twin rudders and steering

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simon.armitage
twin rudders and steering

I am probably late to the pass as usual but have just read an article explaining why boats with a single engine and twin rudders are less manoeuvrable moving forward at slow speeds.

When turning hard a port or starboard to berth alongside the pontoon by inclination I always push the throttle forwards a tad to increase speed and help turn the boat .

It seems that the science is that the wash from the propeller is moving clear astern rather than washing over the rudders while with a single rudder it washes over it giving it a grip to improve steering at low speeds.

I hope any of you are enjoying our new found freedom and others are enjoyed the holiday to catch up on prep for launching.

Simn Armitage

Sowenna 26 M

david.phillips
Re manouvering at slow speed

Re manouvering at slow speed , with engine engaged you have a bit of extra help.

chris.harnan
I would suggest that the

I would suggest that the article is primarily about fixed props (i.e. inboard engines) with twin rudders. This is very different to twin rudders with an outboard where the prop can turn. I fully agree that the rudders at low speed will have little effect with either type of engine.

There are many motor boats out there with only an outboard.

Keeping the drop keel down (when water depth allows) has IMHO a far greater effect in improving low speed handling as it help to stop sideways movement, especially sidewind induced.

Kind regards Chris

david.phillips
The worst thing you can do is

The worst thing you can do is have no keel down. This has happened to me a few times leaving dock and finding it won't steer !

chris.harnan
In high winds, going

In high winds, going alongside in reverse can often be easier as the bow will follow the stern.

Chris

roly.simpson
I think recommendation is to

I think recommendation is to give short bursts of throttle to generate some speed to make rudders work but then minimize the rearward wash that will push boat forwards. Rudder turning is a bit limited on the Mac and on the M especially in one direction unless modified.

david.bayliss
I find that treating it like

I find that treating it like a powerboat in close quarters normally keeps me out of trouble. You cant always trust setting it up like a conventional yacht due to the lack of weight and for a 26ft boat the Mac has significant windage. I keep my keel half up and both rudders down and use the old trick of coasting into the berth at a slow speed at an angle of around 20 to 30 degrees if room permits, and just at the last moment putting her into astern and turning towards the quay to pull the stern in. Hope this helps and there are a couple of RYA videos on youtube that show this technique really well.

Regards

David Bayliss (Mac 26X Marmite)

chris.harnan
We obviously differ about

We obviously differ about having the keel down. How do all other fixed keel sailing boats manage to steer? Could somebody cleverer than me explain why pivoting around a point of lateral resistance hinders steering?

Kind regards Chris

rick.jones
rick.jones's picture
I think everyone's agreed

I think everyone's agreed that at least some keel-board is required, there are different opinions as to how much. My feeling is that at manoeurering speeds the difference between half and full board is probably not significant. Not putting the board full down is wise if you're not sure of the depth at the berth, which may be why it's many people's preference.

As a 19 owner I can testify to the lack of steering control with twin rudders and a non-steering engine. This was the configuration the 19 was originally designed to use, but is a nightmare in practice (especially in reverse)! Like many 19 owners I have arranged my engine to steer, it just takes a bit of invention to link the engine to the tiller.

I can quickly link or un-link the engine steering, and at cruising speed (5+ kts) steering becomes more comfortable with just the rudders and the engine straight, but for low speed you need the engine to steer. You can in fact steer on the engine and leave the rudders straight - when dead slow the engine overrides.

Rick Jones (Treasurer) 1994 Mac 19 "White Lightning", Isle of Wight

david.phillips
I damaged my Mac 26 X the

I damaged my Mac 26 X the first time I launched it at Leverington marina,windy and no keel down,bent the cockpit railings and difficult to straighten which I never did.

mike.clarke
I agree with those that say

I agree with those that say you need the dagger board down - the original 26M instruction manual actually warns you not to attempt close quarters manoeuvres without the dagger board at least half down. I have tested the turning circle at different dagger board depths adn agree with Rick that after its 1/2 down there isn't a lot of difference except that if its windy you need it fully down if possible to avoid leeway. We have a tight space in Tollesbury marina and we can't make the turn into our berth with anything less than half the dagger board down and it has to be fully down if there is any windage at all.

When we first got her I made the mistake of trying to steer without dagger board and its just not possible as the helm is just overpowered by the forward pitch of the propeller even with the motor turning - the hull just doesn't have any grip on the water. even at low speeds. A shame I hadn't read the instructions properly! The 50 HP Yamaha high torque motor doesn't actually go particularly slow when in gear as we make at least 3 knots with the engine in gear even at the lowest throttle setting. I often hae to coast and steer into tight moorings.

Mike C - Tarka 26M

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