Crack in foam rudder all of a sudden

Crazy Dave Condon · May 29, 2018

Dark bottom paints especially will cause the rudder to heat up inside. Put them under cover

rgranger · May 29, 2018

Bummer

I would not use it without fixing first. You will get a water logged core if you do.

Grind out the crack and fair the edges. Then lay in several strips of fiberglass wetted with epoxy

Crazy Dave Condon · May 29, 2018

Send me a private message

isaksp00 · May 29, 2018

Dave is your go-to guy - contact him.

I had some gouges and minor edge cracks on mine. I drilled a hole, maybe 1/4, in the bottom and let it dry - tho I did not actually notice any water coming out. I used thickened West System epoxy on the gouges and enlarged the edge crack a bit with a rotary tool and small cutting disc, then filled with slightly thickened epoxy. Seems to have worked, tho I have no way of knowing if there is any water in the foam. The rudder does float.

mm2347 · May 29, 2018

drewsyntax said:
URGENT QUESTION

Guys - So my rudder was totally fine - I faired it a bit and then painted it with the interlux csc bottom paint (same as the boat).

Anyway - unltra hot day saturday 90 or so - the rudder was laying out cooking while we were painting the cabin. I sprayed it down with the hose to be able to pick it up.

Now looking at it - it has begun to split !

1. Did the hot weather cold water cause this ?
2. And how do I fix it ?

Fbglass guys says hes never seen the heat do that - usaully it happens from being waterlogged from a whole season- but the boats been on land?
pics attached + Thanks

Your problem is not unusual. Most rudders are layed up in two parts, then bonded together. Most boat owners would do well by properly adding a layer of glass cloth and reinforcing the edges of their blade. In the last few years I've repaired rudders from 3 Cats., 2 Odays, and 1S2. All had what looked like only too thin layer of chopped glass on the outside and a foam filled core.
Purchase your resin and supplies from a specialty supplier like Express Composites that can help w/ advice. (I am not associated - only have been a customer ) This is a project that Polyester resin has some benefits over expoy and a 6 to 8 oz E glass cloth would be a good starting point. Very little will be gained using Kevlars or Cabon and it can be more difficult to work with. For those that need added working time ask your supplier about a "summer catalyst" for added working time.
Does anyone know if rudders are designed to float? Of course, weight is always a consideration but a broken rudder will wreck your day.

rgranger · May 29, 2018

mm2347 said:
This is a project that Polyester resin has some benefits over expoy and

Hi @mm2347
I'd love to hear more about this. I always choose epoxy because I HATE the smell of polyester resin and epoxy is so easy to clean up with vinegar. But if there are good reasons to choose polyester, I'd like to learn.

Thanks in advance,
r

rgranger · May 29, 2018

drewsyntax said:
Thanks everyone!
what epoxy should i use for this ?

Lay up resin

mm2347 · May 29, 2018

Certainly poly. smells awful but the chemicals in the expoy hardners are probably more harmful. They just don't smell as bad. All resins are bad so whatever resin you chose to use cover up and wear a mask. If working in an attached garage or basement go with an expoy as the smell of poly or vinyl ester will permeate your whole house. Not enough to kill you but your wife will. If you chose expoy I would suggest the Mas brand expoy as it does not have the amine blush to deal with. Two of the advantages of expoy resins are they are better in adhesion and more flexible. Your rudder however will not flex much and has a large, flat area to bond to. Poly is more than adequate for this job. An overlooked problem when laminating w/ expoy is kind of a two-stage gell. As the resin starts to gell it warms up and gets a bit softer. Areas that have been difficult to get glass fibers to lay down (like the sharp edge of a rudder) are now in a warm, softened resin and lift up pulling air into the area. When Poly or vinyl esters start to gell it continues to get harder quickly. Overall I would use polyester resin as a first choice because 1) Its properties are more than adequate for this job. 2)it will get the job done faster. 3) has less reaction to the sun 4) less concern of what you can cover it with 5) poly is about 1/2 the cost of most expoys. 6) It is a bit stiffer. My thought on resins: The people at West have done a good job. They have gone after the Do It Yourself market supplying small lots of expoys and provide good info on their product--expoy. They spend their advertising dollars in that market. Most of the resin companys want to sell large orders and don't want a 1 quart order and then spend time on a couple of phone calls explaining how to use it.

Crazy Dave Condon · May 30, 2018

There are two resins. Polyester and vinylester. Manufacturers use vinylester resin on anything below the water line as not pourous like polyester resin. Cost more thiugh

Crazy Dave Condon · May 30, 2018

One important thing before you start repairs ensure that the centerboard or rudder is dry as sealin up moisture will be asking for trouble.

Crazy Dave Condon · Jun 4, 2018

Try to keep it out of direct sunlight please with that dark coated anti fouling paint. Keep me posted on. Suggest coating repair area with epoxy barrier coat

Crazy Dave Condon · Jun 4, 2018

Sure but lightly sand surface first. Keep out of sunlight anyway

JimInPB · Jun 4, 2018

drewsyntax said:
Thanks everyone!
what epoxy should i use for this ?

West System Epoxy seems to be the one that everybody trusts. If you go to large fiberglass supply places, they often have their own house brand of epoxy that is less expensive. I have seen very good results from talented people using the lower cost stuff. For the small amount that you are going to need, cost should not be a big issue.

As was already stated, don't just try to glue it back together. Fair it out, and add some glass in the epoxy. If it were me, while I was at it, I would build up the entire leading edge a bit, like maybe 3/16-1/4" & build up the leading corner on the bottom some more. That should make it more impervious to future collisions & soft groundings. Most rudders have scrapes & wear marks on the leading corner at the bottom. Planning ahead will likely save you more work in the future.

Crack in foam rudder all of a sudden

.

Attachments

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.