Mosquito Rudders

Hi Darryn

I've got the same vintage boyer rudders on my mosquito, although I haven't sailed for a long time, I couldn't fault them, but then again the only ones I had before that were homemade in a hurry. Mine are the kick down rudders with the fibreglass rod (I'm assuming thats what you have) and they will now take their place on my soon to finished homebuilt taipan (sorry mozzie guys). I would however strongly recommend if plan on buying a new set at any time, you should definately consider Tony Mckenzies rudders, very very good and excellent finish, when it comes time me thats what I will be buying.

Matt
Ex-Mozzie 741

Matt, if yours are vintage then mine would be ancient. My rudders use a bit of bungy to hold them down, no fibreglass rod.
Agree regarding quality and shape of Mckenzie rudders.

Picture of rudder attached.

Darryn

Hi Darryn

Yeah I know the ones, theres still a few sets of those I've seen around the traps. I'll have a look at mine just to sure how old they are, I think the manufacture date is etched into them somewhere. But mine were probably bought not long after they came out. Just check on the trailing edge of yours, up near the top, they might have the date etched (by hand with a engraver, very small writing) then you'll know exactly how old they, not that it probably matters, but just for arguments sake.

Thanks Matt, I found engraved on them, GA/06/92, so they are coming up to their 14th birthday, not ancient at all really...

Darryn

Hi Darryn

Thats not bad, mine are 1992 as well. I've only just(probably two weeks ago) filled a couple deep scratches in mine, as well a small delamination of the trailing edge on one, which wasn't easy to fix because of a couple of grains of sand stuck between the two halves, but I'm happy with my repair, and will get resprayed before next season.

Regards

Matt

Have a look at Dotan kick-up rudders. Used in South Africa on many Mosquitos.

How much, per set, are these delivered to Oz?

500EUR(excluding delivery) for two rudders. Delivery to any country in the world.

I noticed that the photographed Mozzies have chosen to use the

Steiner

Rudder Blade. On checking the website there is also a

NACA

Rudder Blade(which appears closer to the one I am presently using). What are the advantages/disadvantages of each profile and cross section?

Choice of the rudder is very individual - both by boat and sailor(his technique). In South Africa they tested both blades - Blade 1(NACA) and Blade 2 (Steiner). So they had an opportunity to compare and choose the most appropropriate blade for their needs. From that moment they only ask for Blade 2. I got the following feedback from class association president about blade tests(quotes):

Over the last number of years I have experimented with various rudder shapes and obviously re-invented the wheel! - your blade 02 is VERY similar to my most successfull shape. Since we added asymetric spinnakers to our boats we encountered a great deal of lee helm downwind. This I rectified with adding more mast rake but encountered too much weather helm upwind - kicking in the rudders solved this but left the blades weak because the tips were ahead of the pivot point and would snap if the weather blade left and re-entered the water. Thus the 'curved' forward kicked leading edge was my next option and this worked well!!

Hve to second that opinion, have had no trouble with my Dotans.
They are awesome, no cavitation, can sail straight up the beach without worrying, kick-up system is faultless.
Feel a bit

heavy

when you first sail with them but I think it`s more the rubber joints than anything else. Will not use any other system (unless John P. offers me a set of T-foils for testing purposes <img src=

alt=

/>)

Steve.

I am currently adjusting rudder position as I didn't like the existing system that came with the mozzie I bought and have been forced to move things around. What I am wondering is where does everyone place or prefer to place the leading edge of their rudders... i.e. on the pivot centre line or in front, etc. Also a second question is what about rudder rake. Who has their rudders 90 degree's to the decks and who uses forward rake and who uses rearward rake and by how much and whats the prefered?

Cheers

I have my home-built dagger style rudders raked forward. The bottom is about 15mm forward of the pivot point. Balanced the rudders up nicely and haven't had any issues with them.

Tony,

I run my rudders at 90 degrees to the deck by using a teflon block on the upper pivot gudgeons. The rudders are set up so that the bottom leading tip is exactly in line with the axis of rotation.

I used to have them set up with varying amounts of forward bias to account for poor sail shape but found that they were unpredictable at high speeds and resulted in many out of control reaches. <img src=

alt=

/> If the blade is behind the axis it must behave predictably.

Regards,

Peter

Thanks for the replies..

Now you must remember I am fairly new to this sport as this will be my third season coming up and my first on a mozzie.

I found my rudders were unpredictable as they were some 40mm in front of the pivot point and the lock down system jammed every single time I used them, hence the reason I needed to change.

I have read that adjusting the rudder rake will balance the boat (weather helm) which I understand and that also raking the mast will do the same. So, can you balance using either? What I mean is I have also read that mast rake helps pointing, is this because having a lee helm would force you off the wind rather than into it with weather helm? Is this the only reason for mast rake... to induce weather helm for pointing or is there another reason.. i.e. rake the mast for good pointing then rake the rudders to balance the helm!!! This is what I am not sure about???

Cheers

Hi Tony,

I often hear sailors talk about tucking their rudder blades forward past the pivot point to reduce weather helm, to my understanding this has nothing to do with the weather helm of the boat, it only effects the balance of the rudder blade itself. What it can do is stop you from feeling the weight of weather helm, which I think is a bad thing. I think it is OK to have the leading edge past the pivot point, but not to the extent you have no feel of if you are pulling on the tiller or not.

Weather helm or Lee helm is a result of the balance between the centre of effort in the sails and the centre of lateral resistance of the parts of your boats that are under water, ie.Hulls below the water line, the centreboards and the rudder blades. I don't think there is enough adjustment in any of the parts in the water to make a difference to the weather helm, apart from pulling your centreboards up.

So I always adjust the mast rake to balance the boat to the point where it turns into the wind when you let go of the tiller, but you are not constantly pulling the tiller against the weather helm to keep it sailing straight, close hauled when you are on trapeze in about 15 kts. of wind.

Regards Gary.

Hi Tony

Thought this extract from tuning guide for Nacra F18 might be helpful, different boat, same principles apply..

Moving the mast aft decreases power and makes the catamaran easier to handle, hence further back in heavier winds. Also the lighter the crew, the further back the mast and visa-versa.
Also moving the mast aft, allows the center of effort on the sails to move further aft and so will encourage the boat to point higher. BUT this might mean that you feel “weather helm” through the tiller, if so, “tuck” the rudders further underneath the catamaran by adjusting the screw thread on the rudder casting. When sailing upwind, with two on trapeze, you ought to be able to rest the extended tiller on the top of your index finger and the catamaran should slowly climb up into the wind.

Hope this is helpful.

What type of lock-down system are you using on your rudders?

Cheers

Andrew

Cheers guys...

Both of your posts explain it very well. Makes perfect sense.

1. Mast rake changes weather - leehelm balance due to change of CoE in relation to CoLR position.
2. Rudder rake balances the (amount) of feel of the weatherhelm.

The lock down system on my rudders was purely a peice of 4mm rope connected about 150mm down from the top of the rudder on the leading edge which then went up onto the rudder assembly frame and through a 6mm cleat. Everytime I used it the rope would jam between the rudder and frame and I'd be hanging off the back of the boat trying to unjam it. This would happen everytime on both sides <img src=

alt=

/>. And of course if you hit anything or picked up weed my rudders wouldn't retract, potentially very damaging.

I am replacing that with a bungee setup at the moment. Any idea's (pics) would be appreciated. My rudders are Hallsworth I think.

Tony

I am using the SmartLock lock down system (Boyer) with good results. Like everything, it comes down to personal preference, but these are simple & they work, ie. they stay locked when they should & let go when you run out of water.

Go to http://www.ahpc.com.au/ & look in the Technical Support section for

Using the Smart Lock Snap Down Rudder System

. There is a .pdf file with pics explaining the system. If your rudders don't have the

ears

to take the rod I can explain how that is overcome.

Cheers

Andrew

Andrew

Thanks... I will check that out and no I do not have the ears for the rod to connect to!!! Looks like you still need to hang over the back to lock them in though <img src=

alt=

/>

Does anyone know of any spring loaded systems other than home made of course. Just set and forget... <img src=

alt=

/>

Andrew,

I am interested in hearing about using the smart lock system with a rudder setup that doesn't have

ears

. Do you have further details ? I still like the rudders without

ears

so that you can rotate them beyond vertical and not have to worry about them unlocking themselves when beaching in any sort of beach waves.

I have been using a shock cord locking system for a number of seasons but have ended up many times with the shock cord wedged between the rudder and the frame. Very annoying !!

Regards,

Peter

You can make the ears in such a way that they allow the rudder to rotate upward through 180 degrees.

The European Blades have this setup now. See :

http://www.catamaranparts.nl/BladeF16a.htm

Wouter

Wouter,

Thanks for the advice. The setup looks great and it's just what I need. Are there any closer photos or diagrams of the setup particularly the rod attachment to the rudder ?

Regards,

Peter

Hi Peter

I have re-designed my attachment points on the blades for the lock down to a much lighter arrangement. I am taking the boat for a test run on Lake Bonney on Sunday, along with about 5 others to shake out the cobwebs. Once I am happy the design is sound I will take some photos and explain the nuts & bolts of it. If not its back to the drawing board..
The other option is to send your blades to AHPC & they will insert a bracket to take the lock down assy.

Cheers

Andrew

Andrew,

The Blade image looks like the best setup I've seen but I look forward to your test results and images. Good luck with the test. My rudders are old hand made wooden blades and it would probably cost more in postage costs to AHPC than the ruddes are worth !! <img src=

alt=

/>

Regards,

Peter

I'll try to get some

Wouter

I've used the smart lock system and I am back using shock cord to hold them down, I find it more forgiving with weed/jellyfish etc.

Got a price on the Mckenzie rudders using shock cord, $650. The Dotans come out at aprox $820, both are plus freight.

I have seen Andrews prototype smart lock

ears

, looked like a good way to convert standard rudders over.

Does anyone have a set of Hallsworth rudders laying around that they want to get rid of?

Darryn
1704

Hi Peter

It looks like the revised rudder brackets work OK. We had a variable 5-20 knts on Sunday & the blades didn't budge once locked down. Haven't had the acid test of running out of water but don't expect any problems.
Have attached a photo for interest. If you want more detail let me know by private message & I will email the 8 photos I have and a short description of the design.
Please note, no warranty is implied for anyone using this method, it works for me, but may not for someone else.

Another photo of rudder assembly.