Foam cored rudder rebuild

[davidjet]

Hi guys I'm rebuilding my rudder. Do I have to remove the old foam? It is still hard. Or can I fair and glass over it? Anyone know where to buy cheap urethane foam? It's hard to tell from the pictures but the fiberglass separated from the foam. My first cut was the seed pic, it shows white stuff witch I think is salt. The de lamination was so bad I wanted to check the super structure, ss shaft and ribs. I found some rust and a little pitting.

 

[Apex]

if dry and in good repair, why not keep it? Someone with actual knowledge on the subject may need to chime in, but I would guess you can simply glass over. Will resin penetrate into the foam?

 

[njlarry]

What does the center pic show?
Why did you open it up?
If the foam is dry no need to replace it. While it is open drill down to the lowest web to see if any sign of crevice corrosion from past, should be fine if dry.
search my post on Is this how water got in my rudder , your deck plate may need sealing.

 

[sailingseadragon]

David,

I thought this might be helpful the Boatworks Today video on rebuilding a foam core rudder.

https://www.youtube.com/watch?v=MRXNnFx7DBQ

Garner

 

[Richard Bryer]

I had a spot of de-lamination on the stbd side of the rudder about the size and shape of a football when we bought the boat. I ground out the gelcoat and glass and about 1 inch at the deepest of the foam- I took out all the discolored foam down to solid white. I then built the pocket back up with epoxy and matting cut in increasing size pieces. Covered the whole rudder with a layer of fine mesh cloth and epoxy. Put 2 drain holes in the bottom which I plug with bedding compound each spring before launch and re-drill each fall after haulout. The rudder has been just fine now for over 10 years.

 

[Barnacle Bill]

Just remember you cannot successfully fiberglass over wet anything. So dry it out. The foam you should use is a closed cell foam, but why not just take some polyester resin and thicken it with microballoons (very light mixture/easy to do/easy to sand) and pour it into your voids and when it cures, grind it smooth and then fiberglass over it with polyester resin and cloth or matt?

 

[Bad Obsession]

When I bought my Catalina 30 it had a delaminated rudder. It was replaced as part of the purchase agreement.

Here is the thing, you may be able to fix it but considering how crucial a rudder can be, wouldn't it be better to replace it. You have it off so that is the big thing, the rudder itself can't be that bad for a price.

 

[Tom J]

When I bought my Catalina 30 it had a delaminated rudder. It was replaced as part of the purchase agreement.

Here is the thing, you may be able to fix it but considering how crucial a rudder can be, wouldn't it be better to replace it. You have it off so that is the big thing, the rudder itself can't be that bad for a price.

Amen to that. We were motoring north on the Intracoastal Waterway when a boat sailing south did a sudden 360 degree turn in front of us, and went dead in the water. As we approached him, we spotted his rudder floating toward us, so we lassoed it and towed it to his boat. As he tossed our line back to us, he explained that he had just paid $1600 to have the rudder repaired. Ouch. He was not a happy camper.

 

[Gunni]

Rudders have a lifetime. This one has reached the end. Years of saturation, too much corrosion.

 

[RichH]

Be careful here with the replacement of 'core', as most foam filled rudders are designed for neutral or sometimes even negative buoyancy. If the repair is far different from that original buoyancy you can affect trim of the boat (end to end) and which may affect how the boat behaves in waves (hobby horsing, etc.).
As to what looks like 'salt', thoroughly remove it as it has the potential to 'uptake' water from gaseous 'water vapor' permeating through the fiberglass.
Id suggest a 'test trial' of 'gluing' the existing foam to whatever youre using (probably epoxy) to assure a good 'bond' to that OEM foam ... to validate that the 'aged' core to FRG structure can be done.
Just a small 'coupon' of old core, epoxy it with fiberglass, and then attempt to break that bond. If the 'test' allows it to easily 'rip off', then consider to 're core' the whole damn thing.

 

[DannyS]

I repaired mine

Here's the link to the thread...
http://forums.oday.sailboatowners.com/showthread.php?p=744783&highlight=rudder delamination

 

[DannyS]

Upon further review of your photos, I'd be inclined to buy a new one. Mine delaminated but it didn't look as rotten as yours does. The foam was still rock hard.