transom rudder or spade rudder?

Wheel, tiller and autopilots
Taniwha

transom rudder or spade rudder?

Post by Taniwha » Tue Nov 25, 2008 3:58 am

Until today, my steering world was a simple one: a big fat transom mounted rudder on each hull. Suddenly, I find myself offered a choice of transom or spade ( Mike has redesigned the CC40 with spades to enable hydraulic steering). What do I do, readers?



I know this is not an issue for most of you to consider, but I'd be really grateful for your thoughts (especially if they cover aspects that my simplistic appraisal has missed!!!) Any feedback appreciated.



Here are my own thoughts so far:



Spade

Pro's - prettier, compatible with hydraulic steering, smaller, lighter, useful for a spot of gardening



Con's - less robust?, bearing maintenance, serious damage could affect rudder shaft tube - another way to ship water



Transom

Pro's- simpler, hull integrity maintained if damaged, skeg makes snaring from lines etc less likely, easier to repair on the hoof



Con's- more vulnerable from rear end 'incidents', suitable for cable steering only, not so beautiful



I want simplicity wherever possible, and I am not sure hydraulics is for me. I think I am tending towards a transom mounted rudder (even though Tony's rudders are much prettier) with cable steering and a wheel pilot . What about costs, efficiency etc? Am I missing the bleedin' obvious?

madaz
Posts: 527
Joined: Thu Apr 26, 2007 7:47 am
Location: Hobart, Tasmania

transom rudder or spade rudder?

Post by madaz » Tue Nov 25, 2008 7:05 am

dont know about bearings and maintainance paul. Mine use a carbon/eglass shaft which is actually hollow tube but has a 6mm wall. the corresponding tube is supplied to match and fits around the shaft, the whole thing becomes a bearing... it has been used on Orams i beleive with much sucess.



as far as integrity the tube will snap before the shaft, as it is slightly machined and smaller. also the mini keels have a deeper draft than the rudders so they will hit anything first. The point where they come through the hull is the rear most compartment which is water tight anyway and only slighty under the water line. so not really an issue?

Taniwha

transom rudder or spade rudder?

Post by Taniwha » Tue Nov 25, 2008 7:31 am

Cheers for the info Tony.



I was reading about your glass rudder shaft and tube just after I wrote this post - thats why this site is sooo damned good. I'd have never found anything like that. Must admit that with the glass tube and shaft acting as one big bearing it does appeal more. What are the tangs made of, the same sort of rod but smaller?



Not sure that the back end of my boat will be watertight. The port hull will be with a full size bulkhead, which is all good. On the starboard side there will be a double bunk and the only way into the steering compartment will be through the bulkhead at the foot of the bed. No way to access the area from above. So I won't be able to affect a watertight bulkhead there.



I did wonder, after reading the thread on glass shafts whether a transom ss shaft could experience more abuse and still work to some degree, ie not get jammed in the tube after being bent, or shattered.

44c
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Location: Hervey Bay, Qld

transom rudder or spade rudder?

Post by 44c » Tue Nov 25, 2008 5:18 pm

My boat has kick-up spade rudders with fibreglass shafts and tubes.



in an impact fibreglass shafts will flex, but not bend permanently like SS shafts would. I've heard of SS shafts getting bent and jamming the steering - if mechanically linked one bent shaft could jam both rudders.



It would take a severe impact to break a fibreglass shaft - the rudder would break first. On my boat the rudder would kick up before then.



If you don't want hydraulic steering then go with the transom hung rudders. Hydraulics are generally very reliable though (every car on the road has hydraulic brakes, how often do they fail?) and certainly the simplest to install.

puremajek
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Joined: Thu May 04, 2006 7:36 pm
Location: Brisbane Australia

transom rudder or spade rudder?

Post by puremajek » Wed Nov 26, 2008 4:46 am

Here you are Taniwha...to add an opposite opinion



I have mechanically linked rudders within SS shafts bedded with non absorbent 'teflon-type' seals (no steel bearings). Should one shaft be bent through my own stupidity, the shaft is very easily disengaged to allow the other to be operated. It takes about 20seconds to remove a pin and we're away again (also a choice of four pins, two per side).



I am aware of 3 EASY's (and I am sure there are a few more of the 90 odd on the water) that have had SS shaft problems due to pilotage error. Also, of the total, 3 have hydraulic systems (that I am aware of, and I am sure there are a few more again). Having said this, these vessels are around the 3500 - 5000kg AUW mark - not sure if its that, or the actual steering cost or the simplicity of the installations.



Give your designer a call, they will normally give you the figures of what everyone is doing.
James
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http://www.diycatamaran.com
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madaz
Posts: 527
Joined: Thu Apr 26, 2007 7:47 am
Location: Hobart, Tasmania

transom rudder or spade rudder?

Post by madaz » Thu Nov 27, 2008 5:31 am

Paul, if you want to send me a PM with your email address i can send you construction photos of the rudders which will be self explanatory. My steering as mentioned is the teleflex cable system (quick connect 3 turn system rated to V6 outboards) which will work on one tiller head, the other one will follow suit as it will be linked with a conecting bar. if one rudder snaps off the other will still continue to work.

I have UHMWPE washers on the top of the rudder and bottom of the hull, and on the top of the rudder tube and bottom of the rudder stock to take care of any up and down surface friction. I can send you info on those also if you need it.

madaz
Posts: 527
Joined: Thu Apr 26, 2007 7:47 am
Location: Hobart, Tasmania

transom rudder or spade rudder?

Post by madaz » Thu Nov 27, 2008 5:34 am

Paul



These carbon/eglass shafts are used on Perry catamarans, who make significantly larger cats than I. I figure if they are strong enough for his 50 footers, they are well strong enough for mine.



And with the teleflex cable system, it is relatively cheap, simple, and you can get parts for them anywhere you go.

44c
Posts: 1147
Joined: Tue Aug 08, 2006 5:08 am
Location: Hervey Bay, Qld

transom rudder or spade rudder?

Post by 44c » Thu Nov 27, 2008 5:34 am

puremajek wrote:Also, of the total, 3 have hydraulic systems (that I am aware of, and I am sure there are a few more again). Having said this, these vessels are around the 3500 - 5000kg AUW mark - not sure if its that, or the actual steering cost or the simplicity of the installations.


I'm not sure I understand this bit. Are you saying the boats have hydraulic steering because of their weight, or they weigh what they weigh because of the hydraulic steering, or they are that weight because of the cost of something? :?

Taniwha

transom rudder or spade rudder?

Post by Taniwha » Thu Nov 27, 2008 10:02 pm

Thanks all.



Puremajik, I think I know what you mean... since the boats are light not many have opted for hydraulics (?). Thanks for putting it in perspective in terms of the numbers of boats with them; less common than I was thinking. As for asking my designer what others have done, there are only two CC40s being built! Tony's is similar and is the furthest ahead of the lot of us - though I suspect his beneficiary is slowing him down abit now.



Was being a hardcore transom-head, but slowly changing my mind. I like the opportunity for weight reduction at the very end of the boat ( I'll be able to fit a small bazooka instead for getting through the Gulf of Aden).



Tony, thanks for the offer of info. I will go away and try to PM you. Not sure how to yet, so I may BU (balls up).

dialdan
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Joined: Tue Feb 12, 2008 7:28 am
Location: brisbane

transom rudder or spade rudder?

Post by dialdan » Fri Nov 28, 2008 1:20 am

If I was doing it again :lol: I would go transom hung ,mainly because it is very easy to install a trim tab and then a morse cable to your tillerpilot .

The tillerpilot hardly works at all saving your batteries and it has a much longer lifespan because it can be installed out of the elements.

Al

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