Rudder repair

[graemeB1]

Help
the rudder on my old trailer sailer, a french-design Beluga, is in serious need of some remedial repair therapy! Good news is, it is still intact and above the water line my yearly varnishing efforts have kept the plywood in very good condition. Below the waterline it is another story. The wood is getting waterlogged and slowly degrading with wet and dry rot when I dry it out for the winter months in my cellar, good news is it does dry out well to leave a robust major piece. So far it is still in one piece although there are clear cracks in the surface of the wood which do not seem to penetrate thru to the second layer of plywood - it looks like two sheets of plywood were originally bonded together before the rudder was cut out and shaped. The leading/trailing edges are not in great shape with wear/chamfering due to abrasion on my mooring.
So I am a beginner in boat repairs although relatively good at home DIY. I do not know whether to try to fabricate a copy in marine ply or should I consider applying an epoxy coating to preserve the wood on what I have and if so what materials should I use?
Any advice is glady received. Thanks! Graeme B

 

[Spuddy]

Hi Graeme. You say - OLD trailer sailer - so I assume function is your priority. Doubt if it is dry rot, or even wet rot. The first is evil and will have white threads in the fibres, maybe toadstools. Wet rot will blacken the wood and form a rectangular pattern of cracks. Both these are fungi. You are more likely to have old wood syndrome - hard life of soaking then drying out with regular bashes, which can form cracks down the grain even in ply.
Don't expect to encapsulate it in something to keep moisture out; even epoxy won't do that. The risk in skinning is that moisture will get through and be retained inside.
Does it look structurally sound in your judgement as an experienced bodger? If so and if it twere me I'd give it a good wash in fresh water, let it dry out gradually but not in cellar for a good few months. Then fill cracks with epoxy plus microballoons or colloidal silica depending on how long left in water. Front and back edges need a bit of attention - true them up a bit then protect with glass tape and epoxy. This should reduce moisture into endgrain. You could brush epoxy over the lot or use decent wood primer etc. Work out quantities and get stuff mail order - chandleries charge too much - although there's a very useful leaflet by West, I think, on their shelves.
My work is done here, I must go.

 

[oldsaltoz]

G'day Graham and welcome to the YBW forums with your first posting.

This repair is a pretty straight forward DIY project, however there are a few things you need to be aware of:

First and foremost the timber must be DRY and I mean DRY, any moisture left inside will be trapped and continue to damage the timber.

Having established that it's dry the next step is to remove and loose or soft areas, so a good sanding with an 80 grit paper should make short work of this, make sure you only ever sand with a block in your hand or you will end up with ripples in the nice new looking rudder.

After sanding you can fill any low areas and build up the leading and trailing edges with a mixture of epoxy resin and CLOSED CELL micro balloons or 'Q' cells, the latter cost less.

Being your first attempt at this sort of repair you may need to apply this more than once, as any low spots will show up when you sand it after it has cured (24 hours) or you will bog the paper.

When you have the required profile, add a layer of 250 gram cloth, make sure the cloth is designed for epoxy resin, do not use chopped strand mat (CSM) as it will soak up too much resin. Cut your cloth to shape first and plan to lay it over the leading edge and down each side, concentrate on covering the full length of the leading and trailing edges, the top and bottom areas will be needed to hold it in the horizontal position with the leading edge at the top.

place the cloth onto the wet resin and smooth out and wrinkles, then apply more resin starting at the top (leading edge), a small 80 mm roller suitable for use with epoxy is the best method, but a 50 or 80 mm brush can be used. Apply the resin to all the cloth then using a small grooved roller available from the resin retailer to roll out any excess resin. It is important that ALL the cloth is well wetted out, any light coloured areas will need more resin. Also note that rolling out excess resin will make it stronger not weaker.

Let this cure and sand off any high spots then apply cloth and resin to the ends as above, sand of the high spots when cured.

To provide a nice finish and reduce the risk of raw cloth strand ends being exposed after sanding, add a layer or Roving's by repeating the above layup methods. When cured lightly sand and add at least 3 coats of resin wet on tacky to avoid sanding between coats. If this is not done and the resin cures, you will have to sand it before applying the next coat, but you only need to remove the gloss a 200 grit is fine enough for this.

You can now apply a coat of epoxy primer then a light sand and apply a two pot polyurethane for a long lasting and very smooth finish.

The good news is that none or the tasks take long to perform, the bad news it you can't do the job in a couple of days.

One more tip, always wash epoxy coating in fresh water before sanding to remove the residue left by curing, use a plastic scourer, scotchbrite type is fine, run the water over the area and rub till water no longer forms beads, this only takes a couple of minutes and helps reduce delamination under stress.

Avagoodweekend......

 

[fdmarsden]

And, always, always, wear gloves when using epoxy.

 

[Wansworth]

Bodge it up for the summer and make a new one this coming winter.

 

[oldsaltoz]

Yes, Latex examination rubber gloves are good, also mix your epoxy in wide shallow containers, I use 2 litre ice cream containers, easy to clean.

You can use white vinegar to clean your rollers, brushes and containers, then finish cleaning with a little Acetone. If you want to test a roller or brush for suitability with epoxy, wash it in Acetone first, if it melts or falls apart you have not contaminated a pot of resin.

Avagoodweekend.

PS> I,m off to Cairns in the morning on the big silver bird, going to spend a week or two cruising the Great Barrier Reef on our Stevens/Lees Cat.

 

[William_H]

Trailer Sailers like many dinghies have a long rudder which is unsupported except at the top on the pintles and hence are susceptible to side loads snapping it off. If this is the case with yours then it is no fun sailing without a rudder.
Oldsaltoz has given some good advice. I would suggest puting a fairly thick fibreglass cover such that the wood only forms a male mold and all the strength is in the F/G. If you go that way you might like to sand or plane down the wood so the end result is not too thick. (To fit in the rudder cheeks if it is a swing rudder or lift rudder.) However it is not a bad thing to have a thicker rudder especially in the front one third as this give more resistance to stalling. If it is not a deep rudder this might be a good time to increase depth you will find it improves the boat handling especially in strong winds when beating. My 21fter has about 1 metre extending below the hull. I did in fact extend that by 2 inches to improve reaching under spin in strong winds.
To get more strength in the rudder put more glass strands running from top to bottom on both sides about 1/3 way from front to back. If you can get carbon fibre strands that will improve strength even more, (glass is good however).
If you go to a lot of fibreglass that is thick then polyester resin is OK. It doesn't stick to wood well but if the wood is only a mold then it doesn't matter. If the glass is not so thick however you must use epoxy.
When the wood is very dry you can coat it intially with resin with a thinner in it which will carry the resin into the wood. Follow that with resin and glass before the first lot cures. good luck olewill

 

[Lakesailor]

You can buy latex mechanic's gloves in boxes of 100 from motor factors (Partco, etc) for about £5.
Multitude of uses. Leave some in the car for breakdown etc, etc.
Always buy the large size. I don't know who can get the small ones on.

 

[ex-Gladys]

[ QUOTE ]
... also mix your epoxy in wide shallow containers, I use 2 litre ice cream containers, easy to clean.



[/ QUOTE ]

Our first epoxy "experiment" (bonding two bits of 9mm ply to make a base for the heads), we mixed up far too much.... It exothermed marvellously. SWMBO opened the kitchen window and heaved it into the garden PDQ. Taght us the only mix up small quantiites lesson. Another tip from a mate is don't hold the container underneath. the body heat from your hand will speed curing

 

[Lakesailor]

For weeny amounts I use the bottom of those square plastic milk bottles. Ideal and you don't need to clean them as there always be another along in a moment.

 

[graemeB1]

Dear All,
thnx fo rthe excellent advice, I'll give it a go! If you don't hear from me all went well, otherwise I'll be back... Wish me luck, Graeme B