How's it going I'm new here, am the proud new owner of an '81 H18. Started out sailing a '01 Weeks Force5 two years ago. Decided I was tired of leaving my friend on shore while I sailed with the other.
It's not pretty yet, but good deals rairly are. I need to retrivet the mast step, but it won't go down far enough. It contacts the support wire with about an inch to go.
Do I use the weight of the mast to stretch the wire, a scissor jack, or trim the dolphin stiker to fit?
Stretch ing the wire will load the rivets with a tension, not good right. Will it will want to draw tH hulls in, or flex the beam up if the rivets hold.
Edited by 0rion85 on Oct 31, 2015 - 04:41 AM.
Dolphin striker length H18 '81
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Posted: Oct 31, 2015 - 04:38 AM
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Posted: Oct 31, 2015 - 09:50 AM
The dolphin striker on the H18 has two main components - the post and the rod. The post is the vertical compression member which extends below the mast step and is threaded into the mast step. The rod is the tension member (what you are referring to as the "cable"). The rod is secured to the bottom of the post with a piece of aluminum tubing and each end passes through the bottom side of the front crossbar and into the crossbar end caps where the ends are secured with nuts.
What you're describing (the need to re-rivet the mast step) is very common on the Hobie 18. The action of the mast working on the mast step causes the rivets to loosen up over time. The best way for you to fix the mast step is by loosening the striker rod nuts located at each end of the front crossbar castings. This will relieve tension on the rod and allow the post/mast step to seat fully down to the top of the crossbar so new rivets can be installed. Then tighten the nuts back up to re-tension the striker.
The problem is that it is very common for the stainless steel rod to become seized in the aluminum castings. When this happens, the rod will not loosen even if the nuts are loosened. When this happens, full removal of the front crossbar from the boat is typically required to free the striker rod from the crossbar castings. This is the preferred method although it can be a bit involved. You should re-assemble the rod with grease to prevent corrosion/seizing in the crossbar castings.
As an alternative, you could use a scissor jack between the striker rod and the bottom of the front crossbar to push the mast step down and then re-rivet the step. You should definitely NOT cut the striker post.
In either case, when you have the mast step re-riveted, there should be no play/clunking if you try to wiggle the striker rod with your hand. If it clunks, then it is too loose. The rod should make a "twang" sound if you pluck it with your hand.
Also, since you mentioned your boat is a 1981, it is likely you have the original 2-rivet mast step. This step was later updated to a 4-rivet configuration which is stronger and stays better affixed to the front crossbar. You might want to consider replacing it (this would require an new striker post and mast step).
You can also bed the mast step in epoxy when re-riveting it to help hold it more securely to the crossbar. http://www.hobiecat.com/forums/viewtopic.php?f=13&t=42441&hilit=mast+step
You can also do a search for mast step on the Hobie 18 forum of the Hobie website for a lot more info.
sm
Edited by Dogboy on Oct 31, 2015 - 09:54 AM. -
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Posted: Oct 31, 2015 - 01:16 PM
Thx for the info -
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Posted: Oct 31, 2015 - 01:23 PM
Orion, Welcome to TheBeachcats.com, and welcome to Hobie 18 sailing! You will love it, just get some local help if you can, will make your learning curve so much easier.
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Posted: Oct 31, 2015 - 01:51 PM
I had the same problem and wanted a temp fix for the weekend. I tightened the rig and this eliminated the play in the mast step. Have someone hang off your trapeze rigs and move shrould(s) down on the chainplate. Trade offs in doing this, but it will get you on the water if you are in the mood for that over working on the boat.
Edited by mattson on Oct 31, 2015 - 01:52 PM.
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Posted: Oct 31, 2015 - 06:10 PM
Thanks I just got it installed. I don't like installing rivet in tension. What do y'all think about through bolting it? -
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Posted: Oct 31, 2015 - 06:16 PM
Thru-bolting all the way through the crossbar? That's a lot of holes in the center of the crossbar. Maybe drill and tap the top surface of the crossbar extrusion for #12 machine screws.
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Posted: Nov 01, 2015 - 04:33 AM
What about a roll pin through the striker under a washer below the beam? -
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Posted: Nov 01, 2015 - 07:21 AM
My only thought, if you have access to a lathe, would be to thread the top 5" or so of the post and put a nut and washer on the bottom side, similar to what is done on the Hobie 17/20 striker post. Otherwise, stick with the current setup and re-rivet it every few years. If you maintain the striker rod so it doesn't seize in the end castings, re-riveting is not a big deal.
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Posted: Nov 01, 2015 - 03:33 PM
Well I used alum. rivets, they came out the first time I put the mast hinge on. Going to try stainless next. Though they will cause corrosion. -
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Posted: Nov 01, 2015 - 06:02 PM
Look at the original rivets. They were stainless. Were they corroded? I have not seen corrosion related to the mast step rivets on an 18. The main issue is that once the step gets loose the rivet holes in the front beam
elongate and won't hold even with new rivets. On my first H18 I bit the bullet and replaced the entire striker
setup with the upgraded 4 rivet design. On my second H18 I installed larger stainless rivets in the 2 bolt step.
Both methods worked well. If using larger rivets you will need a very large rivet gun.
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Posted: Nov 01, 2015 - 09:10 PM
The rivets definitely need to be stainless. If the holes in the crossbar have enlarged to the point that 3/16" rivets will not hold, then you either need to put washers behind the rivets (reference the link in my prior post) or use 1/4" diameter rivets.
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Posted: Nov 02, 2015 - 06:53 PM
The rivets need to be Monel, a version of stainless that will corrode less with aluminum.
Murray's has them,
http://www.murrays.com/19-5023.html
and they offer tubes for oversize holes that help seal the hole:
http://www.murrays.com/19-5020.html
and just plain bigger rivets:
http://www.murrays.com/50-8011231.html
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