cracks near spreader bases

M

millerkm81

.
Oct 2, 2005
86
Greetings from Puerto Rico!

We're currently in Salinas on the south coast of PR with the mast down
and the rigging stripped. It appears that what people say is true:
cruising is boat maintenance in exotic locations!

Before we left the Dominican Republic, we discovered some small cracks
and pitting on the mast near the spreader bases. Our spreader bases
are welded on to the mast and it appears that this has weakened the
aluminum. In order to fix this, we think we will grind the spreader
bases off, install large pieces of aluminum (cheek plates) on both
sides of the mast and rivet new spreader bases to the cheek plates.
This seems like a logical, and moderately straightforward, fix to us.
Does anyone have any experience with this kind of repair? Any advice
from the peanut gallery?

Also, does anyone know the correct spreader angles?

Thanks!

Kristne & Hans
s/v Whisper
under30undersail.blogspot.com
 
C

capt_sail

.
Oct 30, 2019
60
Hi Kristen & Hans,

Be sure to use stainless rivets. They're harder to work with and more expensive, but WAY stronger than the aluminum. As you install each rivet coat it with goop, since you'll have two different metals together. Otherwise you'll potentially have corrosion issues at the rivet holes ( this is what causes paint bubbling on painted spars).

Bed your cheek plates to fill any gaps behind them. From your post I'm not sure how big (tall) you plan to make the plates, but if large it might also be good to taper the top and bottom of the plates rather than a rectangular shape, just so you don't have as much of a hard spot and resultant bending stress concentration at the plate ends. If you're just talking a foot or so then this isn't an issue.

Good luck with the repair,
Bill Burke
#1390
 
C

capt_sail

.
Oct 30, 2019
60
Hi David,

I've never used monel rivets before, but I suspect they'd work just fine (if you can find them in Puerto Rico outside of San Juan...) Most sparbuilders use either ss rivets or tap the spar for ss machine screws when attaching tracks, cheek blocks, etc. Maybe its a cost/availability thing, but ss seems to be the common practice in my experience. In any case, the most important thing is not to use the aluminum rivets that are sold in hardware stores, etc.

Bill Burke
#1390
 
A

albinvega3283

.
Oct 30, 2019
234
Bill

You are quite correct I can get Monel rivets easily in the UK whilst I might have difficulty in the more remote parts of the world. I agree totally with you that aluminum rivets should not be used and that using SS the precautions that you define are required to prevent reaction between the different metals.

David
#3283

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M

millerkm81

.
Oct 2, 2005
86
Hi,
Good news! The cracks were just superficial, so we were able to sand
them out, anodize the spots we sanded and restep the mast. We'll be
sailing again!
thanks for everyone's input,

Kristen
 
P

pjacobs55

.
Oct 30, 2019
1,459
Kristen,
I'm glad it was a non-problem. How did you re-anodize the sanded
portion? I've got some bare spots on my mast.

Peter
#1331 'Sin Tacha'
 
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