[Public-List] Mast Failure at the Spreaders

[John Birch]

Hi Michael,

Harry Grigat, who sailed A-30 Dolce Vita for a number of years, was a 
retired aircraft engineer who had considerable experience with aluminum 
fatigue issues.

Harry was of the opinion that the Alberg masts suffered from a lack of the 
compression tube and was critical of the excessive number of holes Whitby 
had in the area of the spreaders including installing the steaming light so 
close to the spreaders.

Harry installed an aluminum compression tube where the main bolt passes 
through the mast at the spreaders. It is a pain in the butt job to do, but 
he accomplished getting it  installed by running light line from the 
spreader hole out the bottom, then inserting the tube in the line and 
leading it back up to the hole on the opposite side.

He then pulled the tube up through the base by pulling on the line equally 
on both sides of the spreader bolt hole. When it got to where he wanted it 
he then reinserted the main bolt through the tube out to the other side.

When a mast fails at the spreader it is often difficult for an amateur to 
correctly diagnose the failure that started the collapse as everything is so 
distorted.

Harry was also extremely critical of Whitby's use of rivets, (usually 
aluminum) and that he preferred using SS drilled and tapped machine screws 
with caulking used as a thread anti seize.

I am just repeating what Harry told me personally.

Danny Klacko, a well regarded mast maker and restorer was also critical of 
the cast aluminum bolted heads on Alberg masts and preferred plate 
fabricated and welded heads. Danny always uses compression posts on his 
masts, though he welds them in.

Danny is an excellent aluminum welder and about the only one I know who I 
would trust to weld aluminum. Aluminum can easily distort if not welded 
properly.

Klacko spars is located on 3rd line in Oakville Ontario.

Danny more or less concurred with Harry's concerns. Both believed Whitby 
should have used a larger, but thinner mast section, but that is a whole 
other story.

Also, if you have nicro presses on your shrouds at the mast head and 
spreader bases instead of proper terminals, there is a unanimous consensus 
from Harry, Danny and every surveyor I know that this is a bad bad bad 
practice. They should be swaged terminals at least, norseman or staloc's 
being much much better.

Best

John





----- Original Message ----- 
From: <crufone at comcast.net>
To: "Alberg, Public List" <public-list at alberg30.org>
Sent: Saturday, January 16, 2010 7:24 PM
Subject: [Public-List] Mast Failure at the Spreaders


>
>
> John Birch Wrote
> Oversize the chain plate bolts; ensure the rig is not too loose; ensure 
> the
> wire is in good shape and robust enough; sight the mast to ensure it is
> remaining in column; replace the wire every 10 -15 years in salt or 15-20 
> in
> fresh water; use mechanical terminals like norsemen or stalocs; make sure
> there is a compression tube inside the mast at the spreaders; ensure the
> spreaders are in good shape and not flexing or rotting if wood; and fix 
> the
> laminated wood beams on the older boats - use the time proven Rankin 
> method
> and if you hate aluminum put a wood covering piece at the aft end of the
> beam.
>
> John,
>
> I am curious about this compression tube or fitting that you mention which 
> is inside the mast at the spreaders. Is this a part of the original 
> equipment on the Alberg 30 or is it some type of aftermarket upgrade? If 
> it is an important upgrade, how does one install this fitting halfway up 
> the inside of the mast.
>
> I thought that most rig failures on the Alberg 30 were from spreader (the 
> spreader material failing or the socket on the mast failing), shroud 
> failures (either turnbuckles, fittings or wire failure) or chain plate 
> failures. I wonder how many Alberg 30's have had the mast collapse inward 
> under the spreader socket (First) and then have the mast buckle because of 
> the crease in the outer skin at the spreader socket?
>
> I must admit that this is a new bend (pun intended) in the equation. I 
> have never heard of mast failure on the Alberg 30 mast in this manner.
>
> Michael #133
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