Mast Tube And Daggerboard Trunk Repair

lazerschool

New Member
A week ago i bought my first sunfish. Its a 78 and in pretty decent shape. It does have a few spots that Im worried about leaking, so im going to do a little repair work before sailing it.

In particular, the resin inside of the mast tube and the daggerboard trunk needs to be repaired. There are several "open spots" where i can see that the fiberglass matte has no resin on top of it. I imagine these were spots where the resin bubbled and was chipped off.

Does anyone have any words of advice. I saw on sunfish direct that they recommend sanding it before applying more resin, then sanding again afterwards. I dont see how i can physically sand the inside of the daggerboard trunk. Has anyone out there found a good trick or tool to get in there and do this? Any advice would be greatly appreciated!

thanks
 
Sanding the inside seems to be the easy part as I would attach sand paper to a wood board. But how do you plan to put resin on the sanded surfaces? Attach the sandpaper to the board with a foam under layer that way it expands once past the lip of the daggerboard and puts pressure in order to sand.
 
From your description, it looks like the (thin layer of) gelcoat has come off.
I suggest you do a leak test to see if those areas actually let water in.
 
The foam behing the sand paper is a great idea!
But how do you plan to put resin on the sanded surfaces?
On the sunfish direct page they suggest using an old hacksaw blade. I really dont have a good idea yet, but i will prob try that and maybe something like a yardstick.


Also, Wavedancer, I will most definitely try a leak test first before i go through all this trouble. However, on this sunfish, it looks like the gelcoat stops at the lip of the mast tube and and the daggerboard trunk, and in the middle area (where my big divits in the resin are) looks like just bare resin/fiberglass. I can reach down and feel exposed fiberglass matte, which is all dry and white. I was always under the impression that exposed fiberglass matte was a bad thing...

thanks again for the advice!
 
The foam behing the sand paper is a great idea!

On the Sunfish Direct page they suggest using an old hacksaw blade. I really dont have a good idea yet, but i will prob try that and maybe something like a yardstick.

Also, Wavedancer, I will most definitely try a leak test first before i go through all this trouble. However, on this sunfish, it looks like the gelcoat stops at the lip of the mast tube and and the daggerboard trunk, and in the middle area (where my big divits in the resin are) looks like just bare resin/fiberglass. I can reach down and feel exposed fiberglass matte, which is all dry and white. I was always under the impression that exposed fiberglass matte was a bad thing...

thanks again for the advice!

Brain spasm on my part; I should have taken a look at my own fish (a 2006 Vanguard) before writing my earlier post. The deck (gelcoat) is a light grey. The mast tube is white on the inside (except for the lip, which is light grey and part of the deck), and so is the inside of the daggerboard slot (except for the (light grey) lip). I don't know what the white material is. I presume it covers the polyester resin/glass structural material. Or stated somewhat differently, on my hull, I don't see exposed fiberglass mat inside the mast tube or daggerboard slot.
Unfortunately, this info doesn't help you much with respect to the repairs that may, or may not, be necessary on your boat.
 
I think all the older boats didn't have the mast tube cavity sprayed covered by gelcoat - at least those in my vintage (1972) did not.

I had to repair typical mast tube cavity wear and tear stress crack(s) repair a few years back, and had good luck using the flexible 3M "foam" sandpaper pictured below. It's sandpaper on a foam base, as theorized above, and I had good luck working the product around in the cavity on a paint stick.

Rather than opening up the deck to do a proper structural repair, I just first cleaned the stress crack area in the cavity out with long screwdriver, squeezed in and then gooped around some Marine-Tex on a paint stick, threw some matt on top, and then slowly hand sanded away with the 3M product once all was dry. It's held for a couple of years now and was a pretty good down and dirty repair.
 

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Hey Everyone, I know if been a while, but I did find a technique that worked. I thought i would share some of the details here. Maybe this will help someone else out in the future.

So I did confirm that I was leaking in the mast tube. The daggerboard trunk was not as bad, but since i found a technique that worked I went after both of them. Here is the take home lesson, "It's all about finding/creating the proper tool!" I tried the yard stick and paint stick, but i couldn't really get tight to the inside wall because of the lip on the top. So i grabbed a thin piece of wood and cut it into an L shape (see attached pics)

tool1.jpg tool2.jpg tool3.jpg

This allowed me to get into the hole, then get good contact with the inner wall, while the handle part cleared the lip. I mixed up a bunch of fiberglass resin, poured it onto my new custom tool, and spread it all over the inside walls of the mast tube and the dagger board trunk.

Once this dried, I used that same tool to sand it. Inspired by Sailcraftri's comment, I first wrapped some paper towels around the thicker part (i didn't have any foam around) so that i had a way to put pressure evenly while sanding. Then I wrapped it all in sandpaper and used a staple gun to secure everything to the wood.

sanding1.jpg sanding2.jpg

I hit it with some 80 grit then 120. It seems to have done the job. No more leaks. Again, thanks for all the advice. I wouldn't have thought of any of this without your comments!
 
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