Hobie 18 leaky mast

You may mean comp tip instead of foam plug. While the mast is upright I would drill out one of the bottom rivets that hold the mast base in place and let the mast drain throughly. Then either pop in a new rivet or a ss screw. (I use a ss screw so I can remove on occasions to se if there is any water in the mast.) Then use a good grade marine silicone sealant and seal anywhere and everywhere there is a through mast fitting or rivet, including the mast head and mast base and if you have a comp tip make sure that you take extra time sealing where the comp tip and metal part of the mast meet. There is a lot of flex and bending at this junction. I have seen hobie masts take in rain water at this location and fill with water 5 or 6 feet up the mast.

I wouldn't do that yet..... the bottom of the mast (should) have some kind of silicone sealant in the bottom and I think it goes almost up to the mast rotator thinggy or gooseneck. Someone did put it up here on the site~~ let me see if I can find it. Try this~~ H-18 Mast Plug Replacement - Catamaran Sailing

Also you might want to find out where it's coming in from.
On a calm day take your mast off the boat and take it down to the water and submerge it and look for bubbles. I gotta do that to mine this year. I thought I had it sealed, untill I took it out for the winter~~'drip drip drip' I really don't wanna do the bottom thing yet... Sailins fun and all that but sometimes it can be a pain in the "arse" :-O

around the point the forestay and shrouds attaches to the mast (what's that point called, anyway?).

called the Mast tang

OK I guess that link didn't wanna work and I can't copy the URL from the properties... Go to 'tech gallery~ go to page 2 "H18 plug replacement"

HULLFLYER wrote: You may mean comp tip instead of foam plug.

My boat ia a 1979, so it's ancient. It has a one piece all aluminum mast with no comp tip. I had noticed that the hook at the top was loose. After I turtled it, the harbor patrol came and righted me. This action ripped off the hook, tore up the main sail and ripped one of the jib blocks off.

There were huge oxidized holes where the hook was riveted on. I've fashioned a stainless steel reinforcement plate to cover it and bought a replacement hook from Murray's. I'm aware of the galvanic issues between stainless and aluminum and will take steps to mitigate the problem.

Andrew Scott wrote: called the Mast tang

Thanks, I'm a newbie although I've had the boat for over 10 years.

There were huge oxidized holes where the hook was riveted on. I've fashioned a stainless steel reinforcement plate to cover it and bought a replacement hook from Murray's. I'm aware of the galvanic issues between stainless and aluminum and will take steps to mitigate the problem.

This is what I made for the same problem.

Thanks, I'm a newbie although I've had the boat for over 10 years.

haha, cool.

I like to say i am the "new kid" on the beach, i have only been sailing 30+ years 🙂

I had water dripping out the masthead of the comp tip from my H18, when I moved it from storage this spring. That needs to be sealed, obviously. I would like to remove the masthead to do a real good job, but don't see how it's attached. Any clues?
I capsized 3 times last season and turtled within 10 seconds, most likely due to taking on water inside the mast. Submerging the mast in calm water to look for bubbles is a good idea. Has anyone added additional floatation media somehow?

On a comptip, the rivets for the halyard hook are what holds the masthead in place.

Has anyone added additional floatation media somehow?

Edited by DaveW70 on Apr 08, 2012 - 03:02 PM.