Mast Issues & Renovation

[SkipperJer]

A picture of a the tried and true impact driver is attached.  It's got nothing to do with an air compressor and a lot to do with swinging a hammer with care.  It redirects downward force into rotation through banging on that massive handle.   It works better on screws of substantial size. Small ones tend to get buried deeper in aluminum as I can attest from experience.  I just drill those out and upsize the fastener.

Make sure the bit fits firmly in the slot of the screw.  If its loose it just bungs up the metal or slips out causing foul language and excessive drinking.   I got mine from J.C. Whitney.

[Rico]

Ok... Every single reference I found talkes about SCREWS for the sailtrack on the mast....

(Sorry to remind many of you of this ardous business of painiting spars...)

But how come all I see on my mast sail track are Aluminum rivets??? About 20-30 of the total 110 of them should be replaced too...

Have your rivets been replaced with screws, or have my screws been replaced with rivets!

[ebb]

Be great to get something SOLID on this.

See masts in the yard with what looks like aluminum rivets.  They are frowned on by all authoritys (except Brion Toss of all people!) I have seen because the aluminum rivet would be a different alloy than the spar and the small size of the fastening would make it likely to corrode.  A s.s. rivet is unlikely to corrode in an aluminum spar - while an aluminum rivet more likey to - so it is said.

I have someone's mast next to Little Gull that is being stripped:  mast track and mast steps all popriveted with stem included.  No corrosion evident. and every rivet sheered. IE the top was touched carefully with a drill bit and the fitting pryed off leaving the rivet to be punched out.

However it is impossible to tell whether they are aluminum or stainlees or monel.

If you decide on pop-rivets, the bigger the size (3/16 on up) the more difficult the install.  S.S. and monel rivets are harder and stronger materials and will require a bigger long handled tool to beg or buy.  1/4" rivets may require a hydrolic tool.
You need marine aluminum rivets (5000-6000 series) not homedepot stuff.  Also if you are using closed rivets, the mandrel is a concern, as very often the stem is plain steel.  Marine aluminum blind rivets will probably have a s.s. stem or even aluminum.  MacMasterCarr rather than JamestownDist is probably the source for poprivets.  They will tell you what the alloys are and give you more choices, altho they are NOT marine specific. Don't use 18-8 fasteners on your boat, for-crying-out-loud!!!

Imco, in the heavy wall mast we have, machine screws in a threaded hole, not sheet metal screws!, are probably the best way to upgrade.  At least you can assure yerself of the material you are using.  The most passive s.s. (316L) is the way I will go, if you can find the stuff.


Isolation and lube -

ANY fastener (including aluminum)  in aluminum spars has to be isolated.  Anhydrous lanolin which used to be available from the pharmacy - LanoCote (WM - Forespar distributes it now) - Alumalast (anybody used this?) - and TefGel (has Teflon in it) are all barrier goops used to isolate fastenings.  Lanolin, sheep wool fat, has traditionally been used to keep water OUT of larger fastenings like turnbuckles and shackles.  Every cruising source since Slocum speaks well of it.  TefGel comes in nice tidy tiny tubes making it easier to put the stuff where you want it.
{LanoCote grease comes in jars, 7oz spray and 4oz tube.  It can specifically be used for stainless screws to aluminum, along with more traditional uses including battery terminals.  The ANHYDROUS lanoline from the drug store is most likely pretty pure and usable for your skin - and battery terminals.  Some have tried it on their propshafts and propellers.  Have heard that it can run out of where you put it if it gets real hot.  Be good to know if LanoCote gets runny when it heats up.....}
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Let me add here that SuperLube makes a white synthetic grease that is potable water certified.  McMCarr also lists a high temp synthetic and a NSF-61 certified.  My understanding is that you are not dealing with a petroleum product using these.  I haven't used these BUT it would be great to find something that would lube pumps, not eat up plastic valves and O-rings and still be good on your mast and anchor shackle!;)

[mrgnstrn]

C-Pete,

So, after 2 years of use, how is the mast paint holding up?
Still shiney?  Any places where it's not sticking and flaking off?

I am going to have to paint the mast on the C&C sometime in the next few years.  Any pointers (do's, don'ts)?

..for those who are counting, that is 53' feet of mast, and 14 feet of boom to deal with on the C&C..anybody wanna help?

[mbd]

..for those who are counting, that is 53' feet of mast, and 14 feet of boom to deal with on the C&C..anybody wanna help?

Heh! Now if only you'd kept your more maintenance-friendly  Ariel, Keith...  

[commanderpete]

The job is sort of a science project, so you need to do a bit of research. I might look into using the Vinyl-Lux Primewash Interlux is making.

If I had to do it over again, I would learn how to use a spray gun. Lay down one coat after another.

The paint is holding up beautifully.

This is my happy face

[Rico]

Thank you Ebb...

I will do a bit of  a test with the screws; If nothing else, to avoid riveting... I will remember the goop.

I may leave the ones that in good shape alone... BUT I guess I'll decide that as I start the job.

What about holding power? Will the screw develop as much holding power as the rivet?? Hmmm...

[mrgnstrn]

Heh! Now if only you'd kept your more maintenance-friendly  Ariel, Keith...  

Yeah, if only I could have kept the maintenance of the Ariel and had the space and speed of the C&C.

...Compromises all around.....

[tpalmer]

I'm ordering a new mast from Dwyer aluminum. The size of the old mast is 3 1/2 x 6. In the manual the size is listed as 5 1/2 x 7. Dwyer has one that is 3.6 x 5.6 @ $45 /sq ft and another, 4.80 x 7.30 @ $70 / sq ft. How much variation do I have on picking a mast size? what are the pro and cons?

[Bill]

The Ariel mast is the same as the mast on the 28' Triton and therefore probably way more than a 26' boat requires.  IMHO, the 3.6 x 5.6 is probably more than adequate.  Of course, if you are planning a round the world cruise, go for the 3.6 x 5.6 :cool:

[ebb]

Interesting.
The mast on (well, not ON yet) 338 is 3.5 X 6 and

a full 1/8" thick extrusion.
The 1/8" is the PRO for this cruiser to be.

It has a very handsome rounded 'teardrop' cross-section. That is the front is rounder and the aft side skinnier, as in  a generalized wing or foil shape.  

The aft edge is flat where the T track for the sail is attached.  It's 5/8" across and has 7/8" wide s.s. track on it.  There are no internal extrusion shapes.

It's a MAST.
Can't see this mother buckling, even with the sails full of water.
What does Dwyer have?  I've looked at their profiles.  Only a few of their smaller ones have the profile similar to the Ariel's.  Which one are you choosing?


Looked on the net for old mast graveyards, aren't any.  Lien sales, parting outs, local yards.  I know ours, where my boat lives, has a collection of spars and every so often a notice appears on the yard office door threatening to disappear them!  

What happened to your old mast?  carl231, currently on the Board, has a mast that the DFO cut a foot of it off before he sold it.  Suggested tabernacling to make up the length - in an effort to save it.  These are good old masts worth keeping.
Imco, as usual,

[bill@ariel231]

ebb,

hmmm.. an interesting puzzle and thought experiment. the boat has a lot of righting moment with 2500# of lead on about a 3' to 3.5' moment arm. i'm not sure that a 29' mast filled with water is going to beat that (although it's worth trying to compute the relative righting moments).

keep in mind you'd need to keep the mast completely submerged for several minutes for the mast to fill completely with water (after all where will the air leak out?)

as for functionality, i've found stripping, cleaning and greasing my main halyard sheeve when ever the mast is pulled clears up any problems i've encountered.

cheers,
bill@ariel231

if you really want to address better righting moment, a carbon fiber spar may be in order...  

[ebb]

Bill,  
The pardey puzzle is not something that I thought to work out.  The best way to find the weight of seawater in the mast is to stand  it up on end, pour in one gallon of water (or a cubic foot if you have one around), lower a tape with a ball on the end until it hits the water inside, then read the feet left over, and do the calculations.   Simple.

How to figure the weights viz the righting arm isn't a proposition my head can get around.  
But suppose you're down, the sails are in the water, you've been over too long because the swells are big, and the sails are filling...  The weight of water IN the mast in that scenario seems tiny compared to combined weights of water and wind in a dangerous situation.  It is a matter of how quick the boat can recover - for instance  how much water is getting below through the deck?

Suppose one large murphy swimming back to the boat finds the masthead and grabs on to it - would the boat right itself?
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Pulling maintenance on the sheave sounds like you have to be able to remove the S.S. bolt.
There is no inside tube spreader here.  It may be better for the resistance of the s.s. bolt that it is not covered up inside.  I notice that the nut side of the  bolt in my mast has  its threads riding in the hole.  How do you insulate for that?  
The upper shroud tangs are  part of the action here along with major weight put in the formula with the halyard tension.  This is one hard working bolt that goes through the masthead sheave that actually holds  the mast up as well as the main sail.  Hard working holes in the aluminum mast.  The shroud tangs show a little hole egging as well.

The SLOT as it is won't have any trouble displacing air and gulping water, imco.   Also a serious knockdown might include the sail scooping water and thereby help to keep the boat over.  Any scenario is murphy.

The sheave box can be redesigned to have a top and bottom which it doesn't have now - and that would take care of the major water port.  The hole can be shut.  Then it is a matter of what electrics have to exit the mast for lights and antenna for a fairly water resistant masthead.  It this possible?


Better to leave well enough alone on this one?  Instead of obsoleting the old wire sheave, change it out for a rope one in a closed off box?  I've located a few other corroding spots up top, so we'll see what we have disassembled.  The after-the-sheave-freezed-up block tang fitting could maybe stay there and act as the  back-up halyard - if the big sheave can be saved.

What really would be cool is to put this together so the bolt can  easily be replaced!  THAT would be excellent!  Taking it apart right now is a federal case.  Looking at the tangs and HOPING they're OK isn't something I'm OK with.  I'd like to be able to take these major attachments apart again sometime without a grinder.  Wishful thinking, huh?

A titanium bolt here in a delrin tube with  insulated washers and a new phenolic or delrin or even aluminum sheave  sized for 1/2" braid might be the ticket.  We see how extensive the  corrosion is around the holes.

The old sheave certainly must have had wire in it at one time.  Easy to see is the trail of black scaring  running down and fading as the distance grows from the sheave hole - like poop from a bird box.  Can imagine the s.s. wire halyard gouged and rubbed this  part of the mast at one time leaving the marks.  That would mean the diameter of the sheave's wire run was smaller then the mast.  Hope it is mostly marking and not a whole bunch of corrosion pitting in the old anodizing.

[Bill]

But suppose you're down, the sails are in the water, you've been over too long because the swells are big, and the sails are filling...  The weight of water IN the mast in that scenario seems tiny compared to combined weights of water and wind in a dangerous situation.  It is a matter of how quick the boat can recover - for instance  how much water is getting below through the deck? (

That would seem to be the answer.  FWIW - Commanders and Ariels have sailed around the world without encountering the above hypothesized problem in righting the boat following a knockdown, or whatever.  IMHO, if it were a problem, Zoltan and his Commander would never have arrived in the Med and we would have read a different story about his voyage from Los Angeles.:eek:
 
Masts filling with water, of course, can cause problems righting dingies, but the weight/volume of water to boat displacement is far different than that found in a 26 foot, full keel yacht.  

[ebb]

OK. Taking the mast apart I discovered BAD corrosion above the main sheave slot where an aftermarket curved tang was fitted to hang a block for line halyard.
I believe the tang is fairly common, perhaps not the installation method  on 338.  Some kind of filler was used between the s.s tang and the mast.  Where the filler was has eaten totally through the aluminum.

In a separate thread I strongly suggest nobody uses their mast's similar tang fitting to ascend.  
338"s is totally compromised and the halyard could have at any moment been  pulled away from the mast!  The s.s screws were crystallized.

For redundant safety (the halyard going through the mast) the large main halyard sheave could be remade with a rope groove and used for the #1 halyard.  
I would like to rig another halyard (or two) as the back up.  May have to custom a tang fitting that includes the repair to the top of the mast.  Anyone???


There is plenty of meat (1/8") throughout the extrusion  for common machine screws to gain thread enough to hold well.  That's imco.  What I did notice in taking screws out is that the best holding fasteners were 8-32, 10-24 and 12-24.  If I have 1/4" fastners I will use 1/4-28 to get more thread on the mast wall.  There are posters who say always use the finer threads.
 Sheet metal screws were used in places for incidental eyes and small blocks.  The Hitachi cordless impact driver worked well to back these out and some strange very coarse thread small machine screws.
While the 'normal' screws backed out like they should, the oddball ones held at first until freed by the impact driver and THEN SUDDENLY LET GO.  This is because the holes were not tapped.
DO NOT USE SHEET METAL SCREWS ON THE MAST.  Or straight panhead screws.  Right, they are used for sheetmetal and woodwork.

The white aluminum oxide* plays a big role in freezing fastenings.  I believe all fastenings in this project have oxide at the interface.  The least amount is with the more precise machine screw and tapped hole.  Of course with tef-gel - but no remaining indication of an anti-seize was found on 338's mast.

Nearly all the aluminum cleats at the deck end were through cut with a carborundum blade isolating the fasteners which were then successfully turned out of their holes using the chunk of aluminum they were embedded in.  I think the oxide in the relatively long bury in the cleats keeps the screw from turning. There is at this point to see NO CORROSION where the fittings bear on the mast nor in the tapped holes.
All cleats were held on with two fastenings and seemed completely tight.
It was hard to accept cutting through these very handsome aluminum mast fittings - as they were, except for their protective oxide surface, unaffected by time and tide.

I used Alumiprep 33, Gibbs Penetrating Oil, PB Blaster, Freeze Off, Mapp Gas, and Whacking 101 in attempts to loosen screws.  I don't believe any of this actually penetrated.  What did work on short fastenings was the Hitachi.

The mast track appears free of any aluminum oxide*.  What appears to be bronze track (because of its patina) was laid down on what appears to be black plastic tape, and fastened with (#6-32 ?) s.s. phillips head screws.
As I say, the aluminum seems happiest with nicely fine thread tapped holes and stainless steel machine screws.  The track looks very secure. B.Toss in a post on his forum mentions using UHMW (polyethylene) tape under fittings.  May do the same.

Fixing the corrosion on the top of the slot seems like a job for some added aluminum sheet.  The top of the mast is a hard working zone.  Some rumination is required for procedure.  Hope there's input on this.
The single 1/2" bolt holes show "MILD" corrosion under the tangs.  There is/was oxide crust buildup around both very hard working holes.  Slight, slight elongation on the downside.  The bolt shank did not go all the way through the mast befor the nut thread.  The hole on the side of the bolt threads IS slightly larger.

I'm wondering if a custom bolt could be made from solid rod with the ends threaded in precisely to allow the tangs also to hang on smooth metal.  Nuts could be the castellated type (which tightens when threaded on the bolt end) or the bolt might be cotter-pinned on the outside of the nuts - like you see on bolt shackles.  I always wonder why the nut itself cannot be through drilled and cotter pinned?  That's what I'd like to do - unless somebody objects?
A bolt to me is a kind of clamp.  There is no clamping needed up top, just a lot of good shear bearing surfaces. Come back on this?
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We have nicely shaped tangs for the shrouds.  While they all look OK, the uppers look more worked and were against oxide crust.  Stainless has a rep of looking good until it just lets go. I think Prudence wants them replaced.
Is there a source?  Most of RigRite and Dwyer look like strapping - and they don't say what the material OR the gauge is......

The originals are slightly truncated in their length, wider at the top than the bottom.  They are 13 gauge I believe, all rigging holes look great except slight wear mentioned above.
I'm moving up to 1/4" wire - maybe something like 10 gauge is called for. YES?
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Years later EDIT 1/2012)
*aluminum oxide (AL-230) is what forms on new clean bare aluminum.  Aluminum hydroxide is the poultice - white powdery stuff.  Chloride ions causes the location pH to become more acidic which enhances corrosion because aluminum ions are positively charged which increases the 'battery' effect.
Salt water is the culprit, along with dirt or anything that 'limits the migration of oxygen.'  It's a fairly complicated subject made comprehensible at:
http://marginalmaritimeadvice.blogspot.com/2011/03/poultice-corrosion_5740.html
The BEST three page aluminum corrosion specific paper I've read yet.  Thanks, John.
Marginal Maritime Advice: Poultice Corrosion