Hobie uses a piece of foam and plate like this to seal the mast water tight at the top such that it doesn't take on water during a capsize/righting.

http://www.murrays.com/50-20060000.html

How does NACRA accomplish this? How about the mast base? My boat is a 1983 model.

Thanks in advance

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Hobie 16 (3 formerly)
MacGregor 25 (formerly)
Chrysler Dagger 14 (formerly)
NACRA 5.0 (currently)
High Point, NC
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Your Nacra has a plate at the top, that holds the sheaves for raising the sail. Put some marine grade silicone on the join & all the rivet heads,(though they were supposed to have used sealant when installed), at the mast head, tang that holds the sail up, mast hound, spreader, & diamond tangs.
If you have the old style straight thru spreader bar, it is very difficult to seal as it moves a bit.
Have a close look at the base, NAcra use several different bases, some leave a 1/4" triangle gap on each side, underneath. There is a thread somewhere here on that subject.
The mast will float, & with the Cat on its side, the mast will be under up to about the hound. As long as you get off the hull quickly, it won't turtle. Hang around on the high hull in a stiff wind, & it will.
Some folks leave a 1/8" hole at the base so any water will drain out. You can plug it with a plastic push pip. If you do that, remember the base extends 1" up into the extrusion.

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Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
Nacra 5.7
Nacra 5.0
Bombardier Invitation (Now officially DEAD)
Various other Dock cluttering WaterCrap
--

Here it is;
http://www.thebeachcats.c…opic/topic/12662/start/0

--
Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
Nacra 5.7
Nacra 5.0
Bombardier Invitation (Now officially DEAD)
Various other Dock cluttering WaterCrap
--

Thanks Ed.

Since you brought it up, about the spreader. When I bought this boat, I though my God is it really that big and advantage to reduce the mast section a little in exchange for the hassle of a spreader, diamond wires etc.. Then when I noticed the spreader I thought, you've got to be kidding, the NACRAs are soupposed to be more in to fine design than Hobies yet they bash a hole in the middle of the mast at the point of greatest stress and stick a tube through it. Subsequently, I learned that later 5.0's (mines a 1983) had a more traditional two link arrangement.

Is this one tube arrangement a known problem? Can my mast be refitted with the two link arrangement and should I consider doing it?

Thanks in advance

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Hobie 16 (3 formerly)
MacGregor 25 (formerly)
Chrysler Dagger 14 (formerly)
NACRA 5.0 (currently)
High Point, NC
--

It's not a "problem", it just is. Personally, I would sail the crap out of it, then decide. You can always wait to find a used set off a wrecked boat.
The hole won't weaken the mast, it's basic engineering, the addition of the bar & wires makes it stronger. Adding the diamond wires makes it into a truss & greatly stiffens that noodle.
I think '84 was the year they all went to adjustable.

--
Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
Nacra 5.7
Nacra 5.0
Bombardier Invitation (Now officially DEAD)
Various other Dock cluttering WaterCrap
--