Tobago 35: Repairing a Fountaine Pajot Rudder

[Sonosailor]

Our FP Tobago 35 has developed a crack in the rudder. We took the rudders off to check the bearings, and one, a FP manufactured replacement that was shipped to us in 2007, has a narrow crack along its centre axis, from 4 inches down from the top of the front, along the top to the shaft, and 3 inches behind the shaft.

A look at another damaged rudder that I didn't throw away shows that the rudders are made from two fibreglass shells for the sides, and a yellow/white, solid and rather brittle resin inside. This suggests there is no fibre that was cracked or broken. The rudder is straight and true.

A note to FP about the issue came back suggesting the whole rudder be wrapped in fibreglass. That's a lot of work, and doesn't make sense if the glass wasn't across the crack in the first place.

I was thinking that I have two reasonable methods of repair:

1. Route out the crack about 3/4 inches with the right tool, and fill the area with an epoxy;

2. Grind the area down a quarter of an inch and taper back across the fibreglass shells and lay up fibreglass over the area, maybe 3 light matting and 3 light rovings, alternating; then sand down to original shape.

Of course, these options are not mutually exclusive, are they?

Any comments from you folks? Anybody got a good idea as to what tool to use to route out the crack? Any cautions?

[Dragon Lady]

Option 2 sounds like the best, I wouldn't just fill with epoxy. Be care full sanding back the repair to fair it, you are better off having the matting extending over the area at the expense of a bit of extra drag that you probably won't notice.
At least FP are talking to you.

[Cotemar]

Originally Posted by Sonosailor

Our FP Tobago 35 has developed a crack in the rudder.
A look at another damaged rudder that I didn't throw away shows that the rudders are made from two fibreglass shells for the sides, and a yellow/white, solid and rather brittle resin inside. This suggests there is no fibre that was cracked or broken. The rudder is straight and true.

A note to FP about the issue came back suggesting the whole rudder be wrapped in fibreglass. That's a lot of work, and doesn't make sense if the glass wasn't across the crack in the first place.

If the crack in the rudder was along the seam that holds the two half shells together than I would do as FP suggested and wrap the whole rudder in fibreglass. Yes it may be a lot of work, but it will be done right the first time with no worries in the future.

[DtM]

I agree with cotemar.

More time and effort but a permanent fix

[svquintana]

I have to disagree. If you grind the glass at the joint and make a proper repair, the repair can be stronger than the original panels.
Use epoxy and do not use glass mat (too bulky for a good repair). 12 or 18 oz biaxial would serve you best. Lay up about 36 oz of material over the seam and Bob's your uncle.
To prevent water seeping in by the shaft: Grind the shaft at the rudder and into the glass. Wet out a four inch by 12 inch piece of 12oz or 18 oz biax, roll it quite small (like a long worm) and wrap it tightly around the shaft at the rudder (epoxy only!). Jam it into the groove you made in the glass. to the Hold it tight to the shaft and glass (rudder) with packing tape until it cures. Then grind to a pleasant shape.

None of the previous info is valid if you're not using epoxy.

If you're repairing in canada, write me a note and I'll send you the biax.

Cheers.
Paul.

[Sonosailor]

The repair has to be done in Peake's Yard, Chaguaramas, Trinidad. I believe the supply of epoxy there is by West. Any particular epoxy? I am quite experienced with polyester, but seldom get into epoxy past the 5 minute tubes sold at corner stores.

[svquintana]

West system is a fine epoxy. It doesn't soak into glass as easily as polyester does, but you work it a little and it'll get there.

I'd use a slow or medium hardener in Trini, plus it gives you a little extra time to get it to soak into the glass.

Don't use anything heavier than 24oz, I'd use 12 or 18 oz biax to repair the seam. More layers of a lighter glass is stronger than fewer layers of a heavy glass. And NO MATTING. It just weakens the repair. Epoxy doesn't need matting like poly does.

When you buy glass, be sure there is no mat on it. Also, be sure it's soft and supple like a pair of jeans.

Get a sample and wet it out with your epoxy and be sure it goes translucent and pliable when wet out. If you've glassed with poly, you'll know what I mean. If it's not pliable and soft when wet out, either the binder has gotten old and hard, or the binder is not compatible with epoxy.

Most glass is compatible now days, and I'd say "all" biax and triax would be compatible.

Cheers.
Paul.

[Rapanui]

I did a repair of the rudder on my FP Maldives which is similar vintage to your Tobago with a similar problem, ie cracking along the joining seam of the 2 rudder shells. A friend with a Maldives had the same problem. Clearly FP had relied on bonding the 2 halves together and that did not prove adequate.

I overlaminated the join with woven roving and polyester and that held together fine for the next 10 years I owned the boat. As someone has pointed out, sheathing the whole rudder will not increase the strength across the join, you just need sufficient overlap. Fairing a whole rudder will take much longer than the first 70mm. Epoxy would probably be a bit stronger although I think polyester more than adequate. You should note that once you use epoxy, you cannot use polyester on the same area as it will not cure

[svquintana]

There you go, Rapanui fixed his with poly, and you're familiar with poly, the boat's built with poly, and poly wanna cracker!

1. Sealing the shaft with the "rope" (I think I said "long worm") trick won't work with poly.
2. Poly likes mat between layers of heavy roving.
3. 12 or 18 oz would still be my recommendation, but with mat.

Epoxy is stronger and more water resistant than poly, and is my preferred material. But if poly works, it's much cheaper and you're familiar with it so will likely do a better job.

+1 Rapanui.

Paul.

[Sonosailor]

Thanks to all. I will likely do the following, after reading all of this:


1. Drill small holes from the top of the rudder and drip in a low viscosity epoxy like Gitrot to try to eliminate voids in the rudder, and clamp it during curing;

2. Route out around the shaft and roughen the shaft, and install glass rope with epoxy around the shaft;

3. Lower the surface areas along the rudder top and within 50 mm (2 inches) of the edges, using a small B&D belt sander down about 2
millimetres. Sand rope at same time;

4. Install two layers of biaxial glass cloth using epoxy with slow cure, and then fill to the original surface with epoxy with filler;

5. Sand to fair the repair, and apply bottom paint.

I likely will not do more than roughen up the shaft, as I can't imagine how to do more than barely score it, and suspect I'll get a good enough job. Making a weak spot in the rather narrow shaft kind of goes against something in me.

It makes sense to go at both rudders, since I have both removed. As it is, I think this is easily a 2-3 day job for an amateur, for both of them.

So, um, comments, please?

[Rapanui]

Sounds a good plan in general.

One area you may need to look at is the rudder shaft to rudder body interface. Bonding to aluminium with epoxy is problematic and its generally recommended to wet abrade through the epoxy (messy)so that it cannot oxidise. Assuming you are after a watertight joint, maybe a polysulphide sealant/adhesive with a suitable primer may be better. Its also slightly flexible if you fill a deliberate gap between the glass and the shaft with it.

The other thing you may wish to do is drill a core through from the rudder shell to the shaft/webs to check their condition for corrosion before you spend time strengthening it.

Good luck, it will be a busy couple of days

[svquintana]

Sounds like a good plan to me.

Lightly abrading the shaft is all that's needed (sanding the shaft while it's wet with epoxy is always a good idea, after the initial sanding), there is no need to take away any "meat" from the shaft, just give the epoxy an abraded surface on which to bond.

"Wet sanding" the shaft with epoxy need not be a messy job. Simply wet the appropriate area of the shaft with epoxy, wrap an 8 inch long by 1 inch wide piece of 80 grit sandpaper half way around the shaft and pull back and forth on the ends of the paper. Walk around the shaft while "sanding" so you get it properly surfaced all the way around.

Good luck.
Paul.

[Sonosailor]

I got both rudders done, using the West epoxy system and two layers of 4" tape. It all went rather well, but with many steps. The most important component of the repair was the manufacture of a proper table out of a shipping pallet.

Thanks for all the advice and encouragement.