problems to stop the boat under engine before the wind

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Kai Schulz
Posts: 7
Joined: Fri 10 Aug 07, 17:37
Your Country: Germany, Bremen

problems to stop the boat under engine before the wind

Post by Kai Schulz »

we had problems to stop our 920,before the wind,in this moments
we will drive into the look or get a box in the harbour.
And in all the situations we had to control the boat exactly when folding
on the swing wing and the wind coming from the aft,a little bit fresher.
We put the sprayhood down,to reduce the area before the wind,but
it will every time a difficult moment.The outbord motor
(Yamaha 9,9hp with the orginal prop.) couldnt stop seriously
the boat.The boat break out of the course,when
the outboard motor is running back to stop the boat.
We had no problems with the outboard engine,in heavy weather
or rough seas,and no problems with the speed.
But much problems stop the boat befor the wind.
Are their any other dragonflys with the same problem.?
Bo Wetzel
Site Admin
Posts: 166
Joined: Thu 01 Jan 70, 1:00
Your Country: France, Provence

Controlling the DF920 at strong winds

Post by Bo Wetzel »

As with most boats, to go slowly at strong winds is very difficult if you want to keep good control over the boat. Very often a little extra speed gives better control, specially if you have to turn and suddenly have the wind beam on.

I have had once a similar problem with aft winds (Mistral) and sailing single handed into the harbour. It would have been nearly impossible to enter my box with this kind of wind as I felt I had little control in stopping they boat when I got into my box.

To ease the situation I first turned into the wind to fold the swing wing system and then I tried another approach (also with the spray hood folded down) and decided I still wouldn't want to risk to be driven into the box by too strong aft winds (>30kn). I decided to find another place in port (visitor pontoon near the entrance) where I could land against the wind. Some 5/6 hours later I moved the boat to its right place in safer wind condition.

Sorry, I forgot to add, when trying to stop the boat with the wind from aft you might have to use a lot of revs and power after putting the motor in reverse, which makes the motor scream as you might not have the time to do it gradually, which would be better to avoid cavitation. If you have a motor-tiller connection make sure you keep a firm grip on the tiller to avoid the motor turning the rudder. You best ignore the concerned faces of onlookers and do the best for boat and crew and let the motor scream. :-)
Ipe Piccardt Brouwer
Posts: 64
Joined: Wed 01 Nov 06, 17:17
Your Country: Netherlands, Winkel NH

Strong sternwind

Post by Ipe Piccardt Brouwer »

Recently I entered a lock together with 30 monohulls with a force six straight on the stern. It was not easy.
However, I discovered that it is crucial not to let the boat gain any speed. If it goes faster than 2-3 knots, reversing the engine will result in a lot of cavitation and little braking power. Let the wind blow you into the berth or lock while keeping the engine in reverse (steering will get a surprising quality, practice!). Another advantage of low speed is the lack of damage when things go wrong anyway.
Ipe Piccardt Brouwer
DF920-28 'Ngalawa', Medemblik
Kai Schulz
Posts: 7
Joined: Fri 10 Aug 07, 17:37
Your Country: Germany, Bremen

Post by Kai Schulz »

:( So,i sea that other dragonfly 920 owners have the same problem.
stopping the dragonfly with strong wind at stern,in this moments
they had no place to maneuver ( by example:in the look with other boat's)
With strong wind at stern,our boat get much faster at 2-3knots
forward (without using the outboard),so we had to break the boat
by outboard engine.
I thing the outboard engine couldn't have breaking power,while
the emissions from the engine (in the middle of the prop.)
by going rewards and the air-syphoning (small distance to the water surface)will get ventilation to the propeller.
We will test these weekend,outboard-wings monted one the
cavitation board.i hope they will reduce the problem
:?:
buckle.roger
Posts: 73
Joined: Sat 07 Jun 08, 15:43
Your Country: spain,benissa/alicante

Post by buckle.roger »

Hi

My last boat was a Hunter 43ft with a 50hp engine and before strong winds I needed to give that a great deal of revs engine to stop, so with an outboard with exhaust through the prop the problem is worse. however if you have to orijinal prop it is allmost certain that it is over sized and will cavitate more than is nessesary.
Do you get more revs after half throttle, I do not,ie prop over sized.

i too am tyring to find out what size prop is correct, all I know is that the standard one is not right

roger
Kai Schulz
Posts: 7
Joined: Fri 10 Aug 07, 17:37
Your Country: Germany, Bremen

Post by Kai Schulz »

now we testet at our last saillingstours our new outboardwings
(to stop the boat with wind at stern),it will be a little bit better
than the situation with no outboardwings before.
the outboardwings reduce the ventilation,by slow speed if the
engine run rewards.
now when we had to enter the lock with wind at stern,
we let the engine run with little speed rewards(that help the boat
couldn't get faster and faster)by steering the boat into the lock,
and must be very quick to fix the boat in the lock.
it will be ever a situation my heardbeat run higher and higher
(full speed will give a lot of cavitation and ventilation
and not a lot of breaking power.)
in this lock we had no place to turn the boat,or make other
manovers,the only manover is : drive in and stop the boat
side by side of the other boats
if other dragonfly owner had better ideas,tell about this
friendly regards from kai
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