rust on iron keel (i think its rust, it looks like it) - scuffed rudder need new one

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woozy-UK

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being a total noob and a noob with fin keels.

what is the best solution and plan i should do with this on my keel. i was scraping the barnacles off today really easily. on the keel i saw what looked like fungus or lumps. scraped it off to see what looks like rust.

thanks in advance

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xSenZKd.jpg


g9iUHql.jpg



as for the rudder as some may recall i grounded last july and was towed off thus losing the rudder. someone at the club kindly made me a rudder using guess work for the size and profile going with just the photos i took when i bought her in april. unfortunately it was very heavy to use and was tough to turn. the intros lean a lot too and with the original rudder it was easy to turn even at angles of 35+ degrees. this rudder its heavy to turn and a real arm and shoulder ache even when shes flat in calm weather. so is there anyone here that could make one. thank you

rudder scuff.jpg

original rudder-

frP3HS4.jpg
 
For the keel, I use one of these in an angle grinder (with gloves). Take any paint off and then chose one of the stop rust treatments followed by several coats of Internation Primocon and then the antifoul paint.

http://www.screwfix.com/p/titan-wire-brush-twist-cup-65mm-m14/81337

http://www.por15.com/

It won't stop the rust completely but if you do a good job the first year and you will only have to touch up the following couple of years. BTW that keel isn't too bad.

Pete
 
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The rudder looks like it has a larger blade area than the original. That would make it feel heavier but it is difficult to judge from the photos.

An increase in the balance area ( the proportion in front of a line drawn down through the pintles ) will make the rudder feel light with no "feel".

A rule of thumb for the balance area is that it should be between 10% and 15% of the total area.

EDIT

Seems like i have missread the op. The new rudder has a smaaler area if anything and very little balance are
 
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VicS said:
The rudder looks like it has a larger blade area than the original. That would make it feel heavier but it is difficult to judge from the photos.

An increase in the balance area ( the proportion in front of a line drawn down through the pintles ) will make the rudder feel light with no "feel".

A rule of thumb for the balance area is that it should be between 10% and 15% of the total area.
Click to expand...
Looks more like 30% to me hence my comment, it must be snatching the tiller & pulling his arm out of joint
 
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OP - which rudder pic is which? The bottom one is captioned as the original, but judging from the appearance of the rust patches on the keel the photo was taken at the same time as your photos of the keel "now".

In any case, maybe it's just me, but my reading of the photos is that the area forward of the pintle axis is rather less than 10% in both old and new.

As I see it, the line of the pintle extended downward intersects the leading edge of the rudder within a couple of feet of the waterline - no? If so there's only a tiddly triangle of rudder that's ahead of that line. If not I'm reading the camera angles and geometry all wrong - I guess that's possible.

OTOH it may well be that the "rake" of the whole rudder blade is greater in the new, which would certainly make it feel very heavy.

Seems to me that you need to do one or more of the following:
1) find a dimensioned drawing of the designer's original intention for this rudder
2) find another example of the same class and measure the rudder
3) assuming the present rudder is timber(?), and hence readily hacked about, embark on that time-honoured method of optimisation - trial and error. It looks to me as though you could readily experiment by moving blade a bit in its hangings, for the effort of a few holes drilled and maybe some work with chisel and plane. Half way through next season the front of that rudder might look like a colander, but it'll be hung right! Then either throw it away and get someone to make you a new one per your present plan, or tidy it up and call it good. This strategy will be greatly enhanced by getting the most experienced people you know to come sailing with you and assist in planning and executing the adjustments.

A.
 
As said the keel ain't so bad and is quite a commonm sight for iron keels. Just grind or sand down to clean metal. Treat with a rust converter type acid ASAP form grinding then epoxy or similar paint. then antifoul.
As I see the rudder it has far too much rake backwards and no ballance. (as said) Assuming that the rudder is free to turn easily out of the water then it is the lack of ballance ro if you can imagine you don't have enough leverage on the tiller. Consider that the tiller has perhaps 3 times the length compared to the rudder surface so you ahve a 3 times leverage. Now if the rudder rakes further back at the bottom the rudder has alonger arm so tiller has less leverage so steering is harder.
If you have plenty of steering power (rudder control when heeled over) then you could help the situation by carving off some of the aft area of the rudder. What would be far better however is to build up the leading edge of the rudder.This can be done with a block of wood carved to fit the leading edge and glued on. Make the block smaller so that you can lay fibre glass and epoxy over the bock and onto the existing rudder to stick it on.
You could try just epoxy glue. No terrible problem if it falls off.
The ideal rudder shape will be a vertical leading edge that is some distance (20% is a good figure) forward of the line of the pintle. This will make the rudderr nice and easy to use but still with enough feel.
Ballance here means that when you turn the rudder you have the load of the aft part of the rudder pressing on the water turning the boat. However if area is ahead of the pintle line the nose and effctivelywill move out into the water flow and be pushed aside which helps the deflection of the rudder. it is like the action of a rudder when going astern that it is likely to be snatched out of your hand and be flung to full deflection. Hence just a little ballance not too much. good luck olewill
 
Alan ashore said:
OP - which rudder pic is which? The bottom one is captioned as the original, but judging from the appearance of the rust patches on the keel the photo was taken at the same time as your photos of the keel "now".

In any case, maybe it's just me, but my reading of the photos is that the area forward of the pintle axis is rather less than 10% in both old and new.

As I see it, the line of the pintle extended downward intersects the leading edge of the rudder within a couple of feet of the waterline - no? If so there's only a tiddly triangle of rudder that's ahead of that line. If not I'm reading the camera angles and geometry all wrong - I guess that's possible.


A.
Click to expand...

Gosh you made me look again at the photos.
The top one is the new one, the bottom one is the old one ....... you can verify this by finding the OP's post from when he first asked for help in replacing the rudder.

http://www.ybw.com/forums/showthrea...udder-dimensions-please&p=4283444#post4283444

I'd now therefore say that the trouble with the new rudder is that there is insufficient balance area, even though it may be less raked than the original
 
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Alan ashore said:
OP - which rudder pic is which? The bottom one is captioned as the original, but judging from the appearance of the rust patches on the keel the photo was taken at the same time as your photos of the keel "now".

In any case, maybe it's just me, but my reading of the photos is that the area forward of the pintle axis is rather less than 10% in both old and new.

As I see it, the line of the pintle extended downward intersects the leading edge of the rudder within a couple of feet of the waterline - no? If so there's only a tiddly triangle of rudder that's ahead of that line. If not I'm reading the camera angles and geometry all wrong - I guess that's possible.

OTOH it may well be that the "rake" of the whole rudder blade is greater in the new, which would certainly make it feel very heavy.

Seems to me that you need to do one or more of the following:
1) find a dimensioned drawing of the designer's original intention for this rudder
2) find another example of the same class and measure the rudder
3) assuming the present rudder is timber(?), and hence readily hacked about, embark on that time-honoured method of optimisation - trial and error. It looks to me as though you could readily experiment by moving blade a bit in its hangings, for the effort of a few holes drilled and maybe some work with chisel and plane. Half way through next season the front of that rudder might look like a colander, but it'll be hung right! Then either throw it away and get someone to make you a new one per your present plan, or tidy it up and call it good. This strategy will be greatly enhanced by getting the most experienced people you know to come sailing with you and assist in planning and executing the adjustments.

A.
Click to expand...


Hi, the bottom picture with the whole view of the boat is the original rudder. The whole red rudder with white abrasions is the new one that was made by a handy man at the club.

Theres no plan in existence of the rudder. I tried. Very frustrating to find there were no plans not even from the Thomas family. the original rudder was two bonded sheets of marine ply, the new one is just soft wood joists covered with red coloured epoxy resin

Will read through the posts more when I get a moment.

thanks
 
VicS said:
Gosh you made me look again at the photos.
The top one is the new one, the bottom one is the old one ....... you can verify this by finding the OP's post from when he first asked for help in replacing the rudder.

http://www.ybw.com/forums/showthrea...udder-dimensions-please&p=4283444#post4283444

I'd now therefore say that the trouble with the new rudder is that there is insufficient balance area, even though it may be less raked than the original
Click to expand...
Wow me too. the original looks like a real "clunker" compared with the replacement.
I agree with VicS.
Why was the new one not made more similar to the original photo
 
Stop rust treatments only last a short time. The only way to fix it is grind the keel back to bare metal then apply two coats of zinc rich epoxy paint. It is a good idea to grind and paint one side of the keel then the other side to stop flash rusting caused by humidity, so do it on a day when humidity is low.
 
As said bu to reiterate. A fairly simple fix or at least improvement on rudder tiller loads would be to remove the rudder and then the pintles from the rudder. Cut a slice of the front off the top of the rudder 20mm is proably a limit before compromising the strength of the upper rudder. Then refit the pintles. (or is that gudgeons.) I mean the pivot part on the rudder itself. You may have to carve a bit off the top of blade so that it still clears the hull under the transom.
What this will do is bring the whole rudder forward. This will reduce the moment arm of the balde where it is pressed on by water flow. So reducing out of ballance or improving ballance.
This fix if you don't feel up to modifying the area and location of area of the balde itself. good luck olewill
 
William_H said:
As said but to reiterate. A fairly simple fix or at least improvement on rudder tiller loads would be to remove the rudder and then the pintles from the rudder. Cut a slice of the front off the top of the rudder 20mm is probably a limit before compromising the strength of the upper rudder. Then refit the pintles. (or is that gudgeon's.) I mean the pivot part on the rudder itself. You may have to carve a bit off the top of blade so that it still clears the hull under the transom.
What this will do is bring the whole rudder forward. This will reduce the moment arm of the blade where it is pressed on by water flow. So reducing out of balance or improving balance.
This fix if you don't feel up to modifying the area and location of area of the blade itself. good luck olewill
Click to expand...
Why not just add to the leading edge, a simple job with a preformed foam (or similar) section glassed over with woven glass cloth & epoxy, then fill & fair
 
sailorman said:
Why not just add to the leading edge, a simple job with a preformed foam (or similar) section glassed over with woven glass cloth & epoxy, then fill & fair
Click to expand...

I think that would be the sensible approach, if the OP had accurate information about how the rudder should be configured. Certainly getting info about the Apolloduck boat you linked to would help*. Otherwise it's a trial and error job, surely best attempted with temporary (but robust) stages of modification until satisfactory performance is achieved.

* best approach, I'd have thought, would be a fully side-on photo including some sort of scale measure. Drop this into Photoshop or similar image-editing software, then apply a grid over it to create a scale drawing.
 
I don't think you need worry too much about the 'trial and error' side of things; If you make a new blade which follows the same line as the pintles, but had say 30% in front of the pintle, the helm will be manageable. Err on the side of too much rather than too little area ahead of the pintle, as it is easy to cut wood off, and a rudder that is 'too' light will only encourage a lighter touch by the helmsman. Also any autopilot will last longer and work better.

Your current rudder has not only too little balance, but rather too much area too far back. My old Listang had a straight untapered aerofoil section rudder which slid up and down in a case. the back of the rudder was about 15-18" aft of the pintles. This gave a fairly heavy helm, but not unmanageable, except perhaps going astern. Your's looks to have a very long lever arm at the bottom. Every inch of rudder you can remove* from the bottom rear of your current arrangement will make a surprisingly big difference.

*Either by making the rudder more vertical or by lopping bits off, but don't go too far if moving the top pintle away from the rudder as you'll lose lateral support and bend the unsupported pintle bracket.
 
woozy-UK said:
Hi, the bottom picture with the whole view of the boat is the original rudder. The whole red rudder with white abrasions is the new one that was made by a handy man at the club.

Theres no plan in existence of the rudder. I tried. Very frustrating to find there were no plans not even from the Thomas family. the original rudder was two bonded sheets of marine ply, the new one is just soft wood joists covered with red coloured epoxy resin

Will read through the posts more when I get a moment.

thanks
Click to expand...

Keel: a: Angle grinder back to bare metal. b: treat with any 'rust converter' product c: fill any deep holes with epoxy filler & fair. d: Primocon or (better but costs more) Jotun epoxy metal primer. e: antifoul.

Rudder: Because the pic of the original was taken with the helm over to starboard, it's misled your handyman. As others have said, it needs more area added ahead of pintles. However, I would not modify the new one, because it's made of softwood. It will definitely snap off at (or just below) the lower pintle sooner or later. It needs to be made of marine ply and resin sheathed.

If I can also make another suggestion for a (fairly simple) modification, based on experience:

I had the biggest (33ft) hull-chined sister to your Intro (& her other sisters the Quarto, Hydro and Toledo). She suffered from having an aft swept rudder like yours, but with no 'balance' area ahead of the rudder stock. When well heeled, she became very heavy on the helm and the rudder would eventually 'stall out' because only half of it was immersed - her wide beam & pinched stern made her stick her bum in the air :o

If you look at the 2nd photo, you will see she has a 'bustle' - just like mine did. This is the hull line aft of the keel that looks a bit like a saggy bum, rather than a straighter line flowing up to the transom. It was designed to cheat the IOR rating system. However, when heeled, the water rushes through the gap between this bustle and the rudder, disturbing the flow over the rudder. I attached a grp 'blade' to the centreline of the hull between the bustle and the rudder. It was about 200mm deep at the rudder end, tapering to zero where it faired into the bustle. I cut it to shape from a 50mm wide 'plank' of closed-cell foam using a sharp knife. I then attached it to the hull with epoxy resin, then reinforced with polyester resin & glass cloth and faired it. I then gave it a final coat of epoxy resin. Not only did it vastly improve upwind performance & control, it also made her track straighter downwind. After we did this we won a lot of races :encouragement:

I hope this helps.
 
i apologise in the delay with replying. thank you all for the fantastic replies. to be honest a lot of the terminology went over my head. I have a couple of other intro owners now who are going to send me their rudder dimensions, and another willing to meet me to loan me his actual rudder to work from. as for the "new" one. basically what your saying is i need to have more going under the hull (tiller side) and less on the water side.

my diy skills are **** so am hopefully looking for someone else to make one out of marine ply for me and ill use the "new" one to experiment with and also keep as a spare inside the cabin.

very interesting reading about the "sister" boats of the intro. i was just aware that the Sonata was based off it. though the intro is 10 foot wide.

also to add one of my stanchion bases broke into two when i was in the thames trafalgar race. they seem to be £30 a go. crazy for just a base and a bit of metal.


thanks also for the advise on the rust of the keel. that puts my mind at rest, thought it was all rotten when i saw it.
 
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