Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 11-10-2012, 01:27   #316
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Baltic (Summer) (the boat!); somewhere in the air (me!)
Boat: Cutter-Rigged Moody 54
Posts: 19,737
Re: sailboats can injure and kill

Quote:
Originally Posted by minaret View Post
Hmmm. Basic physics- "The shortest distance between two points is a straight line".
Going upwind, sailing 45 degrees off the rhumbline, towards a destination 100 miles away.

Two legs, one tack in the middle = 140 miles sailed.

20 legs, 10 tacks = 140 miles sailed.

Same with gybing.

Another proof: VMG to destination (and TTG to your waypoint) read off your plotter does not depend on how often you tack or gybe. It is purely a function of SOG and angle between COG and bearing to waypoint.
__________________

__________________
Dockhead is online now   Reply With Quote
Old 11-10-2012, 01:34   #317
Registered User
 
GaryMayo's Avatar

Join Date: Nov 2011
Location: Branched Oak Yacht Club, Wife is an Admiral in the Nebraska Navy
Boat: Clipper Marine 32 CC Aft Cabin Ketch
Posts: 1,211
Quote:
Originally Posted by zeehag
just add a helmet.....or duck...

The duck would be usefull as he could go for help.

Glad all went well with the docs.
__________________

__________________
W.I.B. Crealock when asked what he thought of the easily trailerable Clipper Marine sailboats by a naval design collegue, Gentelman Bill responded, "I am very proud of them".
www.clippermarine.org & www.clipper-sailor.net
GaryMayo is offline   Reply With Quote
Old 11-10-2012, 09:19   #318
Senior Cruiser
 
s/v Beth's Avatar

Cruisers Forum Supporter

Join Date: Oct 2008
Location: Coos Bay, Oregon
Boat: Valiant 40 (1975)
Posts: 4,066
Re: sailboats can injure and kill

Does anyone use a staysail and reduced jib (say a yankee) as a twin headsail setup? And is there any disadvantage to running a reefed main with this setup to reduce the roll?
Finally which of all these setups lends itself best to self steering? I have a feeling that dual jibs could control the wheel directly. But I defer to those that have been there and done that.
__________________
s/v Beth is offline   Reply With Quote
Old 11-10-2012, 10:14   #319
Senior Cruiser
 
DeepFrz's Avatar

Cruisers Forum Supporter

Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 7,930
Re: sailboats can injure and kill

I think that running with a reefed main to control roll, ie: tightly sheeted in the center, would give you a lot of slatting and wear and tear on the main. There was a thread discussing this and one idea was to hoist a trisail higher up the mast to help with the roll. Many other ideas were presented as well, although many of them were used when anchored.
__________________
DeepFrz is offline   Reply With Quote
Old 11-10-2012, 10:19   #320
Senior Cruiser
 
jackdale's Avatar

Cruisers Forum Supporter

Join Date: Mar 2008
Location: Calgary, AB, Canada
Posts: 5,040
Images: 1
Re: sailboats can injure and kill

Quote:
Originally Posted by donradcliffe View Post
How to sail dead down wind:



2. Reaching with main and jib on the same side--you will go faster, but get there slower, plus you have the problem of the jib collapsing and refilling on the waves, with resultant chafe--BTDT
First, that is broad reaching not DDW.

Secondly, I have done three deliveries from Hawaii. When we hit the westerlies, we broad reach and gybe (if necessary). The only chafe about which we have had to be concerned is the preventer contacting the cap shroud.

Third, the VMG is faster on a broad reach. Just watch your GPS.

Fourth, in big waves the boat is more stable broad reaching as there is less wallowing.

In all three deliveries we were hand steering. (The autopilot failed on the first trip and there was none on the next two.)
__________________
ISPA Yachtmaster Ocean Instructor Evaluator
Sail Canada Advanced Cruising Instructor
IYT Yachtmaster Coastal Instructor
ASA 201, 203,204, 205, 206, 214
As I sail, I praise God, and care not. (Luke Foxe)
jackdale is offline   Reply With Quote
Old 11-10-2012, 15:18   #321
Registered User
 
cwyckham's Avatar

Join Date: Apr 2011
Location: Vancouver, BC
Boat: Niagara 35
Posts: 1,870
Re: sailboats can injure and kill

Quote:
Originally Posted by atoll View Post
as far as i understand the argument went as this.
assuming where you want to go is 2500 miles away and dead down wind,on a tradewind passage.

rebel heart advocated,sailing downwind with just a single headsail,as it was safer having no pole up,and no main up,and heading more or less in the right direction..

others advocated gybing downwind on a broad reach,with no pole up,but with head sail and mainsail up and heading 25-60 degrees off the ddw course.

my self and minaret advocated twin headsails,with a pole out to windward and a mainsail sailing within 10-15 degrees of the downwind course and using windshifts to your advantage,to get optimum speed from this rig on a 20 day passage.(carrying potentially a third more sail area than the other combinations)

another scenario would be heading directly ddw to the objective with twin poles,and twin headsails,but no main at all.

i know what works for me!
Thank you, that's a helpful summary. I've often wondered whether you could go deeper with twin headsails than with a single because the windward (poled out) headsail would funnel wind into the one that would otherwise be blanketed. I also notice that you are still broad reaching by a 10-15 degrees that way, but more direct than the more typical 30 degrees without the extra third sail poled out.

Any polar is built around an assumed sail plan. If you change the sail plan, you'll have to build a new polar (or, as in my case, fart around using the VMG reading to see where the optimum wind angle/sail trim is). It may very well be that by adding a third sail, the optimum VMG is obtained closer to DDW and that this VMG will be greater than that with a conventional 2 sail broad reach. I would think that this would depend on the boat, actual sails used, wind speed, and sea state.

I've often wondered if a workable light wind combination would be a deep broad reach with my lightweight 140% Genoa poled out to windward, feeding wind into the assym kite. Haven't tried it yet.

Whatever the combination that seems best, though, I'll always measure success not by boat speed or angle to the wind, but by VMG
__________________
cwyckham is offline   Reply With Quote
Old 11-10-2012, 17:15   #322
Senior Cruiser

Cruisers Forum Supporter

Join Date: Aug 2009
Location: between the devil and the deep blue sea
Boat: a sailing boat
Posts: 17,314
Re: sailboats can injure and kill

Quote:
Originally Posted by cwyckham View Post
(...) I've often wondered if a workable light wind combination would be a deep broad reach with my lightweight 140% Genoa poled out to windward, feeding wind into the assym kite. Haven't tried it yet.

Whatever the combination that seems best, though, I'll always measure success not by boat speed or angle to the wind, but by VMG
A light genoa might work fine, but at 140% you will need an extra long pole to pole it out effectively. Lacking one, you will sail much faster and more comfortable with a smaller sail hoisted along the mast rather than a bigger one hoisted along the forestay - you want max sail area at right angles to the wind. Just have a look at the cosines of your forestay and of the poorly poled out 140% sail and you will see how much of the power you lose (possibly at least 50% with a normal length pole).

IMHO big genoas are a big waste of time downwind.

BTW, all other things equal, pointing X degs off the course (to your target WPT) makes sense only when in doing so you expose (or fly) some extra sail area. Otherwise best VMG is on the direct route. Of course, the speed is also influenced by how the hull interacts with the swells and so minor gains can be had by pointing elsewhere. So to say, hoist everything you have there and go for it.

b.
__________________
barnakiel is offline   Reply With Quote
Old 11-10-2012, 18:02   #323
Moderator Emeritus
 
Ex-Calif's Avatar

Cruisers Forum Supporter

Join Date: May 2007
Location: Singapore
Boat: Maxi 77 - Relax Lah!
Posts: 11,514
Images: 4
Re: sailboats can injure and kill

Lot's of discussion about sail plans and sail area and polars and such. It all matters, of course. As does current and the winds you will encounter tommorow or the next day.

Generally if you can make hull speed DDW - go DDW. Angles and VMG matters below hull speeds but to plan it properly you gotta know your boat's polars.

There are calculators available to "plan" the angles but without polar data they don't work.

Here is a quick and dirty chart that may be of some use. Basically find your boat speed across the top. Find the angle on the Y axis. At the cross reference is the boat speed you need to make on that angle to get paid back.

SVHylites previous post bears this out.
Attached Thumbnails
Click image for larger version

Name:	VMG.jpg
Views:	62
Size:	163.1 KB
ID:	48127  
__________________
Relax Lah! is For Sale <--- Click
Click--> Custom CF Google Search or CF Rules
You're gonna need a bigger boat... - Martin Brody
Ex-Calif is offline   Reply With Quote
Old 11-10-2012, 18:35   #324
CF Adviser
 
Bash's Avatar

Cruisers Forum Supporter

Join Date: Dec 2008
Location: sausalito
Boat: 14 meter sloop
Posts: 7,260
Re: sailboats can injure and kill

Quote:
Originally Posted by barnakiel View Post
IMHO big genoas are a big waste of time downwind.

BTW, all other things equal, pointing X degs off the course (to your target WPT) makes sense only when in doing so you expose (or fly) some extra sail area. Otherwise best VMG is on the direct route. Of course, the speed is also influenced by how the hull interacts with the swells and so minor gains can be had by pointing elsewhere. So to say, hoist everything you have there and go for it.

b.
While I agree wholeheartedly with your point about big genoas, I think you might be missing the mark about VMG. On a slow boat--the type of boat sometimes lovingly referred to as a 4KSB--there is little point to heating up by pointing higher than DDW. That boat is going to go 4 kts regardless of course, sea conditions or the amount of canvas hanked on. However, with a more modern design you can increase the speed significantly by going to a broad reach, especially when an asymmetrical chute is deployed.

Some boats, especially the first generations of ULDB racers, are designed to go DDW, achieving their best VMGs with a conventional spinnaker squared back and the main all the way out on the other side. Others, including most fin-keel cruisers, are going to perform better with an A-chute on a deep broad reach around 155 degrees more or less, depending on conditions.

Jackdale's point about consulting the GPS to determine best VMG applies to all boats. Let the boat tell you how it wants to be sailed off the wind.
__________________
cruising is entirely about showing up--in boat shoes.
Bash is offline   Reply With Quote
Old 11-10-2012, 18:37   #325
Registered User
 
GeoPowers's Avatar

Join Date: Dec 2008
Location: Gulfport, MS
Boat: Beneteau 393
Posts: 947
Images: 27
Re: sailboats can injure and kill

Quote:
Originally Posted by Ex-Calif View Post
Lot's of discussion about sail plans and sail area and polars and such. It all matters, of course. As does current and the winds you will encounter tommorow or the next day.

Generally if you can make hull speed DDW - go DDW. Angles and VMG matters below hull speeds but to plan it properly you gotta know your boat's polars.

There are calculators available to "plan" the angles but without polar data they don't work.

Here is a quick and dirty chart that may be of some use. Basically find your boat speed across the top. Find the angle on the Y axis. At the cross reference is the boat speed you need to make on that angle to get paid back.

SVHylites previous post bears this out.

That is handy, thanks!

Frank
GeoPowers is offline   Reply With Quote
Old 11-10-2012, 19:11   #326
Senior Cruiser
 
atoll's Avatar

Cruisers Forum Supporter

Join Date: Mar 2010
Location: gettin naughty on the beach in cornwall
Boat: 63 custom alloy sloop,macwester26,prout snowgoose 37 elite catamaran!
Posts: 9,311
Images: 75
Re: sailboats can injure and kill

Quote:
Originally Posted by s/v Beth View Post
Does anyone use a staysail and reduced jib (say a yankee) as a twin headsail setup? And is there any disadvantage to running a reefed main with this setup to reduce the roll?
Finally which of all these setups lends itself best to self steering? I have a feeling that dual jibs could control the wheel directly. But I defer to those that have been there and done that.
for cutter rigged yachts this is a great working rig,and very easy to balance the boat,it really comes into its own realm in stronger winds.

having the poled out genoa to windward,the staysail sheeted in,and the main nearly touching the shrouds.

as winds strenthen progressively,reduce the main first,then genoa a few rolls at a time.

untill you reach a point where you drop the main completly,and the genoa is about the same size as the stay sail.

further reefing is achived by completly rolling the genoa and running on staysail alone,this can also be released,so as to spill wind,untill it is time for bare poles,or even smatter storm jib hanked on to the staysail stay.

steering balance is achieved by pulling in the main or letting out the pole or vice versa.
__________________
my catamaran building project updates http://www.cruisersforum.com/forums/...36#post2502136
atoll is offline   Reply With Quote
Old 12-10-2012, 00:47   #327
Registered User
 
cwyckham's Avatar

Join Date: Apr 2011
Location: Vancouver, BC
Boat: Niagara 35
Posts: 1,870
Quote:
Originally Posted by atoll

for cutter rigged yachts this is a great working rig,and very easy to balance the boat,it really comes into its own realm in stronger winds.

having the poled out genoa to windward,the staysail sheeted in,and the main nearly touching the shrouds.

as winds strenthen progressively,reduce the main first,then genoa a few rolls at a time.

untill you reach a point where you drop the main completly,and the genoa is about the same size as the stay sail.

further reefing is achived by completly rolling the genoa and running on staysail alone,this can also be released,so as to spill wind,untill it is time for bare poles,or even smatter storm jib hanked on to the staysail stay.

steering balance is achieved by pulling in the main or letting out the pole or vice versa.
Why is the staysail sheeted in?
__________________
Chris
SailMentor.com - Become the Confident Skipper of Your Own Sailboat
cwyckham is offline   Reply With Quote
Old 12-10-2012, 01:43   #328
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Baltic (Summer) (the boat!); somewhere in the air (me!)
Boat: Cutter-Rigged Moody 54
Posts: 19,737
Re: sailboats can injure and kill

Quote:
Originally Posted by atoll View Post
for cutter rigged yachts this is a great working rig,and very easy to balance the boat,it really comes into its own realm in stronger winds.

having the poled out genoa to windward,the staysail sheeted in,and the main nearly touching the shrouds.

as winds strenthen progressively,reduce the main first,then genoa a few rolls at a time.

untill you reach a point where you drop the main completly,and the genoa is about the same size as the stay sail.

further reefing is achived by completly rolling the genoa and running on staysail alone,this can also be released,so as to spill wind,untill it is time for bare poles,or even smatter storm jib hanked on to the staysail stay.

steering balance is achieved by pulling in the main or letting out the pole or vice versa.
Indeed. The cutter rig really earns its keep in such conditions.

I was amazed when I first got my boat -- my first cutter -- how well she sails under staysail alone. I would have thought that I would need some mainsail up for balance, but nope -- in 35 knots of wind and more, she is perfectly happy with just the staysail up. Won't sail very fast, but I can make 6 knots or so on a reach or a broad reach with very little heeling with just the staysail up, and very good helm balance, and I have not yet found the wind force upper limit for this configuration -- even at 50 knots of wind, still little heel, and good helm balance.

My staysail is on a big roller furler, so theoretically at some point I can start reefing it, but I haven't yet found that point. The only thing is that 40 or 50 knots of wind, the sea state even say in the Solent where there's not enough fetch to build up a dangerous sea state, will not allow me to make any progress in that configuration with the wind ahead of the beam -- I would need more power than the staysail alone will give to punch through. But as long as I'm not trying to claw off a lee shore, I can sail slowly but with perfect comfort and a feeling of great security in quite strong conditions with just the staysail up. BUT -- using the staysail in strong conditions, you have to be really careful to set a running backstay correctly -- more about that below.

If sailing DDW or nearly so, I don't use the staysail, because I would prefer to have the center of effort as far forward as possible. In really strong wind -- 40 knots or more -- I use a little bit of the yankee. Furled way down, the shape of the yankee is no good for anything but sailing downwind, but sailing right downwind you don't care about the shape.

Another benefit in really strong conditions using a bit of the yankee instead of the staysail is stress on the rig. The forestay is balanced by the backstay, which is permanently set and can't be mishandled. The inner forestay, on the other hand, relies on a running backstay -- if you don't set it right, or if someone inadvertently lets it off, you can damage your rig.
__________________
Dockhead is online now   Reply With Quote
Old 12-10-2012, 01:48   #329
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Baltic (Summer) (the boat!); somewhere in the air (me!)
Boat: Cutter-Rigged Moody 54
Posts: 19,737
Re: sailboats can injure and kill

Quote:
Originally Posted by Ex-Calif View Post
Generally if you can make hull speed DDW - go DDW. Angles and VMG matters below hull speeds but to plan it properly you gotta know your boat's polars.
+1

I would even omit the word "generally".

If you can make hull speed DDW, then it is likely, with many boats which are not heavy displacement long-keelers, that you can even exceed it. Then there is obviously no point to gybing towards your destination.

I love sailing like that -- at hull speed or above DDW, or 5 degrees off for a little extra stability, when the wind is strong enough. A wonderful ride.
__________________
Dockhead is online now   Reply With Quote
Old 12-10-2012, 01:50   #330
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Baltic (Summer) (the boat!); somewhere in the air (me!)
Boat: Cutter-Rigged Moody 54
Posts: 19,737
Re: sailboats can injure and kill

Quote:
Originally Posted by cwyckham View Post
Why is the staysail sheeted in?
For directional stability -- the staysail acts like the feathers on an arrow -- and not for drive. A neat cutter-rig trick.
__________________

__________________
Dockhead is online now   Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 06:32.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.