Loose mast base

The base portion of the mast on my H16 is very loose. I can pull the base out about 1/2" on the track side. The rivets are very loose as well. I am sure the base should be snug in the mast end. What is the proper procedure for repair.

Thanks in advance for the responses!

I had a similar problem. One day when stepping the mast, I looked down and the base had almost separated itself from the mast. Turns out the 2 side rivets (I only had 3 originally) had stripped out. We knocked the mast base back into the mast, then drilled two new holes through the mast and base and popped 2 new stainless rivets in. It has held up fine so far (probably 4 trips since).

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1983 Hobie 16 "Rumpshaker"

I agree... and you can do this even if the aluminum in your mast has torn away, or is cracked. You should stop-drill any cracks, though, to keep them from running.

I experience this problem about every 3rd season or so. My normal procedure is…

Drill out the pop rivets
Remove the base
Try to remove any water that may be in the mast.
Scrape out all of the old silicone sealant
Place a bead of new sealant inside where the base contacts the mast including an extra amount at the luff track.
Replace base
Replace rivets, make sure they are snug of course.
Check silicone seal so that it is uniform around the thin gap between base and mast. If not, I use my finger to dab some more in.
Then I clean up the excess silicone with acetone.

I think that in the past this was a weak spot were rainwater would enter the mast. Maybe while trailering in storms. Otherwise I can’t figure out how it got in to that section. Another trick I have used for getting water out is removing the silicone plug in a rivet on the hook that you attach the halyard to. This seems to be the best method.

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"Breach hull all die"
'83 H16
'90 Hobie One 12

I didn't bother putting new sealant around the base of mine when I repaired it. I'm sure it is a good thing to do, but not completely necessary, as the water tight seal for the entire mast is about 1 foot or so up in the mast where there is a big plug of expanded insulation foam (or something similar). Assuming that plug is still intact, you should be good.

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1983 Hobie 16 "Rumpshaker"

The sealant only serves to hold the base in while you rivet. Very handy if you're working alone. But you're right... If the low end plug is intact, the silicone serves no sealant purpose.

Brian C

I am a newbie and just picked up an H16 this summer.

After doing some repairs I was able to get out for a weekend on it. After taking down the mast and attempting to step it again, the mast base fell off. This particular one was welded on via aluminum weld. After doing some reading on it it seems that should only be riveted on. The base was pretty worn so I got a new one and drilled some holes for it and used 2 aluminum rivets to fasten it. When stepping, again the base tore out. This time one rivet sheared and the other pulled through the bottom of the mast.

I'm wondering what the best fix would be in this case and what I'm doing wrong.
More rivets and in different spots?
Stainless steel rivets?
some type of adhesive as well? I have seen the mention of silicone but just as a sealer.
Lastly re-welding? (trying to avoid this one)

Any advice would be great!

Without seeing the condition of the mast base its hard to provide specific advice.

the stock mast base is held on with 3 rivets, I believe. One in front and two on the sides back towards the luff track. 2 rivets would probably NOT be enough to hold it in place during the stress of raising and lowering. I would imagine the welding was someone else doing a repair

I think you have two options.

If the mast itself at the base is in good shape and the holes are not too large or cracked, you could just purchase a new mast base insert. That would ensure the rivets hold well.

Alternatively, don't weld it. But use epoxy and rivets to hold the base in.
Personally, I would only do this if the mast itself at the base was in poor condition (and I would probably consider putting a new mast base in anyway).

My 2 cents.

Definitely need to use stainless rivets. I can't remember the exact size, but they are specified in the Hobie catalog. My '83 has one front-center, and 1 on each side. Newer Hobies I have seen have 5 rivets (one front-center, 2 on each side). I would assume the aluminum rivets were your problem.

Also, check and make sure the stepping hinge isn't binding as you raise the mast (have someone look as you raise it). The hinges can get bent outwards which causes them to bind where they should fit in the mast cup, possibly putting extra strain on the mast base as you shove it upwards.

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1983 Hobie 16 "Rumpshaker"

Aluminum rivets were absolutley your issue. Use only monel rivets & rivet caps. I would also bed the joint with a marine grade sealant, even if there is a plug a little higher up. Who wants to trap ANY water in there mast???

You may need to buy a more heavey duty rivet gun to pull the monel rivets. They are tough buggers.

The rivet caps look like miniture Abe Lincoln top hats. Rivet prophylactics, if you will. They go into the hole first, then the rivet. This will close off the potential leak through the middle of the pop rivet. The rivet can't be longer than the cap depth, so choose lengths wisely.

Years ago I knew some one who made the mistake of riveting a mast tang on there ice boat with aluminum rivets. Can you say dismasting?

Always use monel.

Jon

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Sail Fast, Take Chances.

i hate it when that happens you just about got the rig up and then slam it goes crashing bouncing off hobie bob. i made the mistake of trying aluminum rivets first not good results. ended up making some new holes the origanals were to corroded due to salt and install 5 larger stainless rivets. alls been great since then i also used sikeflex with my rivets i did have any caps .

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1980 h16 chubasco

Not seeing the condition of the base of the mast, it sounds like it is really a mess. If you can't find enough good material for at least 3 stainless or monel rivets, cut a half of an inch off the base and get some good material to rivet through. I know, it sounds drastic, but is better than another material failure. This is a last resort solution, but has worked for me.
If you use stainless, make sure and use the caps or some other way to electically isolate the aluminum mast and the stainless rivet. If not you will have galvanic corrosion in a year or so. Eats away the aluminum and welds the rivet in place.
Also, don't forget to fill in the hole in the middle of the rivet with a sealant to prevent water getting in there.