I try not to use Monel rivets... unless they're coated, they're really bad news in aluminum. Yes, stainless steel pop rivets can work harden, but for most of what I'm using them for, that's unlikely to be much of an issue, and their fatigue resistance and strength is far greater than that of aluminum pop rivets.

[CapnK]

Found another, more exhaustive list of metals re: galvanic properties:

http://www.corrosion-doctors.org/Definitions/galvanic-series.htm

Darn, I guess I have to chuck out the Titanium pop-rivet business idea...  :D

[CharlieJ]

 ;D ;D

Sometimes being old fashioned DOES have it's benefits!!

With our wooden mast and boom, plus wood cleats and fair leads on both, I don't worry over much about corrosion or a mis match of metals.

Oh- our gooseneck is bronze, with bronze fasteners

;D ;D