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Mast Corrosion Repair

NC28460

New Member
I recently discovered some mast corrosion and a used Sunfish that I just purchased. After extensive searching, I am unable to find any specific guidance on mast repair. Damage is on both ends within 3 inches from the caps. I am thinking about bondo filler followed by fiberglassing to help seal the repair areas inside and out. Pics are attached. Can anyone guide me in this repair?
 

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beldar boathead

Well-Known Member
Agree with SC. May be time to consider a new (er) mast! Having it be strong enough to stay in one piece is the big concern! Waterproofing it would be the secondary concern.
 

NC28460

New Member
In some of my searches on other sites I ran across some opinions that welding a mast would weaken in structurally. Is this true for the T6 alloy used in the spars? And is the damage locations considered vital areas that receive the most stress?
 

signal charlie

Well-Known Member
Staff member
There are plenty of backyard fixes for that but I don't like the big gash on the bottom of the mast. Could some kind of backer be fashioned and fix it in place with JBWeld, and fill the hole? I would also swap ends on the mast.
 

NC28460

New Member
Has anyone ran a Sunfish with a modified mast? Would I run into any issues cutting the mast down 3” on each end and recapping. I’ve also ran across a YT videos of with an inner sleeve or outer sleeve on the lower spar (none on the mast) and rivets. Anyone have success going this route on the mast?
 

po-man sailor

Active Member
Maybe a large, cut to fit plug that extends past the holes and run a stainless screw in the side to hold in place. If you have a lathe cut a treated 4x4 down. Pound them in and then JB weld the outside smooth. Till you locate another mast. Or just order some stock from a local aluminum fabricator and move your tips over. I don't believe welding would be your answer to bridge that large a hole.
 

NC28460

New Member
There are plenty of backyard fixes for that but I don't like the big gash on the bottom of the mast. Could some kind of backer be fashioned and fix it in place with JBWeld, and fill the hole? I would also swap ends on the mast.
Unfortunately damage is on both ends. Good thought though.
 

signal charlie

Well-Known Member
Staff member
You can cut off the offending parts, then add a 6 inch wooden bit at the top, 2 1/4 inch diameter, necked to fit inside the the aluminum mast. Put a beehole at the top or a block on an eyebolt or eyestrap, or a sheave. Bingo, hybrid mast, just like they used to make them 70 years ago.

Exhibit A: 1953 Alcort Standard Sailfish spars and sail.

mast and spars.jpg

Exhibit B: Skipper has her hand on where the 1953 Sunfish mast switches from aluminum to spruce. We wrapped the aluminum with black Pro Gaff tape for fun.

image (1).jpg
 

NC28460

New Member
Excellent!! Is this kentblairl on YT?Haha. I spent a a few hours today trying to find a way to reach you in Florida to ask you about this same issue. Thanks for the response, great YT channel. And thank you all for the suggestions, please keep them coming.
 
I remember reading about a mast repair kit that Sunfish Direct sold for reinforcing masts. It consisted of a piece of mast stock with a small slit cut the length of the piece that would allow it to compress to fit inside the mast. I think they were installing it with 3M 4200 at the slit and around the section and then using two aluminum pop rivets 90 degrees on either side of the slit. That should reinforce it and might help with the damaged section.
 
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