TWL: Nordhavn Handling
I have just spent 4 days with a 62 Nordhavn.
The boat has a surprising amount of pounding in a head chop from winds of
20-25 knots.
It really pitches from bow to stern in a most lively manner.
This one had stabilizers and lots of equipment.
It had a Robertson AP 2000 autopilot and we had some difficulty getting the
"Parameters" set to suit us in a following sea.
The best setting was about 1.10 on the rudder and 1.50 on the counter
rudder.I think the proportions of about 2 to 3 is about right. Anything
else resulted in very wide yawing. We tried many other combinations. Large
percentage of counter rudder had a bad result.
The prior captain had set the settings to 1.20 and 2.60 and this resulted
in a bad roll with a following sea. But seemed ok for a head sea.
I have run a number of slow displacement boats like this and they all seem
to have some tempermental quirks with pitching or rolling or maintaining
course.
This begs the question as to whether the stabilizers have any detrimental
impact on any of this handling. I frankly don't know and have not had time
to investigate this further.
I suspect that the lively pitching is a product of bouyancy intended to
make the boat survive a big blow with large waves. A tradeoff with which I
have no quarrel.
I suspect that most of us who have had more experience with
planing/semi-displacement hulls than full displacement in the size range
30-80 feet are not quite certain how to evaluate these results.
I will be around some over the next 10 days to kick this around. Then am
headed for Panama and Florida.
Anyone on the route is welcome to send me private email, we might just meet
up somewhere.
Regards,
Mike
Capt. Mike Maurice
Wilsonville, Near Portland Oregon
I have just spent 4 days with a 62 Nordhavn. The boat has a surprising
amount of pounding in a head chop from winds of 20-25 knots.<<<<
I believe the Nordhavn 62 has a bulb bow. I did most of my sailing on
multihulled yachts, and at one time bulb bows were included on quite a few
Australian catamaran designs to reduce pitching on their long narrow hulls,
and get more bouyancy forward. After a few years of off-shore experience
(mostly in races), the bulbs were abandoned because they led to pounding
when the bows pitched out of the water in rough conditions.
Clearly the behaviour of a heavy-displacement hull, with a fairly wide beam
and deep draught, will differ markedly from that of a light, narrow,
shallow-draught catamaran hull, but I've often wondered about the
desirability of bulb bows on small vessels. If the conditions are rough
enough for the bow to pitch out of the water, then presumably a bulb bow
would slam more as it was driven back through the surface than a
conventional "sharp" forefoot.
I wonder if Capt. Maurice's Nordhavn was pitching it's bow out of the water?
Disclaimer: I am not a nautical architect, so it's quite possible I'm
talking nonsense. What's been the experience of list members who've sailed
on bulb-bowed trawlers?
Best regards, Robert Bryett.
Sydney, Australia.
mailto:rbryett@mail.com
Michael Maurice wrote:
The boat has a surprising amount of pounding in a head chop from winds of
20-25 knots.
It really pitches from bow to stern in a most lively manner.
This one had stabilizers and lots of equipment.
I have interviewed one large trawler buyer who extensively examined the
Nordhavn 57 and 62, but chose the Krogen 58 as being the better sea boat.
Also heard the rumor that N 57s are changing hands quickly as the owners
discover less-than-great handling.
NOTE: The first statement is fact; the second is rumor.
Bob
R C Smith Jr
M/V MARY KATHRYN
Hatteras 58 LRC
At 09:19 AM 10/22/02 -0400, you wrote:
I have interviewed one large trawler buyer who extensively examined the
Nordhavn 57 and 62, but chose the Krogen 58 as being the better sea boat.
Also heard the rumor that N 57s are changing hands quickly as the owners
discover less-than-great handling.
Interesting.
Fact is I was impressed with the 62. Except for the minor things I noted.
Capt. Mike Maurice
Wilsonville, Near Portland Oregon
I find that I must shut off the autopilot ( Cetrek) in large steep
following seas. The autopilot handles the boat under most
conditions of following seas, but does not perform well under more
extreme conditions.
With our boat and in the larger and steeper wave/roller conditions
the wheel (rudder) must be turned prior to the time that the
autopilot would sense the turning action of the stern. This one or
two second lead over the autopilot is, I feel, critical in safe handling
with our boat. To leave it up to the autopilot would risk a bad yaw
and possible roll.
Richard of TWL observed us off the west coast of Vancouver island
this summer as we ran behind him under autopilot with a following
sea. That day I was considering shutting down the autopilot but
didn't. But I was near the limit of my comfort zone with the A/P.
Sandy Floe
Sea Eagle (39 CHB)
Day Island, WA
Michael wrote:
I have just spent 4 days with a 62 Nordhavn.
The boat has a surprising amount of pounding in a head chop from winds
of 20-25 knots. It really pitches from bow to stern in a most lively
manner. This one had stabilizers and lots of equipment. It had a
Robertson AP 2000 autopilot and we had some difficulty getting the
"Parameters" set to suit us in a following sea. The best setting was
about 1.10 on the rudder and 1.50 on the counter rudder.I think the
proportions of about 2 to 3 is about right. Anything else resulted in
very wide yawing. We tried many other combinations. Large percentage
of counter rudder had a bad result. The prior captain had set the
settings to 1.20 and 2.60 and this resulted in a bad roll with a
following sea. But seemed ok for a head sea.
At 11:11 AM 10/22/02 -0400, you wrote:
At 09:19 AM 10/22/02 -0400, you wrote:
I have interviewed one large trawler buyer who extensively examined the
Nordhavn 57 and 62, but chose the Krogen 58 as being the better sea boat.
Also heard the rumor that N 57s are changing hands quickly as the owners
discover less-than-great handling.
Interesting.
Fact is I was impressed with the 62. Except for the minor things I noted.
Here are some more observations and questions about the 62 Nordhavn and
similar boats.
The boat I was on has no liquid in the bulb bow. I was under the impression
that the bulb should have neutral buoyancy.
Another trawler type boat I was on a few years ago had a bulb bow, but I
can't recall whether the buld was filled. I think it was.
But I am sure now that bulb bows have some tendency to slap in some kinds
of chop.
Active fin stabilizers are not very effective at slow speeds and that can
happen if conditions get really rough.
Depending on such stabilizers may be unrealistic in rough conditions.
The active fins may cause some amount of destabilizing effect on straight
line steering. I have not noticed this on semi-displacment hulls like the
Fleming.
These enhancements with stabilizers, bulb bows and so on, are pretty
seductive. Attractive, but very possibly with unwanted side effects.
This begs questions, but I don't have any clear cut answers. Comments?
Capt. Mike Maurice
Wilsonville, Near Portland Oregon
Mike wrote, "These enhancements with stabilizers, bulb bows and so on, are
pretty seductive. Attractive, but very possibly with unwanted side effects.
This begs questions, but I don't have any clear cut answers. Comments?"
Those who live by the gadget die by the gadget? (Except Sat phones) So
don't stick your fingers in a hurricane?
Todd Mains
M/V Pinguino
Portland, Oregon