Mast base

sailcraftri

Well-Known Member
#6
Where is the hole? On the bottom of the base? If so you should probably replace the base with a new one. Or is it the hole used to secure it in the mast? I have new mast base caps, cjo1023 at yahoo dot com.
 
Thread starter #8
It appears that the hole was manufactured in the cap, just like it is on my Laser mast base. I can seal it or get a new cap. I would assume Marine Tex would work although I like the racket all idea.
 
#9
The problem with not properly sealing the mast end (or spar end) is that when the end hits the water, it just sucks the water in. Maybe the engineers here can explain the effect better than I can.

After taking water out of the mast and cleaning out the waterlogged or otherwise ineffective cork, I've sometimes used a quick, small shot of Great Stuff sealant foam as a replacement for the cork. Or something very similar, as long as it is lightweight and seals completely, without absorbing water. It just has to be enough to fill the crossection of each end so there is no leakage. You definately do not want too much, since foams like Great Stuff expand so much.

I also apply a ring of 3M sealant completely around the cap ends before reinserting, including at the two pin-holes. I like the pins themselves to be snug in the mast and cap holes so sometimes I find I have to replace the with pins ( something like brads without heads) that are just slightly larger than original pins, so that too snug and sealed.

I've seen caps and also spar fittings with just hollow pop rivets, which it nuts. Anything like that usuanlly needs a dab of 3m.

I always try to replace the cork, though, with a foam plug.
 

L&VW

Well-Known Member
#11
It's important to have a sealed mast. Any oversight can result in "turtling" the boat upon capsizing. Whether the water is deep— or especially when it's shallow—this can ruin one's day on the water. :(

As it weighs practically nothing, I cut a swim noodle lengthwise to fit, squeezed it smaller with a few turns of masking tape, gave it a shot of WD-40 and struggled to pull it through my near-identical Porpoise II mast. :mad:

Maybe there's a swim noodle sized to fill the mast's interior perfectly. :)
 

Wavedancer

Upside down?
Staff member
#12
It's important to have a sealed mast. Any oversight can result in "turtling" the boat upon capsizing. Whether the water is deep— or especially when it's shallow—this can ruin one's day on the water. :(

As it weighs practically nothing, I cut a swim noodle lengthwise to fit, squeezed it smaller with a few turns of masking tape, gave it a shot of WD-40 and struggled to pull it through my near-identical Porpoise II mast. :mad:

Maybe there's a swim noodle sized to fill the mast's interior perfectly. :)
No need for a swim noodle. Air is lighter.

:) You could use helium though, but that would not be class-legal.
 
#13
I have to resurrect this thread. My mast has no base cap, but I can see the wood insert a couple of inches in. I have a new mast cap, but it is slightly too large to fit. I did some manual sanding but couldn't get it to fit. I looked down the mast and can see what looks like a reinforcement of some kind. The Sunfish is a 1978; did it come stock with no base cap and a mast insert of some kind? Thanks for any advice.
 
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L&VW

Well-Known Member
#14
The cap is a tight fit. Use a sealer anyway.

Your mast should measure exactly ten feet. Perhaps there'd been a cut/repair with a wood insert?

Does the "sticky" end appear cut with a pipe cutter? (Which would make it smaller--and a tighter fit). I'd suggest cutting off 1/4" with a hacksaw.

Could you be seeing a large cork--not wood--cork being a standard part from the manufacturer?
 
#15
The cap is a tight fit. Use a sealer anyway.

Your mast should measure exactly ten feet. Perhaps there'd been a cut/repair with a wood insert?

Does the "sticky" end appear cut with a pipe cutter? (Which would make it smaller--and a tighter fit). I'd suggest cutting off 1/4" with a hacksaw.

Could you be seeing a large cork--not wood--a cork being a standard part from the manufacturer?
Yes, it is cork. I just found elsewhere in the forum that newer sunfish masts have a larger inner diameter than the old ones. So, new mast caps don't fit. Only solution is to laboriously sand down the new cap until it fits. Thank the Lord that I don't have any other hobbies.
 

sailcraftri

Well-Known Member
#16
"Newer masts have a larger inner diameter" does not make sense. The mast wall should be the same throughout the years. There could be some very slight variation in the extrusions over the years, but were talking maybe thousands of an inch.

New masts do come with a sleeve inside to help stiffen the area at deck level. This is another aluminum tube with a slice that gets press fit into the mast. It is usually installed to have enough clearance for the mast base. The mast bases are press in tightly so you may need a hammer to get the base all the way in. I have even seen some plastic get trimmed during this process.
 
#17
I have to resurrect this thread. My mast has no base cap, but I can see the wood insert a couple of inches in. I have a new mast cap, but it is slightly too large to fit. I did some manual sanding but couldn't get it to fit. I looked down the mast stem and can see what looks like a reinforcement of some kind. The Sunfish is a 1978; did it come stock with no base cap and a mast insert of some kind? Thanks for any advice.
My fish is a 78 and the mast has a black cap that fits inside the mast.
 

Webfoot1

Active Member
#18
The hole in the base of the mast/cap originally was for a pin to hold the cap on. Drill
the cap/base for a 1/16 pop rivet, apply 3m 5200 to the cap and reinstall. Better than
the original no cork needed. Remove and seal the upper mast cap using the same method.

The cap is a tight fit but will go on, bevel the edges of the cap and drive in with a rubber
mallet. The trick is to get it to drive in straight and not be cocked at a angle. I've used the
new caps on 4 Sunfish going back to 1972 without problem
 

L&VW

Well-Known Member
#20
Yes, it is cork. I just found elsewhere in the forum that newer sunfish masts have a larger inner diameter than the old ones. So, new mast caps don't fit. Only solution is to laboriously sand down the new cap until it fits. Thank the Lord that I don't have any other hobbies.
Not the ONLY solution. Aluminum is malleable, so a steel pipe or rod of 1" diameter can be rolled forcefully inside (against the very edge) to widen the opening. Manual exhaust pipe straighteners are another option.

Does the cap on the other end appear to be a good fit?

Aluminum comes in different gauges. Could your mast be a mis-matched replacement?

If all else goes well, I'd spray an anti-corrosive inside before sealing.
 
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