I finally got around to checking my mast for leaks. Overall it did fairly well but I did find some bubbles coming from the base of the mast (from somewhere under where the DH's are mounted on my H17) and also a few bubbles coming from the comptip joint (but this was positional).

In looking at the comptip joint area, it looks almost impossible to add silicone sealant to the part of the mast inside the channel where the bolt rope slides. Anyone know of an easy way to do this?

Since the amount of water that enters the mast from these two locations is fairly small and since it's not easy to find the leak at the mast base or fix the leak at the comptip I'm thinking the best course of action is to just periodically drain the mast. On an interim basis, I just removed the two screws holding the sail prefeed bracket in place at the mast base and a few onces of water came out. This would have been easier and more thorough if these holes were located at the very base of the mast, but they're not (which requires that you shake/tilt the mast to get it all out).

So I'm thinking it might be a good idea to drill and tap a hole at the mast base just above the bottom mast plug. That way, even with the mast up, it would be easy to periodically drain the mast. I could use the prefeed bracket screws above as an air vent or add another hole/screw for that purpose.

Two questions:

1) Anyone know how thick the bottom mast plug is? If I know this, I can easily measure up from the exposed bottom of the plug to locate the drain hole at the very bottom.

2) Am I overlooking anything here? Seems like a simple solution with no drawbacks. I wonder why masts don't just come that way since they all eventually take on water. Anyone already tried this and have any good/bad experiences?


Thanks,

Jerry

I've tried it. I had a Hobie 18 compost and also could not find a way to seal the junction between aluminum and compost in the luff groove (kerf). So I istalled a bycicle tire valve at the front of the mast, just above the mast base fitting.

I also saw a need to let in air so that the water would come out, so I routinely pressurized the mast with a bike tire pump before letting water out; this sped up the exit of the water.

I chose a presta valve because it was the smallest diameter valve that I could find at the time. I would prefer the schrader valves used on automobile tires because of their rubber to mast fit, but I was reluctant to drill a hole any larger than necessary to get a valve in there.

If I were to do it again, I'd probably go ahead and use a car tire valve. See a tire buster at a local car repair center for intallation instructions and perhaps to borrow a tool to do so.

GARY

Thanks, Gary, good input.

I was going to tap a small hole (or two, the second one for air intake) and just use a machine screw with a rubber washer but a tire valve sounds like it might be even better. My only concern with pressurizing the mast is the possibility of blowing out existing seals (ie, siliconed areas). Did you have any problems with that?

One advantage of a valve (probably theoretical at best...) is that if you were capsized and took on enough water at your comptip to make righting difficult is that if you had a small handheld pump on board you might be able to push the accumulated water in the mast top temporarily back out the point from which it leaked into the mast in order to right the boat (although you wouldn't be able to get it all out since it will run "downhill" from the point of leaking). This might be worthwile trying if one was cruising, as you do, where you might be quite a ways from help.

Why did you place the valve on the front of the mast instead of on the back? At least on my H17, below the level of the bolt rope prefeeder the back of the mast is cut away exposing the flat wall at the front of the mast bolt rope channel. This seems like it would make a very nice place to place a hole/valve.

Finally and very importantly, do you know how high from the bottom of the mast (ie, point where the mast extrusion meets the mast base casting) to drill so that the hole ends up just above the level of the bottom plug so all of the water can be drained?

Thanks for the help!

Jerry

On one of previous my boats, I found water in the mast. As a result, I drilled a hole, tapped it and used a nylon screw in the bottom of my mast casting. It worked without any other holes.

A couple of weeks ago, I went to the hardware store and got the small shrader valve (the type on your car tires) typically used on top of a well water pressure tank.

Then, I drilled and tapped the back of the mast (about a foot down from the old style aluminum cast head). Next, I put some teflon tape on the valve and carefully screwed it into the mast.

Next, using only a bicyle pump set to 3-5 pounds of pressure , I pressurized the mast....went over it with a sponge full of soapy water...and VOILA, I was able to find all the leaks, mark them, and when the water evaporated, seal the leaks with 5200.

If you are to try this I have a couple of suggestions: the shrader valve comes in two sizes, pick the small one; second, Hobie put the foam mast sealer plugs (if they remembered to put them in at all) at various distances into the top and bottom of the mast, so put your valve a little lower than you might think it needs to be; I tried putting the 5200 on during a day where the air temps were in the low 70's....bad idea...it ran everywhere and took days to cure; lastly, be sure to keep your pressure low...or you will blow out already sealed areas of the mast. If you would like, I can post a picture of the what the completed valve installation looks like.

OldSalt

OldSalt, thanks for the feedback.

I can see the bottom of the lower mast plug by removing the lower mast casting. I would know where to drill the hole for a valve if I just know how thick the plugs are (assuming they're usually the same thickness). Do you know how thick the plugs are? How far from the bottom of the mast did you drill your hole?

Jerry

The foam mast plugs are about 3" thick. If you go 4" up from the side you can see, you should be OK.





Why the cheap shot? Hobie Cat has made several hundred thousand masts - what evidence do you have that they ever "forgot" to put the plugs in? They've been in every mast I've ever opened up - which has been quite a few in the past 30+ years.

Thanks, Matt! That was the magic number I was looking for.

Jerry

I placed the valve in the spot where I felt that I was least likely to snag it with a line. For me that was at the bottom of the mast, in front. I already had something in place to keep the jib sheets from falling down that far.

The mast base extends exactly one inch up from the bottom of the mast. That is one inch from the bottom of the mast extrusion, not from the bottom of the mast base.

GARY

Thanks, Gary.

You said: "The mast base extends exactly one inch up from the bottom of the mast. That is one inch from the bottom of the mast extrusion, not from the bottom of the mast base."

Just to clarify, did you mean the mast base plug is one inch thick?

Thanks,

Jerry

About 1.5". The top of the mast base is 1" above the bottom edge of the mast extrusion, about 1.5" above the bottom of the entire hinged mast base. Just go 2" up and be safe.

GARY