Made a Rudder

[PDA1]

I just finished making a rudder for my boat (Catalina 30).

The total cost was around $800 or so.

It was made following the procedure shown at the Foss foam and Jeffa companies sites. The Jeffa (Denmark) rudder making video was very helpful.


That is;

- The old rudder was used as the pattern to make a split mold. The picture of the mold below shows how good I am at adding pigment to resin.

- 16 lb (cu ft) foam poured into the mold containing the new rudder post and armature.

- Rudder post- 316L (Schedule 80) 2" (1/4" thick wall both sides).

- 1/4" plate 316L Stainless "armature" (I call it a flag) welded to the post.

- 9 "keying" holes Laser cut into the armature.

- Foam glassed over with 2 layers 1708 biaxial cloth.

- one finish layer of 12 ounce cloth.

- 3/8" "eye-bolt" epoxied into the rudder post so I can remove and install the rudder while in the water and not have to worry about it dropping to the bottom of the ocean.


The old rudder made by (I assume) Catalina was glassed over "bondo" and very weakly constructed. 1 layer of Coremat was used with a single woven glass layer finishing it.

The rudder post was cheap 316 Stainless with 1/2" 316 Stainless bars welded to the post. The bars were bent and then welded to the rudder stock. They were severely degraded at the bends probably from moisture.

The "bondo" was entirely cracked into 2-1/2" pieces and show signs that the cracking occurred many years ago.

I had considered using Carbon fiber cloth and a Carbon fiber post and armature but CF is electrically conductive and a galvanic reaction would be established. So, I stuck with 316L as it's easier to work with and won't "flail when it fails".

The only problem remaining is how to electrically isolate the Edson radial from the rudder post.

Lessons learned-

Making a rudder is very easy

Use West System epoxy

No matter what rudder stock material you use it will eventually fail in salt water.

[weavis]

Great Job!

[PDA1]

Even though the original rudder by Catalina had a "bondo" core it took a lot of hammering to break that stuff free from the fiberglass once one side of the rudder was ripped off using a saw, chisel and hammer.

In other words, for those of you with similarly constructed rudders I wouldn't worry about your rudder falling apart while making a turn....so long as the rudder's glass shell isn't cracked.

[colemj]

Originally Posted by PDA1

The picture of the mold below shows how good I am at adding pigment to resin.

Originally Posted by PDA1

The only problem remaining is how to electrically isolate the Edson radial from the rudder post.

Why is this necessary?

Mark

[PDA1]

Originally Posted by colemj

Why is this necessary?

Mark

The Edson radial is Aluminum. My rudder post is Stainless Steel. Those 2 materials set up a Galvanic reaction that will corrode the Aluminum.

The 4 Stainless steel bolts that secure the split Edson radial to the rudder post caused the Aluminum to corrode and essentially lock the bolts in place. They were extremely difficult to remove for fear of cracking the Aluminum casting. One bolt (3/8-16) did break when I removed it.

I cleaned up the radial and coated it with several layers of Shark Hide.

[colemj]

Ours is exactly the same. I just coat the SS bolts with Tefgel and no problems. The actual contact between the post and the radial halves isn't a problem. The bolts are, but Tefgel or similar solves that problem.

Mark

[PDA1]

Originally Posted by colemj

Ours is exactly the same. I just coat the SS bolts with Tefgel and no problems. The actual contact between the post and the radial halves isn't a problem. The bolts are, but Tefgel or similar solves that problem.

Mark

Yes, there is a problem in the post/radial connection.

That aside, the entire radial was moderately oxidized and had to be cleaned up. I had considered getting it anodized but the cost was too much.

At the end of the season I'm going to remove the rudder and take it and the radial home for warm storage.

I forgot to mention- I'm going to pour bees wax into the remaining top portion of the rudder post to prevent any water from seeping past the epoxy which secures the eye-bolt I epoxied in place (see the first post for an explanation of this bolt). There is very little chance any water will get down into the rudder from inside the rudder post- it would have to seep past 7-1/2" of solid epoxy and 22" of closed cell 16 Lb foam.

[TeddyDiver]

I hope you have the radial in the dry side of the hull if so no problem about galvanic isolation...

[PDA1]

Originally Posted by TeddyDiver

I hope you have the radial in the dry side of the hull if so no problem about galvanic isolation...

'Hope you're right. It does get wet but it's not in constant exposure to water. The radial is underneath a removable cover just behind the helm (wheel). If it rains or a wave hits the walk-out transom water can then flow up and into the radial/rudder post area.

While doing research for my rudder project I searched everywhere (on the web) for days and days looking any kind of helpful information. General rudder construction is this; Glass covered foam with a 316L stainless post and armature. There isn't much debate about those materials- only the size and amount of each.

However, preserving the post and armature from degradation is open to much discussion and everyone has an opinion. I came upon this post at MorgansCloud.com;

"Dave Benjamin July 11, 2013, 8:00 pm Henri Amel correctly determined that there was no way you could ever keep a rudder dry long term so he created a “wet rudder” where water simply flows through and there’s a zinc to protect it. Thus you rarely hear an Amel owner crying the blues about a rudder. In fact I’ve never heard of an Amel suffering a complete loss of steering ability."


"I am comfortable with a spade rudder if the engineering is solid. A balanced rudder would be a plus. Love the idea of a tiller."


That's the end of the post from MorgansCloud.com



Amel boats are very much to be admired and I wanted a Super Maramu but circumstances dictated otherwise.

[antoha]

maybe you could schlep a sacrifical anode onto the quadrant? zinc (or magnezium) is going to go before aluminum. so if you have a way of securing it onto the quadrant you're in business - just keep an eye and replace when necessary?

[PDA1]

Originally Posted by antoha

maybe you could schlep a sacrifical anode onto the quadrant? zinc (or magnezium) is going to go before aluminum. so if you have a way of securing it onto the quadrant you're in business - just keep an eye and replace when necessary?

Sounds good to me. It shouldn't be too difficult. There's plenty of area to mount it. I had considered using Silver filled epoxy and securing an anode to the radial. Bolting would be a lot easier.

Thanks.

[antoha]

i suspect you can even mount the anode it on the steering wheel - quadrant connects to steering cables connects to sprocket connects to shaft connects to steering wheel. there's grease everywhere but i doubt that breaks the electric cirruit (there's a simple way to test - with an ohmmeter, if one wire on quadrant and other on steering wheel has finite resistance, there's no disconnect)

[PDA1]

Originally Posted by antoha

i suspect you can even mount the anode it on the steering wheel - quadrant connects to steering cables connects to sprocket connects to shaft connects to steering wheel. there's grease everywhere but i doubt that breaks the electric cirruit (there's a simple way to test - with an ohmmeter, if one wire on quadrant and other on steering wheel has finite resistance, there's no disconnect)

That sounds like a good idea and much simpler too.

I'll give it a try.

Thanks

[colemj]

It is unlikely a zinc removed from the actual corrosion point will be effective. It is actually unlikely a zinc at the actual corrosion point will be effective unless the entire thing is often immersed in water. Without an electrolyte solution connecting the parts, any zinc put on will only protect that part immediately contacting the zinc - and even then, not very well. This is why steel structures and components are completely galvanized instead of just bolting a zinc to them somewhere.

You might try spraying the components with cold zinc galvanizing spray before assembly. Alternately, tefgel and the like is very effective at isolating metal parts.

Mark