Endeavourquay
New member
....full of water, whats the best solution please? at present on the hardstanding, due back in, in /forums/images/graemlins/blush.gif a week
Foam cored alloy braced fibreglassed sheathed rudder
- Thread starter Endeavourquay
- Start date
bigwow
Well-known member
Removal and rebuild, using ply in place of foam IMHO
30boat
N/A
Had a funny feeling when first read the title.Not a good combination of materials for a rudder.As said before rebuild with plywood but use epoxy.There was a good a good article on the making of a rudder by Andrew Simpson on PBO wich can be ordered.
If the stock is alloy I would replace with stainless steel,probably using tube instead of bar to keep weight down.
If the stock is alloy I would replace with stainless steel,probably using tube instead of bar to keep weight down.
oldsaltoz
New member
Re: Foam cored alloy braced fibre glassed sheathed rudder
Water in Rudders:
Entry is most common through the edge joint or via the steel shaft to fibreglass interface at the top of the rudder. Less common is the bottom of the rudder due to damage from grounding.
Foam filling can work provided the foam is closed cell, most rudders are mass produced by factories that specialise in them, very few boat manufacturers build their own rudders because a specialist can build them cheaper. Sadly most are filled with the cheap foam that turns to mush on contact with water.
Repairing a water filled hollow fibreglass rudder:
We a rule that no timber or standard poly resins or open cell fillers will ever be allowed below the waterline.
Using an angle grinder and a thin diamond cutting wheel, cut around the top edge, the rear edge and the bottom or the rudder and up the leading edge. Also cut away the area at the top of the rudder that steel and glass meet. Now take a small 6 mm drill and locate the rudder tangs by drilling holes at 50 mm in a grid pattern in one side of the rudder, do not drill right through to the other side, mark the holes that hit steel till you have a profile of the tangs.
Now use the same thin cutting blade to cut around the profiles on the same side you drilled, you may have more than two tangs. Once the tang area has been cut you can split the rudder by driving in small timber wedges, you may have grind the surface off the tang profiles if it's too tight, some are so tight that a cut just behind the shaft is required, but keep it as close to the shaft as possible or inspecting the tang welds is difficult.
With internals now exposed, clean out the old soggy foam, check that the tangs on the now lower side are well glassed to the lower skin, repair as required. Now inspect the welds on the tangs, repair as needed.
Ready to rebuild:
Start by adding a 60 mm strip of Bi-directional cloth around the edge of the lower half, leaving at least a 10 mm overhang outside, then fill the void with closed cell balloons, spheres or 'Q' cells, you can add sections of closed cell foam to reduce the mixing and application time; no need to be too fussy about the profile just get it as close as you can for now. Let this lot cure for at least 24 hours or more.
Ready for the next stage:
First up you need to remove the residue left by the epoxy curing process, just use a running hose, start at the top and work down, rub with a green plastic scotch-brite kitchen pad till the running water no longer forms beads like a freshly polished car. Dry it off and sand with a 250 grit paper, just enough to remove the high gloss is all you need.
Now pop the top side on and check how it fits, remove any high spots that may be holding it off, it should sit with no edge gaps with no pressure on it. Next have a look at how much more filler you will need to seal it without air trapped.
Mix more filler and a bit more to make sure when you press the top back on the air is squeezed out through the 50 mm drill hole grid we made earlier.
Do not worry about the tang area we cut out at this stage because the rudder has to cure again and get another wash and sanding as above.
Repairing the outer skin:
Start by grinding the edge of the original glass to a taper, not more than 15* degrees, so you should see about 25 mm of freshly ground glass around all cuts, do the same over all the drill holes.
Also grind the joint between the two halves on both sides and glass them up, don't try to wrap the glass around the trailing edge, it ain't gonna happen, keep the overhang to a minimum and they should stick together, you will grind off any dags later.
Pre-cut some cloth making sure that each bit is smaller than the last for large areas and small, you will need 3 to 4 patches for each drill hole and 5 or 6 for the repaired areas. Coat the area to be worked with resin before you apply the cloth, use a small consolidating roller to remove any trapped air and add the next larger patch, you can add several layers and avoid sanding by working wet on tacky if more than 6 layers are added. As each patch is completed let it go tacky and add a coat of resin, let this lot cure and wash sand as above after 24 hours.
Final stage is almost here:
After sanding you will have noticed some areas were low and you may have had a couple of high spots when sanding. We need to fill the lows with closed cell balloons, use a plastic ruler or other flexible item to follow the profile of the rudder and save yourself some sanding. Another cure and wash and sand and your ready to coat the holed side and joints, apply at least 4 coats of resin, wet on tacky will avoid washing and sanding between coats.
Sealing the shaft;
Get two rubber "0" rings that will fit snug onto the rudder shaft (Stock) slide them down to the area at the top of the rudder we cut off before, make a 2 mm gap between them and push in some Vaseline, now push them tight together and clean off any exposed Vaseline, using Bi-directional cloth rebuild the area to it's original profile.
Now you know why they charge so much to repair your rudder.
Hope this helps.
Avagoodweekend......
Water in Rudders:
Entry is most common through the edge joint or via the steel shaft to fibreglass interface at the top of the rudder. Less common is the bottom of the rudder due to damage from grounding.
Foam filling can work provided the foam is closed cell, most rudders are mass produced by factories that specialise in them, very few boat manufacturers build their own rudders because a specialist can build them cheaper. Sadly most are filled with the cheap foam that turns to mush on contact with water.
Repairing a water filled hollow fibreglass rudder:
We a rule that no timber or standard poly resins or open cell fillers will ever be allowed below the waterline.
Using an angle grinder and a thin diamond cutting wheel, cut around the top edge, the rear edge and the bottom or the rudder and up the leading edge. Also cut away the area at the top of the rudder that steel and glass meet. Now take a small 6 mm drill and locate the rudder tangs by drilling holes at 50 mm in a grid pattern in one side of the rudder, do not drill right through to the other side, mark the holes that hit steel till you have a profile of the tangs.
Now use the same thin cutting blade to cut around the profiles on the same side you drilled, you may have more than two tangs. Once the tang area has been cut you can split the rudder by driving in small timber wedges, you may have grind the surface off the tang profiles if it's too tight, some are so tight that a cut just behind the shaft is required, but keep it as close to the shaft as possible or inspecting the tang welds is difficult.
With internals now exposed, clean out the old soggy foam, check that the tangs on the now lower side are well glassed to the lower skin, repair as required. Now inspect the welds on the tangs, repair as needed.
Ready to rebuild:
Start by adding a 60 mm strip of Bi-directional cloth around the edge of the lower half, leaving at least a 10 mm overhang outside, then fill the void with closed cell balloons, spheres or 'Q' cells, you can add sections of closed cell foam to reduce the mixing and application time; no need to be too fussy about the profile just get it as close as you can for now. Let this lot cure for at least 24 hours or more.
Ready for the next stage:
First up you need to remove the residue left by the epoxy curing process, just use a running hose, start at the top and work down, rub with a green plastic scotch-brite kitchen pad till the running water no longer forms beads like a freshly polished car. Dry it off and sand with a 250 grit paper, just enough to remove the high gloss is all you need.
Now pop the top side on and check how it fits, remove any high spots that may be holding it off, it should sit with no edge gaps with no pressure on it. Next have a look at how much more filler you will need to seal it without air trapped.
Mix more filler and a bit more to make sure when you press the top back on the air is squeezed out through the 50 mm drill hole grid we made earlier.
Do not worry about the tang area we cut out at this stage because the rudder has to cure again and get another wash and sanding as above.
Repairing the outer skin:
Start by grinding the edge of the original glass to a taper, not more than 15* degrees, so you should see about 25 mm of freshly ground glass around all cuts, do the same over all the drill holes.
Also grind the joint between the two halves on both sides and glass them up, don't try to wrap the glass around the trailing edge, it ain't gonna happen, keep the overhang to a minimum and they should stick together, you will grind off any dags later.
Pre-cut some cloth making sure that each bit is smaller than the last for large areas and small, you will need 3 to 4 patches for each drill hole and 5 or 6 for the repaired areas. Coat the area to be worked with resin before you apply the cloth, use a small consolidating roller to remove any trapped air and add the next larger patch, you can add several layers and avoid sanding by working wet on tacky if more than 6 layers are added. As each patch is completed let it go tacky and add a coat of resin, let this lot cure and wash sand as above after 24 hours.
Final stage is almost here:
After sanding you will have noticed some areas were low and you may have had a couple of high spots when sanding. We need to fill the lows with closed cell balloons, use a plastic ruler or other flexible item to follow the profile of the rudder and save yourself some sanding. Another cure and wash and sand and your ready to coat the holed side and joints, apply at least 4 coats of resin, wet on tacky will avoid washing and sanding between coats.
Sealing the shaft;
Get two rubber "0" rings that will fit snug onto the rudder shaft (Stock) slide them down to the area at the top of the rudder we cut off before, make a 2 mm gap between them and push in some Vaseline, now push them tight together and clean off any exposed Vaseline, using Bi-directional cloth rebuild the area to it's original profile.
Now you know why they charge so much to repair your rudder.
Hope this helps.
Avagoodweekend......
boatmike
Well-known member
Re: Foam cored alloy braced fibre glassed sheathed rudder
And if you can manage all that in a week good luck!
A full rebuild is frankly the only solution. Bodge ups never work.
If the rudder is sound and not falling apart but has water in it, join the club. Many others are too but don't know it. If you only have a week, leave it and launch. Enjoy your season, but next year as soon as you haul out remove the rudder completely from the boat and take it indoors for a rebuild in the warm. Old Salt lives in Australia and probably doesn't realise it's still too cold for GRP work here at present outdoors, but it is!
And if you can manage all that in a week good luck!
A full rebuild is frankly the only solution. Bodge ups never work.
If the rudder is sound and not falling apart but has water in it, join the club. Many others are too but don't know it. If you only have a week, leave it and launch. Enjoy your season, but next year as soon as you haul out remove the rudder completely from the boat and take it indoors for a rebuild in the warm. Old Salt lives in Australia and probably doesn't realise it's still too cold for GRP work here at present outdoors, but it is!
Ruffles
Active member
Re: Foam cored alloy braced fibre glassed sheathed rudder
[ QUOTE ]
Now take a small 6 mm drill and locate the rudder tangs by drilling holes at 50 mm in a grid pattern in one side of the rudder, do not drill right through to the other side, mark the holes that hit steel till you have a profile of the tangs.
[/ QUOTE ]
oldsaltoz,
Could you use a DIY pipe detector to locate the tangs?
[ QUOTE ]
Now take a small 6 mm drill and locate the rudder tangs by drilling holes at 50 mm in a grid pattern in one side of the rudder, do not drill right through to the other side, mark the holes that hit steel till you have a profile of the tangs.
[/ QUOTE ]
oldsaltoz,
Could you use a DIY pipe detector to locate the tangs?
jwilson
Well-known member
Re: Foam cored alloy braced fibre glassed sheathed rudder
Scrape off antifouling and try shining a really bright light through the blade - at night try a trillion-candlepower power torch (the ones that the batteries go flat in 3-4 minutes). Might work, and much quicker than drilling.
Scrape off antifouling and try shining a really bright light through the blade - at night try a trillion-candlepower power torch (the ones that the batteries go flat in 3-4 minutes). Might work, and much quicker than drilling.
oldsaltoz
New member
Re: Foam cored alloy braced fibre glassed sheathed rudder
Yes you could, but you still have to drill the grid of holes to let the air out later.
Avagoodweekend......
Yes you could, but you still have to drill the grid of holes to let the air out later.
Avagoodweekend......
Bajansailor
Well-known member
Re: Foam cored alloy braced fibre glassed sheathed rudder
Thank you Oldsaltoz for that excellent and most comprehensive rudder repair schedule and method. I have copied and saved it for future reference, as I know it will come in very useful.
Re the subject rudder above, I am inclined to agree with boatmike re if it 'works' ok at the moment, leave it alone now until next winter.
Here is just a thought re a good way of finding out if it will 'work' ok or not - going on the philosophy of 'if it aint broke, dont fix it' :
You could perhaps shanghai a few heavy blokes from Rent A Mob, and get them to apply their collective weight sideways with enthusiasm to the rudder. Perhaps even throw themselves against it if they are rugby players and feeling keen.
If it can cope with that, then it should be ok for a bit longer.
And if it cant, well, it needs fixing.....
Thank you Oldsaltoz for that excellent and most comprehensive rudder repair schedule and method. I have copied and saved it for future reference, as I know it will come in very useful.
Re the subject rudder above, I am inclined to agree with boatmike re if it 'works' ok at the moment, leave it alone now until next winter.
Here is just a thought re a good way of finding out if it will 'work' ok or not - going on the philosophy of 'if it aint broke, dont fix it' :
You could perhaps shanghai a few heavy blokes from Rent A Mob, and get them to apply their collective weight sideways with enthusiasm to the rudder. Perhaps even throw themselves against it if they are rugby players and feeling keen.
If it can cope with that, then it should be ok for a bit longer.
And if it cant, well, it needs fixing.....
Endeavourquay
New member
Thank you all,
Lots of great advice, a customer of mine needed help and ybw responded with lots of great advice.
Down on the hardstanding last night there were quiet a few of us discussing water in rudders and every one of us has water in our rudder to various degrees, so its far more common than first realised.
YBW a great site for sharing advice and experience within the boating community, all around the world. /forums/images/graemlins/smile.gif
Lots of great advice, a customer of mine needed help and ybw responded with lots of great advice.
Down on the hardstanding last night there were quiet a few of us discussing water in rudders and every one of us has water in our rudder to various degrees, so its far more common than first realised.
YBW a great site for sharing advice and experience within the boating community, all around the world. /forums/images/graemlins/smile.gif
oldsaltoz
New member
Water in rudders and the effect:
If you have ever tried to lift a deep skeg rudder you will know they are very heavy indeed.
The void inside the rudder provides flotation that is largely lost when water enters and some buoyancy is lost.
In extreme cases this can cause a significant increase to weight at the stern and effect the performance in all conditions, as well as placing extra stress on the stock support equipment.
Leaving water inside a rudder is an open invitation for complications, degradation of existing fibreglass and any welds.
The worst one I ever saw was a skeg rudder that had broken all the tangs (poor welds) and rudder body was rotating on the shaft, but this rotation only started after the broken ends of the tangs had busted through on side.
Manufacturers and designers have a lot to answer for:
I've seen rudders made to follow the shape of the hull with only a very small gap between hull and top of rudder; supposed to prevent rope getting tangled. That's good, but building it with a solid tang just 12 mm below leaves little chance or a sacrificial beak. The same applies to the bottom of the rudder, you need a gap as big as the rudder type will allow, then if you do ground it, the bottom will break off and you continue on, rather have a bent shaft and possible hole astern.
The above should be checked if you plan to repair or rebuild your rudder.
There, I feel much better now I've had my little rant.
Avagoodweekend......
If you have ever tried to lift a deep skeg rudder you will know they are very heavy indeed.
The void inside the rudder provides flotation that is largely lost when water enters and some buoyancy is lost.
In extreme cases this can cause a significant increase to weight at the stern and effect the performance in all conditions, as well as placing extra stress on the stock support equipment.
Leaving water inside a rudder is an open invitation for complications, degradation of existing fibreglass and any welds.
The worst one I ever saw was a skeg rudder that had broken all the tangs (poor welds) and rudder body was rotating on the shaft, but this rotation only started after the broken ends of the tangs had busted through on side.
Manufacturers and designers have a lot to answer for:
I've seen rudders made to follow the shape of the hull with only a very small gap between hull and top of rudder; supposed to prevent rope getting tangled. That's good, but building it with a solid tang just 12 mm below leaves little chance or a sacrificial beak. The same applies to the bottom of the rudder, you need a gap as big as the rudder type will allow, then if you do ground it, the bottom will break off and you continue on, rather have a bent shaft and possible hole astern.
The above should be checked if you plan to repair or rebuild your rudder.
There, I feel much better now I've had my little rant.
Avagoodweekend......
Endeavourquay
New member
Thank you, Thats very good advice, my boats out of the water now and has a slow but steady drip coming from the rudder so I shall be looking carefully into that, I repaired a hole last year which is why there is so much less water in this year.
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