SailNet Community banner
1 - 8 of 8 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter · #1 ·
I recently purchased a 74 O'Day 20 with a bent mast (appears to be Dwyer DM-375) to learn to sail on. I am in the process of straightening with blocks. I have been making progress taking the bend out. My question is should I place some external braces to reinforce the weakened metal? I was thinking 2" wide 1/8 to 1/4 thick flat stock that extends 2' past either side of the bend. Would this be overkill of would I need to go further?
I live in Arkansas so not a lot of sailboat salvage yards to find any old replacements and I am on a shoestring budget for this boat.

I also have a contact for a cut and weld but I am concerned about adding heat to the mast and that takes the budget from other repairs. And would most likely want to brace that as well.

This boat will be on lakes in Arkansas so I feel wind stresses will not push the capacity of the boat too far. Also my own ability will keep me in lighter wind for quite some time. Please see pictures below:

Plant Wood Grass Boats and boating--Equipment and supplies Lumber

Plant Wood Natural material Grass Groundcover

Plant Automotive tire Road surface Wood Grass

Plant Wood Automotive tire Boats and boating--Equipment and supplies Grass
 

·
Registered
Joined
·
63 Posts
Good job on straightening out the mast. Not an expert here, but if there are no visible stress cracks once everything is straightened out and the slot opened I think that you’ll be fine as is.
I’d hesitate to add stiffening as that may result in stressing other sections.
Masts are supposed to be a bit bendy after all… just not bent 🙂.
There are some good online articles about mast splicing.
 

·
Registered
Argie 15
Joined
·
98 Posts
Hi Coor,

I too had trouble finding a suitable aluminum pole for a mast on a boat build I'm working on. Finally I got my head wrapped around the fact that masts don't have to be made out of aluminum. While not for everybody, something to consider if you can't fix what you've got or find a suitable replacement, is just building a wooden mast. Is that about a 9 m / 30 ft mast? Definitely doable in wood as a hollow birdsmouth mast. Here's a nice example of someone building one out of sitka spruce:

Birdsmouth Mast: a strong wooden mast

Wood Automotive design Art Machine Creative arts


Wood Table Flooring Floor Hardwood


Sky Wood Shade Watercraft Vehicle


Good luck however you end up fixing the stick.

Red
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #4 ·
Good job on straightening out the mast. Not an expert here, but if there are no visible stress cracks once everything is straightened out and the slot opened I think that you’ll be fine as is.
I’d hesitate to add stiffening as that may result in stressing other sections.
Masts are supposed to be a bit bendy after all… just not bent 🙂.
There are some good online articles about mast splicing.
Thanks! The mast still appears to be sound. I just got the track opened while in my latest set of blocks and letting the metal rest. I know with the pressure needed to get it to this point give me a fair amount of confidence it will weather what I need it to as long as I have enough space to connect the forestay and can still tension the aftstay. 1/2 a step closer to splashing.
 

·
Super Moderator
Farr 11.6 (Farr 38)
Joined
·
10,614 Posts
I will start by saying that is a pretty serious kink, and it does seriously compromise the strength of the mast if you have a kink like that in it.

Back in the 1970's I bought a trimaran that had a kink like that in the mast. I bought some cedar (light weight, easy to work with, and not crazy expensive) and shaped it to tightly fit the interior profile of the mast. I then drove it up into the mast so that it's length straddled the area with the kink. In my case the cedar was roughly 6 feet long. You might not need that much length.

Structurally the cedar plug does several things. First it straightens the mast so it stays in column. But more importantly it keeps the sidewalls of the mast from being able to collapse inward and stiffens the spar.

Jeff
 

·
Registered
Joined
·
850 Posts
We used to straighten 6061 T-6 1.5" to 2" tubing that was not "kinked" on hang gliders. Very carefully pressure, release, move slightly, inspect, pressure, release, move slightly, inspect. Discoloration in the tubing (or your spar) in the areas around where it is deflected indicates weakening. Inspect it carefully. I don't see any "kinks" in the extrusion - just a long bend. But there's no photo of the center of the bend. Focus on the apex of the bend.

Putting a plug in tubing causes extreme stress at the ends of the plug (or sleeve). When we did that, the ends of the sleeve would be sliced back a little (cuts into the edge of the tubing) which would allow for relief at that point. Same thing is done with mast splicing. The ends of an internal splice need to be relieved to avoid making two "hard spots" where failure could occur. The "relief" slices "give" if the mast is ever put through enough contortion to mess with the internal splice.

But we were nuts. 6000' off the deck over Ballard Peak in Telluride on President's Day 1977 upside down over the middle of town on a 38# glider (Electra Flyer Cirrus 3). Grinning ear to ear. The first step was a 4000' drop and we gained 2 grand. I doubt you'll be doing that with your O'Day 20. But you'll always be looking up. I, on the other hand, was driven by the consensus that I was never expected to make 30 years old.
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #7 ·
Plant Wood Natural material Grass Groundcover

Plant Rectangle Wood Grass Road surface

Plant Natural environment Wood Vegetation Natural landscape

Hi Coor,

I too had trouble finding a suitable aluminum pole for a mast on a boat build I'm working on. Finally I got my head wrapped around the fact that masts don't have to be made out of aluminum. While not for everybody, something to consider if you can't fix what you've got or find a suitable replacement, is just building a wooden mast. Is that about a 9 m / 30 ft mast? Definitely doable in wood as a hollow birdsmouth mast. Here's a nice example of someone building one out of sitka spruce:

Birdsmouth Mast: a strong wooden mas

View attachment 144086

View attachment 144087

Good luck however you end up fixing the stick.

Red
I may want to do one of these anyway even if I get my aluminum mast straight. That is a great design. Thanks!
We used to straighten 6061 T-6 1.5" to 2" tubing that was not "kinked" on hang gliders. Very carefully pressure, release, move slightly, inspect, pressure, release, move slightly, inspect. Discoloration in the tubing (or your spar) in the areas around where it is deflected indicates weakening. Inspect it carefully. I don't see any "kinks" in the extrusion - just a long bend. But there's no photo of the center of the bend. Focus on the apex of the bend.

Putting a plug in tubing causes extreme stress at the ends of the plug (or sleeve). When we did that, the ends of the sleeve would be sliced back a little (cuts into the edge of the tubing) which would allow for relief at that point. Same thing is done with mast splicing. The ends of an internal splice need to be relieved to avoid making two "hard spots" where failure could occur. The "relief" slices "give" if the mast is ever put through enough contortion to mess with the internal splice.

But we were nuts. 6000' off the deck over Ballard Peak in Telluride on President's Day 1977 upside down over the middle of town on a 38# glider (Electra Flyer Cirrus 3). Grinning ear to ear. The first step was a 4000' drop and we gained 2 grand. I doubt you'll be doing that with your O'Day 20. But you'll always be looking up. I, on the other hand, was driven by the consensus that I was never expected to make 30 years old.
Tire Wheel Automotive tire Tread Wood

We used to straighten 6061 T-6 1.5" to 2" tubing that was not "kinked" on hang gliders. Very carefully pressure, release, move slightly, inspect, pressure, release, move slightly, inspect. Discoloration in the tubing (or your spar) in the areas around where it is deflected indicates weakening. Inspect it carefully. I don't see any "kinks" in the extrusion - just a long bend. But there's no photo of the center of the bend. Focus on the apex of the bend.

Putting a plug in tubing causes extreme stress at the ends of the plug (or sleeve). When we did that, the ends of the sleeve would be sliced back a little (cuts into the edge of the tubing) which would allow for relief at that point. Same thing is done with mast splicing. The ends of an internal splice need to be relieved to avoid making two "hard spots" where failure could occur. The "relief" slices "give" if the mast is ever put through enough contortion to mess with the internal splice.

But we were nuts. 6000' off the deck over Ballard Peak in Telluride on President's Day 1977 upside down over the middle of town on a 38# glider (Electra Flyer Cirrus 3). Grinning ear to ear. The first step was a 4000' drop and we gained 2 grand. I doubt you'll be doing that with your O'Day 20. But you'll always be looking up. I, on the other hand, was driven by the consensus that I was never expected to make 30 years old.
Thanks for sharing. This makes me confident of the repair. I attached some pictures of the area of the bend the only dent I found was where the mast contacted the companionway hatch. Inside there was no crimp, kink, or visible cracks.
 

·
Registered
Joined
·
850 Posts
As long as that dented section I see is in your sail track and not a kink in the mast extrusion. Try it. Wear a helmet the first few times you're hard on the wind. (He said, kinda facetiously). Off the wind it'll break forward anyway. Heavy seas are as much a problem as wind, so remember that. Both wind and seas and, well.
 
1 - 8 of 8 Posts
Top