Rudder, breaking prevention

[LarryE-old]

We have had 2 boats, in this area, where the rudder snapped off.
I have heard of others.
Is there anything anyone has done, other than inspecting, to make the rudder stronger? I heard that someone drilled a hole, from the top, and inserted a SS rod.
Don't think loosing the rudder would be a lot of fun.

[J.D. Kloss]

I added a belt of heavier fiberglass cloth around the break point. It's below the cheek plates but above the water line so it didn't affect fit or hydrodynamics. I now also pull the rudder completely out of the water to prevent dragging across the bottom at my shallow mooring.

Jim Kloss
s/v Ambivalence
S2 7.9 #8

[Stef]

Shortly after I purchased #146 in 2004 I read a post here were the rudder snapped right at the head, the pivot hole being the weak point. Photo's really scared me. My rudder needed some work so there were instructions on adding some stainless steel bars in the head. It involved digging out a 1/2" wide groove on one side, to the glass on the other. I added (2) rectangular stainless bars about 3/8" thick and 2" or 2-1/2" wide, one on each side of the hole about halfway to the edge. One of the bars was quite long and went all the way down into the blade. Buried them in epoxy and reglassed.
The post must be somewhere on this site, along with the photo's.

[LarryE-old]

Stef,
I to have been told about the article on repairing the rudder. I have searched and didn't find it.
Maybe some of the tech guys could find it.
Want to do something as I sail shorthanded a lot now that I have retired.
Wish I still had access to the fab shop, many ways to fix it then.
Where I live, a lot of guys do a parts with Carbon fiber, space stuff. Maybe I'll ask them.

[stephenrwallace]

So does the break typically occur at the rotation pin within the aluminum cheeks or below where J.D. Kloss has added additional fiberglass layers? Is break a straight horizontal crack starting at forward edge of rudder or diagonal? Do others think a cord with pad eye anchor at lower rudder and cleat at top to strenghen tension(forward) edge would help? This would also serve as a rudder lowering mechanism.

[LarryE-old]

The two that I have seen snapped off right where the Alum plate ends.
In looking through the parts left over from boats that I have owned, I found a 1/2 in. SS rod 15 in. long.
Thinking of drilling down from the top and epoxying in.

[AJ Oliver]

I notice that when the boat is balanced (mast raked) I get less weather helm, and thus less stress on the rudder. I single hand a lot too, and tend to use a number three head sail - again, less stress. Seems to me that the BIG stress comes when the boat rounds up due to a puff or having too much head sail up.

[stephenrwallace]

The rudder sounds out as hollow when tapped with knuckle, ie foam core at the top stem extends into cheek plates. Installing SS rods would mean you'd probably have to open up rudder and cut out foam and clean fiberglass inner layer for good bond of epoxy bedding for new dowels if they are to be effective. Recessed, surface mounted SS straps as described by Stef may be more effective.

You can see the problem as stem extending into cheek plates is too short for long blade moment arm resulting in high bending forces. You'd have thought S2 would have tested rudder during original design and either increased stem height in cheek plates for increased resisting moment or increased shell glass layers for added strength. Seems that this is an infrequent problem perhaps occurring only in sustained high weather helm situations. Rarely mentioned on this board.

[LarryE-old]

Most of the boats will be 30 years old soon, if not now.
I think the rudder issue will become a bigger issue, as time goes by.
I don't see it as a small problem when 2 of the boats, out of 5, had the rudder snap off, at our club.

[Stef]

I have made a quick sketch of what I did. At the time I did this, most rudders were breaking at the pivot hole point. This fix will help with that, or below the head. I also removed the foam where the bars are, making it pretty rigid should it try to flex at the head. Bars go in sideways.

Document (7).png (30.01 KiB) Viewed 10381 times

[bwelden_395]

Attached is a picture of my rudder after breaking. Mine broke at the bottom of the cheekplates, presumably due to excessive pressure in big chop plus 30 years of age. This picture give a great cross-section view of the inside of the rudder.

Bart Welden
Peregrine, #395

[LarryE-old]

That's exactly where the two that I have seen looked like.
What is the round area. Looks like a support rod. Don't remember seeing that before.

[stephenrwallace]

Thanks for sharing this photo, Bart. The red foam core is obvious. Then there appears to by some kind of white filler puddy around foam core topped by thin layers of glass and gelcoat. The fractured rod or shaft is puzzling. Appears to be some kind of cast aluminum, doubt cast iron: obviously brittle and not very strong or ductile.

The fact that multiple rudders all of a sudden become a problem after about 30years suggests some kind of fatigue due to cyclic loading. If/when I do repair would look at aluminum strap about 2.5' on each side and recessing-in at cheeks and thru-bolted at botton coupled with partial replacment of foam and filler with solid epoxy such as MarineTex at cheek area.

[bwelden_395]

This is the first time I have seen the inside of an S2 rudder, so I assumed the aluminum tube was standard and provided the primary structural strength. Based on Larry and Steve's comments this is not standard? The tube is filled with the same material that surrounds the foam core. There is nothing on the rudder that indicates the tube was added after-market.

[LarryE-old]

I have pictures of the rudder off 107 when it broke. Broke at the pin hole.
There was no tube in it, just foam.
I have heard that S2 became aware of an issue and did some rudder changes. Maybe then the tube was added.
Would be interesting to know when