Reverse with an Atomic 4?
Bob Belas
I've been sailing for nearly 10 years and for the last 4 on a 1974
Ericson 27 with the venerable Atomic 4. I love sailing this boat, but
have never mastered using the Atomic 4 in reverse: it has the nastiest
"walk" to port when in reverse. This makes it impossible to use the
engine to back up into the slip. (I just shut down the engine and pull
the boat into the slip with port and starboard guidelines that I
installed.) I think I read that such walking is fairly normal in reverse
with two bladed props and Atomic 4s, but is there any remedy, such as a
different prop or some technique that I just don't know about? I'd like
to master this because there just might come a time when I really need
reverse, god forbid.
I'd appreciate any advice or suggestions. Thanks.
Bob
Pierre Mitham
I'm just getting ready to replace my atomic, but here's what I used to do.
When I wanted to back out of my slip, I wouls engage reverse (well as much
as possible with the atomic) then crank up the rpms FAST. and then shift
into nuetral as soon as the boat picks up momentum in reverse, then steer
with the rudder. I've seen a few people do this, it seems to be the
prefered technique. your problem also has a lot to do with boat design!
todays boats have huge rudders that can overcome the props desire to pull
the boat one way or the other. I've seen a friend back his 99' jeaneau all
the way down our row of slips under complete directional control.
Pierre.
ps. join the atomic 4 mailing list.
Bob Belas <be...@umbi.umd.edu> wrote in message
news:37C5AA83...@umbi.umd.edu...
Chavez
I have been sailing an E27 for about 12 years on the US West Coast. I have
an Atomic 4. The fact that your engine in an atomic for is not important
here. My boat however has a collapsing prop and this makes the problem much
worse. Do you have a collapsing prop? I feel that the difficulty maneuvering
under power is far outweighed by the improved performance under sail. I’m
a licensed master and do deliveries and teach sailing in the SF Bay area so
I have had a chance to maneuver a lot of sailboats under power. The E27 is
I think worse in reverse then many boats. I feel this is closely related to
the reasons the helm performs poorly in gusty winds. The spade rudder cants
radically because the stern raises rapidly abaft the keel. Try starting
your back-down maneuver with some right rudder and use lower revs on the
engine and be patient for the boat to start moving. Don’t rev the engine.
Bob Belas wrote in message <37C5AA83...@umbi.umd.edu>...
Mark Petrush
Your transom walk doesn't have so much to do with your Atomic Four as it
does with the way it is installed in the boat. The angle of the propeller
shaft with regard to both the waterline and the centerline of your boat and
it's relationship to the pitch of your propeller mostly determines the
severity of your torque reaction in reverse. The transom walk can be
countered somewhat with the rudder, check it out in Chapman's Piloting and
Seamanship. (This is written for powerboats which have their rudders
directly behind their props for maximum effect, so be careful)
Next time you are out in calm weather, try backing and use some floats
dropped over the side for reference. (plastic bottles partly filled with
water work great for this (remember to pick them up when you're done with
the excercise!)) Watch your speed in reverse and keep a good grip on the
helm as there can be a considerable force on the rudder while backing even
at speeds of only 1 or 2 knots. If it gets away and hits the stop with any
force there could be some real damage done.
Also, look for a slip with the pier on your port side if you have a RH prop
(most likely you do). This will put the transom walk to work for you by
drawing the stern towards the pier when backing. On the way out you can
fend off right from the helm and on the way in it will pull the stern in so
your dockhands don't have to jump so far. When you need the boat in
stern-first just warp her in like you have been doing.
This business with transom walk has been our experience also with our
inboard-powered boats, one with a 3-blade prop and the other with a 2-blade.
But it beats the hell out of the old boat with the outboard, all it did in
reverse was whip up the water and make a lot of noise.
Your boat is a good one, take care of her. Good luck.
Regards, Mark Petrush.
Steve LaBroad
<snip>
>
> ps. join the atomic 4 mailing list.
>
I'm interested. How? Where?
--
Steve LaBroad
My opinion only. Your mileage may vary.
Rich Hampel
The degree of prop walk is due to principally to the efficiency of the prop (in reverse) and how
close the prop blades come to the bottom of the hull.
On most A4 installations (A4 with direct drive) the pitch and diameter is typically VERY wrong....
so that you will only develop about 1500-1600 rpm in forward at maximum. At this rpm the engine
will develop very low horsepower..... meaning that the you should probably investigate a new prop
anyway!
Eliptic shaped props generate less prop walk. A direct drive A4 should be turning about 2200-2400 at
max loaded rpm. .... or you have the wrong pitch / diameter. There are some very economical and
efficient 'plastic' props that work very well with a direct drive A4.
Consider an eliptic or a smaller diameter prop.
------------------------------------------------------------------------
If you dont want to change, consider practicing, practicing and practicing backing up. Once you
have MASTERED the control of the use of prop walk, you'll probably insist on having a LOT.
If your boat is tillered and the rudder can swing 180 - all the better.
Hope this helps.
Lou Bennett
nothing to do with it. I have found two factors that exagerate the problem.
If the prop is fouled, the prop walk becomes worse due to less thrust being
generated. The solution is clean the prop. Also there is a tendency to
oversteer in reverse. Turning the rudder too far causes it to stall and be
much less effective in turning the boat. Try using smaller rudder
movements. The key is to get the boat moving then steer. The rudder is
useless at zero speed. I commonly back into a slip by starting some
distance from the slip in reverse. This allows geting the boat moving in
open water where the initial prop walk does not cause problems. Then the
boat can be easily steered using small rudder movements. Go slow, and with
a little practice you will be able to back the boat into the tightest slips.
Sometimes it is easier to back down a long alley and turn into a slip than
to reverse near the slip where you have little room to get moving in
reverse. Until you are moving, you have very little directional control.
Lou Bennett
Annapolis MD
dheath
know what it's doing-plan ahead. Try turning to port as you hit reverse but
still have forward way on. As you gain sternway your rudder should start to
take over. One trick I've used is taking the power off after you have
sternway (idle in reverse or neutral). That boat should handle fine then.
Hope it helps
Doug
PS-get it open water near a piling or other fixed object and practice.
Bob Belas wrote in message <37C5AA83...@umbi.umd.edu>...
Timothy Parker
moving astern with judicious use of the throttlefor three seconds or so, and
once the boat's making way backwards, then I throttle down to just a little
faster than idle. This way the now slow-moving prop will not have a great
prop-walk effect. Then I try to use only smaller mvements of the rudder so
as not to stall it by moving it too far to one side.
With any kind of cross wind I'm pretty much screwed trying to back up, so
once I get the boat moving astern, even if it's 45 degrees off of the
desired course, I quickly put the engine in forward gear, throw the tiller
over hard in the direction I want the stern to move, and use one or two
second bursts of half or three-quarter throttle. Then I put the engine back
in low-speed reverse and steer astern again (tiller to the other side from
the forward burst). This straightens out the boat, but doesn't kill off all
of the speed going astern. It probably works well for me because the prop (a
two-blade) is only 4" in front of the rudder, so in forward I get a
powerfull jet of water pouring across the rudder which can be directed to
one side or the other by the rudder. Even though our boat has a full-length
keel (with a cut-away forefoot), we can spin in forwards in 1.5 times our
boat length because of the placement of the prop vis a vis the rudder.
Greg Auleta
How do I get on the Atomic 4 mailing list. I have communicated with Don Moyer
on a number of occasions, but am always looking for more constant feedback.
Let me know. Not sure if my address kicks in automatically on these responses,
so my address is aul...@Oswego.edu Thanks. Greg
Pierre Mitham wrote:
> bob,
>
> I'm just getting ready to replace my atomic, but here's what I used to do.
> When I wanted to back out of my slip, I wouls engage reverse (well as much
> as possible with the atomic) then crank up the rpms FAST. and then shift
> into nuetral as soon as the boat picks up momentum in reverse, then steer
> with the rudder. I've seen a few people do this, it seems to be the
> prefered technique. your problem also has a lot to do with boat design!
> todays boats have huge rudders that can overcome the props desire to pull
> the boat one way or the other. I've seen a friend back his 99' jeaneau all
> the way down our row of slips under complete directional control.
>
> Pierre.
>
> ps. join the atomic 4 mailing list.
>
> Bob Belas <be...@umbi.umd.edu> wrote in message
> news:37C5AA83...@umbi.umd.edu...
JAXAshby
>How do I get on the Atomic 4 mailing list.
send your name to atomic...@sailnet.com
It's a good group.