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yet another cam failure
http://www.hobie.com/au/en/forums/viewtopic.php?f=14&t=31838		 Page 1 of 1
Author:  sunvista [ Fri Sep 17, 2010 9:18 am ]
Post subject:  yet another cam failure
I have had three rudder cam failures in two seasons. These were all new replacement cams. They all split right at the hook where the rudder arm adjustment plate comes in contact with them. I really have very little tension on them, barely enough to launch my boat through the surf without kicking the rudders up so I'm at a loss to understand why this is happening.

Coincidentally, a friend of mine was recently given a 1972 H16 that still has the original cams. I swear those cams appear to me to be made of hard rubber. The replacement cams I keep buying are soft plastic. I wonder if Hobie is outsourcing these to China now or something? Anyone else going through cams like this?
Author:  Jbernier [ Fri Sep 17, 2010 9:58 am ]
Post subject:  Re: yet another cam failure
Might be something as simple as not having the cam plate adjusted correctly - read the tuning guide, if the plate isn't pushing forward enough( or too much even) it will cause damage and perhaps this is the issue?
Author:  56kz2slow [ Fri Sep 17, 2010 10:19 am ]
Post subject:  Re: yet another cam failure
Jbernier wrote:
Might be something as simple as not having the cam plate adjusted correctly - read the tuning guide, if the plate isn't pushing forward enough( or too much even) it will cause damage and perhaps this is the issue?


On newer ones yes, but in that vintage, it's a pin that locks in the cam, not an adjustable plate.
Author:  mmiller [ Fri Sep 17, 2010 10:33 am ]
Post subject:  Re: yet another cam failure
Nope... not china.

No other reports of cam failures with new boats from the field or with replacements. We just did the Worlds in China though... 60 new Hobie 16s and a year worth of sailing on each and every boat. No failures to cams at all. I don't see a difference in the cam materials or way they feel in operation.

Lack of lubrication is the number one cam killer.

Ever have the cams flip locked-down and then try to drop the upper casting pin in? The force from above the hook would damage the cam.
Author:  sunvista [ Fri Sep 17, 2010 12:58 pm ]
Post subject:  Re: yet another cam failure
Nah, I keep them greased up pretty good. After the second one failed on the port side I even changed out the rudder thinking maybe the rudder geometry (drilling) is out of whack. I have parts from a lot of boats. (That actually helped with the weather helm I was getting).

I do have some play in the spindles though. I wonder if my cam initially moved forward a bit before rotating if that would stress it? My first thought was that the adjustment plate was in backwards and hitting it on the sharp edge and not the rounded edge. Nope.

I can see where slamming the rudder arm down on a locked cam could damage it but that would probably leave a visible scar on the top of the cam. Besides, I would remember if a cam was locked down with the rudder up. Its a big hassle to free it. The fracture is at the gusset and there are several scars all on the inside of the cam where the adjustment plate hits it. I'm bewildered.

My garden rake and hose nozzle both disintegrated on me last month and were less than a year old. Both were made of plastic in China. I'm looking for an obvious scapegoat here.
Author:  Hammond [ Fri Sep 17, 2010 3:30 pm ]
Post subject:  Re: yet another cam failure
It's the Andromeda Strain mutating... ...at least it won't kill you anymore.
Author:  mmiller [ Fri Sep 17, 2010 3:59 pm ]
Post subject:  Re: yet another cam failure
Hummm... we have seen some chemicals damage plastics, but never seen it on a cam. Plus the lube is not at the plate, but who knows. We had H18 step assemblies on the shelf and after a period the bearings would fracture. Seems a cutting liquid left on the stainless parts damaged the bearings. Anything weird about the lubricant used?
Author:  SebringSixSpeed [ Fri Sep 17, 2010 7:23 pm ]
Post subject:  Re: yet another cam failure
The cams on my '90 are original and still lock down with a crisp snap every time, even after 20 years, good stuff imho. Proper adjustment and lube is key to long service.
Author:  sunvista [ Sat Sep 18, 2010 5:30 am ]
Post subject:  Re: yet another cam failure
mmiller wrote:
Anything weird about the lubricant used?
I'm just using marine water resistant bearing grease (the blue stuff). I leave my boat on the beach so it gets gritty with sand pretty quick. Every other weekend or so I check it and add some. The cams seem to rotate pretty easily. If I jack the stern up on the beach the rudders lock down with a light touch and unlock with a little fist bump at the bottom of the rudder.

I guess I should be content that a relatively inexpensive plastic sacrificial part gives it up instead of breaking rudders or ripping out gudgeons. I just can't understand how the original cams lasted 25 years and I can't get 25 weeks out of the replacements.

The only difference between this boat and other H16s I've owned, or this boat and an earlier version of this boat, is the adjustable rudder arms. I'm wondering if taking all the fore/aft slop out of the rudders is stressing the cam somehow. All three cams have split on the inside surface right at the plastic gusset.
Author:  rattle 'n hum [ Sun Sep 19, 2010 7:59 am ]
Post subject:  Re: yet another cam failure
sunvista wrote:
The only difference between this boat and other H16s I've owned, or this boat and an earlier version of this boat, is the adjustable rudder arms. I'm wondering if taking all the fore/aft slop out of the rudders is stressing the cam somehow. All three cams have split on the inside surface right at the plastic gusset.


sunvista: I think you've got it figured out.....I had similar experience with my '85 H-16. When adjusting rudder rake, watch the cam area closely and push the bottom of the rudder and the cam plate forward simultaneously until you just feel the plate engage the slot in the cam, then set it. It is possible to force the plate and rudder further forward if you have slop in the gudgeons, rudder pins, and/or castings, but that seems to screw up the geometry of the cam rotation/plate engagement. I'm sure the best fix is to get rid of the slop by other means then reset the rake. (But I never did!)
Author:  sunvista [ Mon Sep 20, 2010 6:46 am ]
Post subject:  Re: yet another cam failure
Yeah, that's kinda what I was thinking. With it slammed up as tight as it will go the locked cam is being constantly worked by the rudders underway. Plastic fatigue so to speak. Still, in theory, isn't that what the cam is designed to do? Hold the rudders down?
Author:  newsreader [ Tue Sep 21, 2010 12:34 am ]
Post subject:  Re: yet another cam failure
Cams made of soft plastic ? Maybe you bought the cams from wrong shop. Try buying from Hobie dealer.
sunvista wrote:
The replacement cams I keep buying are soft plastic.
Author:  MBounds [ Tue Sep 21, 2010 4:16 am ]
Post subject:  Re: yet another cam failure
The cams are made of a slightly flexible plastic - they have to be in order to work properly w/o breaking other parts of the system.

Repeated flexing in one direction (usually perpendicular to the hook) will cause the hook to break eventually.

This can be caused by a misalignment of the latch plate with the rudder cam. If the latch plate is angled slightly upwards, the hook on the cam will be too. Repeat a hundred times and the hook will break.

The upper hole in the rudder may be in the wrong place, causing the misalignment.
Image
Author:  sunvista [ Tue Sep 21, 2010 5:55 am ]
Post subject:  Re: yet another cam failure
MBounds wrote:

The upper hole in the rudder may be in the wrong place, causing the misalignment.
I think you've nailed it. I had taken that rudder off, as I stated in the opening thread suspecting something might be amiss. I went down in the garage today to compare it with another rudder I have and the upper hole is visibly higher. I measured it and it is off by a full 1/4". Its starboard twin broke on my second trip out this season when I was having trouble locking it down. I pushed harder than normal and the top of the rudder just snapped off at the upper bolt hole. That should have been a clue I guess.

When I bought this boat it was totally in pieces and was actually two boats minus a second set of hulls. Then I was given yet another set of parts (rudders, sails etc) from a guy who lost his boat in a storm. I guess just using all the best looking parts is not necessarily the best way to go.
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