rudder repair: kevlar??

[siroismi]

Hi all

I'm in the process of tackling a winter project which is to repair my rudder. I have watched over the last five years or so, the apearance of hairline cracks at first on the bottom third, across and both sides. Pretty much at the level where the rudder stock (fiberglass) ends inside. Year after year new cracks appeared in no particular patterns, and more and more toward the top. Every spring I seamed to notice new ones eventough from the time it started, I started drilling weep holes at the bottom every fall. Never seen any drainage from hole, but one or two spots along crack would weep.

So this year having brought my boat home, I decided to do something about it. Took the rudder off the boat. Brought it home. Sanded the gelcoat off it. Now seeing the full extent of damage. I Vee grinded all the crack, drilled some holes. No drainage per se, but 3 or 4 humid circles around a few holes.

Rudder is foam cored and laminate seems to be only chopped mat (or gun!??). As I said fiberglass stock, tabing ??metal?? inside.

My plan is to let it dry more, not necessarily open it more. Then was thinking of laminating two layer of kevlar 5 oz with West System Epoxy.

Initialy I was convinced it was water inside and freeze thaw cycle responsible. Now wandering if it wasn't more stress?? I'm not an expert..
Does this plan sound good.? Should I stick to fiberglass (fabric vs stich-mat vs ?) or kevlar or hybrid? Epoxy or vinylester resin?

Any advices?

Thanks in advance

Michel

[Pete7]

Michel,

I would stick with epoxy and cloth because it's a known material. Kevlar is expensive and needs special scissors to cut it for a start. You might also find the strength is directional, whilst you will want uni-directional.

Keep it simple (kiss) approach for me.

Pete

[Bash]

check out this blog Fiberglass Materials: Exotics

[atoll]

i wouldnt bother with kevlar,but would reccomend doing a full rebuild on the rudder ie split the two halves,take out the soggy foam,inspect the stainless shaft and stiffners,then reassemble using pu foam and reglassing the two halves,only this way will you be sure of a proper repair,glassing the outside ,if the inside has deteriated is not going to fix the problem

[akio.kanemoto]

Originally Posted by siroismi

Hi all

I'm in the process of tackling a winter project which is to repair my rudder. I have watched over the last five years or so, the apearance of hairline cracks at first on the bottom third, across and both sides. Pretty much at the level where the rudder stock (fiberglass) ends inside. Year after year new cracks appeared in no particular patterns, and more and more toward the top. Every spring I seamed to notice new ones eventough from the time it started, I started drilling weep holes at the bottom every fall. Never seen any drainage from hole, but one or two spots along crack would weep.

So this year having brought my boat home, I decided to do something about it. Took the rudder off the boat. Brought it home. Sanded the gelcoat off it. Now seeing the full extent of damage. I Vee grinded all the crack, drilled some holes. No drainage per se, but 3 or 4 humid circles around a few holes.

Rudder is foam cored and laminate seems to be only chopped mat (or gun!??). As I said fiberglass stock, tabing ??metal?? inside.

My plan is to let it dry more, not necessarily open it more. Then was thinking of laminating two layer of kevlar 5 oz with West System Epoxy.

Initialy I was convinced it was water inside and freeze thaw cycle responsible. Now wandering if it wasn't more stress?? I'm not an expert..
Does this plan sound good.? Should I stick to fiberglass (fabric vs stich-mat vs ?) or kevlar or hybrid? Epoxy or vinylester resin?

Any advices?

Thanks in advance

Michel

I had a similar problem earlier this year during my haulout - but probably of a more impressive nature.

The entire rudder's foam core was soaked.

So I cut the skins off both sides, leaving the trailing and leading edges intact,dried with a hot air gun (paying $200/day for hardstand means I can't wait 2-3 months to let dry properly. :\

Ground all bonding edges back with a taper.

Place rudder on side, pour in two part foam bit by bit and fill every nook and cranny.

Rasp/sand/grind foam back to shape.

Mix up microballoons/West 411 in a thinnish mix and trowel all over the foam to get a smooth, non-porous surface.

Grind/sand back to shape.

Another mix of thin 411, trowelled on and packing the remaining porosity etc...

Grind/sand/fondle to shape.

Then layup glass, overlapping on leading/trailing edges: 1 (or two? can't remember) layer of 750gsm triaxial, then 2 layers of 450 gsm biaxial.

Grind/sand back to shape.

Fairing compound.

Grind/sand/fondle...

4 coats of Barrier coat.

2 coats of antifoul.

voila...

(don't use anything but epoxy btw, these are all secondary bonds)

[atoll]

Originally Posted by akio.kanemoto

I had a similar problem earlier this year during my haulout - but probably of a more impressive nature.

The entire rudder's foam core was soaked.

So I cut the skins off both sides, leaving the trailing and leading edges intact,dried with a hot air gun (paying $200/day for hardstand means I can't wait 2-3 months to let dry properly. :\

Ground all bonding edges back with a taper.

Place rudder on side, pour in two part foam bit by bit and fill every nook and cranny.

Rasp/sand/grind foam back to shape.

Mix up microballoons/West 411 in a thinnish mix and trowel all over the foam to get a smooth, non-porous surface.

Grind/sand back to shape.

Another mix of thin 411, trowelled on and packing the remaining porosity etc...

Grind/sand/fondle to shape.

Then layup glass, overlapping on leading/trailing edges: 1 (or two? can't remember) layer of 750gsm triaxial, then 2 layers of 450 gsm biaxial.

Grind/sand back to shape.

Fairing compound.

Grind/sand/fondle...

4 coats of Barrier coat.

2 coats of antifoul.

voila...

(don't use anything but epoxy btw, these are all secondary bonds)

ditto that,if you have somewhere nice to work it is not that much of a complex repair,and at the end of the day you have piece of mind if ocean voyaging,the rudder has to work 24/7.............

[siroismi]

Thanks guys for opinions,

Atoll- I see your point, altough I don't like to hear it ...thanks.

Shaft is fiberglass for shure. I'm not even certain there's any metal (tabs) inside. Core is definitely not soaked but there's definitely been water inside. But then again how many 10 years old rudder have absolutely no water in it.

I appreciate all your opinions, it's weighing in the balance.

Michel

[MacG]

I am sincerely shocked hearing the sums of money one has to pay for the privilege owning a boat in the US.
200 US$ for a day on the hard is totally unheard of. I pay such prices not even per month for a hard here in Holland. Also other indications show that boaters in the US are falling victim to a society of graverobbers. Now I understand the long distance haulages to get a boat on one' s own yard.

Atoll is more or less right and not less his statement that a rudder has to work 24/7.
Stay away from Kevlar. It is an unsuitable material, when in touch with moisture it loses half it's strength.
Use medium layers of E-glass or S-Glass and conform your rudder to a full laminate, skip any sandwich because it does not make any sense to save weight below the waterline.
A designers stupidity. Make sure that you align the two halves very well.

[atoll]

some photos would be great,is this a transome hung rudder? or conventional skeg and shaft.
so easy to make wrong assumptions due to quick descriptions of the problem!!!!

[siroismi]

It is a spade rudder.

I finaly succeeded in uploading pics. I had to resize them myself.

You see a number of hole drilled to the core. The only wetness I've seen is what you see and also along the seam on leading edge.

Would you guys still split it open?

Michel

[akio.kanemoto]

Originally Posted by MacG

I am sincerely shocked hearing the sums of money one has to pay for the privilege owning a boat in the US.
200 US$ for a day on the hard is totally unheard of. I pay such prices not even per month for a hard here in Holland. Also other indications show that boaters in the US are falling victim to a society of graverobbers. Now I understand the long distance haulages to get a boat on one' s own yard.

Atoll is more or less right and not less his statement that a rudder has to work 24/7.
Stay away from Kevlar. It is an unsuitable material, when in touch with moisture it loses half it's strength.
Use medium layers of E-glass or S-Glass and conform your rudder to a full laminate, skip any sandwich because it does not make any sense to save weight below the waterline.
A designers stupidity. Make sure that you align the two halves very well.

Actually, this is Syney, Australia. The world's most expensive place. :\

I don't the those lucky Americans are paying this much!

As for aligning the halves - I wouldn't split it - leave enough in the leading and trailing edge and just rebuild the skin. It's not worth the effort in trying to keep the skins intact and taping over etc..

[akio.kanemoto]

Originally Posted by siroismi

It is a spade rudder.

I finaly succeeded in uploading pics. I had to resize them myself.

You see a number of hole drilled to the core. The only wetness I've seen is what you see and also along the seam on leading edge.

Would you guys still split it open?

Michel

There's no pic there, but it's like dropping the keel. Do you want peace of mind?

I dropped my keel and redid it for "warm fuzzy feelings" just so I could be sure that everythig was well...

So if you have any doubts, just cut the sides off the rudder, refoam, reglass per my instructions above.

Especially if you can work somewhere nice, it's not that hard or expensive. Took me three days, and 99% of that time was waiting for things to cure.

[motion30]

how about this..... drill with a hole saw several 2'' inspection holes see what the inside looks like before you cut it in half maybe dig out foam and fill with resin and filer then glass the outside with cloth and expoy

[siroismi]

Sorry, pics not attached to previous post

[atoll]

looking at the photo,and since it has a composite shaft that is probably epoxed to the outer moulding i would think that the chance of a catastrafic failure is very small even if the core was totally saturated.

i would recoat with epoxy and 250-350 gm matt ,fair ,prime ,anti- foul cant see there being an inherent pproblem unless there have been other documented failures of the main shaft.