Glass mast idea

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TinkerSailor:
Hello all,

As I progress through building my DN (hull is done and it is sailing as a super DN with Arrow plank and sail now) I find my self pondering a mast. Looking at the rules I see that my stack of old windsurfer masts could work as a starting core for a built up glass mast. The idea would be to measure current deflection properties and then add material and a luff tube to modify the stiffness and profile to fit the rules and desired properties. The masts I have are 2" O.D. And taper.

This seems like a no brainer to me but I have not found any information on anyone else trying this approach.

Has anyone tried this? Did it work? What were the pitfalls?

Also, what is the most desirable mast profile (foil shape)?

Thanks for any response!

Sailfast!
Leigh

Bob Rast DN1313:
The rules allow masts to be built out of anything except Kevlar not allowed
Carbon wood composite all composite ok
There are min and max dimensions to be class legal also a antiquated balance rule and minimum eight
For deflection depending on your weight need somewhere around 1 1/2 stiff heavier sailor to
1 3/4 for lighter base to hound with 100 lbs side measurement will get you in the ball park
You could use the windsurf rig for main tube add a luff tube pvc or fiberglass cover and shape foam and add
Carbon or glass for reinforcement
I build composite masts typical layup aprox 4 layers triaxle
3 carbon for blow molded mast
Good luck
Bob Rast
Dn 1313
Brastco@gmail.com

TinkerSailor:
I went and did some measuring today. For my longest windsurfer mast I found the following...

Length: 189"
Diameter from base to 6': 2.07"
Tapering to 1.63" at 11' and smaller beyond.

I did the bend test between the base and 11' and plotted my results (data points were straightish)

100lb deflection was 3.79"

So. I have a mast which Needs to have an outside profile added to it. It is more than twice as bendy as I need it to be in the end.

Anyone with experience out there care to estimate how much glass or carbon should be added to the sides to bring the bend into the correct range?

What type of material would you consider to build out the sides in order to meet minimum thickness for the rules?

I would consider making a female mould to create the trailing edge/luff tube and then bonding the mast into it. I would then build up some foam to create the leading edge profile before adding final glass or carbon to leading edge which could be used to bring the mast to its final fore/aft bend characteristics.

Thoughts?

Leigh

Bob Rast DN1313:
I use 20 oz triaxle or 5 or 6 oz plain cloth carbon
Each layer will provide aprox a 1/8 stiffer
Product my guess about 3 layers
Plus the luff tube will add some stiffness if you use fiberglass
Tubes , if you use pvc doesn't add much but larger inside diameter
Makes sail go up easier

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