Hobie 18sx Mast Anatomy

Hey all,
Well after an awesome first season with my new boat I was packing her away for the season this weekend. I noticed water sloshing around inside comp-tip mast.
Couple of questions I hoping folks might have the answer too:

1) How do I drain water? Do I have to remove riveted base?
2) Does anyone know the internal anatomy of the mast so I know how best to seal her up? Do I have to remove every tang, comress plate etc?
3) what specific material do folks prefer to seal mast? 3m 5200?
4) I've read mixed reports here on the likelihood of leaks at the comp-tip joint with some people saying it's most likely and other's saying the factory seal is unlikely to be the issue.

Lastly, I should add that the water in the mast may have been from a vertical crack in the mast when I bought it that ran for about a foot just north of Gooseneck. I had it TIG welded and it's not been any issue this season and shows no signs of expanding or opening.
Lots of questions here and I know there's lots of info in forums but a lot of it seem competing or incomplete so hoping someone has some clear solutions on draining and sealing the mast?

Thanks all as always. So sad it's end end of season. Was blowing 20 at the beach this weekend with big surf kicked up by Gonzalo off the coast. Weather made for the 18!
Phil

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'89 18SX

Step one is to determine where exactly the water is located inside the mast. The comptip (fiberglass top section) is sealed separately from the lower aluminum section. There is also a plug in the base of the aluminum section located roughly where the diamond wire/ rotator bolt passes through the mast. If the water is in the main section of the aluminum mast (entered through the crack you described), then you can probably just remove the two screws tha hold on the sail feeder in the mast track opening and drain the water through those holes. If the water is in the comptip, then you will have to remove the head cap from the mast to drain the water. Anyway, the first thing to do is figure out where the water is. You can do this by putting your ear against the mast and tilting the end of the mast up and down (you may want to have an assistant help you). You will hear the water running past your ear.

sm

Thank you!
Had not thought of removing the screws in the sail feeder. That's a great first step. Water is definitely in the aluminum section and not comp-tip.

The plug in the base of the mast around rotator, Does that seal the lower section (below rotator) off from the upper aluminum section? I'm assuming if it's called a plug it does seal it off. Thanks for the advice!
Phil

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'89 18SX

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Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)

WOW!!! Matt that's exactly what I was looking for to geek out on! Thanks so much for sharing!!! I feel a little closer to my 18 now knowing all this!!
Phil

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'89 18SX

I definitely dig the engineering drawings too.

I recommend you remove the sail feeder completely and just reinstall the screws with a dab of silicone to seal up the mast. The feeder does more harm than good.

sm

On a very related note, I know Hobie ensures waterproof rivets by using rivet caps as Matt has in his engineering diagram.

I'm having the darnedest time tracking down these caps and the Hobie part number is not getting me anywhere. Anyone know specs on these caps and where I can get them online? None of the online Hobie dealers seem to carry them.

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'89 18SX

I know Murrays sells them. They call them "rivet casings."

sm

Engineering drawings do not use the same SKU as our parts department.

8011291 RIVET CAP



Readily available through any Hobie Sailing Dealer.

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Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)

I think this tread belongs to the Hobie 18 / 18SX topic and not the F18 forum

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F18 Hobie Wildcat sail nr NED 066 & NED 1111
F18 Hobie Tiger sail nr 973 sold
Hobie 16 sail nr 104195 sold
470 sailnr NED 560 sold

If you are looking for F18 information... you are in the wrong place!

This is: Board index » Hobie Cat Sailing » Hobie 18 / 18SX

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Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)

You moved it to Board index » Hobie Cat Sailing » Hobie 18 / 18SX

And I see it in the board F18 Tiger, Wildcat (opens automatic when i look at this site ) with the moved mast H18 topic

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F18 Hobie Wildcat sail nr NED 066 & NED 1111
F18 Hobie Tiger sail nr 973 sold
Hobie 16 sail nr 104195 sold
470 sailnr NED 560 sold