[Norse]

Hi all ive been thinking about altering my rudder profile as it very small incomparison to other boats of the same size as mine .
its fine when at sea but very slow to react when approaching and leaving my finger berth moorings.:boat:

I was going to perhaps try starting by adding approximately 2" to the overall profile of the rudder and see what that gave me ,there is plenty of room to do this without it fouling any surrounding parts of the boat .
Iam worried that by giving a too larger surface area to the rudder this might cause steering problems when going astern, as ive heard of larger rudders being trouble to get from lock to lock when going astern because of a large surface area being forced against the water.I have spoken to several different people with several different views. :secret:

What has been suggested to me is termed as fish tailing the rudder which involes welding a lenght of angle iron to the trailing edge of the rudder,( like a fish tail ).

This apparently helps when at low speeds and at close quarters by giving the rudder the required lock and by giving quick squirts on the throttle ,causing the prop wash to react on the rudder. :g:

This sounded possible ive not heard of it before and was wondering if anybody has heard of it or used this method before.

Best regards NORSE
Malcolm

 

[Afishionado]

Malcom, in the nicest possible way mate, you are not going to get any worthwhile answer here unless you say what type of boat it is, it's size, engine size, prop size etc. Basicaly as much info as you can.
What I can tell you is that by adding 2" all round could well ruin the boats useability. Unless you know what you are at, rudder size and shape is not something to mess around with.

Afishionado

 

[Davy Holt]

Hiya,

It's not really much help to you but I went down the Increase the rudder size a few years ago. With my boat being a twin engined Cat the rudders were tiny, I increased the size by about 2" all round on both rudders.. the result.. absolutely no difference

 

[Norse]

Hi thanks for the replies i thought i might try on here because ive spoken to several people at different boat yards and unlike a prop or gearbox there seems to be no apparent formular to work out what required,
Thanks anyway
Best regards Malcolm ( Norse )

 

[Afishionado]

Hi thanks for the replies i thought i might try on here because ive spoken to several people at different boat yards and unlike a prop or gearbox there seems to be no apparent formular to work out what required,
Thanks anyway
Best regards Malcolm ( Norse )

As I said a bit more info about the boat will I am sure get you some constructive answers.

Afishionado

 

[TomBettle]

Hiya,

It's not really much help to you but I went down the Increase the rudder size a few years ago. With my boat being a twin engined Cat the rudders were tiny, I increased the size by about 2" all round on both rudders.. the result.. absolutely no difference

Davy

If youhave a twin engined Cat then you could happily drive the thing without rudders anyway!
Why did you try and increase the size when for low speed hadnling you would simply use the engines rather than the wheel.....?

Tom

 

[TomBettle]

Norse

With respect to the knowledge and ability of this forum, you may be better at a more specialise forum such as those found over at YBW.Com

Pose your question there and give as much detail about your boat as possible.

 

[Norse]

Norse

With respect to the knowledge and ability of this forum, you may be better at a more specialise forum such as those found over at YBW.Com

Pose your question there and give as much detail about your boat as possible.

Hi Tom thanks for your info its useful , of course i have got all my boats details and would have posted them up if someone could have helped . but being new to this forum i wasnt quite sure how it worked.

Regards Malcolm (Norse )

 

[Davy Holt]

Hiya Tom,

Davy

If youhave a twin engined Cat then you could happily drive the thing without rudders anyway!
Why did you try and increase the size when for low speed hadnling you would simply use the engines rather than the wheel.....?

Tom

I know, I know The cat has superb handling, I can put the boat in any berth without any fuss and I can turn her around on her own length just using the engines.. the problem arose when trying to steer when you only have one engine running.

Although she is 26', the original rudders were not much bigger than a large dinner plate, this was fine when you had both engines running as you could steer the boat with engine power alone. However with only one engine running she was almost impossible to steer. I had the bright idea that if I made the rudders as big as I possibly could, it would help the steering when under power from only one engine.

I did the modifications and tested it out, there was very little difference to the steering when under power from only one engine which makes it rather difficult to anything with her except get her back on her mooring.

 

[TomBettle]

Davy

You mak it sound like you regularly have to come back on one engine....
Reliability issues?

In fairness, rudders on twin engine boats don't do an awful lot unless you have a reasonable amount of headway. On the Azimut 46 (for example) they are about the size of an A4 sheet of paper. They will just about give some level of steerage when negotiating a marina, but they are only designed to do that in emergencies.

Tom

 

[Davy Holt]

Hiya Tom,

Davy

You mak it sound like you regularly have to come back on one engine....
Reliability issues?

LOL it's not quite that bad, considering the engines had both done over 90k when they came out the cars 4 years ago. I've only had one failure caused by an engine it's self, the pulley on the water pump disintegrated at 2500 revs.. the result a 3 piece cam shaft Other than that the only real problems I've had is a water intake pipe detaching (3 weeks ago) and the other was a bad connection on the heater plug relay causing it not to work.

In fairness, rudders on twin engine boats don't do an awful lot unless you have a reasonable amount of headway. On the Azimut 46 (for example) they are about the size of an A4 sheet of paper. They will just about give some level of steerage when negotiating a marina, but they are only designed to do that in emergencies.

Tom

Mine are not too bad for steering the boat even at tick over, providing I have both engines, it's the occasions when I don't have the both engines it becomes more interesting

 

[TomBettle]

Mine are not too bad for steering the boat even at tick over, providing I have both engines, it's the occasions when I don't have the both engines it becomes more interesting

I'd guessthat is due to two hulls, very far apart?

A mono hull on one engine can be cumbersome, but is just about manageable, I would guess trying to steer both hulls from one side would be tricky and may need more rpm than normal....

 

[Davy Holt]

Hiya Tom,

I'd guessthat is due to two hulls, very far apart?

A mono hull on one engine can be cumbersome, but is just about manageable, I would guess trying to steer both hulls from one side would be tricky and may need more rpm than normal....

Yup.. my keels are 9' apart, with a total beam of 13', not bad for a boat that's only 26' long

Its pretty much like trying to manover with another boat the same size as you tied along side.. makes for interesting stuff

 

[TomBettle]

Davy

In open water (to be safe) have a go on one engine.

Give it plenty of grunt with the wheel hard over to get it moving and then plenty again to stop her momentum.
Once you get the hang of it, it's not too bad, but you need to break all the rules that say everything should be done gently.