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Mast cup issue

po-man sailor

Active Member
Since my boat weighed in at 129 lbs i didn't do a leak test in the mast cup. Now seeing this i will address it THEN do a leak test. I don't want to chance the water going into a now dry hull.
Question...it seems that the outer glass has worn(chipped or flaked)away from the inside walls of the cup. All cloth and bottom step seems to have maintained their integrity. Can you please give your ideas of the best practice you have experienced correcting and cleaning up this situation.
Side question, it seems like at the bottom there is a perfect spherical shape hole below the step. Is this meant for a place where the sand or debris can fall down in there so as not to grind on the mast. It is solid when I poked it with a big dowell.
 

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signal charlie

Well-Known Member
Staff member
The layer of polyester resin has chipped away, the fiberglass looks okay. We smear in a layer of thickened epoxy to replace the polyes, protect the fiberglass and make sure watertight integrity is maintained. The epoxy can be applied with a 1 inch chip brush taped to the end of a paint stick, then smoothed with the straight edge of another paint stick by going around the inside of the hole. We just did a skim coat of epoxy on the inside of a wooden Sunfish mast step.

1671425F-BAED-470B-8FDA-5FDCD73A1BE6_1_201_a.jpeg

There is a spacer at the bottom of the step, I think it is there to help define the shape of the bottom of the tube and it also stops the mast from grinding through the keel, along with the cap on the bottom of the mast. Not sure if there is a reason why it is not solid vs being open in the middle.
 

po-man sailor

Active Member
I may use my thixo thats on order to do that. I had planned on using the brush on a stick to apply a coat or 2 of resin back on the cloth all around inside the cup. But thixo or 610 sounds good as well.
SC, what would it be like if I put coat of resin to report cloth, then did the epoxy for more sturdy surface against mast? Would that be redundant or overkill?
 

signal charlie

Well-Known Member
Staff member
We have never added more cloth, I'd be concerned with mast clearance issues.

And we have not come across a boat that needed the bottom of the cup sealed, not sure of the pros and cons of that. I suppose you could drizzle in epoxy thickened to syrup consistency.
 

Alan S. Glos

Well-Known Member
That "cup" is designed to form a round "shelf" that lets the mast rotate with less friction than a flat bottom and, yes, the space below is sort of catch basin to collect sand and other debris. Truth be known, newer boats do not all have this shelf design and the rotation friction is probably not noticeably worse.
What will reduce the rotational friction is installing a mast mount halyard cleat as you reduce the "down" force vector a bunch.

Yes, clean out the tube and coat with a generous coating of thickened epoxy. If you need to sand it to get the mast to fit, mount a sanding drum on a drill bit extension shaft, and chuck in an electric drill, see photos. This rig works a lot faster than using a large dowell with a sheet of sandpaper stapled to it.

Alan Glos
Cazenovia, NY
 

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po-man sailor

Active Member
Well last structural item on the boat completed. Took SCs advise and dressed and smeared west system 610 thickened apply in the bottom, on the shelf and around the sides and in the top deck seam of the mast cup. Basically completely sealing it. I think I got it smooth enough I won't have to do a lot of sanding. It looks good and looks a little better than just plain resin over the good glass that was there. I'll install one of the Teflon disc in the bottom after trimming it and cutting a hole in the center for sand to go down past the shelf in the little spherical hole if it needs to.
Now I start putting things back together and finishing the cosmetics. Wax on...wax off...
 

po-man sailor

Active Member
Good tip L
I did as Signal chuck suggested and used a paint stick with a 1 inch chip brush, making sure to coat the bottom good to complete the full seal, then took another clean stick and carefully "smoothed the cake icing" around in one single motion while holding a flashlight to see all the way down there. Then when it got firm but not tacky I slowly put the mast in to the bottom and flattened any sharp spikes and moved it in a slow circle to finish smoothing the sides so I wouldn't have to sand. It worked like a charm. Its cured hard now.
SC doesn't realize how lucky he is that he moved away from me when I got this boat. I would be over bugging him on a regular basis on the pretense I was over there to sail.
 

L&VW

Well-Known Member
What happens when you try to take the mast out? :eek:

Good tip L
It worked like a charm. Its cured hard now.
SC doesn't realize how lucky he is that he moved away from me when I got this boat. I would be over bugging him on a regular basis on the pretense I was over there to sail.
SC makes his own luck: He did move away! ;)
 

po-man sailor

Active Member
Ha ha ha...I should have mentioned i pulled it right back out after using it to smooth and press. The epoxy was still pliable but not tacky. Believe me I was nervouse putting it in there. I checked like 3 times to be sure it wasn't tacky. I wanted to avoid a sanding nightmare and more labor.
 

Woodwind

Active Member
That "cup" is designed to form a round "shelf" that lets the mast rotate with less friction than a flat bottom and, yes, the space below is sort of catch basin to collect sand and other debris. Truth be known, newer boats do not all have this shelf design and the rotation friction is probably not noticeably worse.
What will reduce the rotational friction is installing a mast mount halyard cleat as you reduce the "down" force vector a bunch.

Yes, clean out the tube and coat with a generous coating of thickened epoxy. If you need to sand it to get the mast to fit, mount a sanding drum on a drill bit extension shaft, and chuck in an electric drill, see photos. This rig works a lot faster than using a large dowell with a sheet of sandpaper stapled to it.

Alan Glos
Cazenovia, NY
Alan,
if the cleat is relocated on the mast for the halyard, how do you rig the typical recreational downhaul that goes around the gooseneck and down to the deck mounted cleat?
 

Alan S. Glos

Well-Known Member
Woodwind,

Hoist the sail and use the mast mount cleat to keep the upper boom (gaff) fully hoisted. Then run the loose end of the halyard through the deck eye, over the gooseneck, back through the deck eye and then back to the factory issued deck cleat to tighten the downhaul (boom vang) to the desired tension. I know there other rigs but this one is simple and makes it easy to change the tension on the water.

Alan Glos
Cazenovia, NY
 
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