[C38] How to approach an argument with a sailor
les
hlhowell at pacbell.net
Wed Sep 14 16:05:45 EDT 2011
I have to chime in here a bit. JACE hit 14.5 frequently when I really
pushed her, and we actually had a confirmed speed of 16.5 for a bit
during one of our "crusing trips" up the coast past long beach. Once we
were on our 22, and sailed from Dana Point to Newport beach where people
caught us on their much bigger boats during a sail change just outside
the harbor about 1.5miles.
Speed of a sail boat depends on a whole pack of things, and my list is
something like this:
1. Current. With it is always faster by the current + hull speed, and
you can also tack with the current to sustain a longer burst of speed.
2. Wind. If the wind is below 15knots, you are faster into the wind
on a Catalina 38, but once the wind hits 15 or more, you can get the
boat to pull up with a chute, lifting the boat, reducing the wetted
surface, like planing, and gain speed. Most of you racers are clewed
into this one. Also you can again choose to NOT go directly downwind
(by the lee), which is generally a good idea if the wind is up, and
especially in a quartering tide or current.
3. Gear. Is the boat up to the job. Rig, running rigging, blocks,
fixtures, and winches all take a real beating when the wind is up.
4. Crew. Are they up to the task and are they able to stand the
effort, concentration and risk that really high speeds on any vessel
demands of the crew.
5. Risk in general. Does the owner realize and deal with the real
risks to personnel, equipment and so forth that high speeds place on the
crew and boat, along with the expenses of broken or otherwise destroyed
equipment.
As to the planing or non planing of a boat. Any hull can plane. The
problem is picking the hull up out of the trough between the bow and
stern. Some power boats do this with sponsons or flatter bow sections
to begin the plane at lower speeds, some do it with trim tabs at the
rear, almost all use the prop angle to help choose the best lift angle,
and so forth. For sail boats, especially like the Catalina 38, the bow
is designed for best efficiency at 7-15 knots. That is the purpose of
the narrow entry and the round bottom with flats about 40% of the way
back. But this design actually inhibits lifting that flat area out of
the trough. In fact, there is a lot of area with suction holding it
down. Lightening the boat certainly helps. Getting it flat helps, but
our boats are also designed to an IOR rule so that rolling them over to
about 15degrees gives the longest water line, adding to that low speed
efficiency. Going down wind at speed then means using that large Jib,
Genoa or Spinaker to help lift the bow to begin the planing. Weight
only figures in about 20percent of the plane issue. Wetted surface, the
proportion of wetted lifting surface compared to the wetted suction
surface also figures in. Maximize the lift, and minimize the suction
and you get a boat that planes early and runs light on the water.
The things you can do to improve boat speed are:
1. Increase the lift across the sails (watch the tattle tails)
2. Increase the bulk lifting force on the bow.
3. Minimize bow weight (no anchors in the bow or else the minimum
aluminum danforth you can manage like a force) and no chain.
4. minimize stern weight (although it would tend to raise the bow, it
will also drag more of the bulbous flat area into the trough)
5. Balance the boat with crew weight and other means.
6. Gut up and go for broke.
Things that cost speed are:
drag (clean that bottom)
slack in the lines or give (mylar sails and staysetX or technora lines)
Notice that the steel halyards are not quite as good as either of these
in real work. New fibers are stronger and less stretch than steel.
"Give" in the lines can help in some cases, check your means to provide
constant tension under puffs and stalls of wind. This is a judgement
call, based on your own driving methods and your crew.
Rig tension. Many boats are over tensioned. If you increase the "bow"
of the boat, the curve between stem and stern, you actually aggravate
the trough suction, as well as eventually hogging the boat. ON the
other hand, too little rig tension will cause excessive flex and wear.
It's a tough balance, and reading the tech specs from the experienced
tuners and following recommendations with tension gauges will help, but
this also varies with the sailing style, and the way the rig is
stressed. If you do a lot of down wind you may want to up the size of
the Backstay and forestay to manage rig tension and draw.
I'm not a racer, and some of you will probably find that some of this
goes against practices that work for you. I loved the sing of the
rigging and the sound of the water rushing by the hull. I miss JACE
already.
I cannot talk too much about spinnakers. I never used one. Nancy and
I double handed, so a spinnaker was a bit much for us, and we were
really "day sailors" for the most part.
And for the fastest tack, that is the one that gives you the best speed
to the destination given the wind, current, comfort level you want, and
the degree to which you are willing to stress the boat, gear and
yourselves. The polars reflect hull speed and below.
Planing is another whole different thing, as most of the apparent wind
is from boat speed and planing boats always sail into the apparent wind.
So basically a planing boat properly driven at design speeds will really
only use a polar diagram from about 80 degrees abeam either side. i.e.
it always sails into the apparent wind.
However to get there, a good planing boat skipper will turn off the
wind a bit to get the highest polar speed, then keep turning slowly into
the apparent wind until he gets it about 7-15 degrees off the bow,
depending on the design. Those of you who have sailed Catamarans
probably can add something to that. Check out some of the hydrofoil
boats that have really upped the ante on boat speed. Basically that is
how I sailed JACE, except when Nancy wanted to go wing on wing. For
some reason she loved that sensation.
I'll stay a member as long as you guys will tolerate me, and I really
appreciate the information all of you gave me over the years.
Fair winds, following seas and good fortune.
Les H
On Tue, 2011-09-13 at 22:29 -0700, Patrick Harpole wrote:
> I referred to a "displacement " which cannot plane. I have about
> 20,000 pounds in my keel. It will not plane.
> There is no limit to the speed of a planing vessel. That's is why
> catamarans go mast.
> While in Florida I saw Whitbread (if you are not familiar....this is a
> race around the world) boats. I would not call them nor America's Cup
> boats displacement vessels. They are very light and have winged keels
> that bring them out of the water.
> Patrick
> P.S. what is the fastest tack for a sailing boat? Clue: it is not
> downwind.
> ----- Original Message -----
> From: David A Hadfield
> To: Catalina 38 Listserve
> Sent: Tuesday, September 13, 2011 6:16 PM
> Subject: Re: [C38] How to approach an argument with a sailor
>
>
> Patrick
>
> On being uninformed.
>
> The SC37 can plane in downwind attitudes,
> ie. go faster than calculated hull speed.
>
> These are apples and oranges and one must be careful on
> exactly what one is addressing.
>
>
> On Tue, Sep 13, 2011 at 6:10 PM, Patrick Harpole
> <1derful at comcast.net> wrote:
> I sail a Catalina 38 and reached 12 to 14 knots
> sailing from Benecia to Berkeley. The reason for the
> speed is an ebb current at 6 knots.
> There is no way a displacement vessel can reach
> greater than their calculated hull speed. When one
> exceeds hull speed they are unduly stressing their
> rig...which might come down. What a shame for being
> stupid.
> Patrick
> ----- Original Message ----- From:
> <david at dlrfilms.com>
> To: "Catalina 38 Listserve" <listserve at catalina38.org>
> Sent: Tuesday, September 13, 2011 5:47 PM
> Subject: Re: [C38] How to approach an argument with a
> sailor
>
>
>
>
> Not too long ago I saw a video of a CAL 40
> running offshore in a big wind
> with a heavy kite. They were sustaining over
> 15 kts and hitting high
> teens.
>
> Does the Santa Crus 37 plane? If it does,
> 15-20 kts wouldn't be outrageous.
>
>
>
> Advice seeking time.
>
> So, I've got a friend who sails on a
> VERY fast boat. A very winning
> boat. Probably one of the fastest in
> San Francisco. It's crewed by a
> bunch of amazing sailors including
> some Cup guys. However, she's not
> really a sailor and I've had to
> explain things like what a knot is vs
> mph. The boat is a Santa Cruz 37 rates
> in a 27PHRF. Now, she claims and
> has some text messages from other crew
> saying they've hit 26knots in the
> bay. I call BS. I pull out all my math
> on hull speed, plain force
> calculations on what it would take to
> make that boat go into full plane.
> I've tried showing what PHRF means and
> that a 27 means they only average
> 1/2 knot faster than the J/105's. I've
> tried pulling out their race
> times and showing they're only
> averaging about 6-7knots during
> races. .
> This does not matter.
>
> Probably most of us have seen
> exceedences in hull speed for our
> boats
> going down waves and whatnot. However,
> that's not the claim. The claim
> is they REGULARLY go 16-20 knots in
> bay races. This is 2x or more their
> hull speed. .
>
> Thoughts on how to explain this or
> anyone have experience with a SC37?
>
> Anders
>
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