Schilling Rudders Again

[DHutch]

As some of you might know, emilyanne is due to be in drydock shortly (15th-21st april).

- And while she's in there, we plan to equip her with a Schilling rudder, to experiment with the priciple, and hopfully improve her handling.

 

The plan would be to fabricate, or have fabricated, parts which would then be welded to existing rudder to create the desired affect.

 

I have a number of photos of simular rudders, one on a 30ft steam launch, and on off the stokeboats boat seen at the iwa bealepark rally this year.

- However, if anyone has any further infomation on the shape/size/espect ratio we should be aiming for for optimum performance, i would be very interested to hear from you.

- The nominal dimentions of the rudder currently are 600*620mm (H*L) including a 120mm balence plate. And these would remain the same

 

Here are the photos i have, let me know what you think.

 

 

 

The is also *some* infomation on becklers site at http://www.schilling-rudder.co.uk/ (click: products, schilling)

 

 

Daniel

 

 

 

Past thread:

http://www.canalworld.net/forums/index.php?showtopic=970

[fuzzyduck]

or as an alternative what about a Schottel drive?

[DHutch]

Yeah well, that might have to wait till the next boat...

[chris w]

I hadn't heard of these and was intrigued so I did some web research including this article.

 

It seems, from the many articles, that for the fishtail to work at low speed the rudder itself needs to have an aerofoil shape not just a flat plate, but I may be misinterpreting the information.

 

It sounds like a great experiment though.

 

Chris

Edited March 12, 2007 by chris w

[NB Willawaw]

The fishtail varies the water speed over the surface if I remember rightly, which gives it

the special pushing properties for tighter turns.

Am currently working (electrically) on a boat which will have a Becker flap rudder.

As the rudder goes harder over, so the flap angle varies, so you can end up with a 80 degree

angle on the vane for a 35 degree main rudder surface angle.

[chris w]

It appears (though I may be out of kilter on this) that the aerofoil shape causes the water flow to hug the surface of the rudder and the rearside fishtail shape produces a vector force outwards giving the enhanced turning capability. The top and bottom plates seem to be there to prevent the aerofoil flow from dissipating over the top and bottom of the rudder before the fishtail back section has had time to do its work.

 

Chris

[DHutch]

Sounds fiar enough, thats a good link chris, ive found a number of other sketchy bits of infomation, but thats the first thats had a actaul digramatic view of a suggested profile.

 

I think there comments tally with the two ruddered ive photographed above, and the odd few other photos ive come across. As you say, the aerofoil on the leading edge does seam to want to be quite a bit wider the 'fishtail' on the trailing edge.

- Although there does also seam to be the 'Gurney flap' idea also mentioned on that thread. Which goes some way to explan my friends response of "yeah, some people weld a lenght of scaff pole to the back of there rudder.." - Apprently just that can help.

- Becker flap rudders (also on beckers website, see link above) do look very good, and you can certainly see clearing how it work to improve things. However i think its a little out of our scope, for now anyway.

 

 

Daniel

[John Orentas]

Hi Dan.

 

Carrying out research and development on rudders sounds to me like a very time consuming, very expensive exercise given that you will need to get access to the under water bits for every modification. Difficult too, to model this aspect of design as it doesn't seem to 'scale' very well.

 

Might be an idea to take the pragmatic approach, most of those who have done it agree that a true aerofoil works well other than only getting a very small advantage for a lot of effort, the one that Yammy has made and and fitted looks as good as any. The only bit of development I have done is to the size of the balance blade, the conclusion was a very elementary one in that the balance balance blade when on full tiller should just hide the prop when sighted directly from behind. This rough guide seems to give a good compromise between an effective turn, a bit of self centering and reasonable lightness on the tiller.

 

My permanent mooring is alongside the dry-dock at Furness Vale so I make a point of having a nosey when a boat is in there, from my observations most rudders would benefit from a bit of modification, I have even seen some with barely any balance blade at all.

 

I did make significant improvement to the swim area of Squeers but only because it had a particular problem, i.e. a sort of standing wave allowing air to the prop and therefore giving cavitation, this problem is perhaps not as rare as we might think either. I wonder how many builders have ever done any development to the below water bits of their boats, I am sure many would claim they have but many have been known to fib a bit.

 

P.S. I would like to go down to Worsley when you are in a dock, just for a nosey. I moored there for a few years.

Edited March 12, 2007 by John Orentas

[DHutch]

Yeah, im not saying where going to haul out and make alterations frequently, or do anything majorly scientific.

- However, several members of the SBA have such rudders (there trailable, and most have much free time) And they seam to think there good.

- Hence our plan is to just do our best to make it as right as we can, fit it, and see how it goes. As long as its not much worse, we have lost little!

 

In terms of the balence plate, and other rudder dimentions, we're currently happy that they are a good compromise.

- I think ideally it would benifit from another inchs on the balence plate to cover more of the prop, and then proberbly and few more on the rear to compenstate for that (so it doesnt get too light in feel).

- However as it is, its about balenced right. And theres certainly no more room between the rudder and prop, or really too much scope for making it longer eather (we've already been known to catch it on things)

 

We're book into worsley for the week 15th-21st, and you (and anyone else) are welcome to come down, for nosey, a cup of tea, or to play painting rudders and bowprops!

 

 

 

Daniel

[DHutch]

Right ok, just been playing with shapes on SolidEdge for the last hour, So hear goes....

 

The Origanal Rudder

 

Proposed Additional Profile

 

And with the top&bottom plates fitted.

 

Topside Veiw.

[DHutch]

And some with dimentions

 

 

 

 

 

Obvously ive only just knocked these up for visulation more than anything else, but i actaully think the shape looks about right, and while im still struggling to find any hard & fast ratios/dimentions/equations relating the proportions that it should be, and what they are affected by, i have now seen photos of a good 30 of the bloody things, as well as the two/three ive seen in the flesh. And they do all have a very simular shape characteristics.

- The shapes also a little compromised at the bottom left (aft) corner. However this is the shape of the current rudder, and i think it might be pushing it to make it a sharp edge, espcailly with the plate on the bottom of the rudder.

 

The drawings are drawn with 12mm plate for the main blade and top/bottom plates, and 3mm for the curved/profiled bits. Which is again just a finger-in-the-air figure. But again, proberbly about right i terms of a balence strenght and easy of work. Although 10mm inplace of 12mm would be fine too sor of thing.

 

 

Your thoughts please.

 

 

Daniel

[Yamanx]

And some with dimentions

 

Your thoughts please.

Daniel

 

Dan,

 

Pretty good sketches, you want these parts making to these sizes?

 

D

[DHutch]

Hahahaha, yes, urrrm, ive been very busy...

 

I got THIS though.

- You can just about read it too, its a scan of a page in a past issue of 'Funnel' (the SBA's quaterly rag)

 

Im not quite sure what all the points refer too.

- All the points for profile change are fairly clear basicly 20% lead into the aerofoil, 40% leadout, 20% flat, and 20% fishtail.

- But im currently unclear as to what width the sections should be, and have failed to get around to ringing the guy who wrote it.

 

 

 

Daniel

[DHutch]

These are what im now trying to get made. and have emialed to yamanx.

 

 

 

 

 

The top and bottom plates or very simple rectangular plates 180*645 and 180*450 respectivly, with rounded front edge, and radiused rear corners.

- Thickness is not overly fussy, but fairly thick to match the exsiting rudder blade, say 6/8mm.

- Then with a 1inch hole though the marked place for the rudder stock to pass though.

- In the top plate this will then need to cut sideways to allow it to be sliped over the stock when its in place. With the removed peice being kept to be welded back inplace.

 

The profiled Sections can be made however you feel best, or as time allows.

- Eather as one peice each, to spring onto the existing rudder blade as one peice.

- Or else they can be two halves to weld on each side, or however you feel fit.

- The shape is to be as shown, but is not critical to the mm, as long as the overall diamentions are approxmantly right, and the hight is 610mm.

 

 

 

Daniel

[DHutch]

A picture of our preposed bodgings. More blade area time!

- Its starting to get to the point whereit wouldnt be stupid jus to start again, but at the same time with only a week in drydock its properbly best not to start taking the whole lot apart!!

[DHutch]

Right, sorry for the lack of photos, with term starting on the monday stright after we got out of drydock i'd totatly forgotten i hadnt stuck any up yet!!

 

 

Here we go, photo of it in the car, some of it in primmer, and then the final photos which where at about 1 in the morning before she was refloated!

 

We we arrived it was clear that they had very slightly misunderstood our requirements for the detail around the pivot post and a little bit of last minute modifactions whre need just around there. But we where very happy with the job and where greatfull for there help and getting us out of a mess when the prevous welder failed to turn up!

 

 

 

 

 

 

 

[John Orentas]

Right, sorry for the lack of photos, with term starting on the monday stright after we got out of drydock i'd totatly forgotten i hadnt stuck any up yet!!

 

 

It would be more interesting to know if the new design worked.

[DHutch]

It would be more interesting to know if the new design worked.

Yeah, me too!

- We're itching to see how much (is any) diffrence it makes, and ill certainly post back as soo as i know.

- However the boat unfortuantly hasnt moved at all since it left drydock, and almost certainly wont be in steam till mid june at the earlist, so unfortunatly its got to wait.

 

Watch this space tho!!

 

 

Daniel

[blackrose]

Yeah, me too!

- We're itching to see how much (is any) diffrence it makes, and ill certainly post back as soo as i know.

- However the boat unfortuantly hasnt moved at all since it left drydock, and almost certainly wont be in steam till mid june at the earlist, so unfortunatly its got to wait.

 

Watch this space tho!!

Daniel

 

I'll be interested to see how you get on with it Daniel.

 

Yamanx very kindly made me a rudder too but I decided on a plain tapered design because I was worried that any schilling design might exacerbate the very slight tiller wobble that I have with my current rudder. The new one has a tapered balance plate from the rudder stock going forward and a long taper going back to the trailing end of the rudder. (Sorry but I have no luck posting pictures on the forum).

 

I'm not sure when I'll next be out the water to put it on.

Edited May 11, 2007 by blackrose

[DHutch]

Yeah well thats cool, you'll have to let us know how that goes as well! Any photos?

 

 

Daniel

[Phoenix_V]

Hi

Saw your boat at Anderton last week and wondered how the schilling rudder was doing?

[Liam]

I've also bumped into (not literally!) your boat over the past few weeks. It was in Worsley for some time, and then moved onto the Marbury Park area near Anderton. I think I remember seeing it moored on the Bridgewater too? I might be wrong - but I was told that you'd gone past our moorings on the Bridgewater at some point. Unfortunately I wasn't about so couldn't say hi.

 

I was following the Schiling rudder topic with interest but completely forgot and was only reminded about it when it came back up in the list on the forums.

[DHutch]

Yeah sorry, i have mentioned it else where, but clearly not on this thread!

 

The rudders going well, certainly, it still stears and hasnt fallen off yet.

- As for an improvment. I think there is am improvment in turning with the new rudder.

- Its not chalk and cheese and its a bit hard to quantify. But both me and my mum (both baised as hell) recon there is a noticable diffrent. Maybe 10% increase in turning or somthing?

 

So yeah, an interesting play anyway!

- I would have liked to have made it a bit wider, maybe even twice as wide as it is now.

- But that would have required modifications to the boat that we didnt have time for (moving the skeg off center being the most favorable) otherwise it wouldnt have fitted back on. But there we go. Its certainly not done any harm to the handling.

 

 

 

As for our where abouts.

- We where indeed at worsley for a while after our drydocking at easter, then made our way home to the anderton/marbury area on the weekend of the 21st/22nd where we stayed for a week or so.

- Then moved on anticlockwise around the cheshire ring, currently moored in the wheelock area for a few days. The orginal plan of the rochdale/hudderfeild being postponded due to the lack of time available this year, and the ashton stoppage which also prevent us doing the cheshirering clockwise. We also plan to detour onto the upper peakforest and possable also the weaver.

 

 

 

Daniel

[John Orentas]

We also plan to detour onto the upper peakforest and possable also the weaver.

Daniel

 

 

 

Hi Daniel.

 

Try to keep up us in touch with your movements re. the Upper Peak, perhaps we could finally meet up so I can see your boat, perhaps have a pint somewhere.

[DHutch]

Yeah will do.

- Its all a bit in the air at the moment, im rather pre-occupied with this resit ive got to do 5th sept.

- However the weekend 8-9th and 15-16th are looking favourable for boating so far, on from wheelock.

 

 

Dnaiel