Rudder mod

[Bod]

Hi

I've had angle brackets welded to the rudder, to assist in climbing out of the water, they are well down the rudder, to allow a foot hold, when pulling up on the swan neck.

 

I was advised against the small semi-circles on the Uxter plate because of the prop being to close.

 

However my reasoning for using the rudder was two fold, first the bracket was low enough to get on to! and a large plate of steel was between my foot and the prop!

 

Bod

[steelaway]

Oh dear

 

That'll be mine then

 

 

 

 

And mine. Although your's looks a bit further away

 

Alex

Edited October 8, 2012 by steelaway

[blackrose]

And do you think you could climb out using those?

 

Yes, I have done.

 

It's not easy though because as you say most of your body mass is below the step and you're trying to pull yourself out of the water, but I managed because I have good upper body strength. However, if the step is on the rudder at approximately the same height it wouldn't be any easier.

 

The only easy way would either to have some steps inset in the hull like some Dutch barges or a rope ladder or fixed ladder which goes below the waterline.

Edited October 8, 2012 by blackrose

[blackrose]

Hi

I've had angle brackets welded to the rudder, to assist in climbing out of the water, they are well down the rudder, to allow a foot hold, when pulling up on the swan neck.

 

I was advised against the small semi-circles on the Uxter plate because of the prop being to close.

 

 

My semicircle steps are nowhere near the prop, but then my uxter plate is 12ft wide!

[Neil TNC]

On a related topic, what do people think about those horizontal 'fins' just below the waterline that some people have on their rudders? I think they're meant to direct the prop thrust over the rudder area rather than it being lost as turbulence above the waterline. In that sense I suppose on a canal boat they act as a continuation of the uxter plate. But would adding them to a rudder increase rudder judder?

 

N Bear Nest has always had them, as adding then to my last R&D shelled NB made such a big difference. They "hold the water down" when going with any sort of power applied. N Bear Nest must have about the most shake free rudder of any NB I have ever steered.

As for using them for reboarding, I have used them on a few occasions. I get someone to hold the rudder over, then get out quite easily, by grabbing hold of the swan neck, getting up via the cavitation plates and fixed fender stool.

When N Bear Nest was built I had to extend the leading edge by 1" and the trailing edge by 3" to get the steering to my satisfaction. Some people would say it is now on the heavy side (Mrs TNC has rather spindly arms, but she manages OK), but N Bear Nest turns better that most other NB's I have been on (like very useful for turning into Limehouse / Selby / Keadby) and also steers out of gear (I once steered most of the way from Wisbech to Dog In A Doublet out of gear, coming up the tidal Nene on the flood)

With rudder mods, it is best to experiment, to get the steering how *you* want it. Cavitation plates and extensions to the blade can easily be trimmed back with an angle grinder.

[nb Innisfree]

If and when I get around to it I will extend our rudder forward section with steel angle top and bottom of the rudder, bolted either side and acting as sandwich to support the forward extension section. These angles will also act as 'wings and possibly direct the propeller thrust more efficientky. I will use large section angle, maybe 4" wide on the horizontal plane, also easily removed if it proves unsuccessful. Be an interesting experiment. Will also act as a double step up when I fall in while examining the prop wake.

[blackrose]

If and when I get around to it I will extend our rudder forward section with steel angle top and bottom of the rudder, bolted either side and acting as sandwich to support the forward extension section. These angles will also act as 'wings and possibly direct the propeller thrust more efficientky. I will use large section angle, maybe 4" wide on the horizontal plane, also easily removed if it proves unsuccessful. Be an interesting experiment. Will also act as a double step up when I fall in while examining the prop wake.

 

That's not a bad idea. I might try it but just using angle iron for the rear section at the top of the rudder to direct the prop wash. Bolting the angle on is better than welding it on just in case it makes things worse.

 

Two of these should do it for me, or is 200mm too wide for the fins? It does seem a tad expensive for a bit of scrap steel though!

 

http://www.ebay.co.uk/itm/Mild-Steel-Angle-200mm-x-100mm-x-12mm-308mm-long-Angle-Iron-/290758899873?pt=UK_BOI_Metalworking_Milling_Welding_Metalworking_Supplies_ET&hash=item43b294b8a1

Edited October 9, 2012 by blackrose

[bizzard]

We've just bought a new (to us) boat and the surveyor recommended cutting an inch off the forward part of the rudder to improve handling. At the moment she handles much as explained above. Does anyone have a formula to arrive at the correct ratio or is it a different fit for each hull.

You mean your boat steers negatively like i explained?, if so that's horrid, yes either cut some off the balances leading edge or add some area to the trailing edge, or both. IF the surveyor knows his onions when it comes to rudders, and recommends an inch is removed from the leading edge maybe that is all that is required, try that first. If the negative helm is very vicious i'd say it would need more than an inch removing or preferably the trailing edge extending.

[PaulD]

On a related topic, what do people think about those horizontal 'fins' just below the waterline that some people have on their rudders? I think they're meant to direct the prop thrust over the rudder area rather than it being lost as turbulence above the waterline. In that sense I suppose on a canal boat they act as a continuation of the uxter plate. But would adding them to a rudder increase rudder judder?

 

I have them on my rudder. Soar Valley Steel Boats have them as an option on their shells and the principle is the same as hydrofoil fins used on outboards. They are supposed to improve prop efficiency and provide some lift to the stern. There is almost no turbulance breaking the surface even at 2000 rpm engine speed which is nice but I have no way of making a scientific evaluation. It would be no good for the vicar on Oak and Ash!

 

I think it also lifts the rudder in the cup which allows the stock to rattle around a bit at high revs. In fact I have just fitted two grub screws in the top bearing sleeve to see if it makes any difference.

 

I would be interested to hear if any one else has them and their experience. I think Grumpy Git has them and I passed it twice this year on the T&M but no chance to ask.

 

Paul

[nb Innisfree]

That's not a bad idea. I might try it but just using angle iron for the rear section at the top of the rudder to direct the prop wash. Bolting the angle on is better than welding it on just in case it makes things worse.

 

Two of these should do it for me, or is 200mm too wide for the fins? It does seem a tad expensive for a bit of scrap steel though!

 

http://www.ebay.co.uk/itm/Mild-Steel-Angle-200mm-x-100mm-x-12mm-308mm-long-Angle-Iron-/290758899873?pt=UK_BOI_Metalworking_Milling_Welding_Metalworking_Supplies_ET&hash=item43b294b8a1

 

Personally I would use 100mmx50mm, that would make a total width of 200mm+ rudder thickness, 50mm providing enough surface area for a rigid fixing, I think 12mm is too thick, 6mm is ideal IMO. Also remember to cut the leadings edges back at axsuitable angle to maintain prop clearance.

 

 

I think it also lifts the rudder in the cup which allows the stock to rattle around a bit at high revs. In fact I have just fitted two grub screws in the top bearing sleeve to see if it makes any difference.

 

I would be interested to hear if any one else has them and their experience. I think Grumpy Git has them and I passed it twice this year on the T&M but no chance to ask.

 

Paul

 

Maybe angle thecwing down a bit at the front give a slight downward load to the rudder?

[PaulD]

I have them on my rudder. Soar Valley Steel Boats have them as an option on their shells and the principle is the same as hydrofoil fins used on outboards. They are supposed to improve prop efficiency and provide some lift to the stern. There is almost no turbulance breaking the surface even at 2000 rpm engine speed which is nice but I have no way of making a scientific evaluation. It would be no good for the vicar on Oak and Ash!

 

I think it also lifts the rudder in the cup which allows the stock to rattle around a bit at high revs. In fact I have just fitted two grub screws in the top bearing sleeve to see if it makes any difference.

 

I would be interested to hear if any one else has them and their experience. I think Grumpy Git has them and I passed it twice this year on the T&M but no chance to ask.

 

Paul

 

Picture if it works: http://i1199.photobucket.com/albums/aa467/paulndodd/PICT0021.jpg

[nb Innisfree]

Personally I would use 100mmx50mm, that would make a total width of 200mm+ rudder thickness, 50mm providing enough surface area for a rigid fixing, I think 12mm is too thick, 6mm is ideal IMO. Also remember to cut the leadings edges back at axsuitable angle to maintain prop clearance.

 

On second thoughts after looking at PaulD's picture 8" wide might be a bit on the narrow side, maybe 6"x3"

angle giving 12" oa width?

[ditchcrawler]

That's not a bad idea. I might try it but just using angle iron for the rear section at the top of the rudder to direct the prop wash. Bolting the angle on is better than welding it on just in case it makes things worse.

 

Two of these should do it for me, or is 200mm too wide for the fins? It does seem a tad expensive for a bit of scrap steel though!

 

http://www.ebay.co.uk/itm/Mild-Steel-Angle-200mm-x-100mm-x-12mm-308mm-long-Angle-Iron-/290758899873?pt=UK_BOI_Metalworking_Milling_Welding_Metalworking_Supplies_ET&hash=item43b294b8a1

I did something similar with a piece of 10mm plate the same length as the depth of my rudder. Welded to pieces of flat on each side down one edge to make a 10 mm wide grove. This was then slipped, with the aid of a lump hammer on the trailing edge of my rudder, a hole drilled through the top of the two lengths of flat for a bolt to go through passing through the hole you often find in the top of the rudder. Tried it for a few weeks, took it off and cut a strip of the back edge of the 10 mm plate and put it back on. Kept doing this until I got the best compromise of handling /tiller weight. Next time out of the water had a piece of plate of the same size welded onto the trailing edge of the rudder.

[blackrose]

I have them on my rudder. Soar Valley Steel Boats have them as an option on their shells and the principle is the same as hydrofoil fins used on outboards. They are supposed to improve prop efficiency and provide some lift to the stern. There is almost no turbulance breaking the surface even at 2000 rpm engine speed which is nice but I have no way of making a scientific evaluation. It would be no good for the vicar on Oak and Ash!

 

I think it also lifts the rudder in the cup which allows the stock to rattle around a bit at high revs. In fact I have just fitted two grub screws in the top bearing sleeve to see if it makes any difference.

 

I would be interested to hear if any one else has them and their experience. I think Grumpy Git has them and I passed it twice this year on the T&M but no chance to ask.

 

Paul

 

How wide are the fins on your rudder Paul?

[PaulD]

How wide are the fins on your rudder Paul?

 

I uploaded a pic with end view:

http://i1199.photobucket.com/albums/aa467/paulndodd/PICT0015_zps5674a6b4.jpg

 

I think it is around 250mm each side, total 500mm wide. I should get to the boat this weekend and will measure it.

 

Paul

[blackrose]

Yes, I would have thought that the overall width of the fins shouldn't be too much less than the prop diameter, otherwise there's not much point.

Edited October 10, 2012 by blackrose

[PaulD]

Yes, I would have thought that the overall width of the fins shouldn't be too much less than the prop diameter, otherwise there's not much point.

 

It is a 17 inch prop (432mm)

 

Paul

[blackrose]

I'm thinking off chopping off the bit of the rudder that sticks out of the water and attaching a steel plate to the underside of the counter which would extend just beyond the rudder. This would perform the same anti-aeration function as the rudder fins but I have a feeling it might not be as detrimental in terms of tiller vibration. My tiller tends to judder a bit as the prop spins and I wouldn't want that to get any worse.

[PaulD]

I'm thinking off chopping off the bit of the rudder that sticks out of the water and attaching a steel plate to the underside of the counter which would extend just beyond the rudder. This would perform the same anti-aeration function as the rudder fins but I have a feeling it might not be as detrimental in terms of tiller vibration. My tiller tends to judder a bit as the prop spins and I wouldn't want that to get any worse.

 

Doesn't that bit also act as the "end stop" for the rudder?

 

Paul

[blackrose]

Doesn't that bit also act as the "end stop" for the rudder?

 

Paul

 

Yes it does, but boats have different ways of limiting the rudder. Some boats have a chain or I could put some 'stops' on the underside of the plate.

Edited October 11, 2012 by blackrose

[PaulD]

I uploaded a pic with end view:

http://i1199.photobucket.com/albums/aa467/paulndodd/PICT0015_zps5674a6b4.jpg

 

I think it is around 250mm each side, total 500mm wide. I should get to the boat this weekend and will measure it.

 

Paul

 

It is actually 300mm each side, total 600mm.

 

Paul

[blackrose]

It is actually 300mm each side, total 600mm.

 

Paul

 

Thanks.