what is the Composite White Daggerboard made of?

Thread starter #1
I have a white FRP official daggerboard for racing and I dragged into the sand a few times. and noticed that the white finish just wore away to a yellow base material. I'm assuming this is the fiberglass layer.

How do they make these boards and rudders? Has anyone seen a broken one? I'm assuming that the boards are made of a wood or plastic core. then they are fiberglassed and painted white. Does anyone know?
 

Wayne

Member Emeritus
#2
I have a white FRP official daggerboard for racing and I dragged into the sand a few times. and noticed that the white finish just wore away to a yellow base material. I'm assuming this is the fiberglass layer.
I've dinged mine and it appeared to me to be an un-reinforced plastic (no apparent fibers) over a dense foam that resembles a softer version of the outer plastic shell.

The Sunfish Bible has a diagram caption referring to the board material as urethane (polyurethane). It looks to me like it could be a Vinyl ester shell over a urethane foam core.

I repaired mine using epoxy since it won't attack either material.



How do they make these boards and rudders? Has anyone seen a broken one? I'm assuming that the boards are made of a wood or plastic core. then they are fiberglassed and painted white. Does anyone know?
The daggerboard is likely made using a pre-formed foam core sandwiched between two outer shell halves made in a mold just like the boat except more of an all at once process. That's one approach, anyway..., there are other variations.

The rudder is Fiber Reinforced Plastic (fiberglass) and would be a mold lay-up beginning with gelcoat, followed by layers of glass fabric saturated in polyester resin..., maybe built in two halves and laminated into one piece at the last layer.

Or, it could be made by laying up the rudder blade as one piece raw fiberglass and shooting on the gelcoat as a final step. Again, there are process variations that can be employed to achieve the same result.
 

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#3
Good question...Just purchased an 09 boat this summer, came with one of those POS "composite" daggerboards. From my understanding it is a high density foam core with a metal rod going down the leading edge of the board. Marine paint on the outside, no fiberglass involved to my knowledge. I am assuming your racing daggerboard is of the same material, sounds like it anyways. It chips very easily and the daggerboard retainer bungee has put enough pressure on the leading edge to the point where it has small dents in it from the well when resting in the up position. After a small rock took out a chunk of the tip, I refilled it with epoxy/resin mixed with ground up fiberglass (micro) and sanded it back to shape. Then put two layers of bi-directional fiberglass over the tip to prevent such mishaps. Fiberglass itself is a white cloth, when resin/epoxy is added it dries to a light green. Hope this helps

BC
 
#5
I am so glad this issue was raised. I launch in a shallow bay that still has the odd Katrina relic under water and when the water is low, I've dinged my daggerboard on who knows what..rocks, a stove, a TV, it could be anything down there. Am I doing any damage to the board by not addressing this immediately? There aren't any huge chunks missing, but some nice scrapes and minor gouges. Thanks in advance!
 

Wavedancer

Upside down?
Staff member
#6
No, you aren't causing any further damage. In fact, I would just keep on sailing until a big chunk breaks off :eek:. Then it's time for a repair.

The above directions (thanks sunstrom 87) are pretty good, but here's another link (with pictures) for repairing foam daggerboards:
http://www.schrothfiberglass.com/centerboard_and_rudder_repairs.htm

Windward Leg, the Sunfish class magazine, also had good repair advice a few years ago (thanks to Brian Weeks).
 
#7
No, you aren't causing any further damage. In fact, I would just keep on sailing until a big chunk breaks off :eek:. Then it's time for a repair.

The above directions (thanks sunstrom 87) are pretty good, but here's another link (with pictures) for repairing foam daggerboards:
http://www.schrothfiberglass.com/centerboard_and_rudder_repairs.htm

Windward Leg, the Sunfish class magazine, also had good repair advice a few years ago (thanks to Brian Weeks).

You're welcome! Thanks for the correction, I was kind of hoping there was more than one rod going down that thing. :D

BC
 

Wayne

Member Emeritus
#10
here's another link (with pictures) for repairing foam daggerboards: http://www.schrothfiberglass.com/centerboard_and_rudder_repairs.htm

Windward Leg, the Sunfish class magazine, also had good repair advice a few years ago (thanks to Brian Weeks).
Unfortunately, the rods end about 4" from the bottom of the daggerboard, and are only on the front half of the board. Have a look here, and you can see how I know.http://barringtonyc.com/files/2009/03/byc_frostbite_results090301.pdf
Anybody collecting all this fantastic information and getting it into the Knowledge Base ?
 
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